Influence of Ovipositional Resource Quality on Fecundity of the Seedcorn Fly (Diptera: Anthomyiidae)

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Abstract
In the presence of ample food and water, host-deprived seedcorn fly, Delia platura (Meigen), females laid half as many eggs during their lifetimes as did flies exposed to germinating lima beans, which provide strong ovipositional stimuli for seedcorn flies. In addition, host-deprived D. platura matured eggs at about half the rate of undeprived flies and took twice as long to begin ovipositing. We conclude that germinating lima beans acted as a strong reproductive “primer” for seedcorn fly females. Seedcorn flies exposed to beans until 2 d after first oviposition and then offered only moist sand as ovipositional sites deposited eggs at half the rate of their undeprived counterparts for 4 d; for the remaining 6 d of the experiment, egg deposition for the host-deprived group rebounded to 22 eggs per d. Although compensations in release rates for well-primed D. platura can occur in a few days, the cumulative effects of depriving D. platura of highly suitable ovipositional sites are pronounced over a lifetime, giving credence to the notion that highly unpreferred host plants might exhibit partial resistance in a no-choice situation.