CHAPTER 6

ZOOGEOGRAPHICAL CHARACTERISTICS OF THE ENTOMOFAUNA OF THE KURIL ISLANDS

By now, much accumulated paleontological and biogeographical information has shed light on the history of the flora and fauna of North East Asia, presented in numerous paleobotanical papers of A. N. Krishtofovich (1929, 1930, 1932, 1936a, 1936b, 1937a, 1937b, 1946a, 1946b, 1958), V. N. VasilÆyev (1944, 1957, 1958), V. B. Sochava (1933, 1944a, 1944b, 1946), B. A. Tikhomirov (1946a, 1946b), A. I. Tolmachev (1944, 1948, 1954, 1958), T. D. Boyarskaya and E. M. Malayeva (1967), and others, as well as in the biogeographical papers of P. P. Sushkin (1925), G. U. Lindberg (1946, 1948a, 1948b, 1952, 1953, 1955, 1965a, 1965b, 1970), B. K. Shtegman (1936, 1937), A. I. Kurentsov (1947, 1948, 1949, 1952, 1955, 1957, 1959a, 1959b, 1959c, 1960a, 1960b, 1963a, 1963b, 1965a, 1965b, 1966, 1967, 1968a, 1968b), A. I. Kurentsov and G. O. Krivolutskaya (1967), B. F. Belyshev (1962, 1963), O. K. Kusakin (1970), and other scientists. The biogeographical and paleontological investigations, in combination with geological materials, make it possible to formulate a general notion of the ancient outlines of North East Asia and North America, of the seas surrounding them and of the northern Pacific Ocean, and to understand the geographical changes which have taken place in this region in the past.

Biogeography has been used ever more widely since the middle of the 20th century by scientists of various specialties, as it is ôcapable of resolving the problems of the origination of the organic world, and along with this, problems of the history of the recent past of a given territoryö (Lindberg, 1948b, pp. 614-615).

However, usually only particular groups of animals have been used in various zoogeographical constructions, most often vertebrates of a relatively small number of species. Considerably fewer zoogeographical studies have been based on entomological data; this is explained by the inadequate extent to which the entomofauna of particular regions has been studied. The works of A. P. Semenov-TyanÆ-Shanskiy (1935, etc.), N. Ya. Kuznetsov (1938, etc.), and several foreign authors have constituted an exception in this regard. But, as information about the entomofauna of extensive territories has accumulated in recent years, ever greater possibilities for the use of entomological materials in zoogeography have appeared. The large monographs of O. L. Kryzhanovskiy (1965b) on the origin of the terrestrial fauna of Central Asia and of A. I. Kurentsov (1965a, 1967) on the zoogeography of the PriamurÆye and the entomofauna of the mountainous regions of the Far East, and some others, based mainly on entomological materials, that have appeared relatively recently in the domestic literature, may serve as testimony to this.

The insects are a convenient and significant object in the study of the zoogeography of various territories. Due to their diversity, great numbers, small sizes as compared with other animals, the capacity to fall into a state of anabiosis given unfavorable conditions, and their substantial motility, they can persist more easily over time, surviving unfavorable changes in climate, periods of glaciations, and catastrophes caused by tectonic movements of the EarthÆs crust, and active volcanism. As an invariable component of any biogeocenosis, the insects occupy the most varied ecological niches, and at the same time can often be satisfied with a highly limited life space, display diverse ecological connections with plants, animals, and relief, as they possess broad ecological plasticity, can fairly readily adapt to the changing natural situation, not infrequently can shift to a concealed mode of life, and on the whole more completely reflect zoogeographical associations than do other groups of animals. It must be added that in the past, insects, by contrast with many other animals, were not subjected to active destruction by man; this offered some ancient relicts the possibility of persisting until the present. Therefore, the use of insects for zoogeographical analysis enables the investigators to have at their disposal the most extensive, diverse, and as a result of this, fairly reliable and convincing materials. This confirms G. U. Lindberg's point of view (1965b, pp. 14-15) to the effect that ôin resolving the problems of geological history of the recent past, enormous labor is required of a large number of research biogeographers who, on the basis of their material, using the biogeographical method, would compile preliminary schemas of the history of formation of the groups of organisms they have studied and of the history of the formation of clearly geomorphologically limited territories populated by them.