CHAPTER 2

GENERAL INFORMATION ON THE INSECTS OF THE KURIL ISLANDS

As indicated in Chapter 1, a fairly clear notion of the composition of the entomofauna of the Kuril Archipelago has taken shape. However, even now its study cannot be considered complete. More and more new finds on the Kuril Range of genera and species of insects of various orders, which had previously been unobserved or are entirely new to science, attest to this. The first impression of the marked impoverishment and even "defectiveness" of the Kuril entomofauna as a whole, which was made on investigators (e.g., Konakov, 1947) several years ago, prior to the publication of more complete faunistic lists, has now been softened somewhat. However, this relates to the southern islands, and primarily Kunashir, the entomofauna of which is especially rich. With regard to the insects of the central and northern islands, it is actually extremely impoverished and "deficient." A certain impoverishment of the fauna as compared with those of Sakhalin, the nearby Japanese islands, and, all the more so, the continent, does occur in the south of the Range as well. Several orders, families, and genera are absent here; many genera are represented by a limited number of species or are exceptionally rare; this may be judged on the basis of the few well-studied groups of insects.

Although we are unable to characterize in detail all of the orders of insects inhabiting the Kuril Range, we can list the orders and families and provide an estimate of the total number of genera and species recorded on the Archipelago (Table 1). At the present time, only 21 orders of insects are known on the Kuril Islands (which is, as we have said, surely not the maximum number), but the extent to which the various orders have been studied is also far from uniform. This is explained by the fact that special methods of collection and the focused interest of the investigator working in relation to a particular group are necessary in order to identify the fauna of diverse and, particularly, specialized groups. On the Kurils, on the other hand, the large forms, living in the open, such as the butterflies, beetles, dragonflies, and some others, which strike the eye, have been collected and studied first. Such collections have often been made en passant, and have even been made by non-entomologists. Therefore, after one or another group of insects has been studied by appropriate specialists, its scope within the makeup of the Kuril fauna has sharply increased. For example, following the investigations of the flower flies (Syrphidae, Diptera) by Violovich (1955, 1956b, 1956c, 1957, 1960a, 1960b), the number of species known on the Kuril islands increased from 27 to 105; the number of species of crane flies (Tipulidae, Diptera) increased from 11 to 74 following the investigations of Savchenko (1956, 1970; Savchenko and Krivolutskaya, date); the number of species of leaf rollers (Tortricidae, Lepidoptera) increased from 5 to 160 following the work of Kuznetsov (1968a, 1968b, 1969); the number of species of bark beetles (Ipidae, Coleoptera) increased from 3 to 53 as a result of our investigations (Krivolutskaya, 1956, 1958, 1962b, 1963, 1965a, 1968; Krivolutskaya and Kupyanskaya, 1970), etc.

For these reasons, almost all the lower insects living in the soil and in the understory, with the exception of several species of springtails, which happen to be pests of agricultural plants (Kuwayama, 1967), have escaped the notice of investigators and have remained thus far unexplored. The Mayflies (Ephemeroptera), stoneflies (Plecoptera), booklice and barklice (Psocoptera), birdlice (Mallophaga), thrips (Thysanoptera) and some other orders have also been inadequately investigated. Only a few groups may be regarded as relatively well investigated: the orthopteroid insects (Orthopteroidea, including the cockroaches, the orthopterans, and the earwigs), homopterans (Homoptera), hemipterans (Heteroptera), coleopterans (Coleoptera), neuropterans (Neuroptera), and partially the hymenopterans (Hymenoptera) and lepidopterans (Lepidoptera). With regard to the dipterans (Diptera), only particular families (i.e., Tipulidae, Limoniidae, Syrphidae, and Tabanidae) have been studied in detail, while for the remaining families, there are far from complete lists of species, which do not permit a judgment regarding their actual scope. The complexity of the analysis of the materials relating to the dipterans resides in the absence of keys for a number of families; consequently most of our, and apparently Japanese, collections have remained unidentified.

Six orders obviously constitute the main proportion of the insects of the Kuril Islands: Coleoptera, Lepidoptera, Hymenoptera, Diptera, Homoptera, and Heteroptera, representatives of which are encountered throughout the entire Archipelago. However, the numerical ratios of the species included in them will change somewhat by comparison with what is known at the present time. In particular, the number of species of beetles will increase as a result of work on the small-sized forms within various families; the list of butterflies will be substantially supplemented after detailed study of the geometrids (Geometridae) and Microlepidoptera; the number of parasitic hymenopterans (suborder Parasitica) will increase after investigation of the chalcids (Chalcidoidea) and the gall wasps (Cynipidae). The dipterans, which most probably will in fact constitute the most extensive group, will undoubtedly yield a large increase in species. There is still little information regarding the psyllids (suborder Psyllinea) of the order Homoptera, although this group will hardly turn out to be excessively numerous on the Kuril Islands.

Thus, the question of the total scope of the entomofauna of the Kuril Islands remains thus far an open one. At the present time, nearly 3,000 (more specifically about 2,884) species of insects have been recorded on the Archipelago (although Kuwayama, 1967, cited a much smaller number, only 1,917). It must be assumed that in the future the number of species will increase to approximately 5,000. Nevertheless, the data at our disposal at the present time make it possible to form a general notion of the principal features of the Kuril Island entomofauna, its ecological and zoogeographical particularities, its origin, and its formation.