Persistence of Bacillus thuringiensis is an important factor in determining the success of this product as a pest control agent. In this report we present the development of a highly active mosquitocidal formulation with high resistance to UV. LLP29-M19 strain of Bt, selected by repeated exposure to UV was found to be highly resistant to UV. The product was optimized and the methods used were statistically analyzed. Using single-factor experiments it was determined that the optimal concentration of sodium alginate, CaCl2 and hollow glass beads in the formulation were 1.0%, 2.0% and 3.5%, respectively. Plackett-Burman design was used to screen the interaction of the three factors, CaCl2, sodium alginate and hollow glass beads in the sustained-release formulation. The best combined concentration and mutual effects of the three factors were optimized by response surface methodology. The results showed that the most favorable composition was sodium alginate 0.78%, CaCl2 4.52%, hollow glass bead 3.12%, bacterial powder 3.0%, melanin 0.015%, sodium benzoate 0.2%, and mouse feed 0.5%, resulting in the immobilization time of 4.5 h, at which time the corrected sustained-release virulence rose 2391.67 fold, which was 6.07-fold higher than the basic formulation and deviated only 5.0% from the value predicted by RSM.

Biology Centre of the Czech Academy of Science Institute of Entomology Branišovská 31 37005 České Budějovice Czech Republic

State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops School of Life Sciences Fujian Agriculture and Forestry University 350002 Fuzhou Fujian People's Republic of China

State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops School of Life Sciences Fujian Agriculture and Forestry University 350002 Fuzhou Fujian People's Republic of China Fujian Taiwan Joint Center for Ecological Control of Crop Pests Fuzhou 350002 Fuzhou Fujian People's Republic of China

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