here, a predator-prey model with hassell-varley type functional responses is studied. some sufficient conditions are obtained for the permanence and global asymptotic stability of the system by using comparison theorem and constructing a suitable lyapunov functional. moreover, an example is illustrated to verify the results by simulation.

The stinkbug Supputius cincticeps (Stål) (Heteroptera: Pentatomidae) can be found in agricultural and forest ecosystems feeding primarily on larvae of Coleoptera and Lepidoptera, where it can be exposed to insecticide applications. This study therefore aimed to evaluate the reproductive potential of S. cincticeps after exposition to sublethal doses of permethrin (5.74 x 10(-3), 5.74 x 10(-2), 5...

Because research on nematode involvement in trophic interactions, foodweb structure, and biodiversity is constrained by lack of an overview of nematode feeding habits, this outline presents a consensus of current thought on nematode feeding habits. The source of food is fundamental to trophic interactions and provides the basis for our definitions of the essential feeding types: 1) plant feeder...

Protecting children online has been a focus of research in psychiatry and sociology for many years. However, the anonymous nature of the Internet has made finding a solution to the problem of child protection online difficult. The current study proposes going beyond the identification of an individual online predator to the recognition of predatory discourse enacted via coercion within frames o...

The modeling investigation in this paper discusses the system level effects of a toxicant on a three species food chain system. In the models, we have assumed that the presence of top predator reduces the predatory ability of the intermediate predator. The stability analysis of the models is carried out and the sufficient conditions for the existence and extinction of the populations under the ...

To test for direct and indirect effects of a top predator on three lower trophic levels, we conducted two multiyear predator addition experiments in a tropical wet forest. Periodic additions of a top predator (predatory clerid beetle) to a wet forest understory shrub caused a reduction in the predatory beetle's prey (a predatory ant), increased herbivory, and reduced leaf area of the plant. The...

eastern rock nuthatch (sitta tephronota) and western rock nuthatch (s. neumayer) are two closely related and sympatric species in iran, which have been known as the classical case of character displacement since 1950. nevertheless, some questions related their niche partitioning is still unanswered. this study was conducted to determine the diet differentiation, as an important niche dimension,...

The coccinellid predator Coleomegilla maculata (DeGeer) is found throughout the central and eastern United States and is a potential biological control agent for interiorscapes. Currently, the systemic insecticide imidacloprid is widely used in interiorscape and landscape integrated pest management. Effects of imidacloprid on the Þtness and behavior of C. maculata were examined by conÞning grou...