Effect of aqueous extracts of two local plants for the management of O. mutabilis (Coleoptera: Chrysomelidae), pest of cowpea (Vigna unguiculata L. Walp.), in Guinean area of Côte d’Ivoire
Ossey Christian Landry, Tano Djè Kevin Christian, Aboua Louis Roi Nondenot, Obodji Adagba
Ootheca mutabilis is a cowpea pest (Vigna unguiculata L. Walp) that causes significant damage to this crop. Control tests with two aqueous extracts of two local plants and Cypercal were carried out on this pest in Adzopé located in the south of Côte d' Ivoire. The experimental design used was a randomized block with three replications consisting in total of four subplots corresponding to three treatments and untreated control. The lowest mean numbers of O. mutabilis per plant, as well as percentages of damaged leaves and foliar damage indices were recorded on plots treated with aqueous extract of Ricinus communis seed capsules at 70 g/l and chemical insecticide at the stage before flowering, flowering and podding stages. During these three phenological stages, the percentage of the reduction of damaged leaves obtained after application of the aqueous extract of capsules R. communis seed capsules and Cypercal were higher than those obtained on the subplot treated with the extract of Azadirachta indica leaves at 70 g/l. The numbers of pods harvested which were 22.85 ± 0.64 and 22.95 ± 0.63 per plant obtained with seed capsule extracts at 70 g/l and Cypercal respectively were the highest. The yield that was 914.31 ± 28.16 kg/ha after application of the aqueous extract of capsules R. communis seed capsule was as high as that the one obtained with Cypercal (921.35 ± 28.16). Treatments with the aqueous extract of R. communis seed capsule improved cowpea yield more than 180% as high as with Cypercal.