QUALITY CONTROL OF FRUIT FLIES: BACTROCERA AND CERATITIS RESEARCH IN HAWAII

Authors: McInnis, Donald; SHELLY, TODD - USDA/APHIS; Jang, Eric; STEIN, STUART - USDA/APHIS

Submitted to: IAEA-FAO Research Coordination Meeting for CRP
Publication Type: Proceedings
Publication Acceptance Date: 5/24/2003
Publication Date: 9/30/2003
Citation: Mcinnis, D.O., Shelly, T., Jang, E.B., Stein, S. 2003. Quality control of fruit flies: bactrocera and ceratitis research in hawaii. Proceedings of the IAEA research coordination program meeting on quality for control of fruit flies, Perth, Australia.

Interpretive Summary: The sterile insect technique (SIT) relies heavily on the quality of released males to find and mate with wild females in the field. Therefore, producing flies of high quality that can withstand the rigors of artificial rearing conditions, irradiation to sterilize, and packing and shipping to the release sites, is critical to the success of the control method. To this end, collaborative research has been undertaken to utilize the benefits of aromatherapy and genetic sexing to greatly improve the efficiency of the SIT. Aromatherapy involves the release of aromas that make the male fly more sexually active or competitive. To date this method has helped the oriental fruit fly male mating by exposure to the male lure, methyl eugenol, while for the medfly exposure to ginger root oil significantly improves mating ability. Genetic sexing, or the ability to separate the sexes through genetic means, has greatly improved the mating quality of oriental fruit flies, medflies, and most recently, the melon fly. In the last year, a new sexing strain was developed for the melon fly - the first such strain in the world. These sexing strains have been shown to improve fly mating ability by 2 ' fold or more, under field conditions against wild flies. The melon fly sexing strain has been successfully used in Hawaii in an ongoing IPM program to help suppress wild populations in private residences and commercial farms.

Technical Abstract: In Hawaii, research has continued to improve tephritid fruit fly quality for the SIT in several areas since the last IAEA/CRP meeting in Mendoza, Argentina (Nov., 2001). Significant improvements of sterile fruit fly quality continued for 2 Bactrocera species, B. dorsalis (oriental fruit fly) and B. cucurbitae (melon fly), plus Ceratitis capitata (medfly). These fly quality improvements were due to the applications of aromatherapy or genetic sexing. Collaborative research on the medfly continued using ginger root oil as the mating stimulant. Studies have focused on the transition from small-scale to large-scale production of insects to be exposed. Results indicated that significant (doubling to several-fold) increases in mating competitiveness were realized in field cage mating tests after mass-reared male tsl flies were exposed to ginger root oil aroma in either standard PARC release boxes or the relatively new pupal eclosion towers developed in Texas. Other tests confirmed that the normal pre-release chilling of flies did not affect the beneficial effect of ginger root oil. Additional field studies continued to study the natural behavioral phenomenon where medfly males aggregate around 'hot spot' stems on guava or citrus trees, and become sexually stimulated as a result. Research on the melon fly or oriental fruit fly continued in the areas of aromatherapy or genetic sexing. For the oriental fruit fly, at the last RCM in Mendoza (Arg.), research results documented the significant beneficial effects of both aromatherapy (with methyl eugenol) and all-male fly releases, based on standard field cage studies in Hawaii and Suriname, S.A. More recently, results have, unfortunately, shown no effect on adult mating performance after larval exposure to methyl eugenol in their diet. Melon fly studies continued with the pupal color sexing strain, now 2 years old. Quality control studies indicated that the strain can mass-rear adequately, and is very competitive with wild flies based on field cage studies of mating ability and survival. An open field study was conducted in 2002 in which melon fly males were released (ca. 150,000/wk) in an agricultural area, as part of an ongoing integrated IPM program. Results indicated that the sexing strain significantly impacted the wild population, causing high, induced sterility in both residential and commercial areas over a 10 mo. period.