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Insurgental Biological Warfare Against Gipsy Moth

April 29, 2005

Specialists of the Institute of Taxonomy and Ecology of Animals (Siberian Branch, Russian Academy of Sciences) investigate peculiarities of struggle against Asian populations of Gipsy moth - one of the most widespread and economically significant forest pests. The methods applied in the North America and Europe do not work with Asian populations of the vermin. In Siberia, the climate is different, other tree species grow in the region and Gipsy moth is slightly different.

In recent years, outbursts of mass gipsy moth propagation have taken place more frequently and the vermin persistently expand their area. The reasons of this phenomenon are not clear but are probably connected to climate fluctuation. However that may be, the researchers have to fight back. Biological war is one of the most efficient and ecologically safe methods for Gipsy moth quantity control. Hotbeds of vermin propagation are sprayed by suspension of virus, but Asian Gipsy moths are very mobile, and females are capable of active flying. Therefore, the insects simply escape from the lesion focus.

The researchers worked in the territory of West-Siberian plain: in the Novosibirsk and Tumen Regions, Altai Territory and Eastern Kazakhstan. In these areas, Gipsy moths primarily feed on birch-tree leaves. Scarce birch-tree forests cover no more than 15 percent of the territory, the rest of the land is occupied by tillage, meadows and lakes. The Gipsy moth grain layings were processed by Virin-NSh viral preparation produced by the Institute of Taxonomy and Ecology of Animals (Siberian Branch, Russian Academy of Sciences).

The virus causes epidemic polyhedrosis disease with the insects of parental and filial generations. Actually, a lot of insects did fall ill and die in the year processing was performed. At the same time, inhabitants on single trees practically did not suffer on processed lots, and a major part of sick caterpillars died at an older age, having managed to eat a lot of foliage.

The researchers have assumed that the caterpillars which hatched from the grain processed by viral preparation, infect other insects very feebly, therefore, no more than 10 to 15 percent of vermin die from epidemic. This particular percentage of laying was processed by the researchers. As a result, within the first year when the preparation was applied many trees lost up to 90 percent of foliage. Besides, a lot of insects capable of eating through all leaves in the next season hibernated on these lots.

The Novosibirsk specialists applied such high doses of viral preparation that there is no sense in increasing them. To reduce the quantity of vermin significantly, the dose should not be increased, instead the pestholes of propagation should be processed twice. This is the only way to protect birch-trees from almost complete loss of foliage. According to researchers' estimates, complete suppression of Gipsy moth's quantity outburst only in the Novosibirsk Region would require at least 15,000 kilograms of viral preparation. Given its high cost and the lack of necessary production facilities, such needs should be considered unreal.

However, there is no more effective method available, besides, it has its own doubtless advantages. First, the method allows human processing. In Western Siberia, the roads are no good and woods are sparse, that is why there is no sense to use spraying machines. Foresters are quite capable of processing individual layings. In such a way, the preparation consumption is relatively low, and practically all infected territory can be covered thanks to weather during the processing period (late April - early May) being normally dry and warm enough in those regions.

In the conditions of chronical shortage of money, it seems appropriate to ask a question if actions aimed at Gipsy moth quantity control are needed at all? It is known that Russian birch-trees can well survive even significant loss of foliage. Nevertheless, the Novosibirsk scientists believe that viral processing is necessary.

Firstly, during the Gipsy moth invasion the trees do not practically grow thicker, thus causing damage to forestry. Secondly, although birch-trees do not perish from the loss of foliage alone, they get impaired and can be destroyed by unfavorable conditions, for example, overdamped soil. Thirdly, defoliated trees almost do not protect from wind. In Kulugunda steppe, soil erosion increased due to outburst of Gipsy moth quantity. On top of that, social aspect is also important as vital activity of population in rural districts is tightly connected with woods. So, the Siberian foresters will have to examine every tree and to spread the preparation on each discovered laying.

Informnauka (Informscience) Agency