1. Midge Tolerant Wheat Retailer Training
Module 1
Midge Tolerant Wheat Technology

2. Presentation Overview
Orange Wheat Blossom Midge
Life Cycle
Midge Damage
Midge Tolerant Wheat
Varieties
How it Works
Single Gene Resistance
Interspersed Refuge System

3. Wheat Midge Life Cycle The orange wheat blossom midge has 4 stages:
Adult – Adult flies emerge in late June/early July, mate and females lay eggs on newly emerged wheat heads during warm, calm evenings. Emergence peaks mid-July.

4. Wheat Midge Life Cycle
Eggs – Eggs are laid, either singly or in clusters of 3-4 eggs, on the wheat heads. This stage lasts 4-7 days.
Larvae – Upon hatching, the larvae move into the florets to feed on the developing kernels for 2-3 weeks. Then they crawl off the wheat head and over-winter in the soil.
Pupae – Once temperature and soil conditions end the over-wintering period, larvae move to the soil surface to pupate. Emergence of adult flies begins in late June/early July and can continue for up to 6 weeks.

5. Midge Damage
Crop damage occurs when midge larvae feed on the developing wheat kernel, causing them to shrivel, become deformed or completely abort.
Damaged kernels cause downgrading in wheat samples.
Crop yields are also reduced as 40-50% of damaged kernels are blown out of the combine during harvest.

6. Midge Tolerant Wheat Varieties
Several spring wheat varieties were developed by Canadian wheat breeders at AAFC in Winnipeg & Swift Current, and the Crop Development Centre at the University of Saskatchewan.
Funding for these projects comes from government, the WGRF check-off program and variety distributors.
All these new varieties contain the single gene (Sm1) which provides midge tolerance.
Sm1 was moved into spring wheat using traditional plant breeding techniques.

7. Midge Tolerant Wheat Varieties
Variety
Refuge
Class
Distributor
Available
AC® Unity VB
AC® Waskada
CWRS
SeCan
AC® Goodeve VB
AC Intrepid
Alliance Seed Corporation
AC® Glencross VB
AC® Burnside
CWES
Faurschou Farms
AC® Fieldstar VB
AC® Shaw VB
AC Domain
CDC Utmost VB
Harvest
FP Genetics
AC® Conquer VB
5701PR
CPSR
Canterra Seeds
AC® Vesper VB
Spring 2013
Enchant VB
AC Crystal
Spring 2014

8. Benefits of Midge Tolerant Wheat
Prevent an estimated $36 per acre* loss from midge damage downgrading and yield reductions.
*Based on the economic threshold of one midge per 4 to 5 wheat at flowering = estimated 15% yield loss if not controlled. Higher midge levels can lead to greater losses. 15% x $6/bu wheat x 40 bu/acre = $36
Reduce reliance on insecticides, the traditional method of midge control.
Gain more flexibility in crop rotations and seeding dates.

9. How it Works
When the insect begins to feed on the seed, the Sm1 gene causes the level of phenolic compounds (naturally occuring acids in wheat kernels) to elevate more rapidly than in wheat kernels without the Sm1 gene.
The higher levels of phenolic acids cause the midge larvae to stop feeding and starve to death.

10. Single Gene Resistance
Midge tolerance is based on a single gene (Sm1) that can become ineffective over a relatively short period of time as insect populations change.
An interspersed refuge system is required to extend the life of midge tolerance from as little as 10 years to 90 years or longer.

11. Interspersed Refuge System
Requires planting a varietal blend (VB) which contains 90% midge tolerant variety and 10% midge susceptible variety.
Ensures the refuge is evenly distributed (inter-seeded) throughout the field.
Objective is to prevent a build-up of naturally occurring virulent midge – midge that are able to attack plants with the Sm1 gene.

12. No refuge system

13. No refuge system

14. No refuge system

15. Interspersed Refuge System

16. Interspersed Refuge System

17. Interspersed Refuge System

18. Please proceed to Quiz 1
Thank you