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  • 1
    Electronic Resource
    Electronic Resource
    Foraging behaviour of the whitefly parasitoidEncarsia formosa on tomato leaflets (1995)
    Springer
    Entomologia experimentalis et applicata 76 (1995), S. 313-324 
    Details
    ISSN: 1570-7458
    Keywords: foraging behaviour ; parasitoid ; Encarsia formosa ; Trialeurodes vaporariorum ; handling time ; walking activity ; walking speed ; success ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract IndividualEncarsia formosa parasitoids were observed continuously until the parasitoids flew away, either on clean tomato leaflets, on leaflets with honeydew, or on leaflets with unparasitized and parasitized whitefly larvae. Encounters with unparasitized and parasitized whitefly larvae, and contact with honeydew arrested the parasitoids on the leaflet. The walking speed increased linearly from 0.179 to 0.529 mm/s between 15 and 25–30°C. The walking activity showed another relationship with temperature: it was below 10% at 15 and 18°C, and increased to about 75% at 20, 25 and 30°C. It was not affected by host encounters or by 1 to 4 ovipositions. The total handling time of hosts was between 1.8–21.8% of the total time on the leaflet. Self-superparasitism was not observed. Conspecific-superparasitism did occur in 14% of the encounters with hosts containing a parasitoid egg, but was not observed anymore when the parasitoid egg had hatched. Experienced parasitoids superparasitized as often as naive females. The foraging behaviour ofE. formosa from landing on a leaf until departure has now been quantified and is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02382997
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  • 2
    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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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Influence of intrapatch experiences and temperature on the time allocation of the whitefly parasitoidEncarsia formosa (Hymenoptera: Aphelinidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 483-501 
    Details
    ISSN: 1572-8889
    Keywords: parasitoids ; patch time allocation ; giving up time ; residence time ; proportional hazards ; Encarsia formosa ; Trialeurodes vaporariorum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of experiences, such as contact with honeydew, rejections of hosts, and ovipositions in hosts, and of temperature on the time allocation of individualEncarsia formosa female parasitoids on tomato leaflets have been studied. Behavioral records were analyzed by means of the proportional hazards model. Analyses were carried out at two levels: (1) the tendency of leaving and (2) the tendency of changing from one leaf side to another. The patch-leaving behavior ofE. formosa can be described by a stochastic threshold mechanism, which is characterized by a certain tendency (probability per time) to leave. The median time from being placed on the leaflet or, if it occurred, from the latest encounter with a host until leaving was 18.6 min. The median time for changing from one leaf side to the other was initially 11.6 min and dropped to 5.7 min after both leaf sides had been visited. The effect of temperature, ranging from 20 to 30°C, was negligible. The presence of honeydew as well as the first oviposition in an unparasitized host decreased the tendency to leave, thus increasing the giving up time (GUT) since the latest encounter with a host. Encounters with parasitized hosts did not affect the GUT since latest encounter; as a result, the total residence time increased. After the first oviposition in an unparasitized host the tendency of changing from the lower leaf side on which hosts were present to the upper side was decreased. The presence of honeydew did not affect the tendency of changing leaf sides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025445
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