Publication Type

Journal Article

Journal Name

Journal of Chemical Ecology

Publication Date

1-1-1996

Abstract

Membrane feeding studies were conducted to determine the effects of raw juices and chemical extracts of leaves of aphid-resistant (ICV-12) and aphid- susceptible (ICV-1) cultivars of cowpea [Vigna unguiculata L. (Walp.)], on the survival, growth, and reproduction of cowpea aphid Aphis craccivora Koch. Life table and demographic statistics of the cohort population and subsequent generations were estimated. Compared to ICV-1, the leaf juices and chemical extracts of ICV-12 exhibited significant (P ≤ 0.05) adverse effects on aphid survival, growth, and reproduction. Raw leaf juice and ethyl acetate extract of ICV-12 in both water and sucrose significantly (P ≤ 0.05) limited aphid performance. The adverse long term effects were often more extreme than those resulting from a diet of distilled water alone. Methanol extract of ICV-12 showed an intermediate level of adverse effects on aphids, being generally less than that of ethyl acetate but greater than that of hexane. Compared to the other ICV-12 extracts, the hexane extracts in water or sucrose media did not significantly affect the aphid performance. Overall, it was determined that antibiosis was a governing modality of aphid-resistance in ICV-12. Postingestive intoxication was caused by foliage components of seedling plants of that cultivar.

Keywords

antibiosis, aphid performance Vigna unguiculata, Aphis craccivora, cowpea aphid, cowpea resistance, ethyl acetate extract, ICV-12, membrane feeding, Net reproduction rate, postingestive intoxication, sucrose

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