Active Dispersal of Trichogramma chilonis Ishii and T. pretiosum Riley Towards Host Eggs Under Confined Condition and Their Parasitisation Efficiency


                                The active movement of two trichogrammatids viz., Trichogramma chilonis and T. pretiosum towards eggs of Leucinodes orbonalis Guenee and Corcyra cephalonica Stainton was assessed in 2cm diameter PVC tubes of 1, 2, 3, and 4 meters. The trichogrammatids moved up to 3m towards the eggs of L. orbonalis and C. cephalonica. T. chilonis showed more active movement than T.pretiosum. At a distance of 1m, 50.05 per cent of T. chilonis was recaptured on L. orbonalis egg cards which got subsequently reduced on the increase in the length of PVC tubes, which was 14. 64 per cent at 2m and 1.19 per cent at 3m and became nil in a length of 4m, while the dispersal behaviour of male and female parasitoid was compared. The female wasps were more active than male wasps and dispersed to a maximum distance of 3m in both the species. The study also showed that the preference of trichogrammatids towards the natural host (L. orbonalis) was more when compared to the factitious host (C. cephalonica). The recapture of T. chilonis and T. pretiosum at release distance of 1m was 50.05 and 28.58 per cent in L. orbonalis respectively whereas, C. cephalonica eggs attracted 41.25 and 9.66 per cent parasitoids respectively. Among T. chilonis, T. japonicum and T. pretiosum, T. pretiosum showed a higher parasitisation of 90.00 per cent and emergence of 91.03 per cent on one day old eggs of L. orbonalis. The study also showed that the age of host was a matter in parasitisation as well emergence of trichogrammatids. The increase in host age was negatively associated with parasitisation as well as emergence of trichogrammatids irrespective of species.

Key words : Trichogramma chilonis, T. pretiosum, Leucinodes orbonalis, Active dispersal, Parasitisation

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