The potentials of using plant-derived botanicals as bio-active pesticides in Nigeria

Several reviews have shown that plant-derived pesticides have great potential for the natural control of pests, particularly in tropical countries like Nigeria. Many of these plant species, apart from being readily available, cheap and eco-friendly, possess one or more useful properties such as repellency, antifeedant, fast knock down, flushing action, bio-degradability, broad-spectrum of activity and ability to reduce insect resistance. These are unlike synthetic chemical pesticides that have high persistence in the soil after use, high cost of application, environmental pollution, toxic residues in food, high lethal effects on non-target organisms and direct toxicity to users. There has been a steady increase in recent times, in the use of plant-based products as a cheaper and ecologically safer means of controlling pests, especially in the tropics. In South Nigeria, rural farmers mix chilli pepper and wood ash of Parkia biglobosa (African locust bean), Corymbia citrodora. or Azadirachta indica, to control Podagrica sp.on okra plants, Abelmoschus esculentus. The natives in this area also use the mixture of Chromolaena odorata L. (siam weed) and Ocimum gratissimum L. (basil) leaf extracts to repel termites and soldier ants around their houses. Similarly, an admixture of water from fermented cassava (Manihot esculentus Crantz) tubers and bitter leaf (Vernonia amygdelina L.) has shown potency against tailor ants infesting local pear fruits and leaves. In storage pest control, a lot of work has been done to investigate the efficacy of powder, oil and juice extract of many botanical plants on the survival of various insect pests, such as C. maculatus and S. zeamais, with 100% control.