Experimental studies on acarine predator–prey interactions: distribution of search effort and predation rates of a predator population in a patchy environment (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (12) ◽  
pp. 3001-3009 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

The responses of a population of adult female Phytoseiulus persimilis and Amblyseius degenerans in a patchy environment were examined for 2 days in the laboratory. Progressive prey exploitation caused continuous redistribution of P. persimilis among the patches of prey, and although more individuals tended to occupy the highest density patch than other patches, there was an indication that "interference" limited the tendency of the predators to aggregate in this patch. In contrast, there was little redistribution of A. degenerans among the patches despite extensive prey exploitation. This species did not show an aggregative response nor was there any "interference" between the predators. The predation rates of P. persimilis declined with time and their foraging behaviour was not optimal on either day. In contrast, A. degenerans completely exploited the prey in all patches. The feeding and searching strategies of the two predator species are discussed in terms of their respective food habits. The implications of the characteristics of the predators for biological control are also briefly discussed.

1982 ◽  
Vol 60 (12) ◽  
pp. 2979-2991 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

Laboratory experiments revealed that Phytoseiulus persimilis distributed its search effort in relation to prey density in a patchy environment, whereas Amblyseius degenerans distributed its search effort randomly among patches of prey. The main factor responsible for the aggregative response of P. persimilis was the length of its first visit to the patches. Although the functional responses of both predators changed with time, only those of P. persimilis closely reflected changes occurring in its distribution of search effort. The spatial complexity of the environment did not affect the overall predation rates of P. persimilis but it reduced its reproductive output. However, the predation rates of A. degenerans were adversely affected, suggesting that its fecundity would also be reduced in a spatially complex environment. Phytoseiulus persimilis distributed its progeny among patches containing relatively high prey densities and avoided ovipositing in the patch containing fewest prey. Neither species foraged optimally and possible reasons for this are discussed.


1982 ◽  
Vol 60 (12) ◽  
pp. 2992-3000 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

We examined the effects of temporal changes in the environment on the searching behaviour, predation rates, and fecundity of Phytoseiulus persimilis and Amblyseius degenerans in the laboratory. Phytoseiulus persimilis demonstrated an ability to respond quickly to changes in prey distribution in a patchy environment and maintained its searching efficiency despite these changes. In contrast, A. degenerans was rather insensitive to temporal changes in prey distribution and when it found a profitable patch its visits to other patches were restricted. Thus, this species was unable to maintain its searching efficiency in the changing environment. Phytoseiulus persimilis distributed its progeny in relation to the distribution of prey in the changing environment and avoided oviposition in patches without prey, whereas A. degenerans showed no such discrimination. The fecundity of both species was not adversely affected by changes in prey distribution although their fecundity was lower than when all of the prey were in a single patch and their dispersal was restricted.


1982 ◽  
Vol 60 (4) ◽  
pp. 611-629 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

Experiments on the responses of two species of predacious phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans, to their own density revealed that, with the exception of adult female P. persimilis, the individual predation rates of all instars of both species increased as predator and prey densities were increased within certain fixed predator to prey ratios. "Interference" between adult female P. persimilis was suggested as a possible reason for this result, and this was confirmed by the application of Hassell and Varley's model to data from an experiment where predator density was increased within various prey densities. Interference did not influence the predation rates for other instars of either species and other factors are considered to account for the results obtained.Increasing predator density caused the functional response of all instars of both species to increase over an increasingly wider range of prey densities. However, due to interference between adult female P. persimilis the functional response curves increased curvilinearly and reached plateaux at progressively lower levels of prey killed per predator as predator density increased. With the other instars of both species the responses became less curvilinear with increasing predator density, and trends in the data suggested that plateaux would be reached at similar levels of prey killed for different predator densities provided sufficient prey are present.


1982 ◽  
Vol 60 (4) ◽  
pp. 630-638 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

Laboratory experiments revealed that increasing the density of the immature instars of Phytoseiulus persimilis had little effect on their survival rates. However, due to the high prey requirements of the immature instars of Amblyseius degenerans and the tendency for underfed individuals of this species to become cannibalistic, their survival rates decreased with increasing predator density. Increasing predator density reduced the fecundity of P. persimilis and caused its numerical response to prey density to reach plateaux at increasingly lower levels of fecundity as the predator density increased. In contrast, increasing predator density did not affect the fecundity of A. degenerans to such an extent and its numerical response appeared eventually to reach maximum levels when sufficient prey were available. The emigration rates of P. persimilis tended to increase with increasing predator density whereas those of A. degenerans increased or decreased depending on the density of the predators and the prey.


1981 ◽  
Vol 59 (7) ◽  
pp. 1407-1418 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

The numerical responses of two species of phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans, were studied in the laboratory. Developmental times and survival rates were examined in the immature instars and oviposition rates in adult females. Prey requirements for development, survival, and oviposition were lower with P. persimilis than A. degenerans due to the nature of their respective feeding and searching behaviour. The fecundity of P. persimilis increased linearly with increasing numbers of prey killed, whereas that of A. degenerans increased curvilinearly. Experiments on the effects of the feeding history of adult females on their fecundity showed that their response depended not only on their most recent nutritional history but also on prey conditions experienced early in their adult lives. The ability of the females to respond to an increase in prey density may be enhanced or reduced depending on the prey conditions experienced. The manner in which the requirements for prey, and the feeding and searching behaviour of the predators, influenced their responses is discussed.


2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Guohong Zhang ◽  
Xiaoli Wang

We study a Lotka-Volterra type predator-prey model with a transmissible disease in the predator population. We concentrate on the effect of diffusion and cross-diffusion on the emergence of stationary patterns. We first show that both self-diffusion and cross-diffusion can not cause Turing instability from the disease-free equilibria. Then we find that the endemic equilibrium remains linearly stable for the reaction diffusion system without cross-diffusion, while it becomes linearly unstable when cross-diffusion also plays a role in the reaction-diffusion system; hence, the instability is driven solely from the effect of cross-diffusion. Furthermore, we derive some results for the existence and nonexistence of nonconstant stationary solutions when the diffusion rate of a certain species is small or large.


Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Xuejuan Lu ◽  
Yuming Chen ◽  
Shengqiang Liu

In this paper, we propose a stage-structured predator-prey model with migrations among patches in an n-patch environment. The net reproduction number for each patch in isolation is obtained along with the net reproduction number of the system of patches, ℛ0. Inequalities describing the relationship among these numbers are also given. Furthermore, threshold dynamics determined by ℛ0 is established: the predator dies out if ℛ0<1 while the predator persists if ℛ0>1. Focusing on the case with two patches, we obtain that the dispersal decreases the net reproduction number ℛ0. By numerical simulations, we find that the dispersal may be a good thing or a bad thing because the dispersal could make the predator population thrive or extinct, and hence we might seek steady state in the ecological environment by controlling parameters related to the prey and the predator.


1982 ◽  
Vol 60 (4) ◽  
pp. 639-647 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

A laboratory study was conducted to determine the effects of prey distribution in an homogeneous area on the searching success and functional response of two species of phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans. The results indicated that the spatial distribution of the prey affected the searching success and functional response of P. persimilis but not of A. degenerans. More prey were killed by the former predator when prey were clustered, followed by random and uniform distributions. In contrast to A. degenerans, the degree of prey aggregation at a given prey density also affected the number of prey killed by P. persimilis. With both predators, prey depletion affected the comparative success of the predators at certain prey distributions. It is concluded that P. persimilis is adapted to search for prey which aggregate, whereas A. degenerans is not. The results are discussed in terms of their potential importance in predation and biological control studies.


1970 ◽  
Vol 48 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
R. Stewart Anderson

Experimental studies on Diaptoimus shoshone, D. arcticus, D. nevadensis, Cyclops bicuspidatus thomasi, C. vernalis, and Branckinecta gigas show that these predatory species can capture and eat many prey species of various sizes. B. gigas probably combines raptorial with filter feeding and can eat 150 or more smaller crustaceans per day. Adult D. shoshone, D. arcticus, and D. nevadensis eat up to 12 or more cyclopoids or diaptomids per day. Rotifers are also preferred prey. Predation rates are inversely proportional to prey size. Cannibalism probably causes the uniformity in body size and instar of predaceous diaptomids in some populations, C. vernalis and C. b. thomasi can eat six or more prey animals daily, depending on the size of the prey. Predaceous diaptomids and cyclopoids will eat the same prey species at rates which are influenced more by hunger than by abundance of prey. Furthermore, each species is a potential predator on the other, where the role of predator or prey is determined by the relative size or instar of the two groups. Hence, codominance of the zooplankton by predaceous diaptomid and cyclopoid species is unlikely.


1981 ◽  
Vol 59 (7) ◽  
pp. 1387-1406 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant

Laboratory experiments were performed to determine the functional response to prey density of various instars of two species of predacious phytoseiid mites, Phytoseiulus persimilis and Amblyseius degenerans, and to examine the effects of predator age and nutritional history on their responses. The experiments showed that the nutritional requirements of the predators, the time that they are exposed to prey in relation to their life-span, increasing age, and differences in nutritional history, can have important effects on predatory behaviour and the functional response. Prolonged exposure to one density of prey can cause lags in predation rates when the prey density is changed. The results indicated that functional responses are probably multiform in certain predators and the above factors may provide an explanation of the variety of responses previously reported for species of phytoseiid mites. Phytoseiulus persimilis appeared to be more sensitive to some of these factors than A. degenerans and was shown to be different in many aspects of its predatory behaviour.


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