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Journal of Entomology

Year: 2011 | Volume: 8 | Issue: 2 | Page No.: 164-173
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Authors

N. Geetha

R. Balakrishnan

Keywords

Research Article

Temporal and Spatial Dispersal of Laboratory-Reared Trichogramma chilonis Ishii in Open Field

N. Geetha and R. Balakrishnan
Laboratory-reared Trichogramma chilonis Ishii was assessed for its ability to move in open field through parasitism on sentinel cards of Corcyra cephalonica placed at distances of 1, 3, 5, 7, 10, 15, 20, 25 and 30 m, from the point of release of parasitoids at eight cardinal directions. Sentinel cards were recovered from the field after 1-7 days time at 24 h interval to observe parasitism and adult emergence. The dispersal rate was affected significantly by the time allowed as well as by the distances from the release point while the impact of direction was not significant. The overall dispersal rate was found to increase from 23.56% at 24 h to 37.07% on the completion of third day, irrespective of the distance or direction at which the cards were kept. The mean dispersal rate over the seven time periods tested was quite high at 1-10 m distance (73.78 to 32.05) which decreased to 7.67 at 30 m. Adult emergence did not show a definite influence by the interactive elements. High rates of adult emergence was observed (77.72-92.44%) in the cards that were left in the field for 1-7 days. Overlapping but significant variations in the emergence rates (76.06-91.9%) were observed in the cards kept at different distances from the release point. Results indicated that three days of time stabilized parasitoid dispersal and that at least 13 release points are required per acre of release area for ensuring uniform dispersal.
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