Bioactive fractions of n-hexane extracts from Vigna pods against the legume pod borer, Maruca vitrata Fabricius

Abstract

The identification of resistance factors in Vigna species has been a major constraint to the development of effective host-plant resistance against the major insect pests of cowpea. We studied the effects of some fractions of the n-hexane extract of green pods of three Vigna species namely V. vexillata, V. oblongifolia and V. unguiculata on the growth, development and fecundity of Maruca vitrata Fabricius. When incorporated in the artificial diet, the phenolic, acidic and basic fractions had no significant effect on larval growth and development. However, the neutral fraction from the three Vigna species showed antibiosis by significantly reducing larval weight, percentage pupation and adult emergence. There was no pupation on diet with V. vexillata neutral fraction. We conclude that neutral fractions of the green pods of wild Vigna species contain metabolites which can be exploited in the genetic engineering of cultivated cowpea for resistance against M. vitrata