Abstract
Background:
Environmental changes and rising temperatures have intensified the emergence of insect species as significant agricultural pests. Understanding the physiological and molecular responses of these pests to heat stress is essential for developing effective pest management strategies.

Aim:
To investigate the antioxidant enzyme activities and gene expression profiles of Ceratitis capitata under heat stress, spinosad exposure, and their combination to understand adaptive mechanisms and potential pathways for pest control.

Methods:
In this study, adult Ceratitis capitata were collected from grapes (Vitis mustangensis), mangoes (Mangifera indica), and yellow guava (Psidium guajava) cultivated in Egypt during June, July, and August 2023. Laboratory experiments assessed antioxidant enzyme activities (SOD, CAT, POD, MDA, and GST) and gene expression levels of heat-shock protein 70, cytochrome P450, CYP6a9, and metallothionein. Adults were exposed to three conditions; high temperature (40°C); spinosad at its LC50 (3.2 µg/mL) at 25°C, and combined spinosad exposure and high temperature.

Results:
Heat stress significantly increased the activity of antioxidant enzymes and the expression of stress-response genes in C. capitata. Spinosad exposure induced moderate increases in these activities, suggesting a detoxification response. The combined treatment of spinosad and heat stress amplified these effects, indicating a synergistic stress response.

Conclusion:
These findings provide insight into the molecular mechanisms underlying C. capitata’s heat tolerance and suggest potential pathways for pest control interventions under climate change.

Key words: Fruit fly, Ceratitis capitata, Heat-shock proteins, Antioxidant enzymes, Spinosad