The connectivity of a surface (structural complexity) can have a significant effect on the host finding behavior and efficiency of parasitoids that must search the surface for hosts. We investigated whether the generalist egg parasitoid, Trichogramma nubilale Ertle and Davis (Hymenoptera: Trichogrammatidae), found hosts more efficiently on simple or complex surfaces, and evaluated the potential genetic basis of this variation using a full-sib/half-sib mating design. Of the egg masses parasitized 63.8% were on the simple surface while only 36.2% were on the complex surface. There was significant repeatable variation among females (repeatability =0.59, n=19 females), with some better at finding hosts on simple surfaces and others better on complex surfaces. These results reinforce previous findings that structural complexity can affect host finding by parasitoids. The additive genetic variance in this character was not significant (sires =23, dams =46, progeny =92), but the maternal plus dominance variance (Vm+1/2Vd) was significant (P<0.036), and accounted for 48.8% of the total phenotypic variance. The maternal or dominance effects could have complex evolutionary consequences, causing the evolution of other foraging traits to be retarded, to overshoot their optima, or to have complex selective regimes. Thus, the evolution of foraging behavior may depend strongly on the mechanistic details of foraging behavior, including the effects of structural complexity on host finding.
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Acknowledgements We thank Vid Bhatker for his assistance and insights in collecting these data and David Prokrym for early discussions on the experimental design. We thank B. Rector and two anonymous reviewers for comments on this paper. This work was supported by USDA North Central Regional Research Project 205, Ecology and Management of Stalk Boring Insects of Corn and NSF DMS-0083468.
- Maternal effects
- Plant architecture