Laboratory investigation on efficacy of extract from sweetflag (Acorus calamus Linn.) rhizomes on brown planthopper (Nilaparvata lugens Stal.)
1995
Duangdean Cheramakara | Kwanchai Sombatsiri | Sunsanee Choowaew (Department of Agriculture, Bangkok (Thailand). Agricultural Toxic Substances Div.)
Insecticidal efficacy of sweetflag (Acorus calamus Linn.) rhizome extract on brown planthoppers (Nilaparvata lugens Stal.) had been examined under laboratorial conditions. The crude extract used in this study were obtained by various extraction methods. Fresh rhizomes were crushed, maceration with water, liquor and ethanol. The dry rhizomes were ground and extracted in Soxhlet extraction apparatus with ethanol. Bioassay tests for contact and stomach poison to nymph and adult brown planthoppers of fresh rhizome extract indicated that ethanol crude extract (ECE) gave the highest nymphal and adult mortality. The ECE at 150 mg/ml caused the death of nymphs and adults, 95.85 percent and 98.98 percent via contact poison, where as the death caused via stomach poison were 36.94 percent and 48.01 percent, respectively. The toxicity of dry rhizome ethanolic extracts (DEE) via contact and ingestion at 40 mg/ml to nymph and adult was over 50 percent mortality. The extract of the same concentration also inhibited hatchability by 73.13 percent. The adults from nymphs fed on rice treated with DEE at 20 mg/ml showed no effect on egg production. However, at this concentration could repell 62.10 percent of insects. In addition, the extract at the concentration of 80 mg/ml showed systemic action, causing 90.00 percent nymphal mortality. Under shade and sunlight condition, The toxicity of the DEE extract sprayed on plants decreased quickly. Addition of some chemicals such as piperonyl butoxide, white oil and neem oil to the extract did not increase the efficacy and prolong the shell life of the extract.
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