EFFECTIVENESS OF SOME SYNTHETIC INSECTICIDES AGAINST THE WHITEFLY, Bemisia tabaci ON TOMATO, Lycopersicon esculentum MILL. AND INFESTATION IMPACTS ON CERTAIN PHOTOSYNTHETIC PIGMENTS CONCENTRATIONS OF TOMATO PLANT LEAVES

Abstract

Field experiments were carried out at Al-Quaren village, Sharkia governorate during seasons 2016 and 2017 to evaluate the efficiency of three synthetic insecticides belonging to two groups, synthetic pyrethroid (lambda-cyhalothrin) and neonicotinoids (thiamethoxam and acetampride) towards the tomato whitefly, Bemisia tabaci on tomato crop. As for, estimation of certain pigments content of fresh tomato leaves (chlorophyll a, chlorophyll b and carotenoids) had been conducted. The experiments were verified on randomized complete block design (RCBD) with three treatments Viz., T1; thiamethoxam (Actara 25% WP, 0.58g/2.88L),T2; acetampride (Mospilan 20 % SP, 0.72g / 2.88L), T3; lambda-cyhalothrin (Cyhalothrin 5% EC, 1.44 Cm 3/2.88L) and control. All treatments were repeated three times. The results revealed that all treatments of whitefly populations dropped in appreciable levels during 2016 and 2017 seasons. Furthermore, the results showed that the treatment after spraying with lambda –cyhalothrin gave the highest reduction in whitefly populations followed by 86.61, 71.99 and 67.80%, respectively, within 14 days of post- treatment. Respecting the impact of B. tabaci infestation on tomato pigments, the results showed that there were highly significant differences in all the mean content of pigments (chlorophyll a, b and carotenoids) in intact tomato leaves compared with the infested tomato leaves. The mean contents of chlorophyll A, B and carotenoids in intact tomato leaves were 9.155±0.134, 2.355± 0.126 and 2.436± 0.053 mg/g fresh tomato leaves, respectively, while in infested tomato leaves were 8.427± 0.710, 2.053± 0.288 and 2.759± 0.274 mg/g fresh tomato leaves, respectively. In conclusion, it could be recommended using lambda-cyhalothrin besides thiamethoxam in combating the tomato whitefly, B. tabaci, in integrated pest management (IPM).