Lavicidal potential of Aspergillus terreus conidial suspension and metabolites against anopheles mosquito

Abstract

Aspergillus terreus, a common soil saprobe produce conidia that are pathogenic to Anopheles gambiae (s.s) and Anopheles Coluzzii larvae. The bioassay was conducted according to WHO-2005 protocol with slight modification. The LC50s of conidia was found to be 6.43×106 and 4.55×104 conidia/ml at 24 and 48-hours respectively. Mycelium extracted metabolites of A. Terreus also showed promising larvicidal activity against A. gambiae S-form and A. colluzzii, ethyl-acetate extract is most active compared to ethanol and diethyl-ether extracts (LC50s; 664.73, 873.14 and 1509.12μg/ml respectively), but least active compared to chemical larvicides (Temephos and Malathion). GC-MS characterization of ethyl-acetate extract showed 7 major compounds viz. 9- Octadecanamide (Z) (16.59%), Octadecanamide (14.70%), 9- Octadecanamide, N, N- diethyl (11.80%), N- Isobutyl (6Z, 8E) decadienamide (8.37%), Lupenyl acetate (6.25%), 9, 12- Octadecadienoic acid, methyl ester (5.27%) and γ- Tocopherol (3.75%), and the effect of some or all of these compounds and perhaps some of the minor compounds might be responsible for the observed larvicidal activity of the extract.