# Geographic Divergence in Heat Tolerance and Cross-Generational Responses of the Invasive Mealybug Dysmicoccus neobrevipes

## TL;DR

This study shows how mealybug populations from warmer regions are better at surviving heat stress and how heat exposure can affect future generations.

## Contribution

The study reveals geographic variation in heat tolerance and cross-generational effects in an invasive mealybug under acute heat stress.

## Key findings

- Mealybug populations from warmer regions showed higher heat tolerance and better reproduction.
- Heat stress had nonlinear effects, with moderate heat sometimes improving performance but extreme heat causing rapid declines.
- Parental heat exposure influenced offspring survival and reproduction, indicating cross-generational effects.

## Abstract

Understanding how insects cope with extreme heat is essential due to continual global warming. Here, we examined four local geographic populations of the invasive mealybug Dysmicoccus neobrevipes from southern China and compared their responses to acute high-temperature stress. Under acute high-temperature stress, populations from warmer regions (Guangdong and Hainan) showed higher heat tolerance, better survival, and more stable reproduction than those from cooler areas (Guangxi and Yunnan). Moderate heat sometimes improved survival and reproductive performance, but temperatures beyond physiological limits caused rapid declines in both traits. Heat stress also affected the next generation, indicating that thermal conditions experienced by parents influenced offspring performance. These findings demonstrate that local climate conditions shape population-level thermal adaptation and that heat tolerance involves nonlinear physiological limits and life-history trade-offs. The results aid in predicting future population expansion under global warming and provide guidance for region-specific pest management strategy development.

As a result of global climate change, insects are increasingly being exposed to extreme temperature events; yet population-level variation in heat tolerance and its underlying mechanisms remain poorly understood. In this study, we investigated thermal adaptation in four geographically distinct populations of the invasive mealybug Dysmicoccus neobrevipes from southern China. The populations were subjected to acute heat stress across a gradient of temperatures where survival, fecundity, offspring viability, and sex ratio were quantified. We found pronounced geographic divergence in upper thermal limits: populations from warmer regions (Guangdong and Hainan) exhibited better survival, more stable reproductive output, and greater tolerance in offspring compared with populations from cooler regions (Guangxi and Yunnan). Thermal responses followed a nonlinear pattern, with moderate heat often enhancing performance, while temperatures above physiological thresholds triggered abrupt declines. Under heat stress, life-history strategies differed among populations, with some exhibiting stress-induced reproductive investment and others showing vulnerability across all traits. Importantly, acute heat exposure produced cross-generational effects, highlighting that parental thermal history can influence offspring performance. These results demonstrate that population-specific climatic adaptation, nonlinear physiological limits, and life-history trade-offs jointly shape thermal tolerance. Understanding these mechanisms provides a predictive framework for anticipating invasive pest expansion under future climatic warming and informs region-specific pest management strategy development.