Study on the ecological control technology against Bemisia tabaci(Gennadius)on facility vegetables

To develop methods to control Bemisia tabaci(whitefly)on protected vegetables,we systematically studied the effects of growing castor-oil plants outside of sunlight greenhouse including chilli,planting celery between rows of tomato,adjusting the planting time,and spraying methyl jasmonate on the chilli.The number of B.tabaci adults and nymphs on greenhouse-grown chilli was reduced by 74.27% and 53.48%,respectively,when castor-oil plants were grown outside of the greenhouse.Using tomatoes harboring B.tabaci at low population density,we grew celery between rows of tomato at tomato-to-celery ratios of 3∶1and 8∶1,which resulted in a reduction in the number of B.tabaci adults of 89.33%and 88.00%,respectively,as well as a 50.00%reduction in the number of nymphs;in tomatoes harboring B.tabaci at high density,the adult population was reduced by 70.61%and 52.25%,respectively,and the nymph population was reduced by 70.21% and 52.36%,respectively.After a single spraying of methyl jasmonate at a concentration of10-4,10-5,10-6 and 10-7 mol·L-1,the number of B.tabaci decreased by 75.08%,58.81%,45.04%and 30.70%,respectively.As the frequency of spraying increased,the number of B.tabaci significantly decreased.In the autumn,the planting time of chilli should be postponed to avoid the peak time at which B.tabaci enters the greenhouse,which would reduce the population density significantly.Compared with an area in which B.tabaci was controlled with imidacloprid,the comprehensive control area(celery,castor and MeJA treatment)showed better performance,and the number of B.tabaci adults and nymphs decreased by 63.4%and 59%,respectively.