Hexane extracts of certain botanicals were evaluated in the laboratory for their oral, contact, fumigant toxicity and repellent activity at 5% concentration against rice weevil Sitophilus oryzae L. at the Natural Pesticide Laboratory, Department of Agricultural Entomology, Agricultural College and Research Institute, Madurai, Tamil Nadu during 2019-2021. The results revealed that all the botanicals were effective. Considering the contact toxicity, 5% hexane extract of Mentha spicata 5% (80.00%) performed better at 72 hr after treatment. M. spicata and Vitex negundo 5% hexane extract exhibited maximum oral toxicity (90.00%). Fumigant effect was maximum in V. negundo (73.33%), M. spicata, Ocimum sanctum and Tagetes erecta flower extracts (70.00%). Ocimum sanctum (70.56%) and M. spicata (67.22%) exhibited maximum repellency. Thus, M. spicata at 5% was the most effective as contact, oral, fumigant toxicant and repellent against S. oryzae in stored maize.
Keywords
Sitophilus oryzae, Hexane Extracts, Botanicals, Contact Toxicity, Oral Toxicity, Repellency, Fumigant, Mentha spicata, Vitex negundo, Ocimum sanctum, Curcuma longa.
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