Population density of cereal aphids parasitoids and their rolein suppressing cereal aphids on wheat plantations at Mansoura district

Abstract

Experiments were carried out in wheat fields of Economic Entomology Department, Faculty of Agriculture, Mansoura‐University, during two successive seasons 1997 and 1998. The cereal aphids, Schizaphis graminum (Rond.), Sitobion avenae (Fabr.), Rhopalosiphum padi (L.) and Rhopalosiphum maidis (Fitch.) are the serious pests of the wheat crop at Mansoura district. Four hymenopterous parasitoid species, namely Aphidius uzbekistanicus Luz., Aphidius matricariae Hal., Praon gallicum Hal. and Aphidius rhopalosiphi De Stefani, were recorded as primary parasitoids on the cereal aphid species. The numbers and ratios of these species were as follows: A. uzbekistanicus 516 individuals (40.8%) in 1997 and 488 individuals (44.2%) in 1998, A. matricariae 350 individuals (27.6%) in 1997 and 286 individuals (25.9%) in 1998, Praon gallicum 231 individuals (18.3%) in 1997 and 192 individuals (17.4%) in 1998, A. rhopalosiphi 168 individuals (13.3%) in 1997 and 139 individuals (12.6%) in 1998. The dominant aphid parasitoids species among them was A. uzbekistanicus during the two seasons of study.