Impact of hymenopterous parasitoids (Hymenoptera: aphidiidae) attacking the cowpea aphid, Aphis craccivora Koch (Homoptera: aphididae) infesting broad bean plants at Assiut governorate

The present study was carried out in Refa village at Assiut governorate during 2017-2018 and 2018-2019 seasons. The role of primary parasitoids attacking the cowpea aphid was evaluated under field conditions. The obtained data revealed that, the population density of the cowpea aphid began to appear on the faba bean plants after one month of sowing and developed progressively up to the end of March. The start of warming weather seems to be the favorable condition for development and multiplication of the cowpea aphid, Aphis Craccivora Koch. In addition, the rapid increase of the pest during the vegetative growth of the plants might be related to suitability of the host plants in these stages. Four species of primary parasitoids; Aphidius colemani Viereck, Aphidus matricaria (Haliday), Diaretella rapae (M'Intosh) and Paraon necans (Mackauer) were recorded and identified belonging to family Aphidiidae. Furthermore, two hyperparasitoid species belonging to two families, Cynipidae; Alloxysta sp. and Pteromalidae, Oachyneuron sp. densities tended to rise and fall in synchrony and there was a marked increase in number of mummified aphids at start of the aphid population decline.