Author
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Blackmer, Jacquelyn |
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CROSS, DALE - U OF A TUCSON, AZ ENTOMOL |
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Submitted to: Sweetpotato Whitefly Progress Review Proceedings
Publication Type: Proceedings Publication Acceptance Date: 4/1/2002 Publication Date: 6/1/2002 Citation: N/A Interpretive Summary: Technical Abstract: In the southwestern United States, Eretmocerus eremicus (Hymenoptera: Aphelinidae) is a native parasitoid of the Bemisia complex (Homoptera: Aleyrodidae). However, little information currently exists on its potential as a biological control agent of whiteflies or on the factors that influence its tendency to disperse. Information on this parasitoid's dispersal propensity might alter the release strategy employed. Low dispersal rates could mean that multiple release sites might be necessary for optimal distributions relative to its host. Our study examined the host-habitat/host location phase(s) of host-finding behavior for E. eremicus. In this study, we examined the flight behavior of male and female E. eremicus in response to skylight (here simulated by a mercury-vapor lamp) and plant cues (a 550-nm filter) in a vertical flight chamber. The visual plant cue was presented to the parasitoid in the absence of whitefly stimuli. Approximately 90% of the parasitoids took off in response to the skylight cue. Both sexes were capable of sustained flights in excess of 60 min; however, average flight durations were 15.6 + 3.8 min for males and 7.8 + 2.6 min for females. When a plant cue was presented during the parasitoid's phototactic flight, four relatively distinct responses were observed. Fifty-one percent of the individuals responded to the plant cue throughout their flight by flying toward or by landing on the cue. The majority of these parasitoids were females. Approximately 12% of the wasps exhibited an intermittent, positive response to the plant cue. Twenty percent exhibited a 'migratory' response. These parasitoids, which were predominantly males, failed to respond to the plant cue until they had flown for a considerable period. Finally, 17% failed to respond to the target during their flight. Approximately 37% of the individuals that showed a positive response to the plant cue actually landed on it and the majority of these were female. However, in the absence of additional whitefly stimuli, tenure time on the visual plant cue was relatively short. The differential response to the plant cue by male and female parasitoids could be, in part, because females are driven to locate hosts in which to oviposit, and males are driven to find mates. Additional studies need to determine how biotic and abiotic factors influence the dispersal tendencies of E. eremicus, the role of visual and olfactory information in the host-finding process, and whether the vertical flight chamber might be a useful tool for screening the flight propensity of potential biological control agents. |
