Estimation of the competitiveness of Ephedrus plagiator in relation to other parasitoids from the subfamily Aphidiinae

Abstract

The parasitoid species Ephedrus plagiator (Nees, 1811) (Hymenoptera: Aphidiinae) is one of the most important biological agents against pest aphids. We investigated whether this species was in competition with some other aphidiine species for the same hosts. We thus examined its role in biological programs to control aphids. We applied an unsupervised artificial neural network, a self-organizing map (SOM), which classified the competitive parasitoids into seven groups. The SOM also visualized the distributional pattern of 31 parasitoid wasps along the neural network, revealing their competitive ability in relation to E. plagiator. Indicator value (IndVal) analysis quantified the competitive ability and showed that the most competitive species with regard to E. plagiator were Lysiphlebus testaceipes (Cresson, 1880), L. fabarum (Marshall 1896), L. cardui (Marshall 1896) and Binodoxys angelicae (Haliday, 1833). These species appeared in four different SOM groups and mostly parasitized the Aphis fabae Scopoli, 1763 (Hemiptera: Aphididae) host.