BIOLOGY OF APHELINUS-SPIRAECOLAE (HYMENOPTERA, APHELINIDAE), A PARASITOID OF THE SPIREA APHID (HOMOPTERA, APHIDIDAE)

The biology of nonindigenous Aphelinus spiraecolae Evans & Schauff on spirea aphid, Aphis spiraecola Patch, was investigated in Florida. Rep roduction, fecundity, longevity, oviposition, and host feeding behavio r were examined in the laboratory. A. spiraecolae showed a distinct pr eference for 1st- and 2nd-instar spirea aphids for both oviposition an d host feeding, although all aphid life stages were acceptable. Longev ity 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 less than or equal to 30 s indicated nonacceptance for host feeding and oviposition, whereas inse rtion time of 31-120 s was correlated with oviposition, and >120 s ind icated host acceptance for feeding but not for oviposition. A. spiraec olae was confirmed to be arrhenotokous. The intrinsic rate of increase was 0.33 female offspring per female per day, the net reproductive ra te was 67.3 female progeny, and population doubling time was 1.8 d. Th ese data indicated that A. spiraecolae has a high intrinsic rate of in crease, good host discrimination and preference for young life stages of spirea aphid, and suggests that A. spiraecolae has potential as a n atural enemy of spirea aphid.