The impact of the chemical insecticide Malyphos and the vegetable oil of Neem on the aphid
Abstract
To see the impact of insecticide vegetable oil (Neem) on aphid of the green alfalfa, we conducted tests to compare with the synthetic product Malyphos most used by farmers in our region. Because of these, we treated the plants alfalfa infested by aphids with doses of product and the vegetable oil of Neem. In spring-summer or there is a significant number of plant louses and after a controlled time we determines the percentages dead of this parasite in order to obtaining the mortality according to time and dose of the synthetic product and of this oil. The comparison of the aphid mortality between the Malyphos product and the vegetable oil made it possible to reveal the role of this natural extracts on the limitation of manpower of these parasites and their possible use as plant health naturalness without side-effect on the human health and the environment.
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Introduction
Most months of the year aphid alfalfa are present on crops. Of winters to summer in the neck and then colonized the stems and leaves. In the green alfalfa, such pests as aphids cause damage, in particular to the leaves, which cause discoloration. They attack the young shoots and buds. A severe attack led to the falling leaves. In our region, some species of aphids have been found in large quantities on the green alfalfa fields. Aphids, of the larvae to adults feed on the underside of the leaves.
According to studies, the most important parasitic diseases leading to the development of leaf spots are symptoms of alfalfa that appear first on the lower leaves. The spots are circular, brown to dark brown with irregular margin (finely serrated). On the upper side of the spots, the fungus produces a fruit that is in the form of a small point raised brown, located in the center of the spot. The affected leaves turn yellow and fall (Michel Lacroix, 2002).
We know that pesticides have contributed to increased crop yields in particular the fight against pests, but the side effects of pesticide use are many: effects on the health of the people, the wildlife and flora; contamination of the water, soil and air. The World Health Organization advance the impressive figure of 3 million poisonings each year in the world due to pesticides with 220 000 dead in total (Bouguerra, 1986 ).
The growing interest in the use of pesticides based on plant extracts in the world is motivated by their effects comparable to those of chemical pesticides (Mouffok et al., 2007-2008). This work has for objective to make a comparison the impact of insecticide chemical Malyphos and the vegetable oil of Neem on the aphids of alfalfa green in order to reduce the damage caused by these parasites in protecting the environment and in assessing the effect of insecticide natural products used in this study.
Conclusion
The attack by vegetable oil Neem on aphids of green alfalfa is also affected in the same way by the chemical Malyphos. These shows that the vegetable oil with concentrations were sufficient to cause death of the insect can replace the chemical product Malyphos. The oils of Oregano, Basil, Marjoram, Thyme, Sage, Laurier, Rosemary, Lavender, of Anise, Mint, Celery, Cumin, Citrus Fruit, Coriander and Fennel have been tested and several have caused up to 100 % of mortality in the small borer of cereals (Shaaya et al., 1991).
We obtained in our study the results which have to say that the doses of 0.5 and 1% of products applied to aphids have a lot of impact and enough insecticide action. So the natural insecticide will have great importance on human, animal health and the environment. The high dose of 1 %, all samples showed an interesting activity on aphids. Hour after hour, the extract of Neem in the green alfalfa being the most effective sample and reaches a mortality rate of over 70 % for the high dose in less time.
These results are consistent with Isman, natural plant extracts are a true wealth and can give many substances used insecticides in the fight against parasites (Isman, 2001). It follows that the use of natural molecules ecological and economic interest to the insecticidal properties of lesser toxicity in humans, proves to be an alternative approach to the use of synthetic insecticides.