“Several results of research carried out in the field and in the laboratory have demonstrated the insecticidal action of neem oil (Azadirachta indica) on several pest caterpillars”. The information is from Gerson Adriano Silva, professor of Agricultural Entomology at the Laboratory of Entomology and Phytopathology – Universidade Estadual Norte Fluminense Darcy Ribeiro (UENF).
According to him, the insecticidal action of neem oil has already been proven on more than 500 species of insects and mites. The professor highlights the results obtained against insects belonging to species of caterpillars, beetles, flies, mosquitoes, whiteflies, mealybugs, bedbugs, aphids, thrips, fleas, mites and ticks.
“Neem oil can be used to control pests in organic and conventional agriculture. Among the caterpillars controlled by neem oil, the tomato moth (Tuta absolute), small borer (Neoleucinodeselegantalis) and giant borer (Helicoverpa zea) in tomato, fall armyworm (Spodoptera frugiperda) in corn, stand out. leaf miner (Leucopteracoffeella) in coffee, leafminer (Phyllocnistiscitrella) in citrus and diamondback moth (Plutellaxylostella) in cabbage; the complex of caterpillars that attack soybeans, cotton and fruit trees”, he lists.
The expert explains that the insecticidal action of neem oil is largely due to two groups of molecules: triterpenes and limonoids. Azadirachtin is the triterpene with the greatest insecticidal activity present in the oil. The insecticidal action of neem oil on insects is due to the inhibition of feeding; oviposition repellent action; neuroendocrine effects, inhibition of the development of immature insects and can cause death from acute poisoning.
Neem oil is extracted by cold pressing the seeds of the neem tree, a plant originating in Asia and characterized by rapid growth, tolerance to water stress and nutrient-poor soils. According to Gerson Silva, an adult plant can reach 20 meters in height and 80 cm in trunk diameter. Seed production begins three to five years after planting, with an average productivity of more than 25 kg/plant.
“It is important to highlight that neem oil has enhanced action against caterpillars in the early stages of development, and as the caterpillars get closer to pupating, their susceptibility to the oil decreases. One of the great advantages of neem oil in controlling caterpillars, in relation to conventional insecticides, is the low risk of developing resistance, thanks to the complex composition of the oil, made up of more than 150 biologically active compounds”, he concludes.
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