Preliminary evaluation of the parasitoid wasp, Collyria catoptron, as a potential biological control agent against the wheat stem sawfly, Cephus cinctus, in North America

Authors: Rand, Tatyana; Waters, Debra; Shanower, Thomas

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2015
Publication Date: 10/23/2015
Publication URL: http://handle.nal.usda.gov/10113/61789
Citation: Rand, T.A., Waters, D.K., Shanower, T.G. 2015. Preliminary evaluation of the parasitoid wasp, Collyria catoptron, as a potential biological control agent against the wheat stem sawfly, Cephus cinctus, in North America. Biocontrol Science and Technology. 26(1):61-71. doi:10.1080/09583157.2015.1076377.

Interpretive Summary: The wheat stem sawfly is the major pest of wheat in the northern Great Plains of North America. The development of management tools, such as biological control, to complement traditional approaches using resistant wheat varieites will be critical to the successful control of this pest. Foreign exploration carried out by the USDA-ARS identified Collryia catoptron, a parasitoid wasp collected from Cephus fumipennis in northern China, as a potential biological control agent. In this study we carry out a preliminary evaluation of the potential of Co. catoptron to successfully control Ce. cinctus. Specifically we set out to: 1.) Determine variability in parasitism rates on the native host from collection areas in northern China across sites and over six years, and 2.) Determine whether Co. catoptron will lay its eggs and complete development in the novel targeted sawfly. Maximum parasitism of the native host in the native range was 38%, exceeding the threshold below which successful biological control has never been observed in mathematical models. The percentage of sites with parasitoids present was high (83%) suggesting very good colonization abilities. Co. catoptron clearly recognized and attacked the North American sawfly, with parasitism levels on Ce. cinctus greater tgab those observed on the native co-evolved host from China, Ce. fumipennis. However, we found no evidence that Co. catoptron can complete development in Ce. cinctus. No adults were reared from this host in either year of the study. In contrast 50-60% of the parasitoids survived and emerged as adults on Ce. fumipennis. Thus we suggest that Co. catoptron is unlikely to be a suitable biological control agent against Ce. cinctus, and that resources would be better directed towards developing conservation biological control approaches using native parasitoid species already present in the USA.

Technical Abstract: The wheat stem sawfly, Cephus cinctus (Hymenoptera:Cephidae) is the major pest of wheat in the northern Great Plains of North America. The development of management tools, such as biological control, to complement traditional resistance breeding approaches will be critical to the successful control of this pest. Foreign exploration carried out by the USDA-ARS identified Collryia catoptron, a parasitoid wasp collected from Cephus fumipennis in northern China, as a potential biological control agent. In this study we carry out a preliminary evaluation of the potential suitability of Co. catoptron, as a candidate biological control against Ce. cinctus. Specifically we set out to: 1.) Quantify the spatio-temporal variation in parasitism rates on the native host from collection sites in northern China over six years, and 2.) Assess whether Co. catoptron will oviposit and complete development in the novel targeted host. Maximum parasitism of the native host in the native range was 38%, exceeding the theoretical threshold below which successful biological control has never been observed. Site occupancy levels were high (83%) suggesting very good colonization abilities. Co. catoptron clearly recognized and attacked the novel targeted host, Ce. cinctus, with parasitism levels on Ce. cinctus exceeding those observed on the native co-evolved host Ce. fumipennis. However, we found no evidence that Co. catoptron can complete development in Ce. cinctus. No adults were reared from this host in either year of the study. In contrast 50-60% of the parasitoids survived and emerged as adults on Ce. fumipennis. Thus we suggest that Co. catoptron is unlikely to be a suitable agent against Ce. cinctus due to basic host incompatibility, and that resources would be better directed towards developing conservation biological control approaches using native parasitoid species already present in the USA.