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 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: 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.

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.

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: 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.

THE FUNCTIONAL RESPONSE OF PHYTOSEIULUS PERSIMILIS (ACARINA: PHYTOSEIIDAE) TO VARIOUS DENSITIES OF TETRANYCHUS URTICAE (ACARINA: TETRANYCHIDAE)

1979 ◽  
Vol 111 (1) ◽  
pp. 7-10 ◽  
Author(s):  
P. Everson
Keyword(s):  
Functional Response ◽  
Tetranychus Urticae ◽  
Adult Female ◽  
Response Curve ◽  
Prey Density ◽  
Handling Time ◽  
Phytoseiulus Persimilis ◽  
Activity Level ◽  
Artificial Substrates ◽  
Successful Search

AbstractThe functional response of the predacious mite Phytoseiulus persimilis Athias-Henriot to increases in the prey density of adult female Tetranychus urticae Koch was examined. Previous studies on artificial substrates have described the functional response curve of P. persimilis to adult female prey as dome-shaped, because as prey density increased the predator was disturbed by prey activity.An experiment to determine the effect of artificial and natural substrates on the activity level of T. urticae was conducted. T. urticae showed a significant increase in activity on artificial substrates of plastic and waterproof paper compared with a substrate of excised bean leaf (Phaseolus vulgaris L.). Since prey activity was significantly influenced by substrate, the functional response of P. persimilis to adult female T. urticae was re-examined. P. persimilis exposed to various densities of T. urticae on excised bean leaf disks (5 cm2) showed a functional response curve having a curvilinear rise to a plateau as prey densities increased from 0.2 to 10.0 prey/cm2.The functional response curve predicted by Holling’s disk equation did not differ significantly from the observed functional response curve.The rate of successful search and the handling time predicted by the disk equation were 0.194 and 10.34 h respectively.

Estimation of Functional Responses of Predators on Juvenile Salmon

1978 ◽  
Vol 35 (6) ◽  
pp. 797-808 ◽  
Author(s):  
Randall M. Peterman ◽  
Marino Gatto
Keyword(s):  
Functional Response ◽  
Chum Salmon ◽  
Pink Salmon ◽  
Experimental Studies ◽  
Functional Responses ◽  
Response Curves ◽  
Response Component ◽  
Predation Mortality ◽  
Salmon Fry ◽  
Salmon Population

Several studies have shown that predators can eat large portions (up to 85%) of emerging salmon (Oncorhynchus spp.) fry populations. To understand salmon population dynamics and the effect of salmon enhancement projects, it is necessary to determine how present predation mortality varies with prey density. To predict the shape of this relation outside the range of past observations, we must examine the basic components of the predation process, the functional and numerical responses. A review of past, sparse data on the functional response component shows that predators of salmon fry and smolts were mostly not being saturated (i.e. maximum attack rates were not being achieved) at high prey densities. A method to estimate functional responses from certain types of existing field data is derived and applied to Hooknose Creek pink salmon (O. gorbuscha) and chum salmon (O. keta) information. Results from 7 out of 9 yr corroborate earlier observations that predators are normally operating on the low end of their functional response curves and are therefore capable of causing high mortality on larger prey populations. Also, competition among predators is demonstrated to be significant, resulting in changes in slopes of functional responses. More experimental studies of functional responses are needed, and such research should be carried out in conjunction with perturbations in salmon fry abundance which will result from enhancement projects. Key words: salmon fry, predation, freshwater survival, enhancement, functional response, predator competition

Functional response analysis of size-selective predation by the notonectid predator Anisops deanei (Brooks) on Daphnia thomsoni (Sars)

1984 ◽  
Vol 35 (6) ◽  
pp. 725 ◽  
Author(s):  
JG Reynolds ◽  
MC Geddes
Keyword(s):  
Functional Response ◽  
Prey Type ◽  
Size Class ◽  
Response Analysis ◽  
Response Curves ◽  
Selective Predation ◽  
Size Classes ◽  
Effective Predator ◽  
Typical Type ◽  
Predation Rates

The functional response of A. deanei to uncrested D. thomsoni was calculated by predation experiments in the laboratory. A. deanei produced typical type 11 functional response curves when presented with increasing densities of any given size-class of D. thomsoni Predation rates were highest for small size-classes and decreased for prey sizes above 2 mm In mixed-prey populations A deanet showed a greater preference towards the smaller, preferred prey than was predicted from the angle-prey-type expenments, thus demonstrating an exercise of choice by the predator. Crests developed by the smaller, preferred size-classes of D. thomsoni did not act as effective anti-predator mechanisms against A. deanei which may be able to remam an effective predator on crested populations of D. thomsonl.

Sign in / Sign up

Export Citation Format

Share Document