LIFE CYCLE AND MORPHOLOGY OF PARUTERINA RAUSCHI N.SP. and P. CANDELABRARIA (GOEZE, 1782) (CESTODA) FROM OWLS, AND SIGNIFICANCE OF PLEROCERCOIDS IN THE ORDER CYCLOPHYLLIDEA

1957 ◽  
Vol 35 (3) ◽  
pp. 349-370 ◽  
Author(s):  
Reino S. Freeman

Paruterina rauschi n.sp. is described from the barred owl, and P. candelabraria (Goeze, 1782) is redescribed from the snowy owl; both species grow in the great horned owl. The life history and development of the plerocercoid of both species of worms in various rodents is described. Natural infections with the plerocercoid of P. rauschi n.sp. are reported from Tamias striatus and Peromyscus leucopus. Plerocercoids are not uncommon in cyclophyllidean life cycles, and their significance in the taxonomy of the order Cyclophyllidea is discussed. It is concluded that any future taxonomic revision of this order must consider the morphology of the immature stages if such a revision is intended to clarify natural relationships.

The Condor ◽  
2000 ◽  
Vol 102 (1) ◽  
pp. 35-51 ◽  
Author(s):  
Jerry D. Jacobs ◽  
John C. Wingfield

Abstract Most organisms live in seasonal environments that fluctuate on a predictable schedule and sometimes unpredictably. Individuals must, therefore, adjust so as to maximize their survival and reproductive success over a wide range of environmental conditions. In birds, as in other vertebrates, endocrine secretions regulate morphological, physiological, and behavioral changes in anticipation of future events. The individual thus prepares for predictable fluctuations in its environment by changing life-cycle stages. We have applied finite-state machine theory to define and compare different life-history cycles. The ability of birds to respond to predictable and unpredictable regimes of environmental variation may be constrained by the adaptability of their endocrine control systems. We have applied several theoretical approaches to natural history data of birds to compare the complexity of life cycles, the degree of plasticity of timing of stages within the cycle, and to determine whether endocrine control mechanisms influence the way birds respond to their environments. The interactions of environmental cues on the timing of life-history stages are not uniform in all populations. Taking the reproductive life-history stage as an example, arctic birds that have short breeding seasons in severe environments appear to use one reliable environmental cue to time reproduction and they ignore other factors. Birds having longer breeding seasons exhibit greater plasticity of onset and termination and appear to integrate several environmental cues. Theoretical approaches may allow us to predict how individuals respond to their environment at the proximate level and, conversely, predict how constraints imposed by endocrine control systems may limit the complexity of life cycles.


1972 ◽  
Vol 50 (2) ◽  
pp. 201-204 ◽  
Author(s):  
Doris N. Jensen

The life cycle of the brachylaemid trematode Scaphiostomum pancreaticum McIntosh, 1934, was completed experimentally in the laboratory. Eggs were obtained from trematodes removed from naturally infected Tamias striatus. Eggs are mature when laid and hatch naturally only after ingestion by a snail. In vitro hatching and subsequent examination of the miracidium was accomplished in snail gastric juice. Sporocysts developed in Anguispira alternata and cercarial emergence began 129 days after infection. Metacercariae developed in the kidney of A. alternata, Triodopsis albolabris, and Haplotrema concavum and were infective to the chipmunk after 5 months, and ovigerous adults were obtained in 30 days. This is the first description of the life cycle of a member of this genus.


Parasitology ◽  
1998 ◽  
Vol 116 (S1) ◽  
pp. S47-S55 ◽  
Author(s):  
J. C. Koella ◽  
P. Agnew ◽  
Y. Michalakis

SummarySeveral recent studies have discussed the interaction of host life-history traits and parasite life cycles. It has been observed that the life-history of a host often changes after infection by a parasite. In some cases, changes of host life-history traits reduce the costs of parasitism and can be interpreted as a form of resistance against the parasite. In other cases, changes of host life-history traits increase the parasite's transmission and can be interpreted as manipulation by the parasite. Alternatively, changes of host's life-history traits can also induce responses in the parasite's life cycle traits. After a brief review of recent studies, we treat in more detail the interaction between the microsporidian parasite Edhazardia aedis and its host, the mosquito Aedes aegypti. We consider the interactions between the host's life-history and parasite's life cycle that help shape the evolutionary ecology of their relationship. In particular, these interactions determine whether the parasite is benign and transmits vertically or is virulent and transmits horizontally.Key words: host-parasite interaction, life-history, life cycle, coevolution.


1969 ◽  
Vol 101 (9) ◽  
pp. 955-963 ◽  
Author(s):  
David Evans

AbstractA 5-year study of Laspeyresia pseudotsugae n. sp. (Lepidoptera: Olethreutidae) yielded considerable data on the habits, life history and immature stages of this insect, which gained attention because of its conspicuous bark-mine scars on the trunks of young Douglas-fir trees, Pseudotsuga menziesii (Mirbel) Franco. The mines are not deep enough to cause serious damage. L. pseudotsugae has a 1-year life-cycle. Three species of ichneumonid parasites were recovered, and several predators were identified.


1930 ◽  
Vol 7 (2) ◽  
pp. 132-142
Author(s):  
HUGH H. DARBY

Constant division rate in ciliates can be maintained by keeping the culture medium at constant optimum H-ion concentration. The variations in division rate found in the typical protozoan life history, including gradual decline and death, can be reproduced experimentally by altering the pH of the medium. When cultures are maintained under optimum conditions, encystment and conjugation can take place at any age; the life cycle disappears. An explanation based on experiment is given for the apparently contradictory findings of Maupas. Neither conjugation nor endomixis has any effect on the division rate under constant conditions. The length of the endomictic period is affected by the H-ion concentration of the medium.


Parasitology ◽  
2016 ◽  
Vol 144 (4) ◽  
pp. 464-474 ◽  
Author(s):  
C. LAGRUE ◽  
R. RINNEVALLI ◽  
R. POULIN

SUMMARYA number of parasites with complex life cycles can abbreviate their life cycles to increase the likelihood of reproducing. For example, some trematodes can facultatively skip the definitive host and produce viable eggs while still inside their intermediate host. The resulting shorter life cycle is clearly advantageous when transmission probabilities to the definitive hosts are low. Coitocaecum parvum can mature precociously (progenesis), and produce eggs by selfing inside its amphipod second intermediate host. Environmental factors such as definitive host density and water temperature influence the life-history strategy adopted by C. parvum in their crustacean host. However, it is also possible that information about transmission opportunities gathered earlier in the life cycle (i.e. by cercariae-producing sporocysts in the first intermediate host) could have priming effects on the adoption of one or the other life strategy. Here we document the effects of environmental parameters (host chemical cues and temperature) on cercarial production within snail hosts and parasite life-history strategy in the amphipod host. We found that environmental cues perceived early in life have limited priming effects on life-history strategies later in life and probably account for only a small part of the variation among conspecific parasites. External cues gathered at the metacercarial stage seem to largely override potential effects of the environmental conditions experienced by early stages of the parasite.


Parasitology ◽  
2008 ◽  
Vol 135 (10) ◽  
pp. 1243-1251 ◽  
Author(s):  
C. LAGRUE ◽  
R. POULIN

SUMMARYParasites with complex life cycles have developed numerous and very diverse adaptations to increase the likelihood of completing this cycle. For example, some parasites can abbreviate their life cycles by skipping the definitive host and reproducing inside their intermediate host. The resulting shorter life cycle is clearly advantageous when definitive hosts are absent or rare. In species where life-cycle abbreviation is facultative, this strategy should be adopted in response to seasonally variable environmental conditions. The hermaphroditic trematode Coitocaecum parvum is able to mature precociously (progenesis), and produce eggs by selfing while still inside its amphipod second intermediate host. Several environmental factors such as fish definitive host density and water temperature are known to influence the life-history strategy adopted by laboratory raised C. parvum. Here we document the seasonal variation of environmental parameters and its association with the proportion of progenetic individuals in a parasite population in its natural environment. We found obvious seasonal patterns in both water temperature and C. parvum host densities. However, despite being temporally variable, the proportion of progenetic C. parvum individuals was not correlated with any single parameter. The results show that C. parvum life-history strategy is not as flexible as previously thought. It is possible that the parasite's natural environment contains so many layers of heterogeneity that C. parvum does not possess the ability to adjust its life-history strategy to accurately match the current conditions.


Parasitology ◽  
1933 ◽  
Vol 25 (4) ◽  
pp. 518-545 ◽  
Author(s):  
S. Benton Talbot

1. The life histories of Lechriorchis primus Stafford, L. tygarti n.sp. and Caudorchis eurinus n.gen. et sp. have been experimentally completed in three hosts, the first complete life histories to be worked out for species of the subfamily Reniferinae.2. The definitive hosts of the three forms were found to be two species of garter snakes, Thamnophis sauritus and T. sirtalis.3. Three species of snails, Physella gyrina, P. parkeri, and P. ancillaria, have been found to serve as the first intermediate host in the life cycles of Lechriorchis primus and Caudorchis eurinus n.gen. et sp., and two species of snails, Physella gyrina and P. heterostropha, in the life cycle of Lechriorchis tygarti n.sp.4. The tadpoles of two species of frogs, Rana clamitans and R. pipiens, were found to serve as the second intermediate hosts in the life cycles of all three trematodes. The cercariae penetrate larvae of Triturus and small fish, but live only a short time in these animals.5. Every stage in the life history of Lechriorchis primus, including egg, miracidium, mother sporocyst, daughter sporocyst, cercaria, metacercaria, and developmental stages in the definitive host, has been described in detail.6. The mother sporocyst of forms having a stylet cercaria is described for the first time.7. The flame cell pattern of the cercariae of L. primus, L. tygarti n.sp., and Caudorchis eurinus n.gen. et sp. has been determined to be of the “2 × 6 × 3’ type. Also the adult stage of C. eurinus was determined to have the same type.8. It has been pointed out that the life histories of the members of the subfamily are uniform in that their life history stages display a remarkable similarity.9. It has been suggested that this uniform type of life cycle and remarkable similarity of larval stages offer the most logical basis for establishing the subfamily Reniferinae as a natural group.


1977 ◽  
Vol 34 (10) ◽  
pp. 1464-1466 ◽  
Author(s):  
A. H. Weatherley

Perca fluviatilis was introduced into Australia during the nineteenth century. Its extensive distribution in Australia and the range of climatic and topographic conditions over which it occurs make it possible to distinguish the roles of high temperature, breeding conditions, and flow characteristics in rivers in limiting the spread of the species. By extrapolation the distributional limits of the species throughout the world can be largely explained and, by analogy, those of the closely related species P. flavescens in North America. A model of a fish life cycle arising out of knowledge of Perca life cycles is presented as a possible tool for clarifying and predicting the success or failure of species introduced into new environments. Key words: Percidae, Perca, zoogeography, life history, introduction in Australia, predictive model, management, Eurasian perch


Zoosymposia ◽  
2021 ◽  
Vol 20 ◽  
Author(s):  
ZHI-QIANG ZHANG

The Anystidae are a family of over 100 species of predatory mites commonly seen in soils and on plants worldwide. A few species of genus Anystis have potential as biocontrol agents against some insect and mite pests. Herein I provide a review of the lifespan of the Anystidae as part of a series on the lifespans in the Acari. The full life cycle in this family includes six immature stages (the egg, prelarva, larva, protonymph, deutonymph and tritonymph) and adult males/females. Life history data are only available for a few species. Developmental times from eggs to adults (44 to 82 days at 21 or 22 °C) were reported for three Anystis species. The total lifespan was measured for only one species (Anystis agilis): 66 days at 21 °C. There are two to three generations per year for Anystis species in the field. Summer aestivation was reported for Anystis baccarum, either as eggs or tritonymphs; aestivating tritonymphs may have a developmental time and total lifespan of over 200 and 300 days, respectively.


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