Insecticide resistance in field populations of the legume pod-borer, Maruca vitrata Fabricius (Lepidoptera : Pyralidae), on cowpea, Vigna unguiculata(L.), Walp in Nigeria

The legume pod-borer, Maruca vitrata Fabricius, from two locations (Shika a nd Samaru) was found to be resistant to cypermethrin, dimethoate, and endos ulfan. When compared with a susceptible reference strain, resistance ratios ranged from 17- to 53-fold for cypermethrin, 27- to 92-fold for dimethoate , and 15- to 37-fold for endosulfan. Low level of tolerance to lambda-cyhal othrin (3-4-fold) was observed in Samaru. Non-chemical approaches or the us e of chemical insecticides only when necessary is recommended to prevent or delay the development of resistance to insecticides.