Spores and Extracts of Entomopathogenic Fungal Isolate (Paecilomyces formosus) as Potential Biolarvicide of Anopheles Mosquitoes

Abstract

Introduction: Paecilomyces formosus is a geographically widespread entomopathogenic fungus that produces infectious conidia against Anopheles mosquito larvae, which curtail the uprising resistance of mosquitoes against synthetic insecticides. These mosquitoes are known vectors of human and animal pathogens, millions of people are killed by mosquito-borne diseases every year such as malaria, dengue, chikungunya, Zuka, yellow fever, encephalitis and filariasis.  Aim: This study investigated the spores and extract sourced from entomopathogenic (Paecilomyces formosus) fungal isolates as potential biolarvicide of Anopheles mosquitoes. Methods: The conidia and extract bioassays were conducted according to WHO-2005 protocol with slight modification. The most active extract ethylacetate was characterized using Gas Chromatography-Mass Spectroscopy. Results: From the conidia bioassay, The LC50 mortality of the larvae was found to be 1.4×104 conidia ml-1 at 24 hrs 6.1×105 conidia ml-1 at 48hrs 8.8×104 conidia/ml at 72 hrs. Solvents used for the extract bioassay includes; Diethyl-ether, Chloroform and Ethyl-acetate of which, Ethyl-acetate extract is found to be most active (LC50s; 101.5 μg/ml, 735.6 μg/ml, 769.0 μg/ml after 48-hours post exposure time. Gas Chromatography-Mass Spectroscopic analysis of ethyl-acetate extract showed 6 major compounds (R.T) 3, 4-Altrosan (9.14), I, 6-anhydro-β-glucopyranose (9.30), Pentanoic acid (10.97), methylpropandioic acid (9.69), Cyclobutanol (10.97), and Diethylpropylmalonate (15.63). Conclusion: These results indicated that Paecilomyces formosus spores and extracted secondary bioactive metabolites could serve as promising lead organism for the development of potential novel and effective insecticidal compounds.