Thermal “red flags”: impact of global warming and fungicide exposure on mate selection and reproductive behaviour of Lobesia botrana

Abstract

While climate change and pesticide use expose insect pests to multiple stressors, their combined effects remain poorly studied. Rising temperatures can accelerate insect life cycles and alter reproductive behaviours, while pesticides can impair physiological functions, reproduction, and survival. Understanding how global warming and pesticide exposure interact is crucial for predicting pest population dynamics and their impact on agroecosystems. As mating behaviour, including mate choice, plays a fundamental role in population growth, studying how these combined environmental stressors influence reproduction is critical. This study investigated how Bordeaux mixture fungicide affects the development, mating behaviour of Lobesia botrana under current (2002–2021) and projected (2081–2100) climatic scenarios. Larvae were reared with two fungicide concentrations and under two climatic conditions. Larval mortality, development time, and adult longevity were monitored. Mating behaviour was assessed using no-choice and choice experiments, measuring pre-mating latency, mating success and duration, fecundity and fertility. Key life parameters (R₀, T, Dₜ, rₘ, and λ) were estimated to investigate population dynamics. Results show that fungicide exposure negatively affected the development and survival of larvae until emergence, but these effects were modulated by climatic conditions. While Bordeaux mixture exposure prolonged development time, future climatic conditions shortened development time compared to current conditions. Choice experiments revealed that under future conditions, moths preferred unexposed partners, whereas no preference was observed under current conditions. These findings emphasize the importance of integrating climate change effects into pesticide risk assessments, as their interactions may have unexpected consequences for pest populations and sustainable management strategies in agroecosystems.