Сезонная динамика зараженности Harpalus rufipes (Coleoptera, Carabidae) грегаринами в агроэкосистеме

摘要

Relationships in the “parasite-host” system are closely interrelated and occur at all levels from the molecular to behavioral and population ones. There are two models of realization of these relations. The first case is when the parasites are uniformly distributed in the host population. High extensiveness of invasion is accompanied by its low intensity. The second case is when a part of host population is infected with parasites, but the negative impact is manifested to the maximum extent. Invasion of the ground beetle Harpalus rufipes (De?Geer, 1774), dwelling in sweet corn agroecosystems located in the vicinity of Dnipropetrovsk near Doslidnoe village, by several gregarines species is investigated in this study. H. rufipes is an abundant, ubiquitous species, living in extremely wide range of terrestrial ecosystems, with especially high populations inhabiting anthropogenically transformed environments. H. rufipes has a wide range of feeding. This species is distributed in the Central and Eastern Europe, and introduced to North America. Gregarines were found in the intestines of 20?individuals of H. rufipes from 190 (10.5%): Gregarina ovata Dufour, 1828, G. steini Berndt, 1902, G. amarae (Hammerschmidt, 1839) Frantzius, 1848, Clitellocephalus ophoni (Tuzet and Ormieres, 1956) Clopton, 2002, Torogregarina sphinx Clopton, 1998, Gigaductus macrospora Filipponi, 1948 and G. elongatus (Moriggi, 1943) Filipponi, 1948. There is high level of infestation of C. ophoni and G. steini. At the same time, not more than three species of the gregarines were localized in the beetle body. Seasonal dynamic of occurrence of the gregarines is as follows. Maximal indices of occurrence are found at the end of August (22.2%) and minimal ones at the end of June (4.8%). The highest total number of gregarines (383 ind.) is recorded at the end of August, the lowest one is fixed at the beginning of September (33?ind.). Indices of gregarine species dominance are as follows: C. ophoni – 34.0%, G. macrospora – 28.9%, G. steini – 20.6%, T. sphinx – 9.3%, G. amarae – 5.5%, G. ovata – 0.9% and G. elongatus – 0.4%. High temperatures in July and August helped to increase infection of H.?rufipes by almost all gregarines compared to cool and wet conditions in June. The highest value of the index of abundance corresponds to the time of high average intensity of infestation by three common species of gregarines. Decline in abundance index by the end of summer and early fall may be due to the death of heavily infected individuals. High level of infection does not cause the pathogenic effect on the host organism.