Cereal leaf beetle (Oulema melanopus) - The CLB simulation model will be used to monitor this insect pest's development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of development stages based on biological parameters for this species.
As of June 7, 2020, cereal leaf beetle (CLB) simulations indicate that oviposition continues and that 42% of the population is currently in the egg stage (Table 1). Larvae are predicted to be in first, second and third instars (Table 1). The graph for Regina illustrates occurrence of first, second and third instar larvae (Fig. 1). The second graph demonstrates that development is slower around Grande Prairie (Fig. 2).
Table 1. Predictive model output estimates for O. melanopus development (% of total population for each location) at selected sites across the Canadian prairies (as of June 7, 2020).
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| Figure 1. Predicted cereal leaf beetle phenology at Regina SK. Values are based on model simulations (April 1-June 7, 2020). |
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| Figure 2. Predicted cereal leaf beetle phenology at Grande Prairie AB. Values are based on model simulations (April 1-June 7, 2020). |
Manitobans - Dr. John Gavloski is looking for samples of cereal leaf beetle larvae this growing season to determine their range across Manitoba, their population density, and the rate at which larvae are parasitized. Please contact John.Gavloski@gov.mb.ca or @JohnTheBugGuy if you observe cereal leaf beetles in your fields.
Canadians - Dr. Haley Catton is looking for samples of cereal leaf beetle larvae this growing season too! Help her monitor for the tiny beneficial wasp, Tetrastichus julis, that lives inside the larvae of cereal leaf beetle. Tracking these biological control agents will help Dr. Catton learn more about their distribution and value in fields. Please check her Twitter poster for more details or contact her at @HaleyCatton or Haley.Catton@canada.ca . Access the recently released Pests & Predators podcast by Real Agriculture which features Dr. Haley Catton and this powerful parasitoid!
Lifecycle and Damage:
Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 3). The thorax and legs are light orange-brown. Females (4.9 to 5.5 mm) are slightly larger than the males (4.4 to 5 mm). Adult beetles overwinter in and along the margins of grain fields in protected places such as in straw stubble, under crop and leaf litter, and in the crevices of tree bark. They favour sites adjacent to shelter belts, deciduous and conifer forests. They emerge in the spring once temperature reaches 10-15 ºC and are active for about 6 weeks. They usually begin feeding on grasses, then move into winter cereals and later into spring cereals.  |
| Figure 3. Adult Oulema melanopus measure 4.4-5.5 mm long (Photo: M. Dolinski). |
Egg: Eggs are laid approximately 14 days following the emergence of the adults. Eggs are laid singly or in pairs along the mid vein on the upper side of the leaf and are cylindrical, measuring 0.9 mm by 0.4 mm, and yellowish in colour. Eggs darken to black just before hatching.
Larva: The larvae hatch in about 5 days and feed for about 3 weeks, passing through 4 growth stages (instars). The head and legs are brownish-black; the body is yellowish. Larvae are usually covered with a secretion of mucus and fecal material, giving them a shiny black, wet appearance (Fig. 4). When the larva completes its growth, it drops to the ground and pupates in the soil.
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| Figure 4. Larval stage of Oulema melanopus with characteristic feeding damage visible on leaf (Photo: M. Dolinski). |
Fact sheets for CLB are published by the province of Alberta and available from the Prairie Pest Monitoring Network. Also access the Oulema melanopus page from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" available as a free downloadable document in either an English-enhanced or French-enhanced version.