Bioactivities of essential oil from Elletaria cardamomum (L.) Maton. to Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst)

Contact and fumigant toxicities and antifeedant activity of the essential o il of cardamom, Elletaria cardamomum, to two stored-product insects, Sitoph ilus zeamais and Tribolium castaneum, were investigated. Topical applicatio n was employed for contact toxicity studies, and filter paper impregnation was used for testing fumigant action. The adults of S. zenmais and T. casta neum were equally susceptible to the contact toxicity of the oil at the LD5 0 level, with LD50 values of 56 and 52 mu g mg(-1) insect respectively. How ever, S. zeamais was more susceptible than T. castaneum at the LD95 level. For fumigant toxicity, S. zeamais adults were more than twice as susceptibl e as T. castaneum adults at both LD50 and LD95 levels. Furthermore, 12-day larvae of T, castaneum were more tolerant than the adults to the contact to xicity of the oil, but 14- and 16-day larvae had the same susceptibility as the adults. The susceptibility of the larvae to contact toxicity increased with age. In contrast, all the larvae (12-16 days old) of T. castaneum wer e much more tolerant than the adults to the fumigant action, and larvae of different ages had similar susceptibility. Cardamom oil applied to filter p apers in the concentration range 1.04-2.34 mg cm(-2) significantly (P < 0.0 5) reduced the hatching of T. castaneum eggs and the subsequent survival ra te of the larvae. Adult emergence was also drastically reduced by cardamom oil. When applied to rice or wheat, the oil totally suppressed F1 progeny p roduction of both insects at a concentration of 5.3 x 10(3) ppm. Feeding de terrence studies showed that cardamom oil did not have any growth inhibitor y or feeding deterrence effects on either adults or larvae of T. castaneum. However, it significantly reduced all the nutritional indices of the adult s of S, zeamais, but with very slight feeding deterrence (27%) at a concent ration of 1.44 x 10(4) ppm. (C) 2000 Elsevier Science Ltd. All rights reser ved.