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Submitted to: International Rubus Ribes Symposium
Publication Type: Abstract Only Publication Acceptance Date: 6/11/2015 Publication Date: 6/15/2015 Citation: Sampson, B.J., Marshall-Shaw, D.A., Stringer, S.J. 2015. Environmental ethanol as an ecological constraint on the dietary breadth of the Spotted-Wing Drosophila, Drosophila suzukii Mat. (Diptera: Drosophilidae) and its implication for integrated pest management. International Rubus Ribes Symposium. pg.26. Interpretive Summary: Technical Abstract: Spotted-wing Drosophila (SWD), Drosophila suzukii, is a recent exotic insect pest of the Americas. What makes SWD particularly destructive is the female’s double bladed and prominently serrated ovipositor, which inserts eggs below the epidermis of intact berries. Unlike the vast majority of Drosophila species, D. suzukii is not saprophagous, and therefore does not readily colonize damaged and decaying fruit. In saprophagous species, adults and their developing larvae must normally contend with a buildup in ethanol resulting from alcoholic fermentation. Ethanol at low levels can actually serve as a dietary supplement in many drosophilids. At higher ethanol concentrations, however, physiological stress due to increasing toxicity of breeding sites can become a major reproductive constraint for fruit-breeding Drosophila species. Currently, nothing is known about the degree to which D. suzukii can metabolize or catabolize environmental ethanol, which could have important implications for host selection, reproductive potential, chemical control, and the necessity for crop sanitation. Therefore, we designed a series a laboratory experiments and bioassays to address the effect of environmental ethanol on the critical life history traits of D. suzukii feeding on Rubus and Vaccinium: adult survivorship, sex ratio, oviposition rate, host choice, and reproductive output. Our hypotheses included 1) Spotted-wing Drosophila will display a lower tolerance for ethanol, which compromises reproduction and survival when compared with saprophagous species such as D. melanogaster, (2) Both sexes of SWD will be equally susceptible to the toxic effects of higher ethanol concentrations. (3) Ethanol levels in fruit are perceived by females, and eggs are preferentially laid in berries containing no supplemental ethanol, and (4) ADH isozyme activity reflects the disparate dietary niches of D. suzukii, its close relatives (D. biarmipes, and D. subpulcherella), and D. melanogaster. |
