IN-VITRO INSECTICIDAL ACTIVITY OF CRUDE EXTRACTS OF STREPTOMYCES SP. AGAINST LARVAE OF SITOPHILUS ORYZAE

Abstract

The present study was performed to evaluate the insecticidal potential of Actinomycetes isolated from the soils of the Dublarchar and Kochikhali, Bangladesh. The actinomycete isolates were identified by various parameters such as colony morphology, spore arrangement, staining, and biochemical reactions. Insecticidal activity of different concentrations of ethanolic extract of the isolates was determined against the second instar larvae of Sitophilus oryzae. The larvicidal effect, in terms of mortality of larvae, of the extracts was determined by counting the number of dead larvae after 24 hours. Ten actinomycete isolates were recovered from the soil sample and one was subjected to identify (Due to potent antibacterial activity) as the species of Streptomyces on the basis of microscopic, biochemical, and staining characteristics. The insecticidal potential of ethanolic extracts, in terms of larval mortality, was found to be dose dependent. The isolate showed a marked insecticidal activity. At a concentration of 24mg/ml, the isolate caused 100% mortality of the larvae. The lethal conc. 50 was found 3.16mg/ml. Isolation and characterization of active constituents from the ethanol extract possessing insecticidal potential are to be investigated.

Key words: Streptomyces, Antibiotics and Insecticides.