Effect of Pre-harvest Sprays of Neem (Azadirachta indica A. Juss) Seed Products and Pirimiphos-methyl and Harvest Time Modification on Infestation of Cowpeas by Storage Bruchids in the Field and Store in Maiduguri, Nigeria

KABEH, J. D. and LALE, N.E.S.

ABSTRACT: The efficacy of combining three harvesting times with pre-harvest spray of two botanicals obtained from neem seeds and the synthetic contact insecticide pirimiphosmethyl in reducing field infestation of cowpea pods was investigated in Maiduguri located in the Sudan savanna zone of northeastern Nigeria during the cropping seasons of 2001 and 2002. The harvesting times included harvesting dry cowpea pods 3 weeks
after ripening (WAR) commenced, as well as 4 and 5 WAR. Neem seed oil (NSO) was mixed with water and applied at the rate of 20 ml/L, aqueous neem seed extract (ANSE) applied as filtrate obtained from soaking neem powder in water at the rate of 50 g/l and pirimiphosmethyl (Actellic 25 EC)(PMM) was applied at the rate of 2 ml/L to plants in experimental plots at each of the harvesting times. Unsprayed plots were included in the trials to serve as control. In both cropping seasons, pods from plots protected with the botanicals/insecticides were infested significantly less with bruchid eggs than pods from unsprayed plots. In the 2002 cropping season. storage bruchid eggs
infested results showed that pods that were harvested 5 WAR significantly more than pods that were harvested 3 or 4 WAR. The percentage of insecticide-protected pods that were infested with bruchid eggs was significantly lower than that of unprotected pods in
the 2001 cropping season. Bruchid infestation generally increased with delayed harvesting in both seasons. In 2001, percentage of pods that were protected with ANSE end harvested 5 WAR were infested significantly more with bruchid eggs than pods

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