LETHBRIDGE – It’s new to the Prairies and it’s nasty.
Cereal leaf beetle is an oat-loving pest prevalent in the United States and Europe that can cut yields in that crop by 55 percent and by 25 percent in wheat and barley.
The insect chews on plant leaves as larvae and adults. Larvae damage appears as a window-like slice from the leaf because the larvae strip away only the green tissue. Mature beetles cut right through the tissue and take longitudinal slices from the leaves.
Entomologists say the damage is often misdiagnosed as leaf disease.
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The small, black insect is a couple of millimetres long when mature and has an orange head. Unfortunately, so does one of the helpful insects, which makes it important to recognize the correct bug. Analyzing leaf damage is key to knowing whether the bugs are around.
“The larvae use a disgusting trick of covering themselves in their own feces so they look like tiny, black, stinky sticks,” said Hector Carcamo of Agriculture Canada during the Southern Applied Research Association’s Diagnostic Field School held July 10-12 in Lethbridge.
“It seems to keep predators like birds away.”
So far the insects appear to be limited to southern Alberta and were found at a diagnostic field school in Lethbridge in 2005.
Lloyd Dosdall of Alberta Agriculture, who has been monitoring the cereal leaf beetle’s progress, said it successfully overwintered and has been increasing in the subsequent two seasons.
“They have been in Ontario for years and have a population in the Creston Valley (of British Columbia). Likely some hay was brought into southern Alberta that contained the beetles and now they are making their way across the Prairies,” Dosdall said.
The Canadian Food Inspection Agency lists the cereal leaf beetle as a quarantined pest.
Until its discovery in the County of Lethbridge and subsequent appearances in the Municipal District of Taber, hay and straw were allowed to move freely from those areas. Since then a movement certificate is required for all hay and straw leaving the region.
Carcamo said American cereal growers have found that the insect takes about three seasons to build up a population that requires control.
“We don’t have economic thresholds (for crop damage on the Prairies). But in the U.S. one larvae per flag leaf and it’s time to spray,” Carcamo said.
“This insect is a serious pest and potentially an international export issue. California doesn’t have this pest. It’s in the Pacific Northwest. We don’t want to make this insect a trade issue, not to mention the insect is seriously yield limiting in cereal crops.”
Dosdall said it is already present in the Dakotas, Montana and Idaho and populations are exploding in areas like Ohio where the industry thought it was under control.
Environmental control is available through parasites introduced to the U.S. in the 1960s. Those insects attack both larvae and eggs and have been found in the Lethbridge area.
Entomologists say despite the beneficial parasites, it is likely that beginning next year prairie producers will find themselves spraying for the new pest.
