Host exploitation and contest behavior in a generalist parasitoid partially reflect quality of distinct host species

Abstract

Information use determines parasitoid adaptive behavior in general, and host specialization or fitness in specific. Information regarding host suitability could affect sex allocation behavior, host exploitation, or aggressiveness in dyadic contests. In this paper, we relate aggressiveness of the pupal parasitoid Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae) with sex allocation and host exploitation when presented with different host species. More specifically, we presented parasitoids with puparia of five different Dipteran species: Drosophila melanogaster (Drosophilidae), Musca domestica (Muscidae), Anastrepha obliqua, Anastrepha fraterculus, and Ceratitis capitata (Tephritidae). Puparia of above species greatly varied in size and volume, were parasitized to differing extent and had varying fitness implications for P. vindemmiae. Using a composite measure of selected fitness currencies (i.e., parasitism level, offspring size, longevity and sex ratio), we typified D. melanogaster and A. obliqua as ‘low quality’ hosts for P. vindemmiae while puparia of C. capitata and A. fraterculus were considered of ‘high quality’. In contest dyads, female aggressiveness and host exploitation behavior differed between host species. Wasps exhibited highest frequencies of antennal striking and rival pursuit, and high degrees of puparium mounting, antennating and probing on C. capitata. Antennal striking frequency however was equally high on ‘low quality’ hosts such as D. melanogaster and A. obliqua. This work shows that a generalist parasitoid such as P. vindemmiae assesses host quality when confronted with hosts of differing species, size or nutritional suitability and employs such to define sex allocation, host exploitation, and contest behavior. However, contest and exploitation behavior only partially indicate host quality and broader parasitoid fitness implications. This work has further implications for parasitoid mass rearing and use of P. vindemmiae for biological control of Dipteran pests.