摘要:

SummaryI. This review provides a background to those aspects of the biology and behaviour of Lepidoptera infesting stored products which may be important in terms of population dynamics.2. The general biologies of four common species of Phycitid moth are described.3. Both the fecundity and the fertility of the adult can be influenced by the diet of the female, the size of the female, the numbers of adults per unit area and a variety of environmental factors.4. Egg mortality may be caused by sterility or cannibalism. Larval mortality may be caused by starvation or cannibalism. Crowding leads to emigration, reduced size and extended developmental period. Pupal and adult mortalities are of minor importance. Pupae may suffer developmental disorders and adults are killed by spiders and lost by emigration.5. Parasitoids, predators and diseases, which also contribute to mortality of eggs, larvae, pupae and adults, are described.6. The importance of planning and sampling in order to obtain detailed data on populations are discussed, together with the analysis of the data.7. It is shown that Lepidoptera which infest stored products and the parasitoids associated with them have proved convenient experimental tools for the elucidation of certain aspects of population dynamics. A small number of studies have succeeded in identifying the main factors or processes responsible for fluctuation or regulation of the densities of these moths.

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1973.tb01113.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary1. The sites occupied by adult helminths in the alimentary tracts of vertebrates, the events leading to the establishment of the helminths in these sites and some of the factors involved in extensions or changes of site have been described and discussed in an attempt to summarize the present state of knowledge and stimulate more research into the ecology of helminths in the tract.2. In an attempt to reduce confusion and ambiguity in the future literature on the ecology of helminths, definitions have been proposed for the termssite, emigrationandmigration.3. Since it has been assumed that the distribution and survival of some species of helminth in the tract are related to phases of digestive activity or inactivity, the morphology, histology and physiology of the alimentary tract of vertebrates have been considered with emphasis on events and features which appear to be of significance to helminths.4. Many phases of a helminth's association with its host appear to be related to the host's intestinal motility.5. Digestion in vertebrates is considered to be an ordered sequence of events producing different conditions in different parts of the tract. These conditions, however, are not entirely predictable; digestion is affected by the nature of the diet, the feeding routine and the psychosomatic state of the animal in question.6. An accurate description of a helminth's site is fundamental to our understanding of its ecology. The description should include information about (I) the helminth's linear distribution, (2) the helminth's radial distribution, (3) the length of time which passed between the death of the host and finding the parasites, (4) the time of day when the search was made, (5) the stage of digestion in progress on the death of the host, (6) the season of the year when the parasites were observed, (7) the parasite's reproductive state and (8) the worm burden and the other species of parasite present in the host's alimentary tract.7. Special care must be taken when describing the site of a cestode because of the nature of the strobila and the degrees of independent existence shown by the proglot‐tids of certain species.8. The distribution of sites occupied by the adults of 252 species of helminth in the alimentary tract of vertebrates is given in Tables 2–6, and some sites are illustrated diagrammatically in Figs. 36–57. The sites given in the tables should be accepted with caution, for not all the authors recognized the need for information of the type proposed in paragraph 6 above.9. The adult stages of most species of Acanthocephala and of most species of Cestoda are confined to the lumen and paramucosal lumen of the small intestines of their hosts. Their mode of feeding and dependence on their hosts' digestive processes fit in with their observed distribution. Acanthocephalans and cestodes are likely to be competitors because their restriction to the small intestine and their feeding behaviour suggest that they may have similar ecological niches.10. The adult stages of Nematoda can be found in most regions of the alimentary tract, from the mouth to the rectum and from the lumen to the serosa. They do not appear to be successful parasites of the biliary system. The occupation of so many sites in the tract by nematodes may be correlated with the small size of many species and the fact that many species feed independently of their hosts' digestive activity.11. The co‐existence of various species of nematode in the same site may result from their varied dietary requirements and feeding habits.12. Although the sites of adult digenetic Trematoda are to be found throughout the length of the alimentary tract, most species appear to be restricted to the paramucosal lumen and mucosal and epithelial tissues. Their limited radial distribution may be related to the conclusion that most species have become adapted to feeding on the mucosa and material associated with it.13. The observation that some species of helminth occupy different sites in the tracts of related hosts shows that some helminths can tolerate conditions as varied as those in the anterior part of the small intestine of one host and those in the posterior part of another are believed to be. Thus, the fact that a helminth is usually found in a particular zone of the host's tract does not necessarily indicate that it is dependent upon the conditions prevailing there.14. The events leading to the establishment of the adults of many species in their sites can be considered in three general categories; (I) the direct arrival of immature stages in the site of the adults, (2) emigration by the immature stages in the direction of gastro‐intestinal flow to the site of the adults, and (3) emigration by the immature stages against the direction of gastro‐intestinal flow.15. Much of the evidence for emigrations is indirect, circumstantial and difficult to interpret.16. Circumstantial evidence and the results of experiments involving the transplantation of helminths from one host to another indicate that both immature and adult stages of several species of helminth can orientate themselves in the alimentary tract and find their normal sites.17. Extensions of site occur in response to both intra‐ and interspecific reactions. In the case of an intraspecific reaction, extension of site is usually indicative of an increase in population density.18. What determines the populations of different helminths in the alimentary tract of vertebrates has been insufficiently investigated. More studies are needed if the ecology of helminths is to be understood.19. In the case of interspecific reactions, some species of helminth change site or become confined to one part of their normal site when another species is present.20. Some species of helminth appear to extend or change their site in response to an immunological reaction of the host.21. In general, adult helminths emigrate less than their immature stages. Extensions and changes of site may ensure the survival of the infection during events which are deleterious to individual parasites.22. The conclusions in paragraphs 9–21 are based on information recorded in the references cited in Tables 2, 3, 4 and 6. They may not apply to all the species of helminth known to live in the alimentary tract.23. The cestodeHymenolepis diminutaundergoes an exogenous, circadian migration in the small intestine of rats. The migration is superimposed on the anterior emigration and involves the cestode's release of its hold on the mucosa and its attachment elsewhere. There is corresponding change in the position of the biomass, the migration being related in some way to the feeding and digestive activity of the host. Decisive experiments are needed to elucidate the nature of this relationship.24. Some preliminary observations suggest that other species of helminth make periodic migrations in the tracts of their hosts.In addition to the acknowledgements already made, I also thank the following publishers and copyright owners: Blackwell Scientific Publications for Figs. 1, 4, 6, 47, 56 and 57; Cambridge University Press for Figs. 36, 38 and 39, and Figs. 2, 40, 42, 52, 54 and 55 fromParasitology;Urban&Schwarzenberg for Figs. 3, 5 and 8; Company of Biologists Ltd. for Fig. 20; Prof. John Morton for Fig. 21; Mrs E. C. Greene for Fig. 23; Cornell University for Fig. 27; Dr P. M. Hine for Fig. 37; Marine Biological Association of the United Kingdom for Fig. 41; Academic Press for Figs. 43, 44 and 46 fromExperimental Parasitology;Macmillan (Journals) Ltd. for Fig. 48 fromNature;American Society of Parasitologists for Fig. 49 fromJournal of Parasitology;Pergamon Press Ltd. for Fig. 50 fromInternational Journal for Parasitology;Editorial and publications section of C.S.I.R

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1973.tb01114.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary1. Non‐shivering thermogenesis (NST) is a heat‐production mechanism participating in the chemical thermoregulation of mammals.2. NST is additional to shivering and takes place at temperatures close to the thermoneutral zone.3. NST occurs in newborn mammals and in those that hibernate. In some adult mammals it can be induced by adaptation to cold.4. In small mammals NST produces approximately the same amount of heat as shivering. It becomes less important with increasing body weight of the animals.5. NST is regulated by the hypothalamus and it is based predominantly on the calorigenic action of noradrenaline released from sympathetic nerve‐endings.Participation of other calorigenic substances and of the specific dynamic action of food cannot be excluded.6. NST is localized mainly in skeletal muscles and in brown adipose tissue. Small amounts of NST may come from liver, intestine, heart and brain.7. The biochemical basis of the calorigenic action of noradrenaline has not yet been fully eluci

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1973.tb01115.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

Summary1. Meiosis in the Oomycetes is gametangial.2. The life‐cycle of the Oomycetes is therefore haplobiontic, type B.3. The gametangia are multinucleate prior to septation. Vegetative nuclear divisions may occur in the hyphae subtending the gametangia, but there is no evidence for such divisions occurring in the gametangial primordia nor is there any indication that nuclei may move out of the primordium against any cytoplasmic flow.4. Some abortion of supernumerary nuclei probably occurs after the gametangium is cut off from the vegetative thallus by the septum. Meiosis then takes place.5. The spindle of the first metaphase is almost certainly within a persistent nuclear membrane, but there remains some doubt as to whether this membrane persists to the second telophase in all Oomycetes.6. In the higher Peronosporales, and possibly the Rhipidiaceae, meiosis is accompanied or preceded by zonation into the periplasm and ooplasm. Spindle orientation and the timing of zonation movements probably account for the differences in the number of presumptive oosphere nuclei recorded between many Peronosporales. In some Albuginaceae, at least, it is possible that only one nucleus completes the meiotic division, but this needs confirmation.7. A smaller number of nuclei enter the male gametangium and undergo a more or less simultaneous meiosis.8. Some variation in the pattern and degree of synchrony of meiotic division within and between gametangia occurs in different species.9. Nuclear abortions may precede, accompany or follow meiosis, but only in a few instances (Pythium debaryanum, P. deliense, Phytophthora himalayensis, Aphanomyces laevis) does the male gametangium finally contain only a single gamete nucleus.10. Cytoplasmic cleavage, involving the tonoplast and central vacuole of the oogonium, occurs after meiosis in the Saprolegniales, thus offering an alternative mechanism to zonation movements for the production of uninucleate oospheres. The presence (Edson, 1915; Patterson, 1927b; Murphy, 1918) or absence (Trow, 1901; Saskena, 1936) or an homologous central vacuole in the Pythiaceae is disputed.11. Karyogamy must follow antheridial penetration in those species which are not agamospermous, but the degree of facultative agamospermy is unknown. The timing of karyogamy, as opposed to somatogamy, is apparently variable between and within species (Wager, 1899; Arens, 1929, Moreau&Moreau, 1935; McDonough, 1937; Flanagan, 1970; Win‐Tin, 1972). There are a few indications that karyogamy may be precocious and other evidence that it may be considerably delayed, even after the oospore has achieved morphological maturity, and exceptionally until germination.12. It would appear that the majority of the oospores of most Oomycetes eventually contain only one fusion or diploid nucleus, but there are exceptions (Albugo bliti, A. platensis, A. portulacaeandAplanopsis terrestrisrespectively) and without further study it would be unwise to assume that this is necessarily true even for closely related species.13. Mitosis immediately following karyogamy is reported as occurring in some species ofAlbugo, but in most Oomycetes it is delayed until the period immediately preceding any cytoplasmic or morphological change at the start of germination.14. The nuclear divisions of the germinating oospore are mitotic, but they may differ in the detailed morphology of the spindle apparatus or the degree of condensation of the chromosomes.15. Interpretations of the cytology of the small nuclei of the Oomycetes have been profoundly influenced by the prevailing climates of scientific opinion. In particular, the development of studies of meiosis and the science of genetics on the one hand, and the appreciation of the polyphyletic origin of the fungi, especially the algal origins of the Oomycetes on the other hand, have necessitated a re‐evaluation of much of the older liter

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1973.tb01116.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

ISSN:1464-7931    

DOI:10.1111/j.1469-185X.1973.tb01117.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY