Stored Products
Jacobs Mobolade Adesina; Titilayo Elizabeth Mobolade-Adesina
Abstract
Purpose: The study was conducted to evaluate the infestation and tolerance of Callosobruchus maculatus to stored cowpea treated with Anchomanes difformis extracts. Research Method: Different concentrations of A. difformis extracts were admixed with 20g of uninfested cowpea seeds in 250ml plastic dishes. ...
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Purpose: The study was conducted to evaluate the infestation and tolerance of Callosobruchus maculatus to stored cowpea treated with Anchomanes difformis extracts. Research Method: Different concentrations of A. difformis extracts were admixed with 20g of uninfested cowpea seeds in 250ml plastic dishes. Ten unsexed adult C. maculatus were released into each treatment and toxicity was assessed at 24 hrs interval days after infestation, number of eggs laid on cowpea seeds was counted. At the end of the experiment, seeds were reweighed, number of emerged adult and damaged seeds were recorded. Findings: All extracts were significantly toxic to C. maculatus as concentration increased. Ethyl acetate (EA) extract exerted highest mortality ranged 90-100%, while methanol recorded highest longevity. Maximum reduction in egg laid was observed with EA extract (51.44-74.45%), followed by methanol extract at 100 (58.69%) and 150 µl (69.56%). While maximum adult emergence inhibition was observed at 150 µl (93.33%) with EA. Cowpea seeds in control dishes suffered the heaviest infestation (31.76%) compared to EA and acetone extracts that recorded zero infestation at 100 and 150 µl concentration respectively. Susceptibility of cowpea seeds treated with extracts was significantly lower compared to control with 100%infestation.Limitations: No hindrances was encountered during the study. Originality/Value: The study revealed that A. difformis possesses oviposition deterrent and adult emergence inhibition properties against C. maculatus that can be utilize for the management of C. maculatus in stored cowpea seeds. Further studies are recommended for exploring the active compound responsible for its insecticidal activities and toxicological effect using albino rats as a model.
Postharvest Biology and Technology
James Machingura
Abstract
Purpose: The control of stored-grain insect pests is predominantly done through the use of synthetic insecticides. However, the extensive and constant (mis)use of these chemicals has brought complications that include faster evolution of resistant forms of pests, hence a global call for alternative ...
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Purpose: The control of stored-grain insect pests is predominantly done through the use of synthetic insecticides. However, the extensive and constant (mis)use of these chemicals has brought complications that include faster evolution of resistant forms of pests, hence a global call for alternative control measures to reduce chemical applications. The aim of this research was to evaluate the repellent and toxic effects of E. citriodora leaf powder on adult P. truncatus and Sitophilus zeamais. Research Method: A completely randomized design was adopted in all the experiments. A choice test arena was set up to evaluate repellent effects of E. citriodora leaf powder on P. truncatus and S. zeamais. The toxic effect of E. citriodora was also evaluated, with untreated grain and conventional insecticides used as negative and positive controls, respectively. Findings: Results showed that E. citriodora leaf powder had repellent properties of up to 68.9% against both P. truncatus and S. zeamais populations. Nonetheless, low adult P. truncatus mortalities were recorded when the protective effects of the E. citriodora leaf powder (at the rate of 10% w/w) were tested against the beetle. Additionally, the efficacy of the synthetic insecticides was relatively higher when applied singly than when in combination with E. citriodora leaf powder. Research limitations: Time was the major limiting factor to consider other parts of E. citriodora plant (e.g. roots) on their usefulness in stored-product insect pest management. Originality/Value: Small plantations of E. citriodora may be established to offer a temporary grain protection against primary insect pests.
