Evaluating the effect of host plant resistance and planting dates on the incidence of legume pod borer (<i>Maruca vitrata</i> Geyer) on African yam bean in Nigeria.

Abstract

Legume pod borer (Maruca vitrata (Geyer)) is one of the major biotic constraints to increasing the productivity of most grain legumes in the tropics. In this study, field experiments were conducted to assess the effect of host plant resistance and planting dates on the incidence of African yam bean pod borer Maruca vitrata (Geyer) in Nigeria. Planting of African yam bean (Sphenostylis stenocarpa) varieties in May led to less infested by M. vitrata and differed significantly (P < 0.05) from those planted in June and July. Of all the varieties assessed, TSs9 was the most resistance and differed significantly (P < 0.05) from the rest of the varieties; while TSs84 was the most susceptible with poorest grain yields. All the varieties when planted in May had less post-flowering insect infestations and produced higher grain yields than those planted later. Flowering and podding formation stages of African yam bean (AYB) planted in July coincided with the peak population densities of M. vitrata, resulting in a significant reduction in yields. The highest grain yields were recorded under a combination of early planting with resistant varieties.

Key Words: Maruca vitrata, Sphenostylis stenocarpa, susceptibility