statement of the problem: in this article relationship between social trust and civil society (with emphasis on voluntary associations) is empirically examined. in addition, this article attempts to answer this question: what kind of relationship is there between voluntary associations membership and social trust? method: 457 students of mazandaran university were chosen and the questionnaires ...

A number of studies have shown that an association with mycorrhizal fungi can alter the outcome of interactions between plants and their enemies. While the directions of these effects vary, their strength suggests the need for greater attention to multispecies interactions among plant enemies, plants, and mycorrhizal fungi. We recognize that mycorrhizal fungi could effect plant enemies by impro...

The tritrophic interaction Argia insipida Hagen in Selys, the Trichogrammatidae egg parasitoid Pseudoligosita longifrangiata (Viggiani) and the host plant Tonina fluviatilis (Eriocaulacea), which is a substrate for egg deposition of A.insipid, was investigated. The study locality was a stream with rapids where macrophytes such as T. fluviatilis grow. Information on aquatic egg parasitoids is sc...

We study synchronization in ecological networks under the realistic assumption that the coupling among the patches is sporadic/stochastic and due to rare and short-term meteorological conditions. Each patch is described by a tritrophic food chain model, representing the producer, consumer, and predator. If all three species can migrate, we rigorously prove that the network can synchronize as lo...

Aphids are one of the most serious pests of crops worldwide, causing major yield and economic losses. To control aphids, natural enemies could be an option but their efficacy is sometimes limited by their dispersal in natural environment. Here we report the first isolation of a bacterium from the pea aphid Acyrthosiphon pisum honeydew, Staphylococcus sciuri, which acts as a kairomone enhancing ...

Revealing the links between species functional traits, interaction strength and food-web structure is of paramount importance for understanding and predicting the relationships between food-web diversity and stability in a rapidly changing world. However, little is known about the interactive effects of environmental perturbations on individual species, trophic interactions and ecosystem functi...

A tritrophic food-chain chemostat model composed of a prey with Monod-type nutrient uptake, a Holling Type II predator and a Holling Type II exploited superpredator is considered in this paper. The bifurcations of the model show that dynamic complexity first increases and then decreases with the nutrient supplied to the bottom of the food chain. Extensive simulations prove that the same holds f...