Experimental studies on acarine predator–prey interactions: effects of temporal changes in the environment on searching behaviour, predation rates, and fecundity (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (12) ◽  
pp. 2992-3000 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Temporal Changes ◽  
Patchy Environment ◽  
Changing Environment ◽  
Searching Behaviour ◽  
Predator Prey ◽  
Prey Distribution ◽  
Predation Rates

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.

Experimental studies on acarine predator–prey interactions: the distribution of search effort and the functional and numerical responses of predators in a patchy environment (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (12) ◽  
pp. 2979-2991 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Reproductive Output ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Patchy Environment ◽  
Functional Responses ◽  
Predator Prey ◽  
Search Effort ◽  
Aggregative Response ◽  
Predation Rates ◽  
Main Factor

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.

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
Keyword(s):  
Foraging Behaviour ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Predator Population ◽  
Patchy Environment ◽  
Predator Species ◽  
Predator Prey ◽  
Aggregative Response ◽  
Density Patch ◽  
Predation Rates

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.

Experimental studies on acarine predator–prey interactions: the numerical response of immature and adult predators (Acarina: Phytoseiidae)

1981 ◽  
Vol 59 (7) ◽  
pp. 1407-1418 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Prey Density ◽  
Survival Rates ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Phytoseiid Mites ◽  
Searching Behaviour ◽  
Predator Prey ◽  
Adult Females ◽  
History Of ◽  
Adult Lives

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.

Experimental studies on acarine predator–prey interactions: the response of predators to prey distribution in an homogeneous area (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (4) ◽  
pp. 639-647 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Functional Response ◽  
Prey Density ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Phytoseiid Mites ◽  
Predator Prey ◽  
Prey Distribution ◽  
Uniform Distributions ◽  
Homogeneous Area ◽  
Prey Depletion

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.

Experimental studies on acarine predator–prey interactions: the effects of predator density on prey consumption, predator searching efficiency, and the functional response to prey density (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (4) ◽  
pp. 611-629 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Functional Response ◽  
Adult Female ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Predator Density ◽  
Response Curves ◽  
Phytoseiid Mites ◽  
Predator Prey ◽  
The Individual ◽  
Predation Rates

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.

Experimental studies on acarine predator–prey interactions: the effects of predator density on immature survival, adult fecundity and emigration rates, and the numerical response to prey density (Acarina: Phytoseiidae)

1982 ◽  
Vol 60 (4) ◽  
pp. 630-638 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Prey Density ◽  
Laboratory Experiments ◽  
Survival Rates ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Numerical Response ◽  
Predator Density ◽  
Predator Prey ◽  
Immature Survival

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.

Predator–prey relationships and predation rates for crustacean zooplankters from some lakes in western Canada

1970 ◽  
Vol 48 (6) ◽  
pp. 1229-1240 ◽  
Author(s):  
R. Stewart Anderson
Keyword(s):  
Prey Species ◽  
Prey Size ◽  
Relative Size ◽  
Experimental Studies ◽  
The Other ◽  
Western Canada ◽  
Potential Predator ◽  
Predator Prey ◽  
Predation Rates

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.

Experimental studies on acarine predator–prey interactions: effects of predator age and feeding history on prey consumption and the functional response (Acarina: Phytoseiidae)

1981 ◽  
Vol 59 (7) ◽  
pp. 1387-1406 ◽  
Author(s):  
Eldon S. Eveleigh ◽  
D. A. Chant
Keyword(s):  
Functional Response ◽  
Prey Density ◽  
Laboratory Experiments ◽  
Prolonged Exposure ◽  
Experimental Studies ◽  
Phytoseiulus Persimilis ◽  
Functional Responses ◽  
Phytoseiid Mites ◽  
Predatory Behaviour ◽  
Predator Prey

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.

The effect of chrysanthemum leaf trichome density and prey spatial distribution on predation of Tetranychus urticae (Acari: Tetranychidae) by Phytoseiulus persimilis (Acari: Phytoseiidae)

2003 ◽  
Vol 93 (4) ◽  
pp. 343-350 ◽  
Author(s):  
M.C. Stavrinides ◽  
D.J. Skirvin
Keyword(s):  
Tetranychus Urticae ◽  
Phytoseiulus Persimilis ◽  
Spatial Arrangement ◽  
Predation Rate ◽  
Trichome Density ◽  
Release Point ◽  
Predator Prey ◽  
Leaf Hairiness ◽  
Leaf Trichome ◽  
Prey Patches

AbstractThe effect of plant architecture, in terms of leaf hairiness, and prey spatial arrangement, on predation rate of eggs of the spider mite, Tetranychus urticae Koch, by the predatory mite Phytoseiulus persimilis Athias-Henriot was examined on cut stems of chrysanthemums. Three levels of leaf hairiness (trichome density) were obtained using two different chrysanthemum cultivars and two ages within one of the cultivars. The number of prey consumed by P. persimilis was inversely related to trichome density. At low prey densities (less than ten eggs per stem), prey consumption did not differ in a biologically meaningful way between treatments. The effect of prey spatial arrangement on the predation rate of P. persimilis was also examined. Predation rates were higher in prey patches on leaves adjacent to the release point of P. persimilis, but significantly greater numbers of prey were consumed in higher density prey patches compared to low density patches. The predators exhibited non-random searching behaviour, spending more time on leaves closest to the release point. The implications of these findings for biological control and predator–prey dynamics are discussed.

Bad news for bobtails: understanding predatory behaviour of a resource-subsidised corvid towards an island endemic reptile

2018 ◽  
Vol 45 (7) ◽  
pp. 595
Author(s):  
W. Oversby ◽  
S. M. Ferguson ◽  
R. A. Davis ◽  
P. W. Bateman
Keyword(s):  
Human Activity ◽  
Large Population ◽  
Camera Traps ◽  
Bad News ◽  
Human Settlement ◽  
Tourism Impacts ◽  
Predatory Behaviour ◽  
Predator Prey ◽  
Island Endemic ◽  
Predation Rates

Context Resource subsidisation as a result of urbanisation and other human activity can have positive impacts for some opportunistic predators. Many species of corvid have benefitted from the expansion of human-dominated habitats; however, their impacts on co-occurring prey fauna are generally poorly understood. Aims We aimed to test the hypothesis that urbanisation associated with tourism impacts the predator–prey relationship between Australian ravens, or wardongs (Corvus coronoides), a ubiquitous corvid of southern Australia, and Rottnest Island bobtails (Tiliqua rugosa konowi), a subspecies of bobtail lizard isolated to a small (19km2) island off the coast of Western Australia. Methods Using clay model lizards and camera traps, we assessed the wardongs’ attack rates by distance from the settlement and by whether the model was in closed or open habitat. Key Results We found that while wardongs preyed upon Rottnest Island bobtails, predation was not affected by proximity to human settlement despite the highest number of wardongs being found there. Models in closed vegetation were attacked by wardong significantly more than were those in open vegetation. Implications Increased predation rates in closed vegetation suggests that current revegetation efforts on the island may be increasing the availability of preferred hunting habitat for the wardong. This finding may influence decisions by management on whether to control the large population of wardongs on the island.

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