European field collections and Canadian releases ofCeranthia samarensis (Dipt.: Tachinidae), a parasitoid of the gypsy moth |
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Authors: | N J Mills V G Nealis |
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Institution: | (1) Division of Biological Control, University of California, 1050 San Pablo Ave, 94706 Albany, CA, USA;(2) Great Lakes Forestry Centre, Sault Ste. Marie, Canada |
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Abstract: | A programme to collect, import and release into Canada the gypsy moth parasitoid,Ceranthia samarensis (Diptera: Tachinidae) is described. The parasitoid's potential for biological control in Canada is also discussed.
The parasitoid was collected in Europe by exposing experimental gypsy moth larvae in areas where local gypsy moth populations
were at low densities. Following field exposure, the host larvae were returned to the laboratory and parasitoids reared from
them. This technique has shown thatC. samarensis is the suffers 7–16% hyperparasitism.
From 83–90% of theC. samarensis typically enter diapause as pharate adults within the puparia. Laboratory tests of post-exposure host rearing conditions
indicate that constant temperatures disrupt the normal parasitoid diapause and that this effect can not be offset by use of
either static long or short photoperiods or natural daylengths.
Shipping and cold-storage procedures for puparia are described. Post-storage time to emergence of adultC. samarensis decreased with longer cold storage periods and with higher post-storage incubation temperatures. Emergence requires 112 degree-days
above a threshold of 8°C after a period of at least 8 months cold storage.
Releases of adultC. samarensis into field cages at four locations in southern Ontario are documented. While dissection of host larvae from the field cages
has failed so far to demonstrate evidence of parasitism, we remain hopeful that some establishment of the parasitoid has occurred.
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Keywords: | Ceranthia samarensis France Canada collection release degree-days diapause hyperparasitism |
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