Biology of Aphelinus spiraecolae (Hymenoptera: Aphelinidae), a parasitoid of the spirea aphid (Homoptera: Aphididae)

Abstract

The biology of nonindigenous Aphelinus spiraecolae Evans and Schauff on spirea aphid, Aphis spiraecola Patch, was investigated in Florida. Reproduction, fecundity, longevity, oviposition, and host feeding behavior were examined in the laboratory. A. spiraecole showed a distinct preference for 1st- and 2nd-instar spirea aphids for both oviposition and host feeding, although all aphid life stages were acceptable. Longevity of A. spiraecolae was 17.8 ± 1.6 (mean ± SEM) d, fecundity was 138.2 ± 16.2 eggs, and the parasitoid consumed 27.1 ± 4.0 aphids per lifetime. Ovipositor insertion time of ≤30 s indicated nonacceptance of host feeding and oviposition, whereas insertion time of 31-120 s was correlated with oviposition, and >120 s indicated host acceptance for feeding but not for oviposition. A. spiraecolae was confirmed to be arrhenotokous. The intrinsic rate of increase was 0.33 female offspring per female per day, the net reproductive rate was 67.3 female progeny, and population doubling time was 1.8 d. These data indicated that A. spiraecolae has a high intrinsic rate of increase, good host discrimination and preference for young life stages of spirea aphid, and suggests that A. spiraecolae has potential as a natural enemy of spirea aphid.