Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2000
Publication Date: 7/1/2000
Interpretive Summary: Fruit flies (Tephritidae) are among the most important pests of fruits and vegetables in the tropics and subtropics. In addition to destroying crops, they are responsible for quarantines that hinder the development of agricultural-export economies. One means of protecting commercially grown fruit, and making fruit grown for local consumption more palatable, may be to suppress fruit fly populations through the release of large numbers of mass-reared insect natural enemies (parasitoids). In much of Latin America the tephritids Anastrepha obliqua and A. ludens attack mangos and other fruits. Often the flies that cause commercial damage originate in gardens and wild vegetation surrounding groves. An experiment was performed to see if +-940 parasitoids (Diachasmimorpha longicaudata)/ha released by air over mango groves and adjacent areas could lower the numbers of tephritids. Parasitism in the release areas was significantly higher than in nearby control areas. In release areas there were 2.7 fold fewer adult flies captured in non-commercial (back-yard) orchards surrounding the commercial groves. These results suggest that augmentative releases of parasitoids may provide a non-chemical means of managing pest flies in Mexico and elsewhere.
Technical Abstract: In southern Mexico, the braconid parasitoid Diachasmimorpha longicaudta (Ashmead) was released by air over 1600 ha of commercial mango orchards, backyard orchards, and patches of native vegetation in an attempt to suppress populations of the pest tephritids Anastrepha ludens (Loew) and A. obliqua (Macquart). Releases were made from a helicopter at a rate of +-940 0insects / ha during the mango production cycle (35 weeks) of two consecutive years. A control and release area, 7 km apart, were compared. In the second year the treatments were reversed. In addition to adult trapping, fruits were sampled in order to assess parasitism levels. Highly significant differences in percent parasitism were found between release and control zones in backyard gardens. Furthermore, adult trapping indicated a 2.7 fold suppression of Anastrepha populations in backyard orchards. No such effect was observed in commercial orchards, probably because of very low fly densities. Overall, populations of A. obliqua were suppressed to a greater extent than those of A. ludens. This may be due to differences in the host fruits exploited by the two species. By suppressing pest flies in marginal areas, such as non-commercial groves and backyard gardens, the number of flies moving into commercial groves may be reduced.