Mosquito Larvicidal Activity of Chitinase of Pseudomonas putida Mb 12 against the Human Vector Aedes aegypti

Abstract

The main dengue and Zika vector, Aedes aegypti, is a cosmotropic species. Since dengue fever cases have significantly increased in recent years, these organisms seem to be extremely detrimental. Synthetic pesticides are not biodegradable, are non-selective, and have adverse effects on beneficial organisms being handled in the vector management system. In the present study, the mosquitocidal potential of chitinase from P. putida Mb 12 was evaluated in an effort to identify risk-free options for the control of mosquitoes. Larvicidal toxicity of Pseudomonas putida Mb 12 chitinase were evaluated on IVth-instar larva of Ae. aegypti and their effect on acetylcholinesterase activity and glutathione S-transferase activity were studied. The early 4th instar larvae of Ae. aegypti were exposed to chitinase enzyme concentrations of 50U/mL, 100U/mL, 200U/mL, and 500U/mL for a period of 4 hours to assess their effectiveness. The results showed that as chitinase concentration increased, mosquito larvae mortality increased; after 4 hours, chitinase at 500 U/mL caused 100% mortality. After 4 hours of incubation, 200 U/mL was administered to achieve LC50 (which kills 50% of the exposed organisms), and after 3 hours, 500 U/mL was used to obtain LC90 values. During the study, it was discovered that different quantities of chitinase (100 U/mL, 200 U/mL, and 500 U/mL) inhibited 80% of the activity of the acetylcholinesterase enzyme. This study found that chitinase significantly increased glutathione S-transferase activity. Additionally, it was discovered that the chitinase treatment was non-hazardous to guppy fish. It was assumed that the P. putida Mb 12 chitinase tested was safe to employ in the aquatic habitat because no mortality was observed in the non-target organisms.