Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2006
Publication Date: November 1, 2006
Citation: Chang, C.L., Vargas, R.I., Jang, E.B. 2006. Development and assessment of a liquid larval diet for Bactrocera dorsalis (Diptera:Tephritidae). Annals of the Entomological Society of America. 99(6):1191-1198. Interpretive Summary: The Oriental fruit fly, Bactrocera dorsalis (Hendel), a worldwide pest, has been mass reared using wheat bran or its products as bulking agents for SIT programs in Hawaii, Taiwan and South East Asia. Wheat bran products present the following problems: inconsistency of quality and water absorbency, pesticide contamination, spent diet management, storage space, high costs, labor intensive, sanitation, non-reusable, and non-recyclable. A fruit fly liquid diet without mill feed (a biological bulking agent) possesses many advantages over the conventional mill feed diet used in Hawaii that include simplified spent diet management and reduced labor and space costs because in the case of liquid diet, most of the diet is consumed and spent diet can be disposed of more easily. The Hawaii Fruit Fly Rearing Facility (HFFRF) in Waimanalo, Hawaii, spends approximately $100,000 to purchase the bulking agent, $100,000 to haul away spent diet, and $250,000 to operate spent diet management per year during production of 300 million pupae per week (S. Stein, personal communication). In addition, liquid diet can be more conveniently used as a medium for testing systemic insecticides (Halanda 1976) and nutritional studies than conventional diet because of its liquid form features. With these in mind, development of a low waste liquid larval rearing diet would be very beneficial for insect research and production. The first fruit fly liquid diet without mill feed as a biological bulking agent was successfully developed in a small-scale melon fly, Bactrocera cucurbitae (Coquillett) larval rearing. Melon flies reared on this diet were able to develop, fly, mate, and reproduce normally; however, there was a slightly lower yield in pupal production (about 80%). The objective of this study was to apply the liquid diet rearing technology to B. dorsalis (Hendel), and evaluate various rearing conditions to maximize large-scale production for Sterile Insect Technology (SIT) programs to control fruit flies.
Technical Abstract: Larvae of Bactrocera dorsalis were reared in a liquid form of diet that does not contain mill feed (a biological bulking agent). Sponge cloth was used as an inert supporting material. Experiments were conducted to assess the rearing conditions in a small (bento) and large scale (lid of pupation box) prepared for factory scale of B. dorsalis larval mass rearing. Optimal rearing conditions include tray size (width, length and depth), tray design (flat or ridge bottom), environmental conditions (temperature, humidity and photoperiod), additives (water, brewer's yeast, wheat germ oil, antimicrobials, and linolenic acid), and mother colony (egg volume/tray, ml) were evaluated based on the following parameters: developmental period, pupal production, pupal weight, adult emergence, flight ability, mating, egg hatch, sex ratio, egg production and egging peak period. Data were analyzed by multivariate analysis of variance using the ANOVA and Proc Univatiate procedure of the SAS statistical analysis software package with honet significant difference (HSD).