Effect of plant populations on the incidence of bean stem maggot (Ophiomyia spp.) in common bean intercropped with maize

Abstract

Effects of three intercrop combinations and plant populations on bean stem maggot Ophiomyia phaseoli; O. spencerella and O. centrosematis was observed; with the latter being reported in Morogoro for the first time. The infestation was higher in the pure stands of beans than in the intercrops and decreased gradually down to two-thirds maize. The incidence of Ophiomyia spp. decreased with increasing plant populations. Low counts of larvae and pupae were recorded in intercrops. Stem damage was higher in pure bean plots, which also had higher larvae and pupae counts. The intercrop combinations gave a yield advantage at all plant populations except at population P3 for one - third maize two thirds bean mixture. The highest yield advantage was obtained at P 2 for two thirds maize - one third beans treatment suggesting it to be the optimum combination for the two crops. It is concluded that a combination of BMM (one third bean-two thirds maize) at plant population P2 may be considered as one of the Ophiomyia spp. management strategy in common bean.