Preliminary evaluation of the parasitoid wasp, <i>Collyria catoptron</i>, as a potential biological control agent against the wheat stem sawfly, <i>Cephus cinctus</i>, in North America
<div><p>ABSTRACT</p><p>The wheat stem sawfly, <i>Cephus cinctus</i> (Hymenoptera: Cephidae) is the major pest of wheat in the northern plains of North America, with biological control providing a potentially useful management tool. Foreign exploration by the USDA-ARS identified <i>Collyria catoptron</i> (Hymenoptera: Ichneumonidae), a parasitoid wasp of <i>Cephus fumipennis</i> in northern China, as a potential biological control agent. Here we carry out a preliminary evaluation of the potential suitability of <i>C. catoptron</i>, as a candidate agent against <i>C. cinctus</i>. Specifically we: (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 <i>C. catoptron</i> 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 for successful biological control. Site occupancy levels were high (83%) suggesting good colonisation abilities. <i>C. catoptron</i> clearly recognised and attacked <i>C. cinctus</i>, with parasitism levels exceeding those observed on the co-evolved host <i>C. fumipennis</i>. However, we found no evidence that <i>C. catoptron</i> can complete development in <i>C. cinctus</i>; no adults were reared from this host in either year of the study. In contrast 50–60% of the parasitoids survived to emerge as adults in <i>C. fumipennis</i>. Thus, <i>C. catoptron</i> is unlikely to be a suitable agent against <i>C. cinctus</i> due to basic host incompatibility. Future work will be directed towards developing conservation biological control approaches using native parasitoid species already present in the USA.</p></div
