Phenotypic stress response of Colorado potato beetle unaffected by octopamine inhibition
Semic, Lamija
Semic, Lamija
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Abstract
In agriculture, insect pests are targeted by a wide range of pest management practices that can be physiologically stressful. Sublethal stress 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 of adapting 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 prior to sublethal stress exposure. Larvae were given an octopamine inhibitor treatment (epinastine) or control (water), coupled with one of two stressors: insecticide (imidacloprid) or water control; or a natural predator of CPB (spider) or no-predator control. We predicted that CPB mobility and herbivory would be reduced in response to stress when combined with octopamine inhibition. We observed significant differences in larval survival, mobility, and herbivory only for treatments containing insecticide. Additionally, these changes were not reflected in the larval octopamine levels measured. These findings suggest that the octopamine signaling pathway may not be directly or solely responsible for the phenotypic stress response observed in CPB.
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Date
1/1/2026
Student Status
Senior (Graduating in 2026)
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Poster
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Biological Science
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College of Arts and Sciences
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Life Science