Abstract

ADEBOYE, OYEWALE RUFUS; ONI, MERCY OLAYINKA  and  ADESINA, JACOBS MOBOLADE. Comparative response of Callosobruchus maculatus (Fab.) (Coleoptera: Chysomelidae) to Momordica charantia and Acalypha wilkesiana powders in stored cowpea (Vigna unguiculata (L.) Walp.). rev.colomb.cienc.hortic. [online]. 2020, vol.14, n.2, pp.224-230.  Epub Nov 11, 2022. ISSN 2011-2173.  https://doi.org/10.17584/rcch.2020v14i2.9840.

The post-harvest preservation of cowpea in developing countries has been a major challenge because of Callosobruchus maculatus infestations. This study compared the response of C. maculatus (F) to Momordica charantia and Acalypha wilkesiana powders in stored cowpea seeds under laboratory conditions. Five pairs of freshly emerged C. maculatus adults were introduced into a Petri-dish containing 20 g of cowpea admixed with 0.2, 0.4, 0.6 and 0.8 g of each plant powder. This procedure was replicated three times in a completely randomized design. The adult mortality was recorded at 24 h intervals for 5 days, and oviposition was recorded after 48 h. In addition, newly emerged insects were recorded 30-35 days after infestation, and weight loss was also determined. The treatments had a significant increase in C. maculatus adult mortality as the exposure period and dosage increased; the highest values (90 and 100% for A. wilkesiana and M. charantia, respectively) were observed at 120 h of exposure with the 0.8 g dosage level. At 0.8 g, the A. wilkesiana (66.3) and M. charantia (63.0) treated seeds recorded a significantly lower number of eggs laid. Similar trend was observed for adult emergence and weight loss percentage. This study revealed that both plants had a significant insecticidal effect but M. charantia was more effective than A. wilkesiana, without significant differences in the assessed parameters. This indicated that these plant powders potentially protect stored cowpea seeds from C. maculatus infestations and damage. Therefore, these plants should be included in Integrated Pest Management Strategies for cowpea storage by small scale farmers.

Keywords : bio-insecticides; seeds; postharvest preservation; adult mortality; IPM.

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