Andrei N. Alekseev*, A.V. Semenov** & Helen V. Dubinina*
*Zoological Institute, Russian Academy of
Sciences, Universitetskaja nab., 1, 199034, St. Petersburg, Russia
**Municipal Centre of
Virological Research, Mirgorodskaja st., 3, 193176, St. Petersburg, Russia;
Zoology Section (PhD student), Royal Veterinary and Agricultural Institute,
Torvaldsenvej, 40, DK-1871 Frederiksberg, Denmark
The new methods were used to estimate Ixodes persulcatus tick activity, genetical heterogeneity, infection rate and reactions on abiotical parameters. Ticks were collected in 1998 in the St. Petersburg vicinity known as a tick-borne diseases focus. Collections were made every 10 d during 24 h. Temperature, relative humidity and illumination were checked every 2 h on 3 levels: 1.5, 0 and minus 0.02 m. Gradients between to and humidity on the different levels were calculated. Rate of infection was determined using darkfield microcropy and IFA methods. NAD-dependent malatdehydrohenase was used as a marker of electrophoretic heterogeneity. Nine electrophoretypes were found, which were different in their abundance in population, infection rate, and prevalence during a season, within a day and at the different temperature gradients (TG). The difference between soil surface (0 m) and litter (-0.02 m) temperatures triggered tick appearance.
Electrophoretypes I (64.8%) and IV (16.2%) were met within a whole season and had a 50-55% level of infection. Phoretype I was the most cold tolerant being noninfected or Borrelia—infected. Phoretypes II and IX were highly infected, but were met only in 2.4-0.8% of cases. Phoretypes IX (100% of infection) appeared in June at the litter temperature 21o C and TG 2.5o. Not abundant (3.5%) VIII phoretype being infected only in 50% of cases was most heavily infected. Activity index of ticks showed that Borrelia—infected specimens appeared at the highest TG and became more “warm”- like than the uninfected ones.
Our data suggest that population heterogeneity is a basis of Borrelia focus stability.
Nikolai V. Aladin*, Valentina N. Ryabova**, Yuri S. Chuykov*** & Igor S.
Plotnikov*
*Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St.
Petersburg, 199034, Russia
**St.-Petersburg State University, St. Petersburg, 199034, Russia
***Committee of Ecology of Astrakhan Region, Astrakhan, Russia
Some results of phylogenetic work based on DNA sequence data are presented. Analysis has shown that Podonidae and Cercopagididae are monophyletic and a sistergroup-relationship between the two appears likely. Colonisation of Ponto-Caspian Region occurred once in the Cercopagidiae and once within the Podonidae. Caspian species of Podonidae constitute a monophyletic clade derived from the marine representatives of the family which form a paraphyletic grade. It is thus parsimonious to propose that the Podonidae colonised the Caspian Sea only once. The stem species of the clade came from a marine environment. The colonisation of the Caspian Sea by the ancestor of might have occurred considerably later, in Apsheronian possibly during the Khvalyn. Many species indicated in scientific literature for genera Cornigerius and Cercopagis probably are not real species but are morphological types. Some years ago representatives of genus Cercopagis were found in plankton of the Baltic Sea and in lake Ontario. Originally they lived only in residual reservoirs of Paratethys, but in the middle of our century they begun to penetrate into freshwater reservoirs on the rivers Don and Dnieper (Cercopagis pengoi). Analysis of plankton samples from the Baltic has shown prevalence of C. pengoi among invaders and presence of other species of this genus (or some abnormal forms resembling other species).
Nikita Chernetsov & Andranik Manukyan
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St.Petersburg, 199034, Russia
Diets and foraging strategies of Sedge and Reed Warblers on migration studied by the stomach flushing method were surprisingly similar between species in both seasons, in spring and in autumn. Both Sedge and Reed Warblers utilised prey which was abundant and formed aggregations. Though the taxonomic diversity was large, especially in late summer and in autumn, virtually every prey belonged to a restricted number of ecological communities (insects hibernating in reed stems, insects developing in aquatic/moist conditions, insects connected with reed, insects attracted by plum aphids, etc.). Diet composition differed between seasons, but main principles of foraging strategies remained the same.
Igor G. Danilov
Zoological Institute, Russian Academy of Sciences,Universitetskaya nab. 1, St. Petersburg, 199034, Russia
Differences in the taxonomic composition of the turtle faunas in the late Cretaceous of Middle Asia and Mongolia are analyzed. Two ecological types of turtles in the late Cretaceous of Asia are discussed.Lindholmemys is proposed to inhabit big rivers and estuaries in the coastal plains and Mongolemys lived under seasonal climatic condition and probably occupied ephemeral waterbodies.
Olga V. Dolnik
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg, 199034, Russia
Background: Diurnal periodicity of Isospora oocysts has been recorded from one species of passerine birds in captivity. We checked the existence of this diurnal rhythm of Isospora oocysts from several passerine species in the wild, and compared the results with data from caged birds.
Method: Studies were undertaken on the Courish spit of the Baltic sea; more than 360 birds of 6 species were trapped at different time of day during June and July, 1996-98. Fresh feces were collected and after sporulation were checked using the standard method of Fulleborn. Feces samples from 14 caged birds of four species were collected every 2 hours during several days and were checked using the same method.
Results: There was a clear peak of oocyst output between 4 and 8 p.m. in the wild and a more wide and varying afternoon peak in captivity.
Conclusions: A clear diurnal rhythm of Isospora oocysts’ appearance can be an adaptation of the parasite to host’s behaviour. The time when Isospora oocysts appear in birds’ droppings coincide with the time of evening peak of birds’ feeding activity. This allows parasites to increase the number of infectious oocysts on the places of host’s feeding. By this way the probability to infect a new host of the same species increases. At the same time evening appearance may allow oocysts to avoid straight sunlight and not to be dried up in the first hours after getting out of the host.
Valentina P. Dyachenko
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St. Petersburg, 199034, Russia
The rhythm of activity is often used as a marker for the phase of circadian clock. In experiments with birds that can not exhibit activity in darkness dim background illumination is required. The paper presents evidence that changes in locomotor activity, being able in the presence of dim light, have feedback effects on the photoperiodic time-measuring system. In Experiment I the effect of ultra-short photoperiods on testicular response was examined in Chaffinches. In the presence of dim light LD 3:21 was more effective than LD 9:15. On LD 3:21 testicular weights showed considerable individual variation (from 4mg to 138mg) depending on the pattern of entrainment. The close relationship between duration of activity and the photoperiodic response (r = 0.847) supports the idea that the effect of ultra-short day can be mediated by locomotor activity. In Experiment II effect of testosterone on the rhythm of photosensitivity for migratory fattening response was examined in Chaffinches using asymmetric skeleton photoperiods. The results revealed that in birds pre-treated with testosterone the photoinducible phase is advanced relative to LD cycle, as well as the rhythm of activity. The effect, however, is possible only in the presence of dim light. This is the first evidence for the phase-shifting mechanism of the effect of testosterone on the photoperiodic induction of migratory fat deposition.
Nadezhda N. Erlykova
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St. Petersburg, 199034, Russia
The response of apterous and alate viviparous females of the green clone of Acyrthosiphon pisum Harris for diel photoperiods (from 2L:22D to 21L:3D) is investigated. The remarkable differences between progeny pattern of apterae and alatae and some features of their reproductive periods are revealed.
Under long-day conditions apterae and alatae produce viviparous females. Under short-day conditions alatae, compare with apterae produce fewer males, but more egg-laying females (oviparae). The range of photophases inducing ovipara production in alatae (4-15 h) is nearly twice as wide as that in apterae (6-12 h). Males prevail in the progeny of apterae in 6-13 h photophases.
The composition of progeny sequences is controlled not only by photoperiod, but also by maternal age. The reproductive period of apterae begins by the age of 9-10 days, while that of alatae - nearly two days later, even though females of both morphs moult to adults at approximately the same time. The male production (if any) always begins some days after the onset of larviposition. The reproductive pause occurs between the end of female production and before the onset of the male one. It lasts for 1-2 days in apterae and for hardly a day in alatae. The dynamics of appearance of certain morphs in the progeny sequences of apterae and alatae are similar.
The differences in photoperiodic response and features of reproductive periods of apterae and alatae are consistent with different ecological roles of these viviparous females.
Andrey A. Przhiboro
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St.Petersburg, 199034, Russia
Faunal composition, abundance, seasonal dynamics and distribution of non-chironomid Diptera inhabiting the shallow zone (from water line to a depth of 1m) were studied in two lakes. Along with 115 quantitative and 66 qualitative samples taken, the imagines of the most of species have been reared. Non-chironomid Diptera were common or abundant at the depth of 0.05-1.0 m in places with soft bottom covered with layer of detritus and in locations of developed semisubmerged vegetation (30-100 % of the total area of shallow zone of a lake); their mean biomass ranged from 0.015 to 0.8 g/m2 and usually comprised 20-40 % (up to 60 %) of total Diptera biomass, and 2-6 % (up to 30 %) of total macrobenthos biomass. In the zone of 0.2-1.0 m depth of all lakes only Ceratopogonidae larvae (Dasyhelea and subfamily Palpomyiinae) were abundant, at some sites Chrysops (Tabanidae) and Hemerodromia (Empididae) larvae were common. In the zone of water line non-chironomid Diptera generally predominated over all other macrobenthic fauna. Non-chironomid Diptera are represented in littoral communities mainly as entomophages and detritophages. The data are compared with the author's materials on the another lakes of North-West of Russia.
Aleksey O. Smurov*, Igor S. Plotnikov* & Sergey I. Fokin**
* Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St. Petersburg, 199034, Russia
** Biological Institute of St. Petersburg University, St. Petersburg, Stary Peterhof, Oranienbaumskoye sch. 2, 198904, Russia
Salinity resistance and tolerance of P. trichium, P. bursaria, P. calkinsi, P. nephridiatum, P. caudatum, P. jenningsi and P. sexaurelia were investigated. Existence of two types of the paramecia resistance to salinity impact is shown. Using the linear-fractional hyperbolic regression is proposed to estimate the data on microorganisms’ mortality. Connection the peculiarities of regression analysis and the type of paramecia mortality was analyzed. It is shown that linear-fractional hyperbolic regression of mortality data can be used for estimation of the salinity tolerant limits. Comparison of estimations of tolerant limits obtained by this and other methods was done. Possible use of hyperbolic regression analysis in toxicological studied was discussed.
Eugeny S. Sugonyaev
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab., 1, St. Petersburg, 199034, Russia
The study was undertaken of the morphological and biological adaptations of chalcid-wasps for parasitization on soft scale insects in different climatic zones of the Northern Hemisphere. There are divers trends in evolution of the general adaptational systems of the former in the Tropic, temperate zone and the Hypoarctic where biotes and various seasonal development of their hosts, namely polycyclism, monocyclism and hemicyclism, are common respectively. Three strategies of parasitization directed on reproductive success of the parasite species have been revealed.
Under the trophical condition continuous seasonal development together with species reachness both soft scale insects and their parasites, and resource fragmentation create the ground for formation of general tropic reactions of chalcid-wasps and their ecotopic food specialization. As a result, the outstripping strategy of parasitization with the trend to infest more young host stages is typical here.
Under the temperate and hypoarctic conditions a species reachness of hosts progressively decreases from low to high latitudes while a discreteness between appearance of host life cycle stages during its seasonal development increases. In consequence, high host specificity and sophisticate seasonal cycles of chalcid-wasps take place here. Two strategies by the letter for overcoming the hostless period and guaranteeing of the optimal meeting of mature parasite female with host specimen of definite stage preferable for infestation were found which are referred to as the surviving strategy and the evasion strategy. These two strategies are shown by the structural features both adult and pre-imaginal stages.
Elena B. Vinogradova & Sergey Ya. Reznik
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St.Petersburg, 199034, Russia
Experiments were conducted with several successive generations of three laboratory lines of the blowfly, Calliphora vicina collected in Stavropol (Russia). The flies were kept at 20°C and different photoperiods, the progeny larval diapause was tested at 12°C and darkness. In this species, the larval diapause is dependent on the maternal photoperiod, i.e. as the length of the maternal photophase decreases, the percentage of the progeny diapause increases. Statistical treatment of the results of 70 experiments (ca 250 rafts, ca 100 000 larvae) has revealed a significant correlation between the female age and the progeny larval diapause, this correlation was positive under long day conditions (16-20 h of light per day) and negative - under short day (12-14 h). This data suggest the existence of two components within maternal influence on the progeny diapause: the main component connected with the maternal photoperiod, and the additional component conditioned by female age. Moreover, the spontaneous variation of the percentage of larval diapause was recorded in the successive generations of the same line. The dynamics of the percentage of larval diapause was similar in the “spring” and “autumnal” lines, originated from flies collected in the same location at spring and at autumn, respectively and quite different in two sub-lines of the “spring” line reared under short and long photophases.