Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2004
Publication Date: 10/1/2004
Citation: Vargas, R.I., Long, J., Miller, N.W., Delate, K., Jackson, C.G., Uchida, G.K., Bautista, R.C., Harris, E.J. 2004. Releases of psyttalia fletcheri (hymenoptera: braconidae) and sterile flies to suppress melon fly (diptera: tephritidae) in hawaii. Journal of Economic Entomology. 97(5): 1531-1539. Interpretive Summary: Melon fly is a serious pest of cucurbit crops in Hawaii and throughout the Pacific. The wasp Psyttalia fletcheri kills immature melon flies. Studies were conducted on the efffectiveness of this natural enemy with and without the use of sterile melon fly releases. It was determined that releases of P. fletcheri should be effective in suppressing melon fly populations when used in conjunction with sterile flies. This information will guide USDA and Hawaii State officials in the use of non-chemical approaches to melon fly control during the area-wide pest management program in Hawaii.
Technical Abstract: Ivy gourd, Coccinia grandis (L.) Voigt, patches throughout Kailua-Kona, Hawaii Island, HI were identified as persistent sources of melon fly, Bactrocera cucurbitae (Coquillett), with a low incidence of Psyttalia fletcheri (Silvestri), its major braconid wasp natural enemy in Hawaii. These habitats were used to evaluate augmentative releases of P. fletcheri against melon fly. In field cage studies of releases, numbers of melon flies emerging from ivy gourd fruits placed inside treatment cages were reduced up to 21 fold and numbers of parasitoids were increased 11 fold. In open field releases of P. fletcheri into ivy gourd patches, parasitization rates were increased 4.7 times in release plots compared to those in control plots. However there was no significant reduction in emergence of flies from fruits. In subsequent cage tests with sterile melon flies and P. fletcheri (sterile melon flies alone, P. fletcheri alone, and combinations), combinations of sterile flies and P. fletcheri produced the greatest reduction (9 fold) in melon fly emergence from zucchini (Cucurbita pepo L.). Results suggest that releases of P. fletcheri with sterile melon flies are a biologically sound approach to suppression of wild melon flies in Hawaii. These non-chemical approaches will be tested further in an area-wide pest management program in Hawaii tha includes releases of P. fletcheri and sterile melon flies.