Effect of Faba Bean Weeds on The Population of Cowpea Aphid Aphis craccivora (koch.) And it’s Associated Predatory Insects

These trial was carried out to study the influence of weed cover on population abundance of Aphis craccivora (Koch.) (Hemiptera: Aphididae) and its associated predatory insects in faba bean fields during two successive growing seasons (2012/13 and 2013/14). The population abundance of cowpea aphid A. craccivora in weedy fields of faba bean reached the highest (99.25 and 93.75 individuals) populations during the two successive seasons, respectively. While, in free weedy fields, the highest populations of A. craccivora were 32.75 and 51.25 individuals during the two years, respectively. Results of statistical analysis showed that there was a significant difference in the average number of A. craccivora between weedy and free-weedy fields in the first and second seasons of plantation with the highest averages in weedy fields. The main predatory insects associated with A. craccivora in weedy faba bean fields or free weedy fields were Chrysoperla carnea (Steph.), Coccinella undecimpunctata L., Paederus alferii Koch., Scymnus syriacus Muslant and Orius laevigatus (Fiber). Weeds almost had significant effect of the number of observed predatory adults in faba bean fields. Further, the number of attracted predators to faba bean plants differed significantly in weedy fields during both seasons, but did not in free-weedy fields specifically in the first season.