Abstract: Acorn weevil (Curculio bimaculatus) is a predominant insect pest of acorns, with the damage being closely related with the quality of acorns. Aiming to provide a theoretical basis for the efficient control of acorn weevils and the breeding of resistant oak species, we examined the relationship between the damage from oak weevil superparasitism, the characteristics of Quercus acorns, and the oviposition strategy of acorn weevils in five widespread Quercus species. The difference of acorn size among normal acorns, single-parasitized acorns, and superparasitized acorns was analyzed by one-way ANOVA (LSD). The difference of larval weight in single-parasitized and superparasitized acorns was compared with ttest. The effect of acorn characteristics on the oviposition preference of adult acorn weevil was analyzed with linear regression model. The results showed that the pericarp thickness of the normal acorns was significantly thicker than that of the damaged acorns by weevils for all the five Quercusspecies (P<0.05). The linear regression model showed that the superparasitic rate was significantly correlated with length, diameter, and volume of the Quercusacorns (P<0.05). There was no significant difference in larval weight between the single-parasitized and superparasitized acorns, as well as the weight of the first and later larvae emerging from the superparasitized acorns (P>0.05). The female C. bimaculatus adults preferred acorns with larger size and thinner pericarp. Although superparasitism increased the number of larvae in a single acorn, the quality of larvae was not affected. These results indicated that female weevils prefer ovipositing on larger acorns to reduce the negative effects of superparasitism. Superparasitism is a behavioral adaptation strategy for acorn weevils.

Key words: Quercus, acorn, Curculio bimaculatus, superparasitism, oviposition strategy.