AGE STRUCTURE AND DYNAMICS OF LOCUST NUMBER IN KARACHAYCHERKESSIA IN DIFFERENT ONTOGENESIS PERIODS

Abstract

Aim. To study age structure and population dynamics of locusts inhabiting Karachay-Cherkessia in different periods of ontogeny. Information on the periods of locusts hatching, growing to dominant species and their fertility can be used by plant protection services for the objective assessment of harmful species populations and predict their numbers in the region. Methods. The studies were conducted in the southern, central and northern regions of the republic. Studied material includes more than 6000 locust larvae and imago. Annually we conducted route study of locusts and multiple transect surveys which covered 36 most characteristic habitats. In the field and laboratories, we carried out experiments and studies on egg capsules and larvae. Results. The study revealed features of ontogeny and population dynamics of all the phases of development (egg, larva, imago) of five species of locusts (Omocestus haemorrhoidalis Ch., Chorthippus albomarginatus Deg., Chorthippus bigutullus L., Chorthippus apricarius L., Chorthippus mollis Ch.) in a variety of habitats. Conclusions. The average number of eggs in the egg capsules in the south region is more than in the north; the hatching of larvae is between 11 am and 4 pm, the average developmental period varies by age and region. From the hatched larvae (not more than 80% of the number of eggs laid) usually considerably more than half dies. For the existence of a stable population of the species under study, the annual number of eggs should be 10-20 times the number of adults. It was found that the number of locusts in Karachay-Cherkessia in general increases in dry warm years, and in mowed areas is higher.