Biocontrol potential of extracellular proteins from Xenorhabdus nematophilus on dengue vectors and the enhancement by response surface methodology

Abstract

Dengue fever is a prevalent and rapidly spreading disease. It is best controlled by controlling its vectors. Aedes aegypti and Aedes albopictus are the primary and secondary worldwide vectors, respectively, which are bred in peridomestic man-made water containers. Biological control is the most effective and sustainable method as there is no resurgence effect and does not harm humans. Our study includes the use of extracellular proteins of Xenorhabdus nematophilus, a Gram-negative bacterium widely used as biocontrol agents belonging to the family Enterobacteriaceae. The mortality rates of fourth instar larvae A. aegypti when treated with 250 μg of extracellular proteins of X. nematophilus, recorded to be 40% after 72 hours of exposure. The rate of mortality was observed minimum even at higher concentration. The optimization of the medium through response surface methodology showed that there was an increase in the production of extracellular proteins. These proteins played a very important role in the control of A. aegypti. The maximum rate of mortality was recorded to be 92% when treated with 200 μg of extracellular proteins within 48 hours of treatment. Our research proved that the media optimization enhanced the production of extracellular proteins in the X. nematophilus and it can be used as a biocontrol agent for the control of dengue vector.