First report of parasitoids associated with the spotted asparagus beetle in North America. 58th Western Committee on crop pests

Citation

Hervet V, Douglas H (2018) First report of parasitoids associated with the spotted asparagus beetle in North America. 58th Western Committee on crop pests. Loydminster AB. Oral presentation.

Plain language summary

Canada has two introduced asparagus beetle pests (Crioceris spp.). Two parasitoid wasp species were released in Canada to control the beetle during the 1980s. The parasitoids were initially not recovered. Recent work shows that one of the parasitoid species is present in Canada. Ongoing research is underway to determine whether the other parasitoid is present. This research is also showing that native predators and parasitoids cause some mortality to Crioceris beetles.

Abstract

Abstract: Two parasitoids were introduced to North America in the 1980s to control an invasive pest of asparagus, the spotted asparagus beetle (Crioceris duodecimpunctata). Recovery efforts conducted during the years following releases were unsuccessful and these biocontrol agents were thought to not have established. A survey conducted during the summer of 2018 showed that one of these parasitoids (Tetrastichus crioceridis) is now established throughout Canada and that the other biocontrol species may also be established (pending identification). Other parasitoid species (yet to be identified) associated with the spotted asparagus beetle have also been recovered.

Problems: The spotted asparagus beetle (Crioceris duodecimpunctata) is an invasive pest of asparagus in North America. Although this pest, as well as the common asparagus beetle (Crioceris asparagi), are problematic in asparagus plantations, the current control strategy relies on the use of insecticides. No biocontrol agents are currently known to be associated with either of these tow pests in North America.

Objectives of Research: The main objective is to document the identity, distribution, and control rate of natural enemies of the spotted asparagus beetle across Canada. A second objective is to show that although surveying the establishment of biocontrol agents during the years following releases might be unsuccessful, resuming the survey some years later can yield success.

Summary of Results:
Species recovered:
- Tetrastichus crioceridis occurs throughout Canada.
- In addition to T. crioceridis, three unidentified parasitoid species (an Ichneumonidae, a Chalcidoidea, and a Tachinidae) were recovered from British-Columbia.
- A species of mite (Erythraeidae) was observed to consume large number of spotted asparagus beetle eggs in southern Alberta

Continuing Research: Samples from BC and eastern Canada were obtained late in the season. Perhaps too late to show an accurate picture of parasitoid populations and we might try to obtain additional samples from these regions next summer. In the future, parasitoid species that do not occur throughout Canada could potentially be relocated to regions where they have not been found.
These positive findings open the door for another study: three parasitoid species associated with the invasive “common asparagus beetle” were introduced to North America in the 1980s and never recovered since. The common asparagus beetle is a more serious pest than the spotted asparagus beetle and it would be worthwhile to conduct a similar study on this pest.