Iterative equations were developed that predict the encounter rate between a population of moving animals and a population of stationary objects, where the animals cease to search upon finding an object. The encounter rate through time depends on the number of searching animals (bark beetles), number of stationary objects (host trees), average speed of the animals, average radius of the object,...

Comparative population genetics of ecological guilds can reveal generalities in patterns of differentiation bearing on hypotheses regarding the origin and maintenance of community diversity. Contradictory estimates of host specificity and beta diversity in tropical Lepidoptera (moths and butterflies) from New Guinea and the Americas have sparked debate on the role of host-associated divergence ...

fields of winter wheat and barley were sampled during two years (november to june 1996-1998) in golestan province to determine the occurrence, frequency and distribution of thrips species. a total of 32 species belonging to 3 families and 16 genera were found. haplothrips tritici (kurdjumov) was the dominant species accounting for 70.2% and 55.7% of identified individuals in wheat and barley, r...

  Two hundred forty seven species of parasites from Iranian freshwater fishes are presented in this synopsis. The parasites were recorded from infestations in fish from different parts of the country and summarized according to host species, organs were the parasite infestations occurred, province, faunal region and reference numbers. The following aspects of parasite infestations were a...

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 ...

Dispersal and competition have both been suggested to drive variation in adaptability to a new environment, either positively or negatively. A simultaneous experimental test of both mechanisms is however lacking. Here, we experimentally investigate how population dynamics and local adaptation to a new host plant in a model species, the two-spotted spider mite (Tetranychus urticae), are affected...

Novel pathogens continue to emerge in human, domestic animal, wildlife and plant populations, yet the population dynamics of this kind of biological invasion remain poorly understood. Here, we consider the epidemiological and evolutionary processes underlying the initial introduction and subsequent spread of a pathogen in a new host population, with special reference to pathogens that originate...

Host populations with high genetic diversity are predicted to have lower levels of infection prevalence. This theory assumes that host genetic diversity results in variation in susceptibility and that parasites exhibit variation in infectivity. Empirical studies on the effects of host heterogeneity typically neglect the role of parasite diversity. We conducted three laboratory experiments desig...

fauna of the the aphid parasitoids at southern parts of the zagros submountains, and their host associations have been investigated. a total of 24 parasitoid species were identified in association with 30 aphids on 36 host plant species, representing more than 80 tritrophic associations (parasitoid-aphid-plant). aphidius avenae haliday is newly reported from iran. generally, the area of souther...

Host specificity is often measured as the number of host species used by a parasite, or as their phylogenetic diversity; both of these measures ignore the larger scale component of host use by parasites. A parasite may exploit very few host species in one locality but these hosts may be substituted for completely different species elsewhere; in contrast, another parasite may exploit many host s...