Declining predator diversity may drastically affect the biomass and productivity of herbivores and plants. Understanding how changes in predator diversity can propagate through food webs to alter ecosystem function is one of the most challenging ecological research topics today. We studied the effects of predator removal in a simple natural food web in the Sierra Nevada mountains of California ...

A greater diversity of natural enemies can in some cases disrupt prey suppression, particularly when natural enemies engage in intraguild predation, where natural enemies compete with and prey upon each other. However, empirical studies have often demonstrated enhanced prey suppression despite intraguild predation. A recent theoretical study proposed the hypothesis that, when the intermediate p...

in this paper, the reorganization of the denominator of the discrete derivative and nonlocal approximation of nonlinear terms are used in the design of nonstandard finite difference schemes (nsfds). numerical examples confirming then efficiency of schemes, for some differential equations are provided. in order toillustrate the accuracy of the new nsfds, the numerical results are compared with s...

searching efficiency (a') (attack rate) and handling time are two major components of natural enemies’ functional response and are usually used to evaluate their effectiveness. the age-specific searching efficiency of aphidoletes aphidimyza (rondani) was studied during its larval stage. the experiment was conducted in terms of age-specific functional response to the varying density (5, 1...

We assessed the responses of zooplankton communities with different population densities of an invertebrate predator, Mesocyclops pehpeiensis, to insecticide (carbaryl, 0.5 mgL(-1)) in small-scale mesocosm tanks (20 L). Cladocerans were eliminated by carbaryl application at both high and low predator densities. The density of rotifers increased after the elimination of the cladocerans by carbar...

The aim of this paper is to consider a non-autonomous predator-prey-like system, with a Gompertz growth law for the prey. By introducing random variations in both prey birth and predator death rates, a stochastic model for the predator-prey-like system in a random environment is proposed and investigated. The corresponding Fokker-Planck equation is solved to obtain the joint probability density...

This paper describes the development of a plugin for Pidgin, an open source instant messaging client. The plugin, SafeChat, allows parents to protect their children from Internet predators. SafeChat gives parents a better alternative than other currently available tools by providing a communication-theory based tool.

Although rare, dinosaurs are well preserved in calcareous nodules of the Santana Formation (Early Cretaceous, ?Albian) of the Araripe Basin, in northeastern Brazil. So far, including only a spinosauroid and three coelurosaurs, the dinosaur fauna appears depauperate. High theropod diversity in assemblages where other dinosaurs are rare or absent is not unique to the Santana Formation. It is seen...

predators may adjust their foraging behavior according to herbivore induced plant volatiles innately or through learning. here, first we investigated whether the phytoseiid predatory mites, neoseiulus californicus and n. barkeri were innately able to respond to odors related to tetranychus urticae infested bean leaves. the naïve predator females were reared on washed t. urticae as prey on filte...

one of the most important predator-prey interactions is functional response which its type and parameters are affected by different factors including host plant characteristics. in this research, the influence of leaf surface on functional response and prey consumption rate of third instar larvae of the episyrphus balteatus (de geer, 1776) (diptera: syrphidae) to third instar nymphs of aphis go...