Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2007
Publication Date: 4/25/2007
Citation: Chang, C.L. 2007. Evaluation of yeast products in fruit fly adult diet and liquid larval diet. Symposium Proceedings.
Interpretive Summary: A production of low cost but high quality sterile insects is required for a success of SIT programs. Yeast-based products are the main nutritional component in the diet used to mass-rear the adults and larvae of fruit flies in SIT programs. Brewer’s yeast, Saccharomcyes cerevisiae, and torula yeast, Candida utilis, are the two most commonly used yeasts in fruit fly mass rearing. We have been using brewer’s yeast from Vienna Austria, but it would not be feasible to import it into Hawaii. Therefore, screening for other cost-effective yeasts for adult and larval diet became a priority. We have recently developed a "liquid" larval diet, that alleviates the need for a bulking agent, to replace the currently used "USDA standard" artificial diet for fruit flies (mill feed), which primarily consists of sugar, protein and a bulking agent. If the liquid diet is incorporated into a mass-rearing facility, the costs associated with the disposal of the standard diet can be reduced, and will save potential space and lower environmental impact. In this study, we evaluated 14 yeasts and yeast products for use in the adult, and 21 yeasts and yeast products for use in the adult and liquid larval diet formulation respectively, to determine the best product, and compared various biological developmental parameters to the standard "mill-feed" diet.
Technical Abstract: Several yeasts and yeast products were tested as components of adult diet for Medfly, Ceratitis capitata, Oriental fruit fly, Bactrocera dorsalis, and Melon fly, Bactrocera cucurbitae and larval liquid diet for Oriental fruit fly, Bactrocera dorsalis in mass rearing process. Three hydrolyzed yeasts (FNI LS65, FNI200, FNI210), a glutamine enriched yeast (G, also named Fermaid SuperRelax), an enriched high vitamins yeast (R), Korea yeast, whole cell yeast (LBI2240 series), and nine yeast products (200G, 200R, 200GR, 65G, 65R, 65G R, 210G, 210R, 210GR) were evaluated. Adult flies that were fed on a diet with 210GR produced the highest number of eggs in all three tested fruit fly species. However, no significant difference was seen in egg hatch among these yeast products in comparison to the control. When these yeasts were incorporated into a liquid larval rearing diet, 200 and 65 showed significant difference from 210 and Korea yeast, but with the addition of G and/or R, 200G and 65G performed the best. Among the larvae reared in the diet with 200G, 65G and torula yeast, those reared with FNI LS65+G added wheat germ oil (W) developed the best. In order to select the most cost-effective yeast for liquid diet, 65GW was combined with whole cell yeast (LBI2240 series) and compared to the control diet. A ratio of 3:1 of LBI2240 and FNI LS65 (224065W) was selected as the most cost effective yeast for Bactrocera dorsalis liquid larval diet based on cost and performance parameters evaluated in this study.