African fig fly, Zaprionus indianus Gupta (Diptera: Drosophilidae), is originally from the Afrotropics but has been expanding its geographical range globally, including the United States. It was first reported in Virginia northward in 2012. The current established range of African species is thought to be limited to the southern states in winter, and populations must disperse northward each season. Adults are normally caught in Virginia in mid-summer and later. African fig fly is a competitive invader and affects the dynamics of native drosophilid communities when it invades a new area. While lacking the hardened, serrated ovipositor seen in spotted-wing drosophila, another invasive frugivore, it may come to outnumber that species in commercial plantings. It can lay eggs and develop in many kinds of fruit that have been otherwise injured. However, the ovipositing fly may take advantage of oviposition sites of spotted-wing drosophila, thereby allowing entry of African fig fly larvae, which may outcompete the original inhabitants. Furthermore, African fig fly may be able to infest certain soft-fruit hosts. Biological control in North America and Europe is limited at this time by immunological responses of host larvae; naturally occurring parasitoids have been unable to achieve significant parasitization.

Drosophila suzukii (Matsumura) is an agricultural pest that has been observed co-infesting soft-skinned fruits with Zaprionus indianus Gupta. The characterization of olfactory preferences by species is a necessary step towards the development of species-specific attractants. Five olfactory attractants were used to survey the populations of two invasive drosophilids in cherimoya in Maui, Hawaii. The attractants used were apple cider vinegar (ACV), brown rice vinegar (BRV), red wine (RW), apple cider vinegar and red wine (ACV+RW; 60/40), and brown rice vinegar and red wine (BRV+RW; 60/40). For D. suzukii, BRV+RW resulted in more captures than BRV, ACV, and RW, while ACV+RW resulted in more captures than ACV. No differences were observed between BRV+RW and ACV+RW. BRV had greater specificity in attracting D. suzukii compared to ACV, ACV+RW, and RW. For Z. indianus, no significant differences were observed in either the mean captures or specificity for any attractant used. Collectively, these findings demonstrate that (1) BRV and BRV+RW are effective field attractants and (2) D. suzukii has unique olfactory preferences compared to non-target drosophilids, while (3) Z. indianus’ preferences do not appear to vary from non-target drosophilids, and (4) the accuracy of relative abundance is impacted by the specificity of the attractants.