Efficacy of lipase-producing, wax-degrading bacteria against the solenopsis mealybug, phenacoccus solenopsis tinsley and the striped mealybug, ferrisia virgata cockerell (homoptera: Pseudococcidae) on cotton

Abstract

Lipases (EC 3.1.1.3) are triacylglycerol acylhydrolases that hydrolyze triglycerides to glycerol and fatty acids. The numerous applications of lipases in chemical, food, pharmaceutical, biotechnological, detergents and surfactants, and agricultural industries and in waste treatment plants proved their importance. In this study, 23 wax-degrading bacterial strains isolated from four mealybug species infesting cotton were screened for lipase production. On the basis of the 16S rRNA gene sequences, lipase-positive strains were classified into six genera, namely, Pseudoxanthomonas, Acinetobacter, Klebsiella, Providencia, Enterobacter, and Serratia. Acinetobacter lwoffii PSAD2 and A. beijerinckii PSAD7 isolates showed the maximum lipase production of 2.3 U/mL and 1.7 U/mL, respectively, in the quantification process. In addition, the growth curve analysis confirmed that lipase production is associated with the growth phase of the isolates. The efficacy of the lipase producing wax degrading bacterial isolates was tested against the nymphs and adults of Solenopsis Mealybug, Phenacoccus solenopsis Tinsley and the Striped Mealybug, Ferrisia virgata Cockerell infesting cotton. The results clearly indicated that the bacterial isolates A. lwoffii PSAD2 and A. beijerinckii PSAD7 expressed maximum mortality percentage against the mealybugs. The results of this study will be helpful in developing lipase-based microbial insecticides for the management of waxy cuticle-protected insect pests.