Oviposition preferences of the Hessian fly and their consequences for the survival and reproductive potential of offspring

1. The relationship between oviposition preference and offspring performanc e was investigated experimentally for the Hessian fly Mayetiola destructor (Say) using 10 grass genotypes that represented five different genera and s ix different species. Oviposition preferences were quantified in a choice t est using arrays of 200-400 plants. Offspring performance was estimated by recording survival during three phases of the insect-plant association and by measuring wing length, a correlate of adult reproductive potential. Dens ity effects were examined for all offspring variables, and were taken into account when offspring performance was compared across the 10 grasses. 2. Egg counts from the oviposition choice test revealed a consistent rankin g of plants: 18ITSN triticale > Otane bread wheat = Caldwell bread wheat = Stacy bread wheat > 3424 bread wheat = PND durum wheat = Fleet barley = Val etta barley = Matua brome grass > Awapuni oat. 3. Survival and adult wing length varied significantly on the 10 plant type s. Survival was ranked: Otane bread wheat > 3424 bread wheat = Fleet barley = Matua brome grass > Caldwell bread wheat = Valetta barley > 18ITSN triti cale = PND durum wheat = Stacy bread wheat > Awapuni oat. Adult male and fe male wing lengths were greatest on Otane, the bread wheat that also provide d the best survival. 4. For Hessian flies on each of the 10 plant types, data on survival, wing length, and wing length-fecundity relationships were combined into a single fitness measure. When these fitness measures were compared with egg counts , no overall pattern emerged. On seven of the 10 plant types, there was a p ositive linear relationship between egg counts and offspring fitness. On th e other three plant types, egg counts were high while fitness was low. Poss ible reasons why Hessian fly females lay eggs on plants that are poor hosts for their offspring are discussed.