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871.
Barbara L. Thorne 《Behavioral ecology and sociobiology》1984,14(2):117-136
Summary ecological aspects of monogyny and polygyny in social insect colonies are important in comparing individual queen reproductive success. Inseminated, fecund, multiple foundresses are common in some groups of ants and eusocial wasps, but true polygyny in termites has not previously been studied. One third of Nasutitermes corniger (Isoptera: Termitidae) colonies sampled in areas of young second growth in Panama contained from 2–33 primary queens (not supplementary or neotenic reproductives). All queens in polygynous associations were fully pigmented, physogastric egg layers within a single royal cell. Multiple kings were found less frequently; true polyandry is apparently restricted to immature polygynous colonies.Data on queen weight and morphological features, and on colony composition, show that queens in polygynous nests are young and that a transition from polygyny to monogyny probably occurs after several years. The escalated growth rate of multiple queen colonies removes them from the vulnerable incipient colony size class more rapidly than colonies initiated by a single foundress, and gives them sufficient neuter support staff (workers and soldiers) to enable earlier production of fertile alates. Using a population model (Leslie matrix) I construct isoclines of equal population growth which show values of early age class probability of survival and reproductive output favoring monogyny or polygyny under individual selection. This model of queen mutualism accounts for the risk of a female in a polygynous group not succeeding as the final surviving queen.Multiple primary queens are considered rare in termites, but a review of the literature demonstrates that they may be more widespread than is currently recognized. Polygyny in termites has received scant attention but is of significance as an example of a further ecological and evolutionary convergence between the phylogenetically independent orders Isoptera and Hymenoptera. 相似文献
872.
Ronald L. Rutowski George W. Gilchrist Barbara Terkanian 《Behavioral ecology and sociobiology》1987,20(5):319-322
Summary During copulation, males of the alfalfa butterfly, Colias eurytheme, transfer nutrients and sperm to the female. Recently mated males produce only about 40% of the quantity of material produced by males that have not recently mated (Rutowski and Gilchrist 1986). In this study, females that mated with recently mated males died sooner, had a lower lifetime egg output, and laid fewer eggs per day overall, but especially during the first 2 days after mating. We conclude that the effect of the materials (nutrients and sperm) passed by males at copulation on female oviposition and receptivity is such that the male's genetic return from nutrients passed is maximized. 相似文献
873.
To understand the consequences of human accelerated environmental change, it is important to document the effects on natural populations of an increasing frequency of extreme climatic events. In stream ecosystems, recent climate change has resulted in extreme variation in both thermal and hydrological regimes. From 2001 to 2004, a severe drought in western United States corresponded with earlier emergence of the adult stage of the high-altitude stream mayfly, Baetis bicaudatus. Using a long-term database from a western Colorado stream, the peak emergence date of this mayfly population was predicted by both the magnitude and date of peak stream flow, and by the mean daily water temperature, suggesting that Baetis may respond to declining stream flow or increasing water temperature as proximate cues for early metamorphosis. However, in a one-year survey of multiple streams from the same drainage basin, only water temperature predicted spatial variation in the onset of emergence of this mayfly. To decouple the effects of temperature and flow, we separately manipulated these factors in flow-through microcosms and measured the timing of B. bicaudatus metamorphosis to the adult stage. Mayflies emerged sooner in a warmed-water treatment than an ambient-water treatment; but reducing flow did not accelerate the onset of mayfly emergence. Nonetheless, using warming temperatures to cue metamorphosis enables mayflies to time their emergence during the descending limb of the hydrograph when oviposition sites (protruding rocks) are becoming available. We speculate that large-scale climate changes involving warming and stream drying could cause significant shifts in the timing of mayfly metamorphosis, thereby having negative effects on populations that play an important role in stream ecosystems. 相似文献
874.
Comparison of IEUBK model predictions and actual blood lead values at a former battery recycling site 总被引:1,自引:0,他引:1
Thomas A. Lewandowski Barbara L Forslund 《Environmental geochemistry and health》1994,16(3-4):217-222
This paper presents an evaluation of US EPA's integrated exposureuptake biokinetic model for lead (IEUBK model) using data obtained during emergency removal operations at a former lead-acid battery recycling plant and the surrounding community. Data employed in the study include soil lead and interior dust lead, air lead levels collected at the site perimeter, drinking water lead levels at the community water main and blood lead data collected from an annual blood lead monitoring programme conducted over a four year period during the remediation activities.Geometric mean soil and dust concentrations were found to be a better predictor of blood lead than arithmetic mean data. However, weight based dust lead data were believed to be an inappropriate measure of dust lead levels. Estimates of household dust lead concentrations based upon surface loading data (g m–2) yielded blood lead predictions which were more consistent with data collected in the blood lead monitoring programme 相似文献
875.
Summary. Oviposition site selection of herbivorous insects depends primarily on host plant presence which is essential for offspring
survival. However, parasitoids can exploit host plant cues for host location. In this study, we hypothesised that herbivores
can solve this dilemma by ovipositing within high plant diversity. A diverse plant species composition might represent an
‘infochemical shelter’, as a potentially complex volatile blend can negatively affect the host location ability of parasitoids.
We examined this exemplarily for the egg-laying response of the generalist leaf beetle, Galeruca tanaceti, in relation to (1) host plant availability and (2) plant species diversity in the field. Further, we investigated the effect
of odours from mixed plant species compositions on (3) leaf beetle oviposition site selection and on (4) the orientation of
its specialised egg parasitoid, Oomyzus galerucivorus. In the field, egg clutch occurrence was positively related to the presence and quantity of two major host plants, Achillea millefolium (yarrow) and Centaurea jacea, and to the number of herbaceous plant species. In two-choice bioassays, female beetles oviposited more frequently on sites
surrounded by an odour blend from a diverse plant species composition (including yarrow) than on sites with a pure grass odour
blend. In the presence of yarrow odour and an odour blend from a diverse plant mixture (including yarrow) no difference in
the oviposition response was recorded. Experienced parasitoid females were attracted to yarrow odours, but showed no response
when yarrow odours were offered simultaneously with odours of a non-host plant. In conclusion, it could be shown in laboratory
bioassays that the parasitoid responds only to pure host plant odours but not to complex odour blends. In contrast, the herbivore
prefers to oviposit within diverse vegetation in the field and in the laboratory. However, the laboratory results also point
to a priority of host plant availability over the selection of a potential ‘infochemical shelter’ for oviposition due to high
plant diversity. 相似文献
876.
877.
桂西北肯福环境移民示范区园地土壤肥力变化状况 总被引:2,自引:0,他引:2
果树业作为肯福环境移民示范区的一项长期的云集产业,在示范区移民的生产、生活中起着不可缺少的作用。为了解示范区园类用地(主要是宜果类用地)开发利用对土壤肥力变化的影响,以便更好地指导移民进行合理的综合性开发,特对开垦前(1996年上半年,此时移民也开始迁入)和开垦后第三年(1998年下半年)示范区的园类用地土壤养分变化进行了调查研究,分析了耕层土样的8个土壤养分指标,结果表明:示范区园类用地土壤肥力整体上基本保持不变,但表现出微弱的下降趋势;其中的长绿果树地土壤肥力略有下降,而落叶果树地土壤肥力有极微的上升趋势;不同的土壤养分元素含量变化又有差异。 相似文献
878.
879.
从废旧聚乙烯的直接再生、改性再生和裂解再生三个方面,讨论了国内外处理和再生利用的情况,并对其再生技术与应用做了比较。我国处理和回收利用废旧聚乙烯时,要加强生物降解塑料等环境无负荷材料的研究与开发;加强固体废弃物的管理与循环利用的立法;实现经济与环境的和谐发展。 相似文献
880.