Reproductive Compatibility, Mating Behavior, and Random Amplified Polymorphic Dna Variability in Some Aphelinus asychis (Hymenoptera: Aphelinidae) Derived from the Old World

Abstract

Reproductive compatibility, mating behavior, and random amplified polymorphic DNA (RAPID) variability were examined in samples of Aphelinus asychis obtained during foreign exploration for natural enemies of the Russian wheat aphid, Diuraphis noxia (Mordvilko). All specimens were reared initially from Diuraphis sp. collected at several Mediterranean basin localities and 2 localities in Central Asia. Using 7 laboratory cultures, we found 3 reciprocally and completely incompatible groups: the 1st group was represented by a culture from northcentral China, the 2nd group by a Kazakhstani culture, and a 3rd by 5 cultures from the Mediterranean basin (i.e., France, Greece, Morocco, Sicily, and Spain). One instance of partial, 1-way incompatibility was detected among the Mediterranean basin cultures. Behavioral experiments with 3 cultures showed that males respond to the sex pheromone of incompatible females and actively court them. However, females usually did not stop moving or elevate their abdomens in response to courtship by incompatible males. With 1 exception, genital contact and sperm transfer did not occur in incompatible pairings. Thus, rejection of incompatible males or failure to recognize incompatible males by females appeared to be 1 cause of incompatibility. In the exceptional case (Chinese males paired with Kazaklistani females), sperm transfer occurred but at significantly lower frequencies than in control pairings. Phenetic analysis of 61 RAPD loci in 6 laboratory cultures and 3 field samples from the Mediterranean basin delineated the same 3 groups as the compatibility experiment. Further work examining the geographic range, host range, and morphology of the incompatible groups is needed to clarify their taxonomic status.