Does winter help reduce wheat stem sawfly populations?

Does winter help reduce wheat stem sawfly populations? 

https://canadianagronomist.ca/overwinter-wheat-stem-sawfly-mortality-unaffected/

Southern Alberta has seen some sawfly damage in the past few years. One may ask: does winter help kill the sawflies?  

Unfortunately, the answer is: no.  

Figure 1. Overwintering wheat stem sawfly larva. Photo credit: Shelley Barkley

Those actively scouting wheat fields in southern Alberta may have found sawfly larvae in the stems. The larvae form you find them in now is how they overwinter.  

The most recent study has found that, unlike many other insect pests, sawfly larvae do not experience winter mortality. In other words, their population is not affected by abiotic or biotic factors during the winter.

The parasitic wasps, Bracon cephi and Bracon lissogaster, are the natural enemy of sawflies. They attack sawfly larvae and help suppress sawfly populations. Parasitoids can be conserved by:  

  • Increasing the height of stubble when harvesting; and,  
  • Reducing insecticide applications in grass ditches where natural enemies of the wheat stem sawfly are abundant. 

For sawfly scouting and management tips, watch this video: Growing Smarter: Wheat Stem Sawfly 

More information on the natural enemies of wheat stem sawfly