background : ligulae intestinalis is a parasitic cestode, which has the economic-health importance in fishery industries. the aim of this study was to determine the prevalence of this parasite in mazandaran. the effects of habitat temperature and kind of pool (sandy-cement) were considered as well. methods : in this study, 103 fish samples were obtained in all stages; the samples (male and fema...

Female animals often prefer males with conspicuous traits because these males provide direct or indirect benefits. Conspicuous male traits, however, can attract predators. This not only increases the risk of predation for conspicuous males but also for the females that prefer them. In the variable field cricket, Gryllus lineaticeps, males that produce preferred song types provide females with g...

Female animals often prefer males with conspicuous traits because these males provide direct or indirect benefits. Conspicuous male traits, however, can attract predators. This not only increases the risk of predation for conspicuous males but also for the females that prefer them. In the variable field cricket, Gryllus lineaticeps, males that produce preferred song types provide females with g...

A comprehensive model of evolution requires an understanding of the relationship between selection at the molecular and phenotypic level. We investigate this in Strepsiptera, an order of endoparasitic insects whose evolutionary biology is poorly studied. We present the first molecular phylogeny of Strepsiptera, and use this as a framework to investigate the association between parasitism and mo...

in this study, the performance of an irreversible regenerative brayton cycle is sought through power maximizations using finite-time thermodynamic concept in finite-size components. optimizations are performed using a genetic algorithm. in order to take into account the finite-time and finite-size concepts in the current problem, a dimensionless mass-flow rate parameter is used to deploy time v...

Despite growing interest in ecological consequences of parasitism in food webs, relatively little is known about effects of parasites on long-term population dynamics of non-host species or about whether such effects are density or trait mediated. We studied a tri-trophic food chain comprised of (i) a bacterial basal resource (Serratia fonticola), (ii) an intermediate consumer (Paramecium cauda...

The population dynamics of major brassica pests and occurrence of their natural enemies were monitored weekly for a period of 9 months on cabbage (var. Copenhagen Market) at a research station plot (no pesticides applied) and a farmer’s field (weekly application of Permethrin 10 EC or Dimethoate 40 EC) in Central Kenya. Pest infestations occurred within 14 days after the seedlings were transpla...

Bird populations in North America's grasslands have declined sharply in recent decades. These declines are traceable, in large part, to habitat loss, but management of tallgrass prairie also has an impact. An indirect source of decline potentially associated with management is brood parasitism by the Brown-headed Cowbird (Molothrus ater), which has had substantial negative impacts on many passe...

How global warming will affect insect parasitoids and their role as natural enemies of insect pests is difficult to assess within a short period of time. Considering that elevation gradients can be used as analogues for global warming, we carried out meta-analyses of 27 correlations between parasitoid richness and elevation and 140 correlations between parasitism rate and elevation in natural a...

Overwinter fawn mortality associated with hair loss syndrome (HLS) is anecdotally thought to be important in declines of Columbian black-tailed deer (Odocoileus hemionus columbianus) populations in Washington and Oregon (USA). We determined prevalence of HLS in black-tailed deer, September and April fawn:doe ratios, and minimum overwinter survival rates of fawns for selected game management uni...