Bioclimatic assessment of abiotic factors affecting relative abundance and distribution of wheat stem sawfly (Hymenoptera: Cephidae) in western Canada

Abstract

Wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), indigenous to North America, quickly adapted from host native grasses to wheat crops (Triticum Linnaeus (Poaceae)) with expansion of agriculture on the Great Plains of North America. Bioclimatic simulation tools, such as Climex, predict the potential geographic distribution and establishment of insects in ecosystems, based on climate. The ecoclimatic index, a measure of ecological suitability, integrates potential population growth with stresses to produce estimates of relative abundance. This simulation software was used to develop a bioclimate model for C. cinctus in western Canada. Results fostered a better understanding of how C. cinctus responded to selected climate variables. Two general circulation models were then applied to assess the response of C. cinctus populations to future climate. Relative to current climate, predicted changes in C. cinctus distribution and relative abundance were greatest for 2030, with a small further increase for 2070. Across the Prairies and Boreal Plains Ecozones, changes in ecoclimatic index were greater than in geographic distribution. Both general circulation models indicated most of this area would be categorised as very favourable. This suggests that the potential for pest populations could expand into areas that do not currently experience economic losses associated with C. cinctus.

Insect pest complexes associated with wheat and canola crops in the Canadian Prairies Ecozone: pest risk in response to variable climates using bioclimatic models

“…Multiple-species models will serve as useful tools to assess potential risks and subsequently reduce risks via crop variety selections, agronomic practices, and pest management decisions. Through increased awareness, the agricultural industry can be more proactive in monitoring, detecting, and managing crop pests (Olfert et al 2019) to minimise their economic impact and to enhance agricultural sustainability. Future iterations of the approach described here will incorporate crop pathogens, weeds, and additional insects to present increasingly holistic risk estimates.…”

“…The bioclimatic modelling process integrates the weekly responses of a population of a given species to climate conditions using a series of annual climate-related indices, as previously described (e.g., Olfert et al 2018Olfert et al , 2019. The location-specific ecoclimatic index values generated by the modelling software range from 0 to 100 and are a measure of the suitability of a given location for survival and population growth of the species being studied (Sutherst 2000).…”

“…Following similar logic, we used an ecoclimatic index value of 15 to indicate areas at risk from S. mosellana because the economic threshold for S. mosellana is 1200 cocoons/m 2 and the species distribution model for S. mosellana showed that populations exceeded the economic threshold where ecoclimatic index (EI) values exceeded 15 (Olfert et al 2016). Based on historical insect monitoring data, observed and modelled output, and published knowledge, we defined threshold ecoclimatic index values to represent crop risk for the remaining species: C. cinctus (EI = 15), O. melanopus (EI = 20), C. obstrictus (EI = 20), B. viridescens (EI = 24), C. nasturtii (EI = 20), and P. cruciferae and P. striolata (EI = 20; Dosdall et al 2002;Mason et al 2003;Olfert et al 2004Olfert et al , 2006Olfert et al , 2017Olfert et al , 2019Olfert and Weiss 2006a).…”

“…Bioclimatic simulation models have been used to predict the distribution and relative abundance of insect pests of annual crops. Models have been published for insect pests of wheat, including wheat midge, Sitodiplosis mosellana Géhin (Diptera: Cecidomyiidae) (Olfert et al 2016), cereal leaf beetle, Oulema melanopus Linnaeus (Coleoptera: Chrysomelidae) (Olfert et al 2004), and wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae) (Olfert et al 2019). Models have also been published for insect pests of canola, including swede midge, Contarinia nasturtii Kieffer (Diptera: Cecidomyiidae) (Olfert et al 2006), cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (Coleoptera: Curculionidae) (Dosdall et al 2002;Olfert and Weiss 2006a), pollen beetle, Brassicogethes viridescens (Fabricius) (Coleoptera: Nitidulidae) [formerly Meligethes viridescens] (Mason et al 2003;Olfert and Weiss 2006a), and crucifer and striped flea beetles, Phyllotreta cruciferae (Goeze) and P. striolata (Fabricius) (Coleoptera: Chrysomelidae) (Olfert et al 2018).…”

A “solid” solution for wheat stem sawfly (Hymenoptera: Cephidae) resistance: Genetics, breeding and development of solid stem wheat

“…Among the biotic factors, overall harvest losses caused by wheat stem sawfly (WSS) (Hymenoptera: Cephidae: Cephus cinctus Norton) (Ainslie, 1920) infestation account for more than 350 million dollars per year in Western Northern Great Plains of United States and regions of Canada (Beres et al., 2011b). Recent reports suggest that the WSS is spreading further into other states such as Colorado, Nebraska, and Kansas, and historical infestations are increasing in the Dakotas and Canadian Prairies (Olfert et al., 2019; Peairs & Irell, 2014). The continuous adaptation of the WSS within historic, and into new wheat growing areas is the major reason for a rapid rise in losses due to WSS in Western North America.…”