Viktor Kuznetsov, Dr. Sc. (Biol.), Laboratory of Entomology, Institute of Biology and Soil, Far-Eastern Branch of Russian Academy of Sciences, discusses the problems related to anthropogenic migration (introduction) of animals and plants beyond their natural areas in an article published in the Dalnevostochny uchyony newspaper {Far-Eastern Scientist).

As the author is a prominent specialist in introductive insects, the main attention in his article is focused on these insects, the more so as the ecology of many of them is significant for humans. In a new territory, the introduced insects can become the cause of numerous troubles: they carry over human, animal, and plant diseases, often previously unknown in this area, they damage agricultural plants, impair houses and other constructions, etc. Small size and hidden life style make the control over these undesirable newcomers particularly difficult even at an early stage of their appearance.

Settlement of foreign animals, plants, and microorganisms is not accidentally called biological pollution. In contrast to other types of anthropogenic influence, such as chemical effluents or radiation, its consequences are as a rule irreversible. This hazard determines specific measures for biological pollution control: they should primarily be preventive.

Harmful insects are with good grounds called "quarantine insects": in order to prevent their penetration and spreading beyond their natural foci of residence, measures for detection of unbidden guests have been developed all over the world. However, these guests get over the quarantine cordons and from time to time get into our country. The main cause is impossibility of thorough inspection of all cargoes crossing the border. Foreign insects are imported in containers, in lorries, with large consignments of fruits, grain, decorative plants and flowers.

Not all migrants appearing in a new territory should be annihilated immediately: chemical control of an imported species can bring more harm than this species itself. Moreover, due to refusal from annihilating measures, it will be possible in a number of cases to avoid the side effects of pesticide treatment and thus preserve the aboriginal fauna of entomophages. In some cases they adapt to invasive species and then the population of "newcomers" drastically decreases or gradually disappears. Some of the "newcomers", finding no sufficient

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fodder, do not multiply to form a sufficiently large population and are not dangerous. However, those which find fodder in excess rapidly conquer huge territories. Practice showed that in this case plant-eating insects propagate independently as a result of active migrations or by natural transfer. This was the case with a well known Colorado beetle: the area of fields invaded by this destructive insect increased over 30 recent years more than 12,000 times, reaching 3 mn hectares.

Sometimes humans fail to destroy the migrant and "help" it, transporting it together with agricultural products, wood materials, etc. If invasion of a harmful species could not be prevented, the most effective means for limiting the increase of its population are biological control methods. Imported weeds or harmful insects are controlled by introducing their enemies. For example, in order to suppress ragweed Ambrosia artemisifolia, invading the Primorye Territory in the 1970s, an American phytophage, striped leaf beetle, was imported in 1987 and successfully acclimatized in the territory. An entomophage of tropical origin Encarisia formosa multiplies and is used in hothouses; it is a specialized parasite of a dangerous pest-hothouse white fly.

Invasion of new territories by undesirable and merely hazardous animals and plants is a problem all over the world. For many years our potato fields endure losses because of Colorado beetle, spread all over the world, while the American grain crops suffer from herbaceous aphid. Chemical control of aphid was ineffective. Finally, due to active participation of Viktor Kuznetsov, lady-bird beetle Harmonia axyridis was imported to the USA; these beetles started eating aphids and independently spread all over populated territory of several states. Later on Kuznetsov's book "Coccinellide Beetles (Coleoptera, Coccinellidae) of the Russian Far East" was translated into English and published.

Kuznetsov V., "Unbidden Guest... Insect Invasions in Terrestrial Ecosystems of the Russian Far East", Dalnevostochny uchyony, No. 1, 2006

Prepared by Andrei BIRYUKOV.