Neem: the organic insecticide that does not create resistance
In recent years, even today, we are firmly committed to the use of alternative ecological products to chemical synthesis compounds.
The development of organic insecticides represents a green alternative, which will help us conserve and improve the health of the soil, biodiversity, but above all it will favor us in our constant fight against pests in a sustainable way, evidently in conjunction with control strategies specific to certain populations of plague arthropods that best suit their circumstances.
We have the need to apply a method of pest control without affecting the environment, it may be the use of plant extracts to be biodegradable and not create resistance in insects.
The study of the insecticidal activity of vegetable extracts and phytochemicals has intensified due to the demand for organic food and the current demands of the phytosanitary defense of horticultural products.
It is currently used for the biological control of pests in agricultural crops as a natural insecticide. Extracts obtained from their seed contain various bioactive agents against fungi and insects. The most potent is the terpenoid known as Azadirachtin, responsible for various physiological properties (growth inhibitor, prolonging the immature stages causing death, decreases fertility and oviposition), as it interferes with the synthesis process of ecdysone and the juvenile hormone, affecting its metamorphosis, presenting malformations produced in any of the stadiums or morphogenetic damage in adults, such as wings, poorly developed oral apparatus among others, causes that the damages that can produce these insects are reduced since their food activity is seen affected, they can not fly, they are sterile, dying quickly.
These effects occur in a combined manner and with a different degree of action, depending on the species of insect, its stage of development, the extraction process and the concentration of the preparation.
It also decreases the levels of proteins and amino acids in the hemolymph and interferes with the synthesis of chitin in different families of insects. Azadirachtin works by blocking the parts of the brain of the insects that produce these vital hormones.
Insecticide properties
The properties of the neem are based on the resemblance that its components present with the real hormones, in such a way that the bodies of the insects absorb the neem components as if they were real hormones and these block their endocrine system.
The resulting deep-seated behavior and psychological aberrations leave insects so confused in their bodies and brains that they can not reproduce, and their populations are greatly reduced. Studies conducted have shown that the aqueous extract of neem produces effects on the larval length, weight and width of the cephalic capsule at 10 exposure dose over Spodoptera frugiperda & Spodoptera thin (Lepidoptera: Noctuidae). In addition, it has been possible to verify the toxicity against this neem species, observing the highest mortality during moulting, which suggests an activity similar to that of a developmental regulator.
It has been shown to have control over insects belonging to several orders, such as Lepidoptera, Diptera, Orthoptera, Hemiptera, Coleoptera, etc., intervening in endocrine events, inhibiting their feeding and growth, through the stimulation of specific chemoreceptor cells and blockade in the shot of the sugar receptor cells, which normally stimulate feeding.
Biological advantages
The azadirachtin appears therefore as an active material of natural origin that is quite effective; in fact, it is so powerful that a simple sign of its presence prevents some insects from even touching the plants.
The residual effect lasts about five days, although the juvenoid effects, that is to say on the growth, lose their activity normally after one or two days under field conditions.
Other notable characteristics of Neem are: difficult development of resistance because it is a mixture of bioactive components, systemic through the roots when applied to the soil, high biodegradability, especially by the action of UV radiation, persistence in 4 field -8 days and possibility of synergism with other natural products such as Bacillus thurigiensis.
Under field conditions, the foliar extracts of azadirachtin last from 4-8 days. However, temperature, ultraviolet light, pH in parts of treated plants, water fall and other environmental factors exert a more or less negative influence on the active ingredients.
The Neem is much more effective in warm climates than in cold areas, where the activity of its principles is greatly diminished.
Photochemical destruction by ultraviolet rays is complete. It has been discovered that the azadirachtin content of its extracts was reduced on an 65% after 14 hours of exposure to ultraviolet radiation.
It was also found that decomposition increased with heat and humidity. Other authors have discovered that after 24 hours exposed to ultraviolet radiation, or after seven days exposed to light, a degradation of 50% occurred.
It has been shown that after 200 hours, (approximately 8 days), of continuous exposure to ultraviolet radiation, azadirachtin is degraded in an 100%.
Source: Hortalizas.com
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