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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of foraging behavior of the whitefly parasitoidEncarsia formosa (Hymenoptera: Aphelinidae) in an experimental arena: A simulation study (1996)
    Springer
    Journal of insect behavior 9 (1996), S. 771-797 
    Details
    ISSN: 1572-8889
    Keywords: foraging behavior ; parasitoid ; Encarsia formosa ; Trialeurodes vaporariorum ; stochastic model ; Monte Carlo simulation ; functional response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foraging ofEncarsia formosa was analyzed using a stochastic simulation model of the parasitoid's behavior. Parasitoids were allowed to search during a fixed time in an experimental arena with immatures of the greenhouse whitefly,Trialeurodes vaporariorum. The model simulates host searching, selection, and handling behavior and the physiological state (egg load) of the parasitoid. The simulated number of hosts encountered, parasitized, or killed by host feeding agreed well with observations on leaf disks. The hypothesis of random host encounter seems to be correct. The number of ovipositions on the leaf at low host densities was strongly affected by the parasitoid's walking speed and walking activity, the probability of oviposition after encountering a host, and the initial egg load. At high densities, the initial and maximum egg load were most important. A strong temperature effect was found at 18°C or below. The number of encounters, ovipositions, and host feedings increased with host density to a maximum of 25, 6.5, and 1.5, respectively, during 2 h at 25°C. The shape of the curves resembled a Holling Type II, which may be the result of the “experimental” procedure, where a parasitoid was confined to a patch during a fixed time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02213556
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  • 2
    Electronic Resource
    Electronic Resource
    Foraging Behavior of the Parasitoid Encarsia formosa on Gerbera jamesonii Leaves (1999)
    Springer
    Journal of insect behavior 12 (1999), S. 105-122 
    Details
    ISSN: 1572-8889
    Keywords: foraging behavior ; residence time ; walking activity ; oviposition ratio ; egg load ; Encarsia formosa ; Trialeurodes vaporariorum ; Gerbera jamesonii cultivars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Insight into the foraging behavior of the parasitoid Encarsia formosa Gahan for whitefly hosts was gained by continuous observation of individual parasitoids on leaves of the ornamental plant Gerbera jamesonii, until females left the leaf. Comparison of the parasitoid behavior on three cultivars gave similar results. Mean searching time on uninfested G. jamesonii leaves of three cultivars was 1 h 30 min and the mean percentage of walking activity of the total observation time on those cultivars was 61%. Both parameters were not influenced by different leaf structures of Gerbera cultivars. Encounters with hosts arrested the parasitoids on the leaves. The walking activity and the percentage of host encounters that resulted in an oviposition decreased with decreasing egg load of the parasitoid. In comparison with tomato, where biological control of whiteflies is successful, only minor differences in the foraging behavior occur, except for the residence time of females, which was about three to four times longer on G. jamesonii leaves, but these leaves are about seven times larger than tomato leaves. The facts that (1) the foraging behavior of E. formosa on G. jamesonii is independant of the cultivar and (2) the foraging behavior is, in many aspects, similar to that on tomato suggest that biological control of whitefly on this ornamental plant is a potential option.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020933332339
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  • 3
    Electronic Resource
    Electronic Resource
    A variable-response model for parasitoid foraging behavior (1990)
    Springer
    Journal of insect behavior 3 (1990), S. 471-490 
    Details
    ISSN: 1572-8889
    Keywords: parasitoids ; foraging behavior ; learning ; experience ; variability ; model ; biological control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An important factor inducing variability in foraging behavior in parasitic wasps is experience gained by the insect. Together with the insect's genetic constitution and physiological state, experience ultimately defines the behavioral repertoire under specified environmental circumstances. We present a conceptual variable-response model based on several major observations of a foraging parasitoid's responses to stimuli involved in the hostfinding process. These major observations are that (1) different stimuli evoke different responses or levels of response, (2) strong responses are less variable than weak ones, (3) learning can change response levels, (4) learning increases originally low responses more than originally high responses, and (5) hostderived stimuli serve as rewards in associative learning of other stimuli. The model specifies how the intrinsic variability of a response will depend on the magnitude of the response and predicts when and how learning will modify the insect's behavior. Additional hypotheses related to the model concern how experience with a stimulus modifies behavioral responses to other stimuli, how animals respond in multistimulus situations, which stimuli act to reinforce behavioral responses to other stimuli in the learning process, and finally, how generalist and specialist species differ in their behavioral plasticity. We postulate that insight into behavioral variability in the foraging behavior of natural enemies may be a help, if not a prerequisite, for the efficient application of parasitoids in pest management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01052012
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  • 4
    Electronic Resource
    Electronic Resource
    Time allocation of the parasitoidAphidius colemani (Hymenoptera: Aphidiidae) foraging forAphis gossypii (Homoptera: Aphidae) on cucumber leaves (1996)
    Springer
    Journal of insect behavior 9 (1996), S. 283-295 
    Details
    ISSN: 1572-8889
    Keywords: foraging behavior ; parasitoids ; patch time allocation ; proportional hazards model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time allocation of individualAphidius colemani female parasitoids foraging forAphis gossypii nymphs on cucumber leaves has been investigated. Apart from experiences on the current leaf (such as density of hosts on the current leaf, density of hosts on a neighboring leaf and encounters with hosts on the current leaf), the effect of previous leaf visits on the time allocation was studied. Behavioral records were analyzed by means of the proportional hazards model, to determine the tendency of leaving the current leaf. The leaving tendency decreased only on leaves with a high host density (100 aphids), thus increasing the giving up time since the latest encounter. Rejection of aphids had no influence on the leaving tendency. To assess the effect of the number of hosts encountered on the leaving tendency, we considered three classes: 0–30 encounters, 31–100 encounters, and 100 or more encounters with hosts. The effect of the number of hosts encountered differed at different aphid densities. When fewer than 10 aphids were present the leaving tendency was much greater after 30 encounters than beforehand. At a density of 100 aphids the leaving tendency was lower than at the other aphid densities and increased only after 100 encounters. The density of hosts on a neighboring leaf, ranging from 0 to 100 hosts, had a negligible effect on the leaving tendency. Repeated visits to leaves with 10 unparasitized aphids resulted in an increase in the leaving tendency after 10 visits. It is argued that the parasitoids have some innate expectancy of host availability and that they concentrate on high-density patches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02213871
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