The Effects of Different Infestation Levels of Callosobruchus Maculatus F. on Stored Cowpea (Vigna Unguiculata Walp)

Abstract

The effects of different infestation levels of males and females of Callosobruchus maculatus on stored cowpea (Vigna unguiculata) were investigated. Observations on the biology of C. maculatus showed that the species is capable of varying fecundity levels giving an average of 90 eggs per female. The ratio of males to females was approximately 1:1. There was an overall increase in the number of eggs laid and emergence holes with increasing initial adult densities. Stored cowpeas suffered severe losses as a result of infestation by C. maculatus Weight loss and other damages varied with different infestation levels but increased from low adult densities to higher infestation densities. It is suggested that since an infestation of stored cowpea by one mated female insect can multiply sporadically, control measures against C. maculatus should be initiated in the field. There is adult dimorphism in populations of C. maculatus with “active” form which is induced to a great extent by crowding of larval populations. Increased initial populations in cultures of cowpeas led to increased production of “active” females and to a higher ratio of “active” to normal females. Also there was a curvilinear relationship of active female production to initial adult population.