Pheromones of some species of butterflies, placed as a bait in a trap, make it possible to collect all the males of this species of insects from extensive, calculated in square kilometers of space. Pheromones are strictly specific, i.e., each of them attracts its own kind of insects, and this is their great advantage compared to the overwhelming majority of other pest control methods. However, obtaining pheromones from insects is very difficult. Thus, out of 20,000 female apple codling moths, 7 µg of the substance was obtained. More than 30 years of work has been carried out on the synthesis of pheromones, and by the eighties more than 50 pheromones of different species were synthesized. Some pheromones are successfully applied against fruit flies and butterflies. Only knowledge of the patterns of change in the number of animals in the population allowed the use of the genetic method of insect extermination proposed by the geneticist, professor of the Moscow University A. S. Serebrovsky in the prewar years (1939-1940).

The essence of the method lies in the fact that males, incapable of giving offspring, are released into nature. Serebrovsky bred room flies, in which the males were outwardly normal, and the females could not fly. Such males were released into nature, and they mated with normal females. In the offspring, all the females were not flying, and the males carrying the sexless gene of female winglessness continued to mate with normal females and produce “killer males” and doomed females. In America, the cochliomia fly was completely destroyed in a large area of ​​the sheep parasite in this way. The released males were sterilized by irradiating with radioactive cobalt. The scientists B. P. Tokin in the 1940s discovered phytoncides, biologically active substances that kill or inhibit the growth and development of microorganisms. Plants secrete repellent or poisonous substances for insects. Only the first steps have been taken to direct the use of phytoncides to protect cultivated plants from pests. Most of all, this method is used by amateur gardeners. For spraying trees and shrubs are used solanaceous infusions (tomatoes, potatoes), hemp and other plants. Sparse planting of marigolds (calendula) among cultivated plants saves them from soil nematodes. A mixed planting of some herbaceous plants provides protection for one of them or mutual protection from many insect pests (onions, garden strawberries, umbrella plants, etc.). Cannabis growing under apple trees turned out to be a good repellent against the codling moth; an elder among berry bushes protects them for tens of meters around from a butterfly of a glass-case, the caterpillars of which inside the branch are inaccessible to toxic chemicals. The phytoncidal method of plant protection is environmentally friendly, since in essence a balanced system of several components is created for plant protection. The method is promising, but developing it is a matter of the future. Friv games play online at this website Play today at the best friv games.