EFFECT OF PLANTING DATE AND CERTAIN WEATHER FACTORS ON THE POPULATION FLUCTUATIONS OF THREE INSECT PESTS INFESTING KIDNEY BEANS IN QUALYOBIA GOVERNORATE

Two field experiments were carried out in Qualyobia governorate during 1995 and 1996 seasons. Each experiment was planted in one feddan divided into four equal parts and cultivated by kindney beans in four different planting dates; during March, April, May and June. The number of eggs and nymphs of Bemisia tabaci (Hemiptera: Aleyrodidae), nymphs of Aphis craccivora (Hemiptera: Aphididae) and larvae of Mela-nagromyza phaseoli (Diptera: Melanagromyzidae) were recorded. The population of the immature stages of Bemisia tabaci was lower on March planting, while on May planting of Aphis craccivora and Melanagromyza phaseoli populations recorded the lowest levels. The effect of three weather factors; day maximum temperature, night minimum temperature and daily mean relative humidity on the pop‌ulation fluctuations of the three pests was studied. Minimum night tem‌perature had a highly significant effect on the number of immature stag‌es of B.tabaci. Minimum night temperature and maximum day temperature had a significant effect on A.craccivora. The three tested weather factors had insignificant effect on M.phaseoli population. The combined effect of the three tested weather factors was low effect on B.tabaci eggs (1.7-11.8 % explained variance), little bit high and slightly higher on nymphs (5.83-23.7%). The effect of the three tested weather factors was rather stronger on A.craccivora nymphs (44.83, 83.1, 44.85%) explained vari‌ance.