Chemicals, sex and sun: how reproductive behaviors of insect pest evolve under climate change and pesticide use?

Funding: Bourgogne-Franche-Comté region

Started in october 2022

Supervisors: Philippe Louâpre & Jérôme Moreau

Abstract

Modern agriculture faces with an exacerbated insect pest pressure in the coming years, partially due to rapid climatic changes. Indeed, the rapid evolution of climate on Earth has deep consequences on agroecosystems, by both impacting crop productivity and pest damages. Therefore, the use of pesticides and other available methods such as mating disruption and the use of natural enemies is expected to increase in the coming years. In the case of Integrated Pest Management (IMP), all these methods are combined with minimal application of chemicals pesticides to control the pests. Then, the current challenge of IMP – which becomes the main paradigm for crop protection in Europe – is to optimize the involved methods by limiting negative interferences between them. For instance, pesticides can impact all the organisms present in agroecosystems (the targeted pests as well as both untargeted pests and auxiliaries) and may have dramatic consequences for other biocontrol methods. They can stimulate immune response of untargeted pest which may increase their pressure of the crops. They can have lethal and sublethal effects on natural enemies, decreasing the performance of biocontrol. They also seem to play pernicious effects on olfactory responses and sexual behaviors of pest insects, that may decrease the efficiency of pheromone-based mating disruption. In the current context of global warming, we hypothesize that such antagonism between methods for the control of crop pests will be exacerbated as temperature is one of the key stone factors determining the life history traits and behaviors of insects. It is therefore essential to evaluate in what extend pesticides interfere with other biocontrol methods in a changing climatic world, to optimize the combination of actions implemented in the field.

The thesis will be devoted to evaluating the sublethal effects of fungicides excessively used in viticulture (copper-based treatments to control grape downy and powdery mildew) on the reproductive traits and behaviors of non-target pest species (GBM – Grape Berry Moth). The GBM, Lobesia botrana (Lepidoptera:Tortricidae) is one of the most harmful viticultural pests in the Palearctic region. Although the mating disruption technique can be used to effectively control L. botrana at low population densities, the technique is not as effective at high population densities, as the ones expected for GBM in the coming years due to climate change. Moreover, climate warming is known to influence sexual chemical signaling and perception in insects, making efficient mating disruption methods more uncertain. On top of that thermal effect, pesticides seem to play pernicious effects on olfactory responses and sexual behaviors of pest insects. Altogether, the thesis will ambition to disentangle the multistress effects of temperature and sublethal effect of fungicides exposure on the non-targeted GBP individuals and population, and to forecast the performance of current monitoring, preventing, and controlling methods under realistic climate change scenarios.

Keywords

Climate change – pesticide – sexual communication – mating disruption – vineyard

Thesis advisory panel

Joffrey Moiroux, Avignon University
Marlène Goubault, Tours University

extrait:

lien_externe:

titre:

« Chemicals, sex and sun » : le changement climatique modifie-t-il la réponse des insectes ravageurs aux pesticides ?

date_de_debut_these:

octobre 2022

nom:

Garinie

date_de_debut_these_numerique:

202210

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kc_raw_content:

Chemicals, sex and sun: how reproductive behaviors of insect pest evolve under climate change and pesticide use?

Funding: Bourgogne-Franche-Comté region

Started in october 2022

Supervisors: Philippe Louâpre & Jérôme Moreau

 

Abstract

Modern agriculture faces with an exacerbated insect pest pressure in the coming years, partially due to rapid climatic changes. Indeed, the rapid evolution of climate on Earth has deep consequences on agroecosystems, by both impacting crop productivity and pest damages. Therefore, the use of pesticides and other available methods such as mating disruption and the use of natural enemies is expected to increase in the coming years. In the case of Integrated Pest Management (IMP), all these methods are combined with minimal application of chemicals pesticides to control the pests. Then, the current challenge of IMP – which becomes the main paradigm for crop protection in Europe – is to optimize the involved methods by limiting negative interferences between them. For instance, pesticides can impact all the organisms present in agroecosystems (the targeted pests as well as both untargeted pests and auxiliaries) and may have dramatic consequences for other biocontrol methods. They can stimulate immune response of untargeted pest which may increase their pressure of the crops. They can have lethal and sublethal effects on natural enemies, decreasing the performance of biocontrol. They also seem to play pernicious effects on olfactory responses and sexual behaviors of pest insects, that may decrease the efficiency of pheromone-based mating disruption. In the current context of global warming, we hypothesize that such antagonism between methods for the control of crop pests will be exacerbated as temperature is one of the key stone factors determining the life history traits and behaviors of insects. It is therefore essential to evaluate in what extend pesticides interfere with other biocontrol methods in a changing climatic world, to optimize the combination of actions implemented in the field.

The thesis will be devoted to evaluating the sublethal effects of fungicides excessively used in viticulture (copper-based treatments to control grape downy and powdery mildew) on the reproductive traits and behaviors of non-target pest species (GBM – Grape Berry Moth). The GBM, Lobesia botrana (Lepidoptera:Tortricidae) is one of the most harmful viticultural pests in the Palearctic region. Although the mating disruption technique can be used to effectively control L. botrana at low population densities, the technique is not as effective at high population densities, as the ones expected for GBM in the coming years due to climate change. Moreover, climate warming is known to influence sexual chemical signaling and perception in insects, making efficient mating disruption methods more uncertain. On top of that thermal effect, pesticides seem to play pernicious effects on olfactory responses and sexual behaviors of pest insects. Altogether, the thesis will ambition to disentangle the multistress effects of temperature and sublethal effect of fungicides exposure on the non-targeted GBP individuals and population, and to forecast the performance of current monitoring, preventing, and controlling methods under realistic climate change scenarios.

 

Keywords

Climate change - pesticide - sexual communication - mating disruption - vineyard

 

Thesis advisory panel

Joffrey Moiroux, Avignon University
Marlène Goubault, Tours University