We monitored population density of white-footed mice (Peromyscus leucopus), burdens of immature black-legged ticks (Ixodes scapularis) on mice, and infection prevalence of host-seeking ticks on six forest plots in southeastern New York State from 1995 through 1999. Despite densities of mice that fluctuated two orders of magnitude, average larval and nymphal tick burdens per mouse remained remar...

BACKGROUND Aedes aegypti (L.) is the primary vector of dengue, the most important arboviral infection globally. Until an effective vaccine is licensed and rigorously administered, Ae. aegypti control remains the principal tool in preventing and curtailing dengue transmission. Accurate predictions of vector populations are required to assess control methods and develop effective population reduc...

Results of previous laboratory studies suggest that high population density often buffers the effects of chemical stressors that predominately increase mortality. Mortality stressors act to release more resources for the survivors and, therefore, produce less-than-additive effects. By contrast, growth stressors are expected to have opposite results or more-than-additive effects. We investigated...

1. In the AÊ land islands of SW Finland, the parasitoid Cotesia melitaearum (Wilkonson) is a specialist on the Glanville fritillary butter ̄y, Melitaea cinxia (L.), which uses two host plants, Plantago lanceolata (L.) and Veronica spicata (L.). 2. Extensive survey data on the butter ̄y and parasitoid populations collected in 1994±97 were used to examine possible associations of parasitoid coloniz...

When larvae of the tenebrionid beetle, Zophobas rugipes, were allowed to disperse among 26 equivalent chambers in a circular dispersarium, distribution patterns were found to be a function of larval weight and number of larvae in the apparatus (N). Small larvae (x wt 250 mg) were significantly aggregated while large mature larvae (, 1000 mg) were highly overdispersed. Medium larvae were interme...

The evolutionary causes of variation in host specialization among phytophagous insects are still not well understood and identifying them is a central task in insect /host plant biology. Here we examine host utilization of the chrysomelid beetle Oreina elongata that shows interpopulation variation in the degree of specialization. We focus on larval behaviour and on what selection pressures may ...

Studies of siblings have focused mainly on their competitive interactions and to a lesser extent on their cooperation. However, competition and cooperation are at opposite ends on a continuum of possible interactions and the nature of these interactions may be flexible with ecological factors tipping the balance toward competition in some environments and cooperation in others. Here we show tha...

Density dependence is the major process keeping the sizes of natural populations within bounds. In organisms with complex life cycles, the stage at which density dependence occurs and whether it occurs in one or several life stages have important consequences for the dynamics of their populations. I manipulated density of pool frogs (Rana lessonae) during the aquatic larval and the terrestrial ...