Document Type : Original Article
Authors
1
plant protection research institute agricultural research center, sabahia , alexandria, egy
2
Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, El-Shatby, Alexandria, Egypt.
3
Plant Protection Research Institute, Agricultural Research Center, Sabahia, Alexandria, Egypt.
4
Institute of Graduate Studies and Research, Alexandria University
Abstract
This study investigates the insecticidal activity of 15 extracts of actinomycete isolates (NAM-1-NAM-15) sourced from diverse soil samples because the actinomycete strains were isolated from soil only against the third instar larvae of Culex pipiens. The isolates were cultured on starch casein agar, purified, subjected to fermentation add then solvent extraction to obtain the crude extracts. In primary Screening of the ethyl acetate extracts at a concentration of 1.0 mg/ml, NAM1, NAM2, and NAM4 achieved 100% mortality within one hour, indicating a high acute toxicity of these three extracts, while the rest of isolates exhibited a minimal toxic effect, with mortality rates as low as 3.33%. After six hours, NAM15 and NAM13 demonstrated moderate toxicity, with mortality rates of 46.67% and 36.67%, respectively. After 24 hours, all extracts (except NAM3) reached 100% mortality, indicating their insecticidal properties. LC50 values showed that NAM1 had the highest toxicity at 0.21 mg/ml, followed by NAM4 and NAM2 at 0.52 mg/ml and 0.60 mg/ml, respectively.Biochemical analyses revealed distinct characteristics among isolates, with NAM2 exhibiting the highest enzyme activity, particularly on lipase and protease. This research confirms the potential of local actinomycete strains as effective biological agents for sustainable mosquito control, contributing to environmentally friendly pest management strategies.
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