Interaction between Dinarmus basalis and Anisopteromalus calandrae (Hymenoptera: Pteromalidae) at different parasitoid densities on Callosobruchus chinensis (Coleoptera: Bruchidae) in red lentil seeds

Abstract

Lentil seeds infested with Callosobruchus chinensis (Linnaeus) for 12–15 days were exposed to Dinarmus basalis (Rondani) alone, Anisopteromalus calandrae (Howard) alone, or to both species, at densities of 2, 4, 8, 16 and 32 insects. Intra-specific competition and host emergence decreased with increasing parasitoid density in both D. basalis and A. calandrae, but progeny production of the parasitoids and parasitoid-induced mortality (PIM) increased with increasing parasitoid density. Dinarmus basalis was much more efficient in parasitizing C. chinensis than A. calandrae. Emergence of D. basalis and A. calandrae, and the PIM were highest at a parasitoid density of 32. Parasitoid density and a combination of parasitoids significantly (P<0.01) affected the number and progeny sex ratio of emerged parasitoids. There were significant (P<0.01) effects of inter- and intra-specific competition on host mortality. Host mortality increased with increasing parasitoid density. Parasitoid combination and parasitoid density also significantly affected PIM.