Scientists at The Connecticut Agricultural Experiment Station announced on March 26 that they have identified key cellular and molecular changes in the olfactory system of the spotted wing Drosophila (Drosophila suzukii) that enabled the pest to shift its preference from overripe to fresh, ripe fruit. The findings were published in the Proceedings of the National Academy of Sciences.
Spotted wing Drosophila was first detected in Connecticut in 2011 across 86 towns. Unlike most fruit flies, SWD females have a serrated ovipositor allowing them to lay eggs inside intact, ripening fruit, which can result in maggots developing within marketable crops. This causes significant economic losses for U.S. growers of soft fruits such as berries and cherries, costing hundreds of millions of dollars each year.
Current management strategies depend on frequent insecticide applications that offer limited protection and may harm beneficial insects. CAES scientists aimed to understand the unique olfactory adaptations that allow SWD to exploit fresh fruit. “Beyond addressing a fascinating biological question—how sensory systems evolve to allow an insect to break bad—this work is essential for developing new environmentally benign tools to reduce the damage caused by this pest,” said Jason C. White, Director of The Connecticut Agricultural Experiment Station.
Dr. Hany K. M. Dweck, lead contact and head of the Chemical Ecology Laboratory in the Entomology Department, said, “We screened every olfactory neuron in SWD and its relatives to identify the neurons that have changed specifically in SWD. We observed functional changes in a small subset of olfactory neurons, characterized by a loss of responses to several fermentation-related volatiles and a gain of sensitivity to fruit-ripening and green-leaf volatiles. This shift in sensory tuning may help explain the species’ shift in preference toward ripe fruit.” Dr. Qi Xue, first author and postdoctoral scientist at CAES, added: “After identifying the olfactory neurons that differ in their odorant responses in SWD compared with its relatives, we used molecular genetics, protein modeling, and gene editing to uncover the mechanisms underlying these changes.” Xue explained how one odorant receptor expanded into four copies expressed across two neuron types; this adaptation enables detection of both fruit-ripening esters and green-leaf volatiles instead of only fermentation-associated compounds.
The research team used CRISPR/Cas9 gene editing combined with behavioral assays to demonstrate that two odorant receptors are essential for locating fresh ripe fruit. Dr. Dweck said: “Understanding the olfactory pathways involved in locating ripe fruit enables strategies similar to those used in drug discovery for treating diseases—such as chemoinformatics, artificial intelligence, and molecular docking—to screen millions of compounds and identify those that act on these pathways. These compounds can then be used to develop lures for monitoring and managing SWD populations.” The Connecticut Agricultural Experiment Station receives support from its Research Foundation, a 501(c)(3) nonprofit organization; it was also the first agricultural experiment station established in the United States.
The Connecticut Agricultural Experiment Station maintains its main campus in New Haven and is governed by an eight-member Board of Control under statutory authority according to its official website. The institution focuses on research and education addressing agricultural, public health, and environmental challenges while aiming to enhance quality of life through scientific inquiry as reported by its official website. More information about this study is available on the official roster page.
