Now is the time when flea beetle monitoring is very important to canola producers!
Flea beetles are important to canola production because they are an economic pest typically emerging from overwintering in the spring which begins to feed on the cotyledons of the canola seedling. Their feeding activity results in characteristic shot-hole damage. More recently, striped flea beetles have been observed to girdle seedlings which immediately kills the plant.
Flea beetles reproduce in the spring and lay eggs near the stem of cruciferous plants. Larvae will feed upon the canola root system but it is the adult or beetle which causes economic damage so in-field monitoring and the application of an action threshold of >25% cotyledon leaf area consumed is critical.
We monitor flea beetles to ascertain when they move into canola fields, to obtain a general estimate of the population densities active in specific fields, and to examine proportions of striped, crucifer, and hops flea beetles along with the lesser-known species that can also occur in our fields. Flea beetles are approximately 2-3 mm long and are usually black, brown, metallic blue or purple and may have yellow stripes on their elytra (i.e., hardened forewings).
Since 2001, our lab has monitored the density and species diversity of flea beetles found in commercial canola fields. Below are photos depicting how we collect flea beetles using yellow sticky trap cards, and what they look like when we process the trap cards by examining them under a stereomicroscope.
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| Flea beetle trap out in the field ready to be collected. The black spots on the card are flea beetles (each 2-3mm long). |
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| One flea beetle (Phyllotreta Striolata) stuck to the trap viewed using our stereomicroscope. |
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| Two flea beetles (Crepidodera spp.) stuck to the trap viewed using our stereomicroscope. |
For more information on flea beetles you can follow this link to our flea beetle protocol .
-Kaitlin