Effects of Intercropping with Maize on the Incidence and Damage Caused by Pod Borers of Common Beans

Abstract

Effects of intercropping common bean, Phaseolus vulgaris L., with maize, Zea mays L., at four plant populations on the pod borers Maruca testulalis Geyer and Heliothis armigera Hubner on common bean were studied. The incidence of M. testulalis and H. armigera larvae was significantly (P < 0.05) lower in intercropped and higher plant populations than in pure stands and lower plant populations of common bean; larval populations of M. testulalis increased 45-59 d after planting, followed by a decrease up to 66 d after planting. Percentages of damage to flowers and pods by larvae of the two pod borer species were significantly (P < 0.05) lower in an intercrop combination of one-third bean-two-thirds maize (BMM) than in pure bean (BBB). Flower and pod damage decreased when plant populations increased from 66,666 to 1,333,333 plants per ha. The relationship of intercrop combinations and individual plant populations to incidence and damage by pod borer larvae was established by exponential and power regression models. Seed yields of intercrop combinations of BBM and BMM were higher than those of the two crops when grown in monoculture at 133,333 and 266,666 plants per ha. Relative yield total thus indicated yield advantages of 16-29% for plant populations of 133,333 plants per ha in both BBM and BMM intercrop combinations, which was associated with lower incidence and damage by pod borer species. Intercropping beans with maize was considered useful as a cultural method for controlling pod borers on common beans and for higher seed yield of the two crops.