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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Publications at this Location » Publication #426169
Research Project: Development of New and Improved Surveillance, Detection, Control, and Management Technologies for Fruit Flies and Invasive Pests of Tropical and Subtropical Crops

Location: Tropical Crop and Commodity Protection Research

Title: Egg-load as a physiological factor driving shifts in olfactory preference between protein food and oviposition sites in a synovigenic insect

Author
item KEMPRAJ, VIVEK - University Of Hawaii
item PEREZ-STAPLES, DIANA - University Of Veracruz (VERACRUZANA)
item Cha, Dong

Submitted to: Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2025
Publication Date: 9/3/2025
Citation: Kempraj, V., Perez-Staples, D., Cha, D.H. 2025. Egg-load as a physiological factor driving shifts in olfactory preference between protein food and oviposition sites in a synovigenic insect. Journal of Experimental Biology. 228(19). https://doi.org/10.1242/jeb.250954.
DOI: https://doi.org/10.1242/jeb.250954

Interpretive Summary: Oriental fruit fly (OFF) is among the most destructive invasive pests and trade-barriers of tropical fruits and vegetables worldwide. The frequency of their invasion to agriculturally important U.S. States such as California and Florida has increased recently. As a part of research project to improve the detection of female OFF, researchers at the USDA-ARS and University of Hawaii at Manoa in Hilo, Hawaii and University of Veracruz in Mexico have been investigating factors that influence odor preference of OFF females between protein food (essential for egg development) and egg laying site (host fruit; necessary for population growth). A series of manipulative tests revealed that female flies with a greater number of mature eggs in ovary prefer and are more sensitive to host fruit odor over protein food odor, while female flies carrying fewer mature eggs exhibit an opposite behavior or response. This indicate a critical role of mature egg-load in modulating behavioral odor preference of OFF females.

Technical Abstract: Synovigenic instects, such as fruit fly Bacrtocera dorsalis, alternate between seeking protein-rich food for reproductive development and oviposition sites to maintain optimal fitness. We investigated the factors influencing this shift in olfactory preference using two odor choices: protein (torula yeast, TY) and oviposition site (guava juice, GJ). The experiment consisted of three sequential steps: (1) gravid flies made an initial odor choice between GJ and TY, (2) flies that selected GJ in the first choice were allowed to lay eggs in response to GJ odor, and (3) following oviposition, the flies odor preferences were reassessed, and their egg-load was quantified after the second choice. Among the flies that initially preferred the GJ odor, individuals that laid fewer eggs tended to exhibit a continued preference for GJ odor during the second choice, while those that laid more eggs shifted their preference to TY odor. Dissections following the second choice revealed that flies with fewer mature eggs remaining in their ovaries post-oviposition exhibited a stronger preference for TY, while those retaining more mature eggs continued to prefer GJ. These findings indicate that the mature egg-load at a given moment is a key driver of olfactory preference shifts in synovigenic insects. In contrast, no consistent relationship was observed between immature egg-load and odor preference. Furthermore, electrophysiological analyses demonstrated heightened sensitivity to protein odors in gravid flies with fewer mature egg-load, and an opposite trend in those with a higher mature egg-load, underscoring the critical role of mature egg-load in modulating olfactory preference in B. dorsalis females.