Canadian Journal of Zoology
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ON THE DEVELOPMENT AND TRANSMISSION OF COSMOCERCOIDES DUKAE OF TERRESTRIAL MOLLUSCS IN ONTARIO Nematodes from the mantle cavity of Discus cronkhitei, Zonitoides arborea, and Deroceras gracile, and the rectum of Rana spp., Bufo americanus, and Ambystoma jeffersonianum in Ontario are referred tentatively to Cosmocercoides dukae (Holl, 1928), In molluscs, females deposit third-stage larvae that leave the mantle cavity and appear in slime trails left by snails; when placed on the foot of snails these larvae entered the respiratory pore and went to the mantle cavity where they developed. Larvae were found in the genital tract and ovary of slugs and in eggs of both snails and slugs. These penetrated into the mantle cavity of embryo molluscs which subsequently hatched. All stages of C. dukae can survive for long periods in tap water or invertebrate saline. Females sometimes laid eggs which hatched if they contained a first-stage larva and the latter developed to the infective stage. Worms of all stages from molluscs fed to frogs were passed at intervals in the faeces and there was no evidence this species could establish itself in amphibians; the occurrence of cosmocercids in amphibians in Ontario is possibly the result of the latter eating infected molluscs, the worms being able to survive passage through the gut. The larvae and adults are described in detail herein.
Canadian Journal of Zoology - Tập 38 Số 4 - Trang 801-825 - 1960
Estrone and estradiol concentrations in peripheral plasma of laying hens as determined by radioimmunoassay An application of radioimmunoassay to measurement of concentrations of estradiol and estrone in peripheral plasma of hens is described. Evidence is presented that the estradiol measured by the procedure was essentially estradiol-17β.For 13 ovulatory cycles the average concentration of estradiol was 123 pg/ml with a range from 36 pg/ml to 284 pg/ml. The corresponding average concentration for estrone was 64 pg/ml with a range from 14 pg/ml to 138 pg/ml. For 12 days of no ovulation the average concentration of estradiol was 142 pg/ml with a range from 42 pg/ml to 364 pg/ml. The corresponding average value for estrone was 91 pg/ml with a range from 18 pg/ml to 242 pg/ml.The results are interpreted as demonstrating the existence of peak levels of plasma estradiol at 22–18 h and again at 6–2 h before ovulation, and a minimal level at 14–10 h before ovulation. The corresponding plasma estrone concentrations displayed a similar cycle but the earlier peak and the minimum occurred 2–4 h later than the corresponding values for estradiol. Such peak values were not demonstrable on days when ovulation did not occur.The results are discussed briefly in relation to variation in the levels of blood progesterone during the ovulatory cycle.
Canadian Journal of Zoology - Tập 50 Số 4 - Trang 395-404 - 1972
Effects of food abundance and wind on the use of tree lines by an insectivorous bat, <i>Pipistrellus pipistrellus</i> We tested the hypotheses that the distance bats fly from tree lines depend on food abundance and protection from wind. We monitored the activity of pipistrelle bats (Pipistrellus pipistrellus) and measured insect abundance and wind speed and direction at fixed distances up to 50 m from tree lines. We compared bat behaviour in different situations: with and without wind and with low and high insect abundances in adjacent open areas. In all situations, pipistrelle bats' activity decreased with increasing distance from the tree line. Within nights, we found no effect of wind speed on bat activity (sound recorded per 5 min) on the leeward side of the tree lines. Between nights, however, bats concentrated their activities closer to the tree lines at high wind speeds or angles of incidence of wind from 45° to 90°. A significant relationship between bat and insect abundances was found only when the tree line was bordered by insect-rich grassland. Since wind and insect abundance only partly explained the distances bats flew from tree lines, two alternative explanations, namely predator avoidance and the use of tree lines as acoustic landmarks, are discussed. Pipistrelle bats using a double row of trees as a commuting route at dusk flew mainly between the tree lines, regardless of insect abundance or wind speed. It is argued that predator avoidance explains this behaviour, being a constraint on movements of bats at relatively high light levels. At high wind speeds and angles of incidence greater than 45°, the proportion of pipistrelle bats commuting on the leeward side of the tree lines increased.
Canadian Journal of Zoology - Tập 77 Số 9 - Trang 1393-1401 - 1999
Spruce budworm outbreaks and the incidence of vagrancy in eastern North American wood-warblers The Tennessee (Vermivora peregrina), Cape May (Dendroica tigrina), Bay-breasted (D. castanea), and Canada (Wilsonia canadensis) warblers and the Ovenbird (Seiurus aurocapillus) appear to show positive numerical responses to outbreaks of the spruce budworm (Choristoneura fumiferana); the Magnolia (D. magnolia), Black-throated Green (D. virens), and Blackburnian (D. fusca) warblers may occur in lower numbers during outbreaks because of increased competition with these budworm specialists. Thus, we predicted that the number of fall vagrant Tennessee, Cape May, and Bay-breasted warblers and Ovenbirds occurring in California are highly positively associated with budworm population density, positively intercorrelated, and negatively associated with numbers of Magnolia, Black-throated Green, and Blackburnian warblers. A 23-year (1972-1994) data set of budworm population densities and vagrant warbler occurrences in California showed that (i) budworm population density was an excellent predictor (explaining about 50% of the variance) of numbers of occurrences of the Cape May, Bay-breasted, and Canada warblers; (ii) all warbler species tended to co-occur, with numbers of Cape May and Bay-breasted warblers especially highly intercorrelated; and (iii) Magnolia Warbler numbers were negatively associated with those of budworm specialists, but Black-throated Green and Blackburnian warblers showed no association.
Canadian Journal of Zoology - Tập 76 Số 3 - Trang 433-439 - 1998
Hyperglycaemia induced by anaesthesia in the american cockroach, <i>Periplaneta americana</i> L. A hyperglycaemic response is elicited in adult males of the american cockroach, Periplaneta americana, within 60 min of anaesthetizing insects using nitrogen, chilling, or diethyl ether. Hyperglycaemia is also produced as a result of handling insects without anaesthesia. Insects which have been anaesthetized with carbon dioxide do not exhibit a marked change in haemolymph sugar concentration.
Canadian Journal of Zoology - Tập 51 Số 3 - Trang 395-397 - 1973
HYDROMERMIS CHURCHILLENSIS N. SP. (NEMATODA: MERMITHIDAE) A PARASITE OF AEDES COMMUNIS (DeG.) FROM CHURCHILL, MANITOBA, WITH OBSERVATIONS OF ITS INCIDENCE AND BIONOMICS Hydromermis churchillensis n. sp. is described. It is distinguished from other species of Hydromermis mainly by the fused spicules and pointed termini of both sexes. One to six larval nematodes may be found in a larva of Aedes communis (DeG.). They emerge to become free-living, molt, mature, mate, and oviposit in 2 months. Host activity is hindered, pupation prevented, and the host usually killed upon emergence of the worm. Worms are found occasionally in adult mosquitoes. Host reaction as encapsulation sometimes occurs. Ectocommensal protozoa are more common on uninfected than on parasitized mosquito larvae. At Churchill, Manitoba, approximately 10% of the mosquito larvae were killed, but in individual pools the percentage reached 80%. Nematodes were irregularly distributed in the forest and transition zones, but no correlation was found between the physical features of the pools and this distribution.
Canadian Journal of Zoology - Tập 38 Số 3 - Trang 465-474 - 1960
Some effects of the nematode <i>Mermis nigrescens</i> upon carbohydrate metabolism in the fat body of its host, the desert locust <i>Schistocerca gregaria</i> Adult desert locusts were experimentally infected with 50 Mermis nigrescens ova and changes in the fat body carbohydrate levels and glycogen phosphorylase activities recorded. At both 2 and 3 weeks after infection, the parasitism caused a significant reduction in the level of glycogen and non-glycogen carbohydrates in the host fat body, together with a progressive depletion of active and inactive glycogen phosphorylases. By feeding extensively upon the blood carbohydrates of the host, the developing nematode deprives the fat body of carbohydrates and thereby effects a reduction in glycogenesis by the host fat body. Increased catabolism (and (or) decreased anabolism) of the fat body phosphorylases, together with a possible suppression of the host "hyperglycaemic factor" by the nematode, prevent further glycogenolysis by the fat bodies of mermithid-infected locusts and allow a low, constant level of fat body glycogen to be maintained in these insects.
Canadian Journal of Zoology - Tập 49 Số 4 - Trang 431-434 - 1971
Evidence for a memory process in the turning behavior of free swimming goldfish Positive correlation was established between the magnitudes of consecutive turns in opposite directions of naive goldfish in a monitor tank. Evidence is presented for a decrease in this correlation with increasing time between turns; no change in correlation could be established with distance between turns. Results are discussed with reference to the literature on spontaneous alternation and the possible effect of walls on this behavior.
Canadian Journal of Zoology - Tập 48 Số 4 - Trang 813-815 - 1970
Helminthes intestinaux du Renard commun (<i>Vulpes vulpes</i> L.) dans le Massif central (France) In the course of an epidemiological survey of Echinococcus multilocularis (Leuckart, 1863), causative agent of alveolar hydatid disease, the autopsy of 154 red foxes, Vulpes vulpes (L.), captured in the Department of Cantal between November 1984 and February 1985 disclosed 144 cases of intestinal helminthiases. Helminths consisted of cestodes and nematodes; no trematodes were found. Multiple infestations were very frequent. Cestoda recorded consisted of the following species: Mesocestoides litteratus (Batsch, 1786) (40 cases; 26%), Taenia crassiceps (Zeder, 1800) (36 cases, 24%), Echinococcus multilocularis Leuckart, 1863 (23 cases, 14.9%), Taenia polyacantha Leuckart, 1856 (17 cases, 11.4%), Amoebotaenia paradoxa (Rudolphi, 1802) (8 cases, 5.2%), and Taenia pisiformis (Bloch, 1780) (2 cases, 1.3%). The following Nematoda were recovered: Uncinaria stenocephala (Railliet, 1884) (90 cases, 58.4%), Toxocara canis (Werner, 1782) (79 cases, 51.3%), Toxascaris leonina (Linstow, 1902) (39 cases, 25.3%), Trichuris vulpis (Froelich, 1789) (25 cases, 16%), Pterygodermatites affinis (Jaegerskioeld, 1904) (6 cases, 4%), and undetermined Trichostrongylidae (4 cases, 2.7%). Hosts were not examined for Trichinella sp. The cartography of each helminthiase revealed propitious areas of maintenance of the parasite. Echinococcus multilocularis had a very limited distribution compared with other taeniid species with a near-identical life cycle. Unknown ecological factors may have an adverse effect on the free stage (egg) of the cestode. The nematode Pterygodermatites affinis is reported here for the first time in France.
Canadian Journal of Zoology - Tập 66 Số 7 - Trang 1562-1569 - 1988
Caractéristiques écologiques et épidémiologiques de l'<i>Echinococcus multilocularis</i> au cours d'un cycle complet des populations d'un hôte intermédiaire (<i>Microtus arvalis</i>) This study, carried out in a medium altitude mountain ecosystem (Doubs, France), was devoted to the analysis of spatial and temporal variations of the infestation rate of Echinococcus multilocularis Leuckart in a microtine secondary host (Microtus arvalis Pallas) during a complete population cycle of the rodent. This analysis, combined with a structural study of the landscape, showed that contaminated rodents were located only in or near ploughed fields. The age structure of the rodent population showed that infestation occurred only during winter (from October to April in the studied area). These results suggest new ways of research for elucidating the mechanisms responsible for the perenniality of the parasite.
Canadian Journal of Zoology - Tập 66 Số 12 - Trang 2740-2750 - 1988
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