What are pheromones of insects and what role do they have?

In insects and other animal groups, meeting sexual partners who are capable of physiological copulation is not random, but through complex mechanisms "transceiver" that enable exchanges of information between individuals, sometimes distant enough.

Chemical communication mechanisms play an important ecological role, allowing the specific and precise tracking of partners across the environment.

Communication mechanisms between the individuals of the same species are physical (sound waves, electromagnetic waves, color, etc.) and chemical, which are predominant (chemical compounds).

Sex Pheromones (hormones that carry the message) are chemical compounds that mediate  sexual attraction between individuals of different sexes. Name of pheromone was used first in 1959 by P. Karlson and I. LUSCHER. The pheromone generally means a chemical emitted by one individual and received by another individual of the same species, causing a specific reaction to the individual which received it.

Sex pheromones are biologically active compounds, which determine sexual attraction of the other sex, closeness of individuals around and all their precopulator  behavior. In most cases, the female is the issuing authority, and the male is the individual receiver. There are also cases where the roles are reversed. Among insects where sex pheromones were identified, most are Lepidopterae followed (in decreasing order) by orders Coleopterae, Hymenopterae, Orthopterae, Dipterae, Isopterae.

From chemical point of view, natural insect pheromones are formed usually from a single chemical compound, it is rarely a mixtures of several compounds. In the latter case, the specific function of the pheromone depends on the proportion of different compounds mixed. The simplest of insect sex pheromone is valeric acid produced by the female of boring worm of the sugar beet, Limonius californicus.

Most pheromones are esters, acids, alcohols and ketones, with long carbon chain, consisting of C-C, with double bonds, which facilitate their isomerization. Molecular conformation of pheromones plays an important role in their biological activity.