Fourth International Bemisia Workshop International Whitefly Genomics Workshop
Isolation of Bacillus thuringiensis Strain from Kuwait’s Soil Effective Against Whitefly Nymphs
Biotechnology Department, Kuwait Institute for Scientific Research, Shuwaikh, Kuwait. Correspondence: yshayji@kisr.edu.kw
The whitefly Bemisia tabaci Gennadius is considered one of the most important insect pests attacking vegetable crops in the greenhouse and outdoors in Kuwait. Current tactics to manage this pest are largely based on insecticide applications. However, recent concern of Gulf countries about the side effects of chemical pesticides on the environment has resulted in the restriction in the use of these products. Biological controls, using Bacillus thuringiensis (Bt) have proven to be a valuable alternative to conventional insecticides. In this respect, we have successfully isolated a strain of Bacillus thuringiensis capable of producing toxins when grown at two different temperatures 30°C and 50°C active against this serious pest that affects crop production in Kuwait. Laboratory studies were conducted to determine the insecticidal effects of this isolated strain grown at the two temperatures on the 1st instar nymphs of B. tabaci. The mortality percentages were 68.2% and 60.0% for the two temperatures respectively, at a concentration of 500μg/ml. Further tests will be followed to study the effect of the toxin on the other stages of Bemisia and to clarify the mode of action of this toxin against this sucking insect. We also found that this strain exhibits insecticidal effects on the aphid Aphis gossypii and the leaf miner, Liriomyza bryoniae. When Bt toxin was grown at 30°C and 50°C, the mortality percentages of aphid nymphs were 93.3 % and 90.0 % respectively and of leaf miner pupae were 88.9% and 77.8% respectively.