Abstract

Suitable techniques were developed under greehnouse conditions to determine mechanisms of resistance to a leafhopper Empoasca dolichi (Paoli) by utilizing field resistant and susceptible varieties of cowpea, Vigna unguiculata L. (Walp.). Results on adult leafhopper preference indicated no significance among any of the 6 varieties tested. Fecundity studies indicated considerable varietal differences; varieties TVu 662, TVu 59, TVu 123, and TVu 4557 showed a significantly lower development of early and late stage nymphs in comparison to TVu 1190E. The basis of resistance in variety TVu 1190E was due to tolerance. All resistant varieties were significantly less damaged due to feeding by adults and 1st instars. The relative growth rate of 5th instars was highest on the susceptible variety TVu 76. Fifth instars caged on resistant varieties TVu 59, TVu 662, and TVu 123 were significantly less in weight, probably due to antibiosis. Resistant variety TVu 123 appeared to show a low survival of 1st and 5th instars. Leafhoppers reared on the resistant variety TVu 123 were more susceptible to insecticide dimethoate than those reared on the susceptible variety, TVu 37. The basis of resistance in variety TVu 123 is attributed to antibiosis.

This content is only available as a PDF.
You do not currently have access to this article.