Weevils for Hound's tongue being bred in Creston

By: Stephanie Sweet, Farm Manager

Welcome to year three of WEEVILS VS HOUND’S-TONGUE. The actual first seeding of hound’s-tongue was in the fall of 2002; the first weevil release was early summer 2003; and the first harvest of weevils for shipment was spring 2005.

The spring catch did not give us the great numbers of weevils originally expected based on our monitoring of production within hound’s-tongue roots in 2004. However, keep in mind that a big part of the project was figuring out what would and wouldn’t work. The problem was not in how many weevils we could produce, but in how many of these we could catch during harvest. Combined with weevils produced in the Lethbridge plots we did manage to catch about 30,000 weevils, which were packaged and sent to many of the project contributors. Hopefully, based on our 2005 experience, we have improved our methods for catching weevils. We feel confident there will be a good supply in 2006.

The collection equipment consisted of an industrial sized shop vacuum, buckets, boxes and plastic bags. Crude but efficient. The hardest part was counting those tiny beasts one by one for each shipment (300 weevils per release).

After the weevils were counted and packaged with food, they were stored in the fridge until enough units were ready to fill each request. We found that the insects will keep for a week as long as they have enough food and the containers are kept clean. Shipping by bus was ideal as they were generally received throughout the province the next day.

Housekeeping in the experimental plots this year was a breeze. I had one reliable person that was available when needed. He also did bear research part time so between both jobs he worked full time.

Just a quick overview of activities and crop problems experienced over the past three years.

· 2002. Seeded crop.

· 2003. Figured out best method of growing hound’s-tongue as a crop, and released weevils into crop. Some plant death due to powdery mildew and weevil damage. Seeded a second hound’s-tongue crop.

· 2004. Repeated studies on growing hound’s-tongue and released more weevils. Hound’s-tongue died prematurely due to powdery mildew, snow mould, and stress from continuous flower head removal and weevil infestation.

· 2005. Weevils from first hound’s-tongue crop collected from hound’s-tongue plants acting as a trap crop

Our plans for spring 2006 are to collect our second harvest of weevils from hound’s-tongue plants that were planted in buffer strips in spring 2005. It’s a good thing we planted these buffers in order to provide food for those weevils that will be emerging this coming spring. Planting the buffer in the spring prior to harvest is best, as those planted in the fall prior to harvest come up too late to be of much use.

We also decided not to do a fall 2005 harvest of weevils in addition to spring 2006. The reasons are that the weevils are easier to find and catch in spring, and we did not want to risk damaging our buffer plants needed for spring 2006 harvest.

Total acres planted to hound’s-tongue during our project were 8 acres in Creston and 6 in Lethbridge, including buffers. To date all plants are dead except for those of the buffer strips. This is not surprising though, considering the stress placed on the plants by weevil feeding, disease and that hound’s-tongue is a biennial plant species (i.e., typically dies after 2 years of growth).

Overall, we were able to develop a reliable method of growing large, hound’s-tongue plants, that were healthy long enough to produce large numbers of weevils. A big part of our lesson was in timing the growing of hound’s-tongue with weevil release, so that the weevils did not wipe out their food plant before their numbers could be produced.

That’s all for now. It has been a very good season for us and we look forward to 2006. Brian and Jim will finish with their work on the project in 2005. Rose returned from her year in Australia in August and will see the project to its end.

Thanks for your continued support,

Added on January 17th, 2006 - Return to Special Features