Introduction
Edible grain legumes have been cultivated worldwide since at least 5000 BC and provide a substantial portion of daily caloric and protein requirements in human diets, with protein content ranging from 18% to 36% (Langer et al., Reference Langer, Hill and Mason1991; Gepts, Reference Gepts1998; Bitocchi et al., Reference Bitocchi, Nanni, Bellucci, Rossi, Giardini, Zeuli and Papa2012). Among these, the common bean (Phaseolus vulgaris L.), which originated in South America, is now grown in 105 countries (Jiménez, Reference Jiménez2019). Following its introduction to Europe in the 16th century, bean cultivation spread rapidly, establishing the crop as a globally important food source (Langer et al., Reference Langer, Hill and Mason1991). According to the Food and Agriculture Organisation, global dry bean production has reached 31.4 million tons (FAO, 2026). In Türkiye, annual dry bean production stands at 279,000 tons, making it the third most cultivated legume after chickpeas and lentils (TurkStat, 2026). Valued for both its nutritional quality and ability to fix atmospheric nitrogen, the common bean is a cornerstone of traditional Turkish cuisine, a significant economic resource for rural communities, and an essential component of crop rotation and intercropping systems (Yeken, Reference Yeken2023; Koca, Reference Koca2026). In regions where meat is expensive, dry beans serve as an affordable alternative protein source, playing a crucial role in household food security (Lisciani et al., Reference Lisciani, Marconi, Le Donne, Camilli, Aguzzi, Gabrielli and Ferrari2024).
Although legumes are harvested during a specific agricultural season, their consumption continues throughout the year or even over several years, necessitating prolonged storage periods (Keskin and Özkaya, Reference Keskin and Özkaya2013). During storage, these commodities must be protected against quantitative and qualitative losses until they reach consumers (Boxall, Reference Boxall2001; Kumar, Reference Kumar2017). Under sub-optimal storage conditions, legumes are highly susceptible to physical, chemical, and biological degradation, resulting in severe economic depreciation. Among the various factors threatening quality during storage, insect pests are the primary constraint, as they can infest the commodity either pre-harvest in the field or post-harvest within storage facilities (Gwinner et al., Reference Gwinner, Harnisch and Mück1990; Abdel-Baki et al., Reference Abdel-Baki, Ibrahium, Aboelhadid, Hassan, Al-Quraishy and Abdel-Tawab2024). These pests often cause significant quantitative losses, estimated at 30–40%, in stored agricultural commodities (Kumar and Kalita, Reference Kumar and Kalita2017).
The bean weevil, Acanthoscelides obtectus Say (Coleoptera: Chrysomelidae: Bruchinae), is recognised as one of the most destructive and economically significant pests of dry beans worldwide. This pest can produce multiple generations per year, leading to severe infestations that begin in the field and rapidly escalate during storage (Mbogo et al., Reference Mbogo, Davis and Myers2009; Şen et al., Reference Şen, Koca and Kaçar2020; Koca and Yılmaz, Reference Koca and Yılmaz2025). Although P. vulgaris is its ancestral and primary host, A. obtectus is an oligophagous species that feeds on a limited range of host plants and exhibits varying levels of development, survival, and reproduction across different legume species and bean cultivars (Elmalı and Toros, Reference Elmalı and Toros1990; Tamer, Reference Tamer1996; Sing and Arbogast, Reference Sing and Arbogast2008; Savković et al., Reference Savković, Đorđević, Vlajnić, Budečević and Stojković2022). Varietal diversity among beans significantly influences pest development time, adult emergence, reproductive potential, and body size. Consequently, the severity of infestation and the extent of damage depend on the host plant species and the specific cultivar used (Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002).
Although integrating mechanically robust seed coats, high seed hardness, and biochemical resistance factors is a promising strategy for reducing A. obtectus damage within an Integrated Pest Management (IPM) framework (Bett and Kiplagat, Reference Bett and Kiplagat2022; Li et al., Reference Li, Tang, Wang, Chang, Wu and Wang2022), the interactions between modern commercial cultivars and local pest populations have not been thoroughly quantified. In Türkiye, dry bean production utilises a diverse range of nationally registered cultivars with distinct agronomic characteristics. Among these, ‘Akın’, ‘Atmaca’, and ‘Berrak’ represent commercially available bean varieties with contrasting physical grain properties. However, comparative evaluations of A. obtectus life history on these specific registered cultivars using age-stage, two-sex life table analysis are currently lacking. Rather than comparing local agricultural varieties, utilising these commercial cultivars with highly contrasting registration profiles as ecological models allows us to quantify the specific demographic constraints imposed by host cultivar identity.
To address this knowledge gap, this study evaluated developmental performance, survival rates, and demographic parameters of A. obtectus on the ‘Akın’, ‘Atmaca’, and ‘Berrak’ dry bean cultivars using the age-stage, two-sex life table framework. We hypothesised that these commercial dry bean cultivars, which differ significantly in their official registration descriptors, would impose distinct physiological constraints on the development and reproduction of A. obtectus under storage conditions. Rather than directly quantifying the physicochemical seed properties or underlying biochemical mechanisms, our primary objective was to thoroughly characterise the resulting demographic outcomes and life-history trade-offs. By linking comprehensive life table outputs to the known physical profiles of these hosts, we aimed to understand how host cultivar identity dictates the outbreak potential of this global pest.
Materials and methods
Plant material and insect culture
Three nationally registered dry bean cultivars representing distinct grain classes and physical seed profiles were evaluated in this study. ‘Atmaca’ (Pinto bean/Barbunya type), registered by the Transitional Zone Agricultural Research Institute (Eskişehir, Türkiye) in 2020, features large-sized, speckled (pinto) seeds with an official 100-seed weight ranging from 58.9 to 66.5 g. ‘Akın’ (Horoz type), registered by the Transitional Zone Agricultural Research Institute (Eskişehir, Türkiye) in 2012, features medium-large, elongated white seeds with an official 100-seed weight ranging from 42.5 to 49.9 g. ‘Berrak’ (White bush/Çalı type), registered by the Ankara Central Field Crops Research Institute (Ankara, Türkiye), features small-to-medium, solid white seeds with an official 100-seed weight ranging from 25.7 to 33.7 g and a protein content of 19.2–25.5%. Prior to bioassays, seed lots of all three cultivars were visually screened to ensure uniform size and testal integrity, and moisture content (nearly 10–14%) was standardised under controlled room conditions.
The initial population of A. obtectus was obtained from stock cultures maintained under laboratory conditions at the Ankara Directorate of Plant Protection Central Research Institute. Prior to our experiments, these source colonies had been continuously reared on unsprayed commercial common beans for approximately 15 generations. The stock cultures were maintained in climate chambers under a photoperiod of 12:12 (L:D) h. To maintain genetic diversity and prevent inbreeding depression, the stock populations were periodically refreshed annually with wild-type individuals collected from local storage facilities. A new synchronised baseline culture was established for experimental procedures. All bioassays were conducted in climate chambers maintained under controlled conditions at 25 ± 2°C, 50 ± 5% relative humidity (RH), and a photoperiod of 12:12 (L:D) h.
Experimental setup and biological assays
Biological parameters of A. obtectus across its life stages (egg, larva, pupa, and adult) were tracked from initial cohorts of over 100 eggs per cultivar, with developmental transitions observed using a Leica M binocular stereo-microscope.
To initiate the tracking process, bean seeds were gently filed down on one side, fixed onto glass coverslips using an adhesive, and placed inside Petri dishes (30 mm diameter × 15 mm height) to facilitate unimpeded observation of egg laying and larval behaviour. Eggs collected during daily monitoring sessions were transferred using a fine camel-hair brush into 10 mL tubes containing a single bean seed. Each tube was precisely labelled with the collection date, original Petri dish ID, and host cultivar type. To evaluate life history traits, an initial cohort of over 100 synchronised eggs was established for each dry bean cultivar. From these initial cohorts, exactly 80 individuals that successfully completed their pre-adult development and emerged as adults (N = 80 per cultivar) were randomly selected and incorporated into the age-stage, two-sex life table analysis. Therefore, the evaluated cohort strictly represents the sub-population that successfully completed pre-adult development, allowing us to assess life table parameters conditional on survival to adulthood. This standardisation allowed us to strictly compare stage-specific developmental durations, adult longevity, and reproductive demographic parameters among the successful cohorts.
To determine adult longevity and reproductive behaviour, single newly emerged adult females were paired with two newly emerged adult males inside individual Petri dishes. Because the experimental cohorts yielded fewer males than required to achieve this 1:2 ratio, supplementary newly emerged males were sourced from the parallel synchronised baseline culture maintained under identical conditions. Additionally, if a male died before the paired female, it was replaced with a new male from the baseline culture to ensure a continuous 1:2 ratio throughout the female’s reproductive lifespan. These setups were utilised to track daily and total fecundity, alongside female pre-oviposition, oviposition, and post-oviposition periods.
Assessment of life-stage parameters and sex ratio
For the assessment of embryonic development, eggs deposited within a 24-hour window by synchronised cohorts of adult beetles under standard chamber conditions (25 ± 2°C, 50 ± 5% RH, and 12:12 h (L:D) photoperiod) were transferred to 10 mL vials and inspected daily to record incubation duration and morphological characteristics. Rearing units were monitored daily to evaluate post-embryonic development. The larval period was calculated as the duration from initial larval eclosion to the appearance of a distinct translucent pre-emergence window on the seed coat surface, which indicates the completion of larval development and the preparation for pupation (Howe and Currie, Reference Howe and Currie1964). The pupal developmental duration was then measured as the time from the first appearance of this pre-emergence window on the seed coat to the final emergence of the adult beetle.
Adult emergence was recorded daily until the last individual emerged, after which the adults were monitored until death to determine total longevity. Furthermore, adult female biological parameters – specifically the pre-oviposition, oviposition, and post-oviposition intervals, daily egg-laying rates, and lifetime cumulative fecundity – were systematically quantified. Sex determination of the emerged adults was established by examining morphological differences on the ventral abdomen under a stereo-microscope. Specifically, the junction line between the final sternum and the pygidium (the terminal segment of the abdomen) appears straight in females, whereas it exhibits a semi-circular, rounded curvature in males (Johnson, Reference Johnson1990; Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002; Gad and Abied, Reference Gad and Abied2019). The population sex ratio (proportion of females) was calculated using the following formula:
Sex ratio = ♀/(♂ + ♀)
Life table analysis
Life table parameters of A. obtectus were investigated across three dry bean cultivars. The analysis was conducted using the computer program TWOSEX-MS (Chi and Liu, Reference Chi and Liu1985; Chi, Reference Chi1988). Daily records of survival and fecundity were utilised to determine the adult pre-oviposition period (APOP) and the total pre-oviposition period (TPOP). All demographic parameters and life table statistics, including age-stage specific survival rate (Sxj), age-specific survival rate (lx), age-specific fecundity (mx), net reproductive rate (R 0), intrinsic rate of increase (r), finite rate of increase (λ), and mean generation time (T), were calculated in accordance with the standard mathematical equations summarised in table 1.
Equations utilised for age-stage, two-sex life table analysis (Wei et al., Reference Wei, Chi, Guo, Li, Zhao and Ma2020; Chi et al., Reference Chi, Güncan, Kavousi, Gharakhani, Atlihan, Özgökçe and Taghizadeh2022)
Table 1 Long description
Rows list named measures used in age stage, two sex life table analysis, each paired with its defining formula. Measures include Age Stage Specific Survival Rate, Sxj, defined using the count at age x and stage j divided by the initial count at age 0 stage 1. Life expectancy, exj, is defined as a sum over ages from x onward and stages from j to beta using a survival term labeled S prime. Reproduction value, Vxj, is defined using an exponential term with r, divided by Sxj, multiplied by summed terms over ages from x onward and stages from j to m that include S prime and fecundity f. Age Specific Survival Rate, lx, is defined as the sum of Sxj across stages from 1 to m. Age Specific Fecundity, mx, is defined as a ratio with a numerator summing Sxj times fecundity fxj across stages 1 to m and a denominator summing Sxj across stages 1 to m. Net Reproductive Rate, R0, is defined as a sum over ages from 0 onward of lx times mx. Mean fecundity, F, is defined as the sum of Ex from age 1 to Nf divided by Nf. Intrinsic Rate of Increase, r, is defined by an equation where a summed exponential term times lx and mx across ages from 0 onward equals 1, and Finite Rate of Increase, lambda, is defined as the exponential of r. Mean Generation Time, T, is defined as the natural logarithm of R0 divided by r.
Additionally, population reproductive performance was further characterised by calculating the gross reproductive rate (GRR = ∑mx), reflecting total expected cumulative egg production, alongside the population doubling time (DT). Furthermore, to evaluate stage-specific longevity and population age structure, the following parameters were quantified: the age-stage specific life expectancy (exj), representing the predicted remaining lifespan at age x and stage j; the age-stage specific reproductive value (Vxj), denoting the expected contribution to future population growth; and the stable age distribution (Cx).
Statistical analysis
All biological parameters (stage developmental durations, pre-adult period, adult and total longevity, APOP, TPOP, oviposition period, and individual female fecundity) as well as population demographic indices (R 0, r, λ, T, GRR, DT, exj, Vxj) and their standard errors were estimated based on the age-stage, two-sex life table theory using the TWOSEX-MSChart software (Chi, Reference Chi2025). Differences among dry bean cultivars for all evaluated parameters were determined using the paired bootstrap test with 100,000 iterations embedded within TWOSEX-MSChart at P < 0.05 (Huang and Chi, Reference Huang and Chi2013; Chi et al., Reference Chi, Güncan, Kavousi, Gharakhani, Atlihan, Özgökçe and Taghizadeh2022). Population sex ratio deviations from the expected 1:1 ratio were evaluated separately for each cultivar using Chi-square (χ2) goodness-of-fit tests with one degree of freedom. Also, life table figures were generated using GraphPad Prism software (San Diego, CA, USA) for effective visualisation.
Results
Developmental times and biological traits
The developmental duration of A. obtectus life stages varied significantly across the three tested dry bean cultivars (P < 0.05) (table 2). Egg incubation duration was significantly shorter on ‘Atmaca’ (6.97 ± 0.14 days) than on ‘Akın’ (8.03 ± 0.14 days) and ‘Berrak’ (7.86 ± 0.15 days). Larval developmental duration did not differ significantly among ‘Atmaca’ (19.60 ± 0.14 days) and ‘Akın’ (19.98 ± 0.10) or ‘Berrak’ (20.29 ± 0.11 days). Pupal developmental time exhibited significant differences among all three cultivars (P < 0.05), being shortest on ‘Atmaca’ (7.88 ± 0.12 days), intermediate on ‘Akın’ (9.97 ± 0.19 days), and longest on ‘Berrak’ (11.09 ± 0.21 days). Consequently, the total pre-adult period was significantly reduced on ‘Atmaca’ (34.45 ± 0.09 days) compared to ‘Akın’ (37.98 ± 0.31 days) and ‘Berrak’ (39.24 ± 0.28 days). Adult longevity showed no statistically significant differences among host cultivars (P > 0.05), averaging between 10.15 ± 0.36 days on ‘Berrak’ and 11.34 ± 0.39 days on ‘Atmaca’. The adult sex distribution yielded 50 females and 30 males on ‘Akın’, 44 females and 36 males on ‘Atmaca’, and 51 females and 29 males on ‘Berrak’. Separate Chi-square goodness-of-fit tests revealed a significant female-biased sex ratio on the ‘Akın’ (χ2 = 5.0, df = 1, P = 0.025) and ‘Berrak’ (χ2 = 6.05, df = 1, P = 0.014) cultivars, whereas the sex ratio on ‘Atmaca’ did not deviate significantly from the expected 1:1 ratio (χ2 = 0.8, df = 1, P = 0.37). Furthermore, analysis of the combined total cohort (145 females, 95 males) confirmed a highly significant overall female bias (χ2 = 10.42, df = 1, P = 0.001).
Developmental duration of Acanthoscelides obtectus life stages on three dry bean cultivars (n = 80)
Table 2 Long description
Developmental duration in days plus or minus standard error is listed for egg, larva, pupa, preadult period, adult longevity, and total longevity across three cultivars: Akin, Atmaca, and Berrak. For Akin, egg is 8.03 plus or minus 0.14 with letter a, larva 19.98 plus or minus 0.10 with letter a, pupa 9.97 plus or minus 0.19 with letter b, preadult period 37.98 plus or minus 0.31 with letter b, adult longevity 11.00 plus or minus 0.48 with letter a, and total longevity 48.98 plus or minus 0.58 with letter a. For Atmaca, egg is 6.97 plus or minus 0.14 with letter b, larva 19.60 plus or minus 0.14 with letter a, pupa 7.88 plus or minus 0.12 with letter c, preadult period 34.45 plus or minus 0.09 with letter c, adult longevity 11.34 plus or minus 0.39 with letter a, and total longevity 45.79 plus or minus 0.40 with letter b. For Berrak, egg is 7.86 plus or minus 0.15 with letter a, larva 20.29 plus or minus 0.11 with letter a, pupa 11.09 plus or minus 0.21 with letter a, preadult period 39.24 plus or minus 0.28 with letter a, adult longevity 10.15 plus or minus 0.36 with letter a, and total longevity 49.39 plus or minus 0.49 with letter a. Letter markers appear after each mean within rows.
Note: Means within the same row followed by different lowercase letters are significantly different (P < 0.05) according to the paired bootstrap test.
Age-stage, two-sex life table parameters
Demographic parameters estimated via 100,000 bootstrap iterations revealed significant differences in population growth potential across cultivars (table 3). Individual female fecundity was significantly higher on ‘Akın’ (24.86 ± 1.41 eggs/female) than on ‘Atmaca’ (16.70 ± 0.62 eggs/female) and ‘Berrak’ (16.29 ± 1.18 eggs/female). The net reproductive rate (R 0) was significantly higher on ‘Akın’ (15.54 ± 1.60 female offspring/female) than on ‘Atmaca’ (9.19 ± 0.99) and ‘Berrak’ (10.39 ± 1.15). The GRR peaked on ‘Akın’ (19.39 ± 1.99), followed by ‘Berrak’ (14.14 ± 1.74) and ‘Atmaca’ (9.79 ± 1.04), with all three cultivars differing significantly from one another (P < 0.05).
Comprehensive demographic parameters, population growth indices, and reproductive intervals of Acanthoscelides obtectus reared on three dry bean cultivars (Initial cohort n = 80 per cultivar)
Table 3 Long description
Parameters are reported for three cultivars, Akin, Atmaca, and Berrak, as mean plus or minus a value, with letter markers after each mean. Net reproductive rate, R0 in offspring per individual, is 15.54 plus or minus 1.60a for Akin, 9.19 plus or minus 0.99b for Atmaca, and 10.39 plus or minus 1.15b for Berrak. Gross reproductive rate, GRR in offspring per individual, is 19.39 plus or minus 1.99a for Akin, 9.79 plus or minus 1.04c for Atmaca, and 14.14 plus or minus 1.74b for Berrak; fecundity in eggs per female is 24.86 plus or minus 1.41a, 16.70 plus or minus 0.62b, and 16.29 plus or minus 1.18b, respectively. Intrinsic rate of increase, r per day, is 0.0645 plus or minus 0.0020a for Akin, 0.0565 plus or minus 0.0030b for Atmaca, and 0.0544 plus or minus 0.0030b for Berrak; finite rate of increase, lambda per day, is 1.0666 plus or minus 0.0030a, 1.0582 plus or minus 0.0030b, and 1.0559 plus or minus 0.0030b. Mean generation time, T in days, is 42.53 plus or minus 0.42b for Akin, 39.23 plus or minus 0.18c for Atmaca, and 43.01 plus or minus 0.57a; population doubling time, DT in days, is 10.74 plus or minus 0.43b, 12.26 plus or minus 0.63a, and 12.73 plus or minus 0.67a. Adult preoviposition period, APOP in days, is 1.00 plus or minus 0.11a for Akin, 0.95 plus or minus 0.06a for Atmaca, and 0.80 plus or minus 0.09a; total preoviposition period, TPOP in days, is 38.94 plus or minus 0.41b, 35.50 plus or minus 0.13c, and 40.16 plus or minus 0.37a. Oviposition period in days is 7.06 plus or minus 0.37a for Akin, 7.70 plus or minus 0.30a for Atmaca, and 6.59 plus or minus 0.28a.
Notes: Reproductive intervals were calculated based exclusively on the number of successfully emerged females within each cohort (Akın: n = 50; Atmaca: n = 44; Berrak: n = 51). Means within the same row followed by different lowercase letters are significantly different (P < 0.05) according to the paired bootstrap test.
Driven by the superior reproductive output on ‘Akın’, both the intrinsic rate of increase (r = 0.0645 ± 0.0020 day−1) and finite rate of increase (λ = 1.0666 ± 0.0030 day−1) were significantly higher on ‘Akın’ compared to ‘Atmaca’ (r = 0.0556 ± 0.0030; λ = 1.0582 ± 0.0030) and ‘Berrak’ (r = 0.0544 ± 0.0030; λ = 1.0559 ± 0.0030). Mean generation time (T) was significantly shorter on ‘Atmaca’ (39.23 ± 0.18 days) than on ‘Akın’ (42.53 ± 0.42 days) and ‘Berrak’ (43.01 ± 0.57 days). Consequently, population DT was shortest on ‘Akın’ (10.74 ± 0.43 days), compared to 12.26 ± 0.63 days on ‘Atmaca’ and 12.73 ± 0.67 days on ‘Berrak’.
No significant differences were observed among cultivars regarding APOP (0.80–1.00 days) or oviposition period (6.59 ± 0.28 to 7.70 ± 0.37 days) (P > 0.05). However, TPOP was significantly shorter on ‘Atmaca’ (35.50 ± 0.13 days) than on ‘Akın’ (38.94 ± 0.41 days) and ‘Berrak’ (40.16 ± 0.37 days) (P < 0.05).
Life table of Acanthoscelides obtectus
Survival rate (sxj) and age-stage specific fecundity (mx) and maternity (lxmx)
The age-stage specific survival rate (Sxj) curves demonstrated that dry bean cultivars influenced the survival, developmental speed, and stage overlap of A. obtectus. Variation in developmental rates among individuals led to significant overlaps between different life stages on all tested hosts. On the ‘Atmaca’ cultivar, the egg survival curve declined rapidly around day 10, resulting in a synchronised larval cohort that developed faster than those on the other cultivars. Consequently, pupal formation peaked earlier, and adult emergence began around day 32. In contrast, the ‘Berrak’ and ‘Akın’ cultivars showed prolonged larval development, shifting the pupal survival curves to older ages. On ‘Berrak’, some individuals exhibited delayed development, leading to a greater overlap of larvae and pupae over time. Additionally, visual inspection of the adult survival curves suggests that the decline in survivorship was more gradual on the ‘Akın’ cultivar. This reflects a descriptively extended survival trend compared to the other hosts, although mean adult longevity did not differ statistically (fig. 1).
The age-stage specific survival rate (Sxj) of Acanthoscelides obtectus reared on three commercial dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’).
Figure 1 Long description
AKIN. Horizontal axis label, Age days. Horizontal axis range, 0 to 60. Vertical axis label, Age stage specific survival rate Sxj. Vertical axis range, 0.0 to 1.2. Legend labels, Egg, Larvae, Pupae, Female, Male. Lines are distinguished by different marker shapes and separate legend entries. Egg series coordinate pairs: (0, 1.0), (5, 1.0), (10, 0.0), (60, 0.0). Key values: egg is 1.0 at age 0 and age 5 and 0.0 at age 10 through age 60. Larvae series coordinate pairs: (0, 0.0), (5, 0.0), (10, 1.0), (30, 1.0), (35, 0.0), (60, 0.0). Key values: larvae is 1.0 from age 10 to age 30 and 0.0 at age 0, age 5, age 35 and age 60. Pupae series coordinate pairs: (0, 0.0), (25, 0.0), (30, 1.0), (35, 1.0), (40, 0.0), (60, 0.0). Key values: pupae is 1.0 at age 30 and age 35 and 0.0 at age 0, age 25, age 40 and age 60. Female series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.6), (45, 0.6), (50, 0.3), (55, 0.0), (60, 0.0). Key values: female reaches 0.6 at age 40 and age 45, then declines to 0.3 at age 50 and 0.0 at age 55 and age 60. Male series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.3), (45, 0.3), (50, 0.1), (55, 0.0), (60, 0.0). Key values: male reaches 0.3 at age 40 and age 45, then declines to 0.1 at age 50 and 0.0 at age 55 and age 60. The image B showing ATMACA. Horizontal axis label, Age days. Horizontal axis range, 0 to 60. Vertical axis label, Age stage specific survival rate Sxj. Vertical axis range, 0.0 to 1.2. Legend labels, Egg, Larvae, Pupae, Female, Male. Lines are distinguished by different marker shapes and separate legend entries. Egg series coordinate pairs: (0, 1.0), (5, 1.0), (10, 0.0), (60, 0.0). Key values: egg is 1.0 at age 0 and age 5 and 0.0 at age 10 through age 60. Larvae series coordinate pairs: (0, 0.0), (5, 0.0), (10, 1.0), (25, 1.0), (30, 0.0), (60, 0.0). Key values: larvae is 1.0 from age 10 to age 25 and 0.0 at age 0, age 5, age 30 and age 60. Pupae series coordinate pairs: (0, 0.0), (25, 0.0), (30, 1.0), (35, 1.0), (38, 0.0), (60, 0.0). Key values: pupae is 1.0 at age 30 and age 35 and 0.0 at age 0, age 25, age 38 and age 60. Female series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.6), (45, 0.6), (50, 0.2), (55, 0.0), (60, 0.0). Key values: female reaches 0.6 at age 40 and age 45, then declines to 0.2 at age 50 and 0.0 at age 55 and age 60. Male series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.5), (45, 0.4), (50, 0.1), (55, 0.0), (60, 0.0). Key values: male reaches 0.5 at age 40, then declines to 0.4 at age 45, 0.1 at age 50 and 0.0 at age 55 and age 60. The image C showing BERRAK. Horizontal axis label, Age days. Horizontal axis range, 0 to 60. Vertical axis label, Age stage specific survival rate Sxj. Vertical axis range, 0.0 to 1.2. Legend labels, Egg, Larvae, Pupae, Female, Male. Lines are distinguished by different marker shapes and separate legend entries. Egg series coordinate pairs: (0, 1.0), (5, 1.0), (10, 0.0), (60, 0.0). Key values: egg is 1.0 at age 0 and age 5 and 0.0 at age 10 through age 60. Larvae series coordinate pairs: (0, 0.0), (5, 0.0), (10, 1.0), (30, 1.0), (35, 0.0), (60, 0.0). Key values: larvae is 1.0 from age 10 to age 30 and 0.0 at age 0, age 5, age 35 and age 60. Pupae series coordinate pairs: (0, 0.0), (25, 0.0), (30, 1.0), (35, 1.0), (40, 0.0), (60, 0.0). Key values: pupae is 1.0 at age 30 and age 35 and 0.0 at age 0, age 25, age 40 and age 60. Female series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.6), (45, 0.6), (50, 0.3), (55, 0.0), (60, 0.0). Key values: female reaches 0.6 at age 40 and age 45, then declines to 0.3 at age 50 and 0.0 at age 55 and age 60. Male series coordinate pairs: (0, 0.0), (35, 0.0), (40, 0.3), (45, 0.3), (50, 0.1), (55, 0.0), (60, 0.0). Key values: male reaches 0.3 at age 40 and age 45, then declines to 0.1 at age 50 and 0.0 at age 55 and age 60. Cross image comparison using the listed coordinate pairs. Larvae reaches 1.0 at age 10 in AKIN, ATMACA and BERRAK. Larvae remains at 1.0 to age 30 in AKIN and BERRAK and to age 25 in ATMACA. Pupae reaches 1.0 at age 30 and age 35 in AKIN, ATMACA and BERRAK. Pupae returns to 0.0 at age 40 in AKIN and BERRAK and at age 38 in ATMACA. Female reaches 0.6 at age 40 and age 45 in AKIN, ATMACA and BERRAK. Male reaches 0.3 at age 40 and age 45 in AKIN and BERRAK and reaches 0.5 at age 40 and 0.4 at age 45 in ATMACA.
The reproductive dynamics and fecundity potential of A. obtectus exhibited substantial variation across the evaluated dry bean cultivars. Age-specific fecundity (mx) profiles, which denote the mean daily production of female offspring per individual, revealed highly distinct reproductive trajectories for each host (fig. 2). Females reared on the ‘Akın’ cultivar demonstrated the highest daily reproductive output, reaching a peak of 2.39 offspring per individual on day 42. Conversely, cohorts developing on ‘Atmaca’ achieved peak fecundity earlier in their life cycle, with a maximum of 1.72 offspring per individual on day 39, whereas those on ‘Berrak’ recorded the lowest reproductive peak (1.26 offspring per individual) on day 42 (fig. 2).
Age-specific survival rate (lx), age-specific fecundity (mx), and age-specific maternity (lxmx) of Acanthoscelides obtectus reared on three dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’).
Figure 2 Long description
The text, AKIN. A multi line graph. Horizontal axis label, Age days, with tick labels 0, 10, 20, 30, 40, 50, 60. Left vertical axis label, Age specific survival l subscript x, with tick labels 0.0, 0.2, 0.4, 0.6, 0.8, 1.0. Right vertical axis label, Fecundity and maternity l subscript x m subscript x, with tick labels 0, 1, 2, 3. Legend entries, l subscript x, m subscript x, l subscript x m subscript x. The l subscript x line stays near 1.0 from age 0 to the mid 30s, then declines between the late 30s and about 60, reaching near 0 by about 60. The m subscript x line stays near 0 from age 0 to the mid 30s, rises sharply in the late 30s to a peak around the early 40s, then declines to near 0 by the mid to late 50s. The l subscript x m subscript x line stays near 0 from age 0 to the mid 30s, rises in the late 30s to a peak around the early 40s, then declines to near 0 by the mid 50s. Readable plotted values as coordinate pairs are not clearly determinable from the image. The image B showing the text, ATMACA. A multi line graph. Horizontal axis label, Age days, with tick labels 0, 10, 20, 30, 40, 50, 60. Left vertical axis label, Age specific survival l subscript x, with tick labels 0.0, 0.2, 0.4, 0.6, 0.8, 1.0. Right vertical axis label, Fecundity and maternity l subscript x m subscript x, with tick labels 0, 2, 4, 6. Legend entries, l subscript x, m subscript x, l subscript x m subscript x. The l subscript x line stays near 1.0 from age 0 to about 40, then declines between about 40 and the mid 50s, reaching near 0 by the mid to late 50s. The m subscript x line stays near 0 from age 0 to the mid 30s, rises to a peak around the late 30s to about 40, then declines to near 0 by the mid 40s. The l subscript x m subscript x line stays near 0 from age 0 to the mid 30s, rises to a peak around the late 30s to about 40, then declines to near 0 by the mid 40s. Readable plotted values as coordinate pairs are not clearly determinable from the image. The image C showing the text, BERRAK. A multi line graph. Horizontal axis label, Age days, with tick labels 0, 10, 20, 30, 40, 50, 60. Left vertical axis label, Age specific survival l subscript x, with tick labels 0.0, 0.2, 0.4, 0.6, 0.8, 1.0. Right vertical axis label, Fecundity and maternity l subscript x m subscript x, with tick labels 0, 2, 4, 6. Legend entries, l subscript x, m subscript x, l subscript x m subscript x. The l subscript x line stays near 1.0 from age 0 to the low 40s, then declines between the low 40s and about 60, reaching near 0 by about 60. The m subscript x line stays near 0 from age 0 to the high 30s, rises to a peak around about 40 to the low 40s, then declines to near 0 by about 50. The l subscript x m subscript x line stays near 0 from age 0 to the high 30s, rises to a peak around about 40 to the low 40s, then declines to near 0 by about 50. Readable plotted values as coordinate pairs are not clearly determinable from the image.
Concurrently, the raw daily fecundity curves (representing total fecundity output by breeding adult females) mirrored these physiological differences among host cultivars (fig. 3). Intense egg-laying activities commenced around day 33 across all cohorts. The total number of daily eggs deposited peaked sharply on day 42 for the ‘Akın’ cultivar, reaching an absolute maximum of 177 eggs. Conversely, oviposition acceleration occurred faster on ‘Atmaca’ and ‘Berrak’ cultivars, both achieving their maximum daily egg deposition capacity earlier at day 38, with total outputs of 136 and 54 eggs, respectively, before progressively declining as adult senescence advanced (fig. 3).
Daily oviposition patterns of Acanthoscelides obtectus adult females reared on three commercial dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’).
Besides fecundity dynamics, the age-stage specific reproductive value (Vxj) was computed to delineate an individual’s potential contribution to future population growth at a given age and stage (fig. 4). The biological initialisation of reproductive value for adult females commenced synchronously at day 33 across all three dry bean cultivars, coinciding precisely with the termination of the pupal stage and the onset of adult emergence. Rather than being evenly distributed across the adult lifespan, reproductive investment was heavily concentrated within a narrow developmental window, achieving its absolute peak (Vx) on day 34 across all host treatments. At this critical physiological peak, the highest reproductive value was recorded on the ‘Berrak’ cultivar (27.32), followed by ‘Akın’ (22.58), whereas the ‘Atmaca’ cohort exhibited the lowest maternal investment capacity (14.19). The exceptionally high Vx value observed on ‘Berrak’ suggests that individuals reaching early adulthood on this cultivar possess a significantly elevated relative reproductive potential, likely as a compensatory mechanism for the lower pre-adult survival rates documented previously (table 2). Following the day 34 maximum, a progressive and steady decline in Vxj was observed across all hosts, as adult senescent advancement and cumulative daily oviposition continuously depleted the remaining reproductive potential of the surviving cohorts until fully exhausted at death (fig. 4).
Age-stage specific reproductive value (Vxj) of Acanthoscelides obtectus reared on three dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’).
Figure 4 Long description
Three line graphs depict the reproductive value (Vxj) over age in days for three different dry bean cultivars: ′Akin,′ ′Atmaca,′ and ′Berrak.′ Each graph has the same structure with the horizontal axis labeled as Age (days) ranging from 0 to 65 and the vertical axis labeled as Reproductive value (Vxj) ranging from 0 to 30. 1. ′Akin′: The graph shows five lines representing different stages: Egg, Larvae, Pupae, Female and Male. The Egg stage starts low and gradually increases, peaking around day 33. The Larvae stage follows a similar pattern, peaking slightly later. The Pupae stage shows a sharp increase around day 33, peaking at day 34, then rapidly declining. The Female stage peaks sharply at day 34 and declines steadily. The Male stage remains low throughout. 2. ′Atmaca′: Similar to ′Akin,′ the Egg and Larvae stages gradually increase, peaking around day 33. The Pupae stage shows a sharp peak at day 34, followed by a rapid decline. The Female stage also peaks at day 34 and declines steadily. The Male stage remains low. 3. ′Berrak′: The Egg and Larvae stages increase gradually, peaking around day 33. The Pupae stage shows a sharp peak at day 34, followed by a rapid decline. The Female stage peaks sharply at day 34 and declines steadily. The Male stage remains low. Each graph includes a legend indicating the color-coded lines for each stage: Egg, Larvae, Pupae, Female and Male.
Life expectancy (exj)
The age-stage specific life expectancy (exj) of A. obtectus denotes the predicted remaining lifespan of an individual at age 
$x$ and stage 
$j$. These prognostic trajectories exhibited distinct variation depending on the host dry bean cultivars (fig. 5). At the onset of the study (day 1, egg stage), the highest initial life expectancy was recorded on the ‘Berrak’ cultivar (49.39 days), closely followed by ‘Akın’ (48.97 days), whereas the lowest initial baseline was observed on ‘Atmaca’ (45.79 days). As individuals advanced through successive developmental stages towards adulthood, the life expectancy curves for both females and males demonstrated a steady, continuous decline across all evaluated hosts. Notably, based on the descriptive life expectancy curves, the predicted remaining lifespan for adults appeared to decline more gradually on the ‘Akın’ cultivar compared to the other hosts. This visual trend suggests that ‘Akın’ may provide a physiologically more favourable nutritional history that descriptively delays cohort senescence, despite the lack of statistical significance in absolute mean longevity.
Age-stage specific life expectancy (exj) of Acanthoscelides obtectus reared on three commercial dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’).
Figure 5 Long description
AKIN. Horizontal axis label, Age days. Horizontal axis range, 0 to 65. Vertical axis label, Life expectancy exj. Vertical axis range, 0 to 60. Legend labels, Egg, Larvae, Pupae, Female, Male. Plotted series use line segments with repeated point markers. Egg series coordinate pairs: (0, 0), (1, 0), (2, 0), (3, 0), (4, 0), (5, 0), (6, 0), (7, 0), (8, 0), (9, 0), (10, 0), (11, 0), (12, 0), (13, 0), (14, 0), (15, 0), (16, 0), (17, 0), (18, 0), (19, 0), (20, 0), (21, 0), (22, 0), (23, 0), (24, 0), (25, 0), (26, 0), (27, 0), (28, 0), (29, 0), (30, 0), (31, 0), (32, 0), (33, 0), (34, 0), (35, 0), (36, 0), (37, 0), (38, 0), (39, 0), (40, 0), (41, 0), (42, 0), (43, 0), (44, 0), (45, 0), (46, 0), (47, 0), (48, 0), (49, 0), (50, 0), (51, 0), (52, 0), (53, 0), (54, 0), (55, 0), (56, 0), (57, 0), (58, 0), (59, 0), (60, 0), (61, 0), (62, 0), (63, 0), (64, 0), (65, 0). Larvae series coordinate pairs: (0, 50), (5, 45), (10, 40), (15, 35), (20, 30), (25, 25), (30, 20). Pupae series coordinate pairs: (0, 0), (5, 0), (10, 0), (15, 0), (20, 0), (25, 0), (30, 0), (35, 0), (40, 0), (45, 0), (50, 0), (55, 0), (60, 0), (65, 0). Female series coordinate pairs: (30, 20), (35, 15), (40, 10), (45, 5), (50, 0). Male series coordinate pairs: (30, 20), (35, 12), (40, 8), (45, 4), (50, 0). Within AKIN, the Larvae series decreases from (0, 50) to (30, 20). Female and Male series both decrease from (30, 20) to (50, 0), with Female higher than Male at (35, 15) versus (35, 12), (40, 10) versus (40, 8) and (45, 5) versus (45, 4). ATMACA. Horizontal axis label, Age days. Horizontal axis range, 0 to 65. Vertical axis label, Life expectancy exj. Vertical axis range, 0 to 60. Legend labels, Egg, Larvae, Pupae, Female, Male. Plotted series use line segments with repeated point markers. Egg series coordinate pairs: (0, 0), (1, 0), (2, 0), (3, 0), (4, 0), (5, 0), (6, 0), (7, 0), (8, 0), (9, 0), (10, 0), (11, 0), (12, 0), (13, 0), (14, 0), (15, 0), (16, 0), (17, 0), (18, 0), (19, 0), (20, 0), (21, 0), (22, 0), (23, 0), (24, 0), (25, 0), (26, 0), (27, 0), (28, 0), (29, 0), (30, 0), (31, 0), (32, 0), (33, 0), (34, 0), (35, 0), (36, 0), (37, 0), (38, 0), (39, 0), (40, 0), (41, 0), (42, 0), (43, 0), (44, 0), (45, 0), (46, 0), (47, 0), (48, 0), (49, 0), (50, 0), (51, 0), (52, 0), (53, 0), (54, 0), (55, 0), (56, 0), (57, 0), (58, 0), (59, 0), (60, 0), (61, 0), (62, 0), (63, 0), (64, 0), (65, 0). Larvae series coordinate pairs: (0, 50), (5, 45), (10, 40), (15, 35), (20, 30), (25, 25), (30, 20). Pupae series coordinate pairs: (0, 0), (5, 0), (10, 0), (15, 0), (20, 0), (25, 0), (30, 0), (35, 0), (40, 0), (45, 0), (50, 0), (55, 0), (60, 0), (65, 0). Female series coordinate pairs: (30, 20), (35, 12), (40, 8), (45, 4), (50, 0). Male series coordinate pairs: (30, 20), (35, 10), (40, 6), (45, 3), (50, 0). Within ATMACA, the Larvae series decreases from (0, 50) to (30, 20). Female and Male series both decrease from (30, 20) to (50, 0), with Female higher than Male at (35, 12) versus (35, 10), (40, 8) versus (40, 6) and (45, 4) versus (45, 3). BERRAK. Horizontal axis label, Age days. Horizontal axis range, 0 to 65. Vertical axis label, Life expectancy exj. Vertical axis range, 0 to 60. Legend labels, Egg, Larvae, Pupae, Female, Male. Plotted series use line segments with repeated point markers. Egg series coordinate pairs: (0, 0), (1, 0), (2, 0), (3, 0), (4, 0), (5, 0), (6, 0), (7, 0), (8, 0), (9, 0), (10, 0), (11, 0), (12, 0), (13, 0), (14, 0), (15, 0), (16, 0), (17, 0), (18, 0), (19, 0), (20, 0), (21, 0), (22, 0), (23, 0), (24, 0), (25, 0), (26, 0), (27, 0), (28, 0), (29, 0), (30, 0), (31, 0), (32, 0), (33, 0), (34, 0), (35, 0), (36, 0), (37, 0), (38, 0), (39, 0), (40, 0), (41, 0), (42, 0), (43, 0), (44, 0), (45, 0), (46, 0), (47, 0), (48, 0), (49, 0), (50, 0), (51, 0), (52, 0), (53, 0), (54, 0), (55, 0), (56, 0), (57, 0), (58, 0), (59, 0), (60, 0), (61, 0), (62, 0), (63, 0), (64, 0), (65, 0). Larvae series coordinate pairs: (0, 50), (5, 45), (10, 40), (15, 35), (20, 30), (25, 25), (30, 20). Pupae series coordinate pairs: (0, 0), (5, 0), (10, 0), (15, 0), (20, 0), (25, 0), (30, 0), (35, 0), (40, 0), (45, 0), (50, 0), (55, 0), (60, 0), (65, 0). Female series coordinate pairs: (35, 15), (40, 10), (45, 5), (50, 0). Male series coordinate pairs: (35, 15), (40, 9), (45, 4), (50, 0). Within BERRAK, the Larvae series decreases from (0, 50) to (30, 20). Female and Male series both decrease from (35, 15) to (50, 0), with Female higher than Male at (40, 10) versus (40, 9) and (45, 5) versus (45, 4). Across AKIN, ATMACA and BERRAK, the Larvae series uses the same listed coordinate pairs from (0, 50) to (30, 20). Female and Male series in all three graphs decrease to (50, 0) and Female values are higher than Male at the shared ages where both are listed.
Discussion
Effect of host cultivars on pre-adult developmental periods
Analysis of the embryonic phase revealed that the shortest egg incubation period occurred on the ‘Atmaca’ cultivar (6.97 days), whereas this developmental stage was significantly prolonged on both ‘Akın’ (8.03 days) and ‘Berrak’ (7.86 days). These findings align closely with existing literature demonstrating an average egg hatching duration of 8 days at 25°C (Franssen, Reference Franssen1962), with hatching typically initiating between the fourth and fifth days and concluding by the ninth day across various bean varieties (Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002). Similar average incubation periods of approximately 6.10 days have also been documented (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Furthermore, oviposition in A. obtectus is characteristically protracted, with egg production extending up to 10 days even under starvation conditions (Parsons and Credland, Reference Parsons and Credland2003).
In terms of larval development, no statistically significant difference was detected among the tested cultivars (19.60–20.29 days), with all larvae successfully completing this stage within a maximum of 22 days. This observation corroborates previous laboratory studies reporting larval durations ranging from 15 to 19 days and 20 to 26 days under comparable conditions (Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002; Sağlam et al., Reference Sağlam, Tunaz and Er2016). Such rapid post-embryonic progression is consistent with the swift larval development observed on highly suitable legume hosts, such as cowpeas (21.7 days) and kidney beans (25.4 days), under optimal dark laboratory conditions (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019).
Nevertheless, microclimatic factors, particularly temperature and humidity, serve as primary determinants of larval developmental velocity. Indeed, larval maturation can extend to an average of 52 days under field conditions due to varietal variations (Özdem, Reference Özdem1994), and developmental periods can reach up to 42.9 days at lower temperatures such as 20°C (Alvarez et al., Reference Alvarez, Hossaert‐McKey, Rasplus, McKey, Mercier, Soldati and Benrey2005). Besides abiotic factors, the literature strongly indicates that larval developmental speed is heavily host-dependent. For example, larval duration is significantly prolonged on less optimal leguminous species, extending up to 28.7 days on chickpeas, 34.7 days on lentils, and 37.1 days on broad beans (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Additionally, both the mechanical structural integrity of the seed coat (testa) and the presence of endogenous biochemical inhibitors within the cotyledons can profoundly influence larval penetration and subsequent developmental performance (Thiery, Reference Thiery1984; Szentesi, Reference Szentesi2021).
The similarity in larval durations across the dry bean varieties examined in our study suggests that the chemical and nutritional quality of the cotyledons in these commercial cultivars does not exhibit radical toxic variations severe enough to restrict larval feeding. Host plant susceptibility and larval performance are known to be profoundly governed by primary and secondary metabolic profiles (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019; Szentesi, Reference Szentesi2021). For instance, nine essential amino acids, including aspartic acid, threonine, glycine, valine, methionine, leucine, tryptophan, and histidine, have been identified as high-quality nutritional components that positively correlate with increased host preference and pest weight loss (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Conversely, non-host plants present severe chemical defences, such as secondary metabolites, non-protein toxic amino acids (e.g. canavanine in Vicia or homoarginine and lathyrine in Lathyrus), lectins, or alpha-amylase and protease inhibitors. These defensive compounds significantly elevate post-embryonic mortality or drastically delay development (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019; Szentesi, Reference Szentesi2021). The ability of A. obtectus larvae to tolerate or adjust to these endogenous inhibitors involves complex detoxification mechanisms, such as host-specific alterations in phosphatase enzyme activity, which are hypothesised to impose severe metabolic and energy allocation trade-offs against developmental speed (Savković et al., Reference Savković, Đorđević and Stojković2019; Szentesi, Reference Szentesi2021). These cultivar-dependent variations in developmental momentum are closely tied to the physical and biochemical defence mechanisms of the host seeds, which act as important antibiotic barriers restricting larval performance (Hamzei et al., Reference Hamzei, Golizadeh, Hassanpour, Fathi and Abedi2023). Similar cultivar-based resistance screenings utilising demographic frameworks have demonstrated that variations in pre-adult duration and reproductive output effectively distinguish susceptible and partially resistant host genotypes (Naseri et al., Reference Naseri, Majd-Marani and Bidar2022; Tahmasebi et al., Reference Tahmasebi, Shakarami, Mardani-Talace and Serrão2022).
In contrast to the larval stage, the pupal developmental period in our study was significantly shorter on the cultivar ‘Atmaca’ (7.88 ± 0.12 days) compared to ‘Berrak’ (11.09 ± 0.21 days) and ‘Akın’ (9.97 ± 0.19 days), causing the total pre-adult developmental period to be shortest on ‘Atmaca’ (34.45 ± 0.09 days). This aligns with reported pre-pupal and pupal variations across different hosts in the literature, where pre-pupal periods range from 1.0 to 3.4 days, and pupal durations range from 3.0 to 5.3 days depending on the structural and nutritional status of the seed (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Physical grain traits and endosperm volume may mediate larval developmental momentum rather than absolute survival under optimal laboratory conditions. We hypothesise that the cultivar ‘Atmaca’, which features the largest 100-seed weight (58.9–66.5 g) and pinto-type testal characteristics, might provide greater endosperm availability, potentially accelerating larval-pupal transitions compared to medium-to-small seeded cultivars like ‘Berrak’ (25.7–33.7 g) and ‘Akın’ (42.5–49.9 g). This observation supports the hypothesis that the physical capacity of the endosperm acts as a primary mechanical bottleneck, fundamentally altering the developmental momentum of A. obtectus independent of its geographic or local agricultural origin.
Reproductive intervals, fecundity, and adult performance
The APOP of A. obtectus remained below 1 day (0.80–1.00 days) across all tested cultivars. This finding is broadly consistent with the findings of Naroz et al. (Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019), who documented a short pre-oviposition period of 1.1–1.2 days on highly suitable hosts, though it indicates a shorter interval than the average of 2 days or 2–3 days post-emergence reported by Yılmaz and Elmalı (Reference Yılmaz and Elmalı2002).
In the present study, the oviposition period varied between 6.59 and 7.70 days depending on the host cultivar, a finding that closely aligns with the 7-day average previously documented in the literature (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). This restricted timeline strongly mirrors the reproductive performance observed on highly suitable hosts such as cowpeas (6.6 days) and kidney beans (5.6 days), whereas oviposition intervals are known to shorten significantly on low-quality or unconventional hosts such as broad beans (4.1 days) (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Although earlier studies have reported wide intra-varietal variations ranging from 3.33 to 7.00 days (Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002), and even prolonged periods up to 10–13 days on certain hosts (Krnjaic, Reference Krnjaic1971). The proximity of our maximum durations to these upper limits indicates that A. obtectus females concentrate their reproductive energy within a narrowly defined, highly critical timeframe. Furthermore, the post-oviposition period was recorded between 4.03 and 4.46 days across the tested cultivars. This duration shows a strong biological similarity to the 4.8 days reported by Atak (Reference Atak1975), while presenting a slightly longer but parallel trend with the more stable intervals (1.7–2.1 days) documented across various leguminous seeds (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019).
Although the mean number of eggs laid per female did not exhibit a dramatic statistical difference, numerical output was highest on the ‘Akın’ cultivar (24.86 eggs) and lowest on ‘Atmaca’ (16.70 eggs). These individual fecundity outputs demonstrate that the reproductive capacity of A. obtectus is highly variable and significantly shaped by the available host variety, microclimatic temperatures, and population-dependent maternal history. While earlier studies on various bean varieties have reported higher fecundity ranges of 38–55 eggs per female (Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002), the broader literature reveals highly fluctuating reproductive outputs depending on the specific host and environmental conditions. For instance, fecundity can drop to a baseline of 11.9 eggs/female on certain kidney beans, whereas it can escalate to 27.83 eggs on chickpeas (Savković et al., Reference Savković, Đorđević and Stojković2019), 44.8 eggs on cowpeas (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019), and even reach 61.6–67.9 eggs under specific laboratory synchronisation protocols (Parsons and Credland, Reference Parsons and Credland2003).
Although the ‘Akın’ cultivar supported the highest individual fecundity (24.86 ± 1.41 eggs/female), it required a longer pre-adult development period. In contrast, the ‘Atmaca’ cultivar promoted faster development but resulted in lower fecundity (16.70 ± 0.62 eggs/female). This illustrates a distinct trade-off between developmental speed and reproductive output, aligning with the bruchid phenomena emphasised by Vuts et al. (Reference Vuts, Woodcock, König, Powers, Pickett, Szentesi and Birkett2018) and Szentesi (Reference Szentesi2021). This demographic pattern is fundamentally tied to the unique reproductive biology of A. obtectus. Unlike most bruchid pests that firmly attach their eggs directly onto the seed surface, A. obtectus females scatter their eggs loosely among stored beans. Because maternal oviposition is not strictly dependent on immediate host quality or seed density, females distribute their eggs broadly, even near less suitable or non-host seeds (Parsons and Credland, Reference Parsons and Credland2003; Savković et al., Reference Savković, Đorđević and Stojković2019; Szentesi, Reference Szentesi2021). Consequently, the critical burden of host selection shifts from the mother to the offspring: newly hatched neonate larvae must actively navigate the storage environment to locate a suitable seed and independently penetrate the seed coat to survive. The significant energy expended by larvae during this active search and penetration process likely contributes to the observed trade-offs in subsequent developmental durations and adult reproductive success across different host cultivars.
In addition to these maternal host-selection traits, external biotic factors such as adult interactions during the reproductive phase play a specific role in post-emergence performance. Our study confirmed that the continued presence of males throughout the adult lifespan does not influence total female fecundity or overall egg hatching viability. In A. obtectus, a single initial mating is sufficient to fully stimulate oogenesis and realise lifetime egg production, meaning females neither benefit from nor suffer a fitness decline as a result of multiple matings or continuous male presence (Parsons and Credland, Reference Parsons and Credland2003).
Life table dynamics and life expectancy
In this study, populations reared on ‘Akın’ and ‘Berrak’ cultivars exhibited a significantly female-biased sex ratio, while those on ‘Atmaca’ maintained an expected 1:1 ratio. Although earlier studies by Howe and Currie (Reference Howe and Currie1964) and Yılmaz and Elmalı (Reference Yılmaz and Elmalı2002) suggested that bean cultivars do not alter gender frequency distributions and typically yield a 1:1 ratio, our findings indicate that certain host cultivars may favour higher female emergence. This female bias on ‘Akın’ and ‘Berrak’ further contributes to the amplified population growth potential observed on these hosts. Analysis of adult longevity revealed no significant variation among the tested cultivars, with lifespans averaging between 10.15 and 11.34 days. This duration is highly consistent with the typical lifespan of this aphagous species under controlled laboratory conditions, previously documented as 8.2–9.4 days for females and 6.6–8.2 days for males (Naroz et al., Reference Naroz, Ahmed, Abdel-Aziz and Abdel-Shafy2019). Furthermore, female individuals generally exhibited greater longevity than males across most cultivars, a demographic trend that firmly corroborates earlier observations (Elmalı and Toros, Reference Elmalı and Toros1990; Yılmaz and Elmalı, Reference Yılmaz and Elmalı2002). From a broader survival perspective, mass adult mortality typically commences after the eighth day (Sönmez, Reference Sönmez2010), while absolute longevity for this pest is generally capped at 16 days under optimal 25°C conditions (Regnault-Roger et al., Reference Regnault-Roger, Hamraoui, Holeman, Theron and Pinel1993).
The integration of the age-stage, two-sex life table (Sxj, lx, mx) clarified the net effect of the dry bean cultivars on pest population dynamics. Among the cultivars tested, the ‘Akın’ cultivar provided the most favourable conditions for geometric multiplication, yielding the highest net reproductive rate (R 0 = 15.54) and the shortest population DT (10.74 days). Analysis of life expectancy (exj) and adult mortality distribution profiles further supported these trends. Visual descriptive assessment of the survival curves indicated that the decline in adult survivorship on ‘Atmaca’ and ‘Berrak’ occurred more rapidly, with mortality appearing to cluster around total cohort ages of 46 and 99, respectively. In contrast, the decline in survivorship on the ‘Akın’ cultivar appeared more evenly distributed over a prolonged period, with adults surviving up to a total cohort age of 60 days. It is important to note that these observations reflect descriptive trends in cohort survivorship patterns rather than statistically tested differences, which aligns with the non-significant variation observed in mean adult longevity. The accelerated adult mortality and reduced life expectancy (exj) observed on cultivars such as ‘Atmaca’ and ‘Berrak’ may reflect the metabolic energetic costs incurred during larval development inside structurally or chemically challenging seed tissues. Similar developmental trade-offs have been documented in bruchid demography, where feeding on less optimal host seeds imposes heavy physiological costs that subsequently compromise adult longevity (Edde and Amatobi, Reference Edde and Amatobi2003; Messina et al., Reference Messina, Lish and Gompert2019; Baş et al., Reference Baş, Aşkın, Saruhan and Akça2026). Furthermore, the emerging cohort on the ‘Berrak’ cultivar displayed the highest reproductive value (Vx = 27.32) during early adulthood. Demographically, this indicates that adults emerging on this specific host cultivar make their greatest expected future contribution to population growth during early adult life. Furthermore, the timing and magnitude of peak age-stage reproductive values (Vxj) serve as key bio-indicators for stored-product IPM decision-making. High and early 
${V_{xj}}$ peaks signal rapid demographic contribution, underscoring the necessity for early monitoring and intervention strategies during initial storage, whereas lower or delayed peaks allow for more flexible, long-term stock management protocols (Bidar et al., Reference Bidar, Razmjou, Golizadeh, Fathi, Ebadollahi and Naseri2021; Baş et al., Reference Baş, Aşkın, Saruhan and Akça2026). Because our life table analysis was constructed using a cohort of individuals that successfully reached adulthood, natural pre-adult mortality was not factored into the calculation of the survival curve. Consequently, the demographic parameters presented in this study represent the maximum intrinsic reproductive potential of the successfully surviving cohort, rather than absolute field-level population dynamics.
Experimental evolution and laboratory selection experiments demonstrate that A. obtectus possesses a high potential to adapt to new or suboptimal hosts (such as chickpeas) over transgenerational time (Savković et al., Reference Savković, Đorđević and Stojković2019). While initial exposure to an unconventional host triggers a severe population drop due to behavioural adjustments and prolonged developmental times, subsequent generations display a steady improvement in reproductive output, shortened developmental periods, and constant population growth. However, this transgenerational host-shift imposes a heavy specialisation cost; when populations selected on alternative hosts are reversed back to once-optimal common beans, they can suffer a drastic reduction in fitness traits due to a severe collapse in immature viability (Savković et al., Reference Savković, Đorđević and Stojković2019). While our current experimental design robustly characterises the immediate demographic response of A. obtectus to different host cultivars, the initial cohorts were transferred from a baseline stock culture without a multi-generational pre-rearing phase. This approach effectively simulates a realistic and highly common post-harvest scenario where an external pest population abruptly infests newly stored commercial bean lots. However, because host shifts can involve maternal legacy effects, future demographic studies incorporating a pre-rearing phase of at least two generations on target cultivars would be highly valuable to differentiate between immediate dietary responses and long-term transgenerational stabilisation.
The A. obtectus population dynamics characterised in this study indicate a dual effect of the host cultivars tested. While the ‘Atmaca’ cultivar is associated with higher short-term density due to rapid development, the ‘Akın’ cultivar is associated with greater long-term population growth potential during prolonged storage due to superior reproductive rates and potentially delayed adult senescence. This distinct variation highlights the evolutionary plasticity of the bean weevil and underscores that cultivar selection must be meticulously integrated with biorational protectants to establish effective long-term storage preservation protocols (Regnault-Roger et al., Reference Regnault-Roger, Hamraoui, Holeman, Theron and Pinel1993; Sağlam et al., Reference Sağlam, Tunaz and Er2016; Savković et al., Reference Savković, Đorđević and Stojković2019; Szentesi, Reference Szentesi2021). These coordinated demographic trade-offs and life-history responses reflect the adaptive potential of bruchids on cultivated host varieties, reinforcing the utility of life table parameters as reliable indicators for screening cultivar resistance in IPM strategies (Naseri et al., Reference Naseri, Majd-Marani and Bidar2022; Ozdemir et al., Reference Ozdemir, Tuncer, Dogan and Kahya2025). Integrating demographic thresholds (r, R0, DT) into cultivar selection provides valuable baseline data for non-chemical pest management strategies. While laboratory life tables do not perfectly replicate complex storage environments, utilising cultivars with reduced intrinsic reproduction rates and extended population DTs may help limit rapid pest population expansion, thereby complementing sustainable post-harvest preservation efforts (Campolo et al., Reference Campolo, Giunti, Russo, Palmeri and Zappalà2018; Baş et al., Reference Baş, Aşkın, Saruhan and Akça2026).
Conclusion
This study quantified the life history traits and demographic parameters of A. obtectus on modern commercial dry bean cultivars (‘Akın’, ‘Atmaca’, and ‘Berrak’) utilising the robust age-stage, two-sex life table framework. Beyond the localised context of specific commercial varieties, our application of this demographic framework demonstrates that differences among dry bean cultivars are fundamental drivers of pest population dynamics. Our findings reveal distinct, cultivar-dependent differences in the population dynamics of this destructive post-harvest pest. The cultivar ‘Atmaca’ significantly accelerates generational turnover by shortening pupal development and TPOP. Conversely, the cultivar ‘Akın’ supports higher potential population growth due to superior lifetime fecundity, a significantly higher net reproductive rate, a shortened population DT, and delayed adult senescence. Interestingly, the cultivar ‘Berrak’ exhibited an intermediate demographic profile, with early adulthood cohorts displaying high peak reproductive value.
From a practical post-harvest preservation and IPM perspective, the cultivar ‘Atmaca’ exhibits demographic characteristics associated with lower potential for long-term population increase among the three tested varieties. Although ‘Atmaca’ supports rapid initial development, it systematically yields the lowest net reproductive rate and individual fecundity, combined with an accelerated, early clustered adult mortality profile that rapidly depletes the breeding cohort. In contrast, the extensive geometric growth potential supported by ‘Akın’ may increase the risk of population growth during prolonged storage if left unprotected. Consequently, relying solely on agronomic performance or field yield improvement during cultivar registration is insufficient for establishing comprehensive food security. Integrating these quantitative, trait-based demographic thresholds into global grain breeding and post-harvest management programs offers a robust, non-chemical decision-support system to predict and mitigate storage outbreak risks on a broader scale.
Author contributions
Conceptualisation: Z.E., C.Y., and H.K.; Methodology: Z.E., C.Y., and H.K.; Investigation: Z.E. and C.Y.; Resources: Z.E.; Data curation, Formal analysis, Software: C.Y. and A.S.K.; Visualisation, Writing – original draft: A.S.K.; Writing – review & editing: H.K. and A.S.K.
Competing interests
The authors declare no conflicts of interest.
