This study aimed to evaluate the effect of certain factors on population of Thrips tabaci & Bemisia tabaci on common bean Phaseolus vulgaris (polesta cultivar) in relation to certain weather factors with regard to their natural enemies.
The results showed that during two seasons' survey 8 insect pests belonging to 5 families under 4 orders and 2predators. However Order: Thysanoptera: Thripidae, Thrips tabaci, Order: Hemiptera: Aphididae, Aphis craccivora and Aleyrodidae, Bemisia tabaci, Order: Diptera: Agromyzidae, Ophiomyia phaseoli, Melanogromyza phaseoli and Lirimyza trifolii as insect pasts and Order: Lepidoptera: Noctuidae, Spodoptera litoralis, as insect visitors. However Order: Coleoptera: Coccinellidae, Coccinella undecim punctate, and Neuroptera: Chrysopidae, Chrysoperla carnea were represented by the most famous predators under Egyptian condition in addition to 2 prevailing climatic factors (temperature, relative humidity). These two pests; T. tabaci and B. tabaci were recorded three beaks during 1st and 2nd seasons. The means number of tested insect pests was higher during second season than the first seasons. T. tabaci and B. tabaci began start appear in the 2nd week of December, late January and the 3 week of 1st week of March in two successive years, these insects are dangerous insect pests in P. vulgaris plants fields. The combination effect of climatic factors and plant age and natural enemies on T. tabaci & B. tabaci population density was presented as explained variance which was 67 and 90% of T. tabaci and 88 and 89% of B. tabaci in the 1st and 2nd seasons, respectively.