TRITROPHIC ASSOCIATIONS AND TAXONOMIC NOTES ON LYSIPHLEBUS FABARUM (MARSHALL) (HYMENOPTERA: BRACONIDAE: APHIDIINAE), A KEYSTONE APHID PARASITOID IN IRAN

An investigation of host associations, distribution and types of reproduction (sexual, asexual) of Lysiphlebus fabarum (Marshall) across 20 provinces of Iran during 2006-2011 was undertaken. The parasitoid was reared from three groups of host aphids belonging to genera Aphis and Brachycaudus, and occasional host aphid genera. Aphis craccivora Koch was the most frequent host aphid for L. fabarum on various host plants, including economically important crops. The field sex ratio generally favored females, but in some cases, only thelytokous (uniparental) populations were found. In those cases, the host was always an Aphis species. Specimens reared from Brachycaudus aphids were all biparental, indicating the presence of a sibling biological species. Overall analysis of diagnostic morphological characters in the forewing indicated intra-specific variability in forewing marginal setae as well as variations in length of the R1 vein.