BioControl (2010) 55, 351-362

W.H. Jenner, U. Kuhlmann, N. Cappuccino and P.G. Mason (2010)
Pre-release analysis of the overwintering capacity of a classical biological control agent supporting prediction of establishment
BioControl 55 (3), 351-362
Abstract: This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding short periods of temperatures as low as -5°C or -10°C, but even much higher temperatures were lethal if sustained for several weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime₅₀ at -12°C, simulating winter temperatures without snow cover, was 4-5 and 6-7 days for males and females, respectively. The LTime₅₀ at -4°C, simulating winter temperatures beneath an insulating snow layer, was 1-2 and 2-3 weeks for males and females, respectively, with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity. Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Peter G. Mason, Naomi Cappuccino, Ulrich Kuhlmann

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
classical biocontrol/new introduction
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Acrolepiopsis assectella		Canada (east)
Diadromus pulchellus (parasitoid)	Acrolepiopsis assectella