Age-dependent response of female melon fly, Zeugodacus cucurbitae (Diptera: Tephritidae), to volatiles emitted from damaged host fruits

Authors: PINERO, JAIME - University Of Massachusetts; Souder, Steven; Cha, Dong; COLLIGNON, ROBERT - Eastern Mennonite University; Vargas, Roger

Submitted to: Journal of Asia-Pacific Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2021
Publication Date: 8/25/2021
Citation: Pinero, J.C., Souder, S., Cha, D.H., Collignon, R.M., Vargas, R.I. 2021. Age-dependent response of female melon fly, Zeugodacus cucurbitae (Diptera: Tephritidae), to volatiles emitted from damaged host fruits. Journal of Asia-Pacific Entomology. 24(3):759-763. https://doi.org/10.1016/j.aspen.2021.06.011.
DOI: https://doi.org/10.1016/j.aspen.2021.06.011

Interpretive Summary: Melon fly is one of most destructive invasive pests on cucurbits. An improved understanding of female response to fruit volatiles may help developing a lure for a better detection and control of the female flies. Researchers at USDA-ARS in Hilo, Hawaii and University of Massachusetts studied the attraction of 1 to 4-week old female melon flies to odors from five different host fruits (cucumber, bittermelon, tomato, eggplant, and zucchini) that are intact or physically damaged. Females did not show much attraction to intact fruit odor. For odors from damaged fruit, females preferred cucumber and bittermelon and their attraction to these fruit odors were stronger from older flies than from younger flies. Our results suggest that melon fly female attraction to fruit odor is modulated depending on female age and qualitative and quantitative changes in olfactory cues. This type of olfactory-driven plasticity of melon fly adds another dimension to our understanding of the host seeking behavior and ecology of melon fly.

Technical Abstract: BACKGROUND: Attraction of gravid female herbivorous insects to suitable host plants is mediated largely by olfactory cues. Here, we quantified (1) the innate attraction of female melon fly, Bactrocera (Zeugodacus) cucurbitae (Diptera: Tephritidae) to volatiles emitted by tomato (Solanum lycopersicum), eggplant (S. melongena), zucchini (Cucurbita pepo), bitter melon (Momordica charantia), and cucumber (Cucumis sativus), and (2) the influence of time of damage and female age on the outcome. Fruits exposed to the females were either, intact, or damaged. In addition, we quantified the amounts of selected green leaf volatiles (GLVs) emitted by damaged fruit using GC-MS and investigated female B. cucurbitae responses to (Z)-3-hexen-1-ol and (Z)-3-hexen-1-yl acetate, each at three concentrations. RESULTS: For freshly damaged tomato, eggplant, and zucchini, the level of female response was comparatively low, and the level of response was not affected by female age. For bitter melon and cucumber, higher levels of response to freshly damaged fruit were documented, and the response increased gradually with female age. For cucumber, 70% of the females responded, over a 20-minute period, when females were 4 weeks old. Females did not respond to tomato and cucumber odor when fruits were damaged > 8 hours before testing. In the last test, female B. cucurbitae showed positive responses to (Z)-3-hexen-1-yl acetate. CONCLUSION: The plasticity of the olfactory-driven behavior observed in B. cucurbitae depending on female age and on the strength of the olfactory cues adds another dimension to our understanding of the host-seeking behavior and ecology of this invasive species.