ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01123.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01124.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAn account is given of the way the temperature‐mediated processes of development and locomotor activity in insects interact with the availability of essential resources to reduce lifetime fecundity below the potential predicted from laboratory performance. Current work on the sheep blowfly, Lucilia cuprina, is used to illustrate the points made wherever possible.Brief reviews of the ecologically important relationships between rate of development and temperature and level of activity and temperature are presented. The ways in which such laboratory‐derived relationships may be applied in the interpretation of field results are described and discussed. The notions of time as a resource and of protein‐food, mates and oviposition sites as limiting resources are presented and these provide the basis of a time/resource/fecundity mechanism limiting reproductive performance during the life‐time of a female insect. Field and laboratory data are used to show the potentiality of such a mechanism for reducing life‐time fecundity in the shee

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01125.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAt three well differentiated sites and over three seasons bushfly abundance at first increased rapidly, but then stabilized or fell slowly through the apparently favourable periods of summer and early autumn, before a rapid end of season decline. Analysis of the characteristics of flies taken regularly in a sampling programme allowed the sequence of population events involved to be elucidated. Adult flies immigrated in spring. They and their first progeny were comparatively large but in the subsequent locally bred generations a progressive decrease in fly size was associated with a gradual decline in the levels of natality and a gradual increase in the levels of mortality. Between site differences could be traced to variation in the balance of these changes. Climate may have a large role in the population dynamics of the bushfly but its effects are largely indirect. Fuller understanding of the bushfly life system requires some way of synthesizing the effects and interactions between the many factors involved.

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01126.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe capacity for increase (Ic) of one laboratory and seven field populations of young adult S. oryzae from different sites in Australia was determined over a thirty‐week period at 15°C, a supposedly marginal temperature, in wheat of 14% moisture content.The average value of Icwas 0.0838 ± 0.0017 and the populations comprised three significantly different groups. Variations in the net rate of increase per generation (R0) which averaged 34.7±1.71, had a major effect on the value of rcwhereas variation in the cohort generation time (Tc), which averaged 41.6±.23 weeks had only a minor effect. The survivorship of adults of the populations did not differ significantly and 93% of females were alive after thirty weeks. Estimates of rcbased on a fifteen‐week period and on an amended value of Tc differed little from those over thirty weeks.The capacity for increase at 15°C of a given population was found to be correlated with its fertility at 27°C and with its body‐weight rather than with its cold‐tolerance, as evidenced by chill‐coma temperature, or with its previous temperature‐history.The temperature experienced by the immature stages of weevils had a profound effect on rcin that weevils reared at 15 and 27°C had respective values of 0.0350 and 0.0707 when subsequently cultured at 15°C.Because all observed values of rcwere higher than expected, possible errors in method were considered. An alternative estimate of R0agreed closely with that observed and indicated that only 17% of the immature stages survived at 15°C. Metabolic heating due to the higher than expected population density shortened the duration of the immature stages by 7% but did not a

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01127.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe capacity for increase (rc) of one laboratory and seven field populations of young adult S. granarius from different sites in Australia was determined over thirty‐two weeks at 15°C in wheat of 14% moisture content.The mean value of rcwas 0.0704 ±0.0016 and the populations differed significantly with respect to this parameter. Variation in the net reproductive rate (R0), which averaged 25.4± 1.29, had a greater effect on the value of Icthan did variation in the cohort generation time (Tc), which averaged 45.7±0.37 weeks. The populations did not differ significantly in terms of adult survivorship and 94% of females were still alive at thirty‐two weeks. The maximum rate of oviposition, about ten eggs per female per week, was achieved in the eighteen‐twenty week age‐interval. About 41% of the immature stages survived to adulthood. Estimates of rcover a twenty‐four week period were only slightly lower than those over thirty‐two weeks.The capacity for increase at 15°C of a given population was shown to be correlated with its fertility at 29°C, an optimal temperature, and with its body weight rather than with its cold tolerance, as indicated by its chill‐coma temperature, or its previous temperature‐history.The temperature experienced by the immature stages had a marked influence on rcin that weevils reared at 15°C and 27°C had respective values of 0.0654 and 0.0786 when subsequently held at 15°C.The differences in the survivorship and fertility of S. granarius and S. oryzae (L.) when both species were reare

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01128.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractChortoicetes terminifera can detect absolute differences of both temperature and photo‐period, as well as the directional change of these parameters. Insects subjected to long‐day conditions, or to an increase in photo‐period during development lay long straight pods, whereas those subjected to short days or to a decrease in photoperiod during development lay short pods, which are usually curved and/or laid obliquely. Temperature does not affect oviposition behaviour at long photoperiod, but at medium and short photoperiod, high temperature or an increase in temperature promotes the production of long pods, whereas low temperature or a decrease in temperature stimulates the production of short pods. When temperature and photoperiod change in opposite directions, the effects of photoperiod override those of temperature. The significance of these findings is discussed in relation to egg development and sur

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01129.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractIn a subalpine association of three Eucalyptus species, phytophagous insects showed strong host preferences even among very closely related Eucalyptus species. Sixty‐three per cent of insect species attacked only one eucalypt species, 30% attacked two species and only 8% fed on all three. Ninety‐seven per cent of individuals belonged to species using one or two hosts. The results are discussed in relation to the degree of host specificity that might be expected when most potential hosts are members of a single genus, the way in which host specificity is determined, and the potential of insects with host preferences to affect the dynamics of plant communit

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01130.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA study was carried out on the physical structure of an ant community in a semi‐arid habitat of southern New South Wales. Thirty‐seven species were collected from the area, and the relative abundance and spatial distribution of colonies of these species were determined in two plots, one in an area dominated by saltbush (Atriplex vesicaria), the other in an area where saltbush had been removed by overgrazing, leaving a simple grassland.The composition and community structure of the populations were found to be little affected by vegetation, and there were no marked differences between the ant faunas of the two areas.Analyses of spatial distribution of the ant colonies showed a variety of patterns, ranging from aggregated to overdispersed, both within and between species. It is suggested that the contemporary structure of an ant community results in the main from processes involving aggressive interactions, determined by the intrinsic properties of the constituent spec

ISSN:0307-692X    

DOI:10.1111/j.1442-9993.1977.tb01131.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY