Experimental studies on predation: Complex dispersion and levels of food in an acarine predator-prey interaction

Abstract

Experimental studies on the role of dispersion and level of food supply in predator-prey relations were continued. They were conducted under controlled laboratory condi tions using the phytophagous mite Eotetranychus sexma* culatus as prey, and the mite Typhlodromus occidentales as predator.Results give additional support to earlier findings that more stable control of a population results when the en vironment is spatially more heterogeneous and there is a balance between the extent of heterogeneity and the amount of basic food. An excess of plant food at first generated large numbers of prey, and then an excess of predators which overexploited their prey and then starved.By using a complex spatial environment consisting of three grid-wire shelves in a cabinet, and a wide dispersion of the basic food material, the predator-prey interaction was continued for 490 days, and the end was brought about by a disturbing disease rather than by overexploitation on the part of the predatory mite.In contrast, trebling the quantity of basic food while maintaining other factors unchanged apparently created an imbalance between numbers of predators generated in the system and the hazards they faced in covering the areas to be searched-thus, they overexploited in each case at the end of the first prey population crash phase.These result^ also suggest the potential role of prédation as a means of synchronizing cycle phase in some natural populations.

Metapopulation dynamics of a persisting predator–prey system in the laboratory: time series analysis

“…This is in agreement with the results of Huffaker (1958), Huffaker et al (1963) and Burnett (1964). The systems of the second experiment consisted of fewer plants than the first experiment, but they were distributed over eight islands connected by a few bridges.…”

“…Most of these time series concern the dynamics of well-mixed populations without an explicit spatial structure. Only Huffaker (1958), Huffaker et al (1963) and Burnett (1964) studied systems that can be considered as consisting of local populations connected through dispersal; all these studies concern acarine predator-prey systems. Huffaker (1958) presented data of one persistent acarine predator-prey system with a complex spatial structure.…”

“…The most well known are those with spider mites and predatory mites in the laboratory by Huffaker (1958) and Huffaker et al (1963). These articles show that considerable complexity has to be introduced into the spatial connection between the local populations to bring about persistence.…”

“…Greenhouses are prone to invasions by other pests, which necessitates the use of various control measures that potentially interfere with the populations under study . The experiments by Huffaker (1958), Huffaker et al (1963) and Burnett (1964) are better suited to an experimental approach, although the complexity of these systems is still considerable.…”

Generalized models – A new tool for the investigation of ecological systems

“…This paradox revolves around the observation that many ecological systems can be destabilized by increasing the supply of nutrients or prey. 26,27 While this was initially felt to be counter-intuitive, the effect is now well understood and hence no longer paradoxical. From a modern perspective the true paradox lies in the fact that many ecological systems observed in experiments are stabilized by an increase of nutrients or prey while almost all models predict a destabilization.…”