Biotic interactions govern genetic adaptation to toxicants

Area of Science:

• Ecology
• Evolutionary Biology
• Environmental Science

Background:

• Environmental stressors can accelerate the genetic recovery of pesticide-resistant populations.
• The role of environmental stressors in the spread of pesticide resistance and their interactive effects remains understudied.

Purpose of the Study:

• To investigate how different types of environmental stressors (intraspecific competition, interspecific competition, predation) influence the microevolution of pesticide resistance.
• To determine the consequences of interactions between different stressors on the development and reversal of pesticide resistance.

Main Methods:

• Experiments using mosquito populations (Culex quinquefasciatus) exposed to the pesticide chlorpyrifos.
• Introduction of stressors: intraspecific competition, interspecific competition (Daphnia magna), and non-selective predation (harvesting).
• Application of a simulation model to generalize findings on microevolutionary dynamics.

Main Results:

• Intraspecific competition accelerated microevolution by enhancing fitness differences between adapted and non-adapted individuals.
• Interspecific competition and predation delayed the selection of the ace-1(R) resistance allele in chlorpyrifos-exposed mosquitoes.
• Predation also delayed the adaptation to non-toxic conditions, while interspecific competition had no significant effect.
• Simulation models confirmed that competition and predation type/degree generally determine microevolutionary trajectories.

Conclusions:

• The type of environmental stress significantly influences the pace of pesticide resistance evolution.
• Interactions with other species, particularly in high-biodiversity ecosystems, can substantially delay the development of pesticide resistance.
• Understanding these ecological interactions is crucial for predicting and managing pesticide resistance in pest populations.