functional response of the female ladybeetle, hippodamia variegata (goeze) (col., coccinellidae) to varying densities (5, 10, 20, 40, 60 and 80) of third instar nymphs of aphis gossypii glover was assessed in a growth chamber (25˚c, 65± ­5% rh and a photoperiod of 16l: 8d h), on the black eyed bean, vigna unguiculata (l.), in an open patch design. the logistic regression showed a type ii functi...

Prior research has quantified prey densities at depth in association with foraging whales and suggests that these predators require a minimal prey density threshold for effective foraging. Even in the few cases where individual whales have been the focus of a directed study, however, it has been difficult to observe the behavior of individual whales in a three‐dimensional environment. We addres...

The classical Holling type II functional response, describing the per capita predation as a function of prey density, was modified by Beddington and de Angelis to include interference of predators that increases with predator density and decreases the number of killed prey. In the present paper we further generalize the Beddington-de Angelis functional response, considering that all predator ac...

Increasingly, ecologists emphasize that prey frequently change behaviour in the presence of predators and these behavioural changes can reduce prey survival and reproduction as much or more than predation itself. However, the effects of behavioural changes on survival and reproduction may vary with prey density due to intraspecific competition. In field experiments, we varied grasshopper densit...

In this paper, a prey-predator model with a social activity of prey population has been analyzed. In some ecological situations, the prey-predator interaction occurs only at the outer surface of a herd formed by prey population. To model this phenomenon, the square root of prey density has been used in the functional response. The basic model is formulated with this modified functional response...

1. Predation plays a major role in shaping the structure and dynamics of ecological communities, and the functional response of a predator is of crucial importance to the dynamics of any predator-prey system by linking the trophic levels. For large mammals, there is a dearth of field studies documenting functional responses, and observations at low prey density are particularly scarce. Furtherm...

The larval feeding requirements and biology of the generalist predatory muscid hunter fly Coenosia attenuata Stein 1903 (Diptera: Muscidae) were investigated at 25 degrees C. Larval C. attenuata were fed second-, third, and fourth-instar (L2, L3, and L4) larvae of the fungus gnat Bradysia impatiens (Johannsen) (Diptera: Sciaridae) at variable rates to determine minimum and optimum numbers of th...

Predators influence prey populations both by consuming individual prey, and by inducing changes in prey behaviour that limit reproduction and survival. Because prey trade-off predation risk for foraging gains, the magnitude of predators' non-consumptive effects should depend on resource availability. Studies of non-consumptive effects generally adopt either of two strategies: (i) maintaining a ...