Evaluation of Insecticidal and Antifungal Potential of some Plant Extracts against Maize Weevil (Sitophillus zeamais) and Fungal Pathogens of Maize (Zea mays L.) in Storage

Abstract

Maize (Zea mays L.) is the world's leading crop widely cultivated as cereal grain and domesticated in Central America. It is the only food cereal crop that can be grown in diverse seasons. There are many varieties of maize, in spite of the regular white and yellow coloured type with nutritional benefits. The study was intended to determine the effect of plant extracts and field inventories on the maize weevil (Sitophilus zeamais) and the fungal pathogens associated with the crop. The varieties (Sammaz 51, Oba 98 and Local maize) were treated with three plant extracts (Carica papaya L., Moringa oleifera Lam. and Ficus exasperata Vahl.) and the synthetic insecticide (Caterpillar force) were used. The standard cultural laboratory technique was used to isolate the mycoflora. The results showed highest weevil emergence in sammaz 51 control (4.16±9.40) and no weevil emergence for sammaz 51 treated with M. oleifera, F. exasperate, synthetic insecticide and local maize variety treated with synthetic insecticide. Weevil death was highest in the local maize variety treated with M. oleifera (4.12±11.63) and highest grain damage was recorded for Oba 98 treated with C. papaya (5.39±7.96) and no grain damage was recorded for sammaz 51 control and local maize variety treated with synthetic insecticide. The results also revealed ten probable fungal pathogens to be associated with the maize varieties in store. These fungi include; Candida species, Mucor mucedo, Fusarium moniliforme, Penicillum italicum, Rhizopus stolonifer, Aspergillus fumigatus, Aspergillus niger, Asgergillus terreus, Fusarium solani and Fusarium oxysporum. The in vitro test with the plant extracts across the maize varieties infected with weevil in store revealed that the zone of inhibition at 50mg/ml by C. papaya was more on Rhizopus and Penicillum (30mm). Aqueous extract of these plant products can effectively be used as a major component for the management of S. zeamais and fungal pathogens during storage.