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Eichhornia azurea (Schwartz) Kunth is one of the most abundant species of aquatic macrophyte in the Upper Paraná River floodplain, and ephemeropteran nymphs frequently inhabit this plant. The objective of this study was to analyze the distribution of ephemeropteran nymphs associated with three sections (apical, intermediate, and basal) of E. azurea in two floodplain lakes of the Upper Paraná River as well as to establish the relation of this distribution to biotic and abiotic factors. The samplings of apical, intermediate and basal sections of E. azurea were carried out monthly from October 1997 to October 1998. Higher concentration of dissolved oxygen may contribute to greater density of nymphs on the apical plant segments near the water surface. Callibaetes willineri was the most abundant taxon, occurring on the apical and intermediate plant sections whereas Campsu- rus spp. were recorded on the basal and intermediate sections of the plant, near the sediment and, mainly during high water. Lower dissolved oxygen concentrations near the lake bottom during the high water phase might suggest that during this phase the nymphs of Campsurus violaceus also migrate to E. azurea roots. It was found that changes in water level influenced the variation of the abundance of nymphs. Other genera, such as Tricorythodes and Leptohyphes, were recorded during the high water phase, when river water enters the lakes and their shores are flooded.
The number and arrangements of the abdominal trichobothria of nymphs and adults in the subfamily Cephalocteinae are described and illustrated. Three types of abdominal trichobothrial patterns were recognized (contrary to all previous data indicating a single uniform type for the whole subfamily), and two different numbers of trichobothria on ventrites III—VII were recorded: 2+2 in adults of Cephalocteus Dufour, 1843, Pseudostibaropus J. A. Lis, 1991, Scaptocoris Perty, 1833, and Stibaropus Dallas, 1851; 1 + 1 in adults of Schiodtella Signoret, 1882, and Atarsocoris Becker, 1967. The abdominal trichobothria of the 5th instar nymphs of Scaptocoris australis J. A. Lis, 1999 and Stibaropus pseudominor J. A. Lis, 1991 were studied and their number and arrangements were found the same as for adults. The taxonomic and phylogenetic significance of the number and arrangement of abdominal trichobothria in the Cephalocteinae is briefly discussed.
All juvenile stages of Limnozetes ciliatus (Schrank, 1803) and deuto- and tritonymph of L. palmeme Behan-Pelletier, 1989 are redescribed and illustrated, and the larva and protonymph of L. palmerae are described and illustrated for the first time. Both species are similar with respect to the body shape, but differ mainly in the shape of some setae in the juveniles, presence of aggenital setae, formula of genital setae, and sculpture of cerotegument in the adult. Relations of species within Limnozetes Hull, 1916 are discussed, and keys to the larvae and nymphs of four European species of this genus are provided.
The behaviour of Dernianyssus gallinae was investigated on two layer farms where two different light programs were introduced in the 40th week of hen life. In layer house No. 1, light was applied continuously for 16 hours during the day, while layer house No. 2 was subjected to 4 hours of light and 2 hours of darkness applied alternately during the day. To monitor the level of red mite infestation, 30 tube traps were placed in every layer house corridor at a height of 1.5 m above the floor. In the first layer house, 280 Dermanyssus gallinae females, 50 nymph larvae and 198 eggs were found in 100 mg of tube trap material during 16 hours of the light phase, while during the 8-hour darkness phase, 1240 females, 70 nymph larvae and 110 eggs were collected. In the other layer house (with an alternating light phase of 4 hours and a darkness phase of 2 hours per day), 387 Dermanyssus gallinae females, 401 nymph larvae and 1060 eggs were found in trap tubes over the 8-hour dark phase, while 343 females, 202 nymph larvae and 1106 eggs were discovered over the 16-hour light phase.
Common European ticks, Ixodes ricinus, have been found in forest areas situated within the boundaries of big cities, and in areas changed by anthropogenic pressure. Monitoring I. ricinus, in the areas used by the public for recreation and leisure, makes it possible to assess the risk of infection with the diseases they transmit. The objective of this study was the comparison of the seasonal activity of ticks, I. ricinus, in the afforested areas of the city of Olsztyn and its surroundings. Material and methods. This survey was conducted at sites located in the afforested areas of Olsztyn and within the Warmiński Forest situated about 15 km from Olsztyn. Ticks, I. ricinus, were caught every 10-14 days from April to October 2001 by the commonly applied method of flagging. During each catch, the temperature (T) and relative humidity (%RH) was measured with a thermohygrometer, 1 m above the duff level. Results. The tick population density at the Warmiński Forest site was higher than that at the sites within the city limits (116.8 and 20.5 ticks per 100 m², respectively). Two peaks of tick activity were recorded in this area - the spring peak in June and the autumn peak (much lower) in September. The activity of ticks in the afforested area within the city limits was much lower - only one (spring) peak occurred, which at most sites was observed in June. At all sites, included in the study, the peak activity of ticks was observed in April. Conclusion. The study suggests that the afforested areas outside the city are more dangerous to people than the area within the city because of the large number of ticks there.
Juvenile stages of Punctoribates punctum (C. L. Koch, 1839) and P. hexagonus Berlese, 1908 are redescribed, those of P. sellnicki Willmann, 1928 are described for the first time, and both juveniles and adults of all species are illustrated. The juvenile stages of these species are similar in body shape and the number of setae on the prodorsum, gastronotum and anal, anogenital and epimeral regions, but differ in the shape and length of some prodorsal and gastronotal setae. Keys to the larvae and nymphs of these species are prepared.
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