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Repeated short-term thermal stress and its impact on reproductive fitness in parthenium beetle, Zygogramma bicolorata (Coleoptera: Chrysomelidae)

Published online by Cambridge University Press:  02 December 2024

Arvind Kumar Patel
Affiliation:
Department of Zoology, Banaras Hindu University, Varanasi, 221005, India
Priyanka Yadav
Affiliation:
Department of Zoology, Banaras Hindu University, Varanasi, 221005, India
Bhupendra Kumar*
Affiliation:
Department of Zoology, Banaras Hindu University, Varanasi, 221005, India
*
Corresponding author: Bhupendra Kumar; Email: bhupendrakumar@bhu.ac.in

Abstract

Insects experience variable temperature conditions in their natural environment, making constant temperature conditions in studies unrealistic. To address this, we investigated the effects of repeated short-term heat stress (STH) and short-term cold stress (STC) conditions on the pre-oviposition, oviposition, and post-oviposition periods, as well as on fecundity and egg viability of the parthenium beetle, Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae). We found that pre-oviposition periods were shortest under STH conditions and at the optimal temperature and longest under STC conditions. Conversely, oviposition and post-oviposition periods were longest at the optimal temperature. Oviposition periods were shortest under STH, whereas post-oviposition periods were shortest under both STH and STC conditions. Age-specific fecundity trends were triangular, and egg-viability trends were plateau-shaped at all temperatures. Females subjected to STH conditions experienced the highest oviposition peaks early in their adult life. Conversely, lifetime fecundity and longevity were highest at the optimal temperature, whereas egg viability was maximal under STH conditions. Regardless of the temperature they were maintained at, middle-aged females exhibited the highest fecundity and egg viability. Based on these results, despite reducing overall fecundity and longevity, STH conditions enhanced daily oviposition in females, with the peak occurring early in adult life. Additionally, both STH and STC conditions increased percentage egg viability in parthenium beetles.

Information

Type
Research Paper
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of Entomological Society of Canada
Figure 0

Figure 1.Effects of repeated short-term cold stress (STC), repeated short-term heat stress (STH), and optimal temperature (control) on pre-oviposition, oviposition, and post-oviposition periods of Zygogramma bicolorata. Values are mean ± standard error; small letters represent comparison of means amongst the three temperature conditions.

Figure 1

Figure 2.Effects of repeated short-term cold stress (STC), repeated short-term heat stress (STH), and optimal temperature (control) on A, age-specific fecundity and B, age-specific egg viability of Zygogramma bicolorata. Values are mean ± standard error; the lines based on polynomial regression analysis show triangular/plateau-shaped patterns.

Figure 2

Figure 3.Effects of repeated short-term cold stress (STC), repeated short-term heat stress (STH), and optimal temperature (control) on A, lifetime fecundity and B, lifetime egg viability of young, middle-aged, and old females of Zygogramma bicolorata. Values are mean ± standard error; small letters represent comparison of means amongst the three age groups per temperature condition.

Figure 3

Figure 4.Effects of repeated short-term cold stress (STC), repeated short-term heat stress (STH), and optimal temperature (control) on A, lifetime fecundity and lifetime egg viability, and B, female survival curves of Zygogramma bicolorata adults. Values are mean ± standard error; small letters represent comparison of means amongst the three temperature conditions.