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TRAP CROPPING AND INTERCROPPING OF PIGEONPEA (CAJANUS CAJAN L. MILLSP.) IN PEST MANAGEMENT OF COWPEA (VIGNA UNGUICULATA L. WALP.) IN SOUTHERN BENIN : COMPETING RISK AND PEST STATUS IN POD ATTACK
Abstract
In the present study, five treatments arranged in a Randomized Complete Block Design with four replications were considered : sole culture of cowpea (T1); cowpea plot surrounded by pigeonpea culture (T2); alternate row intercropping of cowpea and pigeonpea (T3); intercropping of two cowpea rows for one pigeonpea row (T4) and intercropping of one cowpea row for two pigeonpea rows (T5). Only Treatments T1, T2 and T4 were followed up to the end of the experiment because of the unexpected agronomical interactions in treatments T3 and T5. The study is therefore based on
treatments T1, T2 and T4. Larval population densities of Maruca vitrata (Fabricius) (Lepidoptera, Pyralidae) were relatively low as well on cowpea pods as on those of pigeonpea. Concerning the pod sucking bugs (PSB) (Heteroptera), none of them was found on cowpea pod during the experiment whereas they were present on pigeonpea pods. The population distribution of these bugs was bimodal showing two periods of relative abundance with a succession of low and high population densities in T2 and T4. As well on cowpea in T1 as on pigeonpea and cowpea in both T2 and T4, highest attacks of M. vitrata were registered on pod stages II and III. Thus pigeonpea functioned as an excellent trap crop for the heteropteran species in pest management of cowpea. The
pods of stage I were green without visible seeds; in the stage II, pods were green with visible seeds; the pods of stage III were yellowish and in the stage IV, pods were dry
treatments T1, T2 and T4. Larval population densities of Maruca vitrata (Fabricius) (Lepidoptera, Pyralidae) were relatively low as well on cowpea pods as on those of pigeonpea. Concerning the pod sucking bugs (PSB) (Heteroptera), none of them was found on cowpea pod during the experiment whereas they were present on pigeonpea pods. The population distribution of these bugs was bimodal showing two periods of relative abundance with a succession of low and high population densities in T2 and T4. As well on cowpea in T1 as on pigeonpea and cowpea in both T2 and T4, highest attacks of M. vitrata were registered on pod stages II and III. Thus pigeonpea functioned as an excellent trap crop for the heteropteran species in pest management of cowpea. The
pods of stage I were green without visible seeds; in the stage II, pods were green with visible seeds; the pods of stage III were yellowish and in the stage IV, pods were dry
