Deterrent activity of plant lectins on cowpea weevil Callosobruchus maculatus (F.) oviposition

It has been shown that some plant lectins possess insecticidal activity because they exert toxic or detrimental effects on insects. Here we describe the inhibitory activity of a panel of 14 plant lectins on cowpea weevil Callosobruchus maculatus (F.) oviposition. A set of 14 plant lectins was screened in a binary choice bioassay for inhibitory activity on cowpea weevil Callosobruchus maculatus (F.) oviposition. Coating of chickpea seeds ( Cicer arietinum L.) with a 0.05% (w/v) solution of plant lectins caused a significant reduction in egg laying. Control experiments with heat inactivated lectin and BSA indicated that the observed deterrent effects are specific and require carbohydrate-binding activity. However, no clear correlation could be established between deterrent activity and sugar-binding specificity/molecular structure of the lectins. Increasing the insect density reduced the inhibitory effect of the lectins confirming that female insects are capable of adjusting their oviposition rates as a function of host availability.