Host range testing parameters for Diadromus collaris.

Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae), a solitary pupal endoparasitoid of Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae), is a candidate for introduction into Canada as a biological control agent. It is important to assess the parasitoid’s host specificity before its release. To maximize the wasp’s expressed host range, five variables were tested to determine which experimental conditions would motivate D. collaris to oviposit. Of these variables, wasp diet, exposure length, and the presence or absence of diamondback moth cocoons resulted in statistically significant differences in D. collaris emergence or diamondback moth mortality.