Bioinsecticidal Activities Of Azadirachta Indica And Moringa Oleifera Against Maize Weevil (Sitophilus Zeamais) And Rice Weevil (Sitophilus Oryzae) – A Review

Abstract

Control of stored-product insect pests continues to primarily be based on application of synthetic insecticides such as organophosphates, pyrethroids and fumigants because they are effective for the management of insect infestations. The main method of pest control of stored rice grain has been chemical, using phosphine. However, the development of resistance of Sitophilus zeamais and Sitophilus oryzae to these products hinders its control, and alternative measures are necessary for its management. Integrated Pest Management (IPM) is considered the most sustainable way of controlling stored product pests. Plants are considered as a rich source of bioactive chemicals and they may be alternative source of insect pest control agents, examples: Azadirachta indica (Neem plant) commonly known as Dongoyaro and Moringa oleifera leaf commonly known as drumstick. Plant extracts are more effective in the way as they do not cause pollution; produce less toxicity and are bio-degradable and some plants naturally have the repellent effect against many stored grain pests. Various neem extracts are known to act on various insects in varying ways including disrupting or inhibiting the development of eggs larvae or pupae, blocking the moulting of larvae or nymphs disrupting mating and sexual communication, sterilizing adults and deterring feeding as well as inhibiting the production of chitin and the extracts have proven as potent as synthetic pesticides. Synthetic chemical causes many side effects on the environment and humans. Their indiscriminate use can lead to resistance and revival in insects and leach and contaminate the environment hence the need for natural insecticide. Researches on the development of green pesticide from plant and animal extracts and microbes are ongoing. This class of pesticide is much safer and more biodegradable. Higher plants such as neem, moringa and various herbs and spices such as garlic, clove, turmeric, etc., possessed antimicrobial and insecticidal properties. Green insecticides are expected to solve insect resistance and environmental safety. Further researches are needed for a better understanding of the efficacy and applicability of natural pesticides.