Role of octopamine in the behavioral stress response of the Colorado potato beetle (Leptinotarsa decemlineata)

In agriculture, insect pests are targeted by a wide range of pest management tactics that can be physiologically stressful. Sublethal stress exposure may elicit behavioral variation, including changes in mobility and herbivory, both of which may enhance pest performance. Octopamine is a neurotransmitter that is associated with the insect “fight or flight” response. Elevated octopamine levels can stimulate insect mobility and foraging behavior, and separately, stress exposure has been shown to induce octopamine signaling. However, no studies have directly assessed the link between stress, octopamine, and these phenotypes.


The Colorado potato beetle (CPB) displays an extraordinary ability to tolerate and adapt to stress. The beetle has evolved tolerance to many control tactics including all of the major insecticide classes and resistant varieties. The beetle's history of tolerating stress makes it a good model for examining the relationship between stress and phenotype. We used a factorial design to test whether octopamine mediates stress-induced changes in mobility and herbivory by inhibiting octopamine signaling in third instar CPB larvae following exposure to sublethal stress. Larvae were exposed to an octopamine inhibitor treatment (epinastine) or control (water), coupled with one of two stressors: insecticide (10 ppm imidacloprid) or water control; or a natural predator of CPB (spider) or no-predator control. We predicted that mobility and herbivory would be reduced in response to stress in combination with octopamine inhibition. Developing a better understanding of how octopamine influences the phenotypic expression of stress can inform practices used to manage invasive insect pests.