Insect Pest of the Week and the Entomologists that Study Them (July 6): Forage Grass Pests / Feature entomologist: Chrystel Olivier

This week’s Insect of the Week feature crop is forage grasses: common Prairie plants know to be robust, adaptive, and tolerant to grazing. Our feature entomologist this week is Chrystel Olivier.

Crested wheatgrass cc by 2.0 Matt Lavin

Note: 

This year, we're doing things a bit differently for our Insect of the Week. Instead of focussing on a single insect (pest or natural enemy), we're looking at it from a crop perspective. Each week, we'll pick a crop and list the insects that attack it along with additional helpful information. The insect list is based on the information found in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. The field guide offers information describing lifecycle, damage description, monitoring/scouting strategies, economic thresholds (where available) and control options) for each economic pest.

 

In addition to an Insect of the Week, we'll also feature one of the entomologists that helps support the PPMN, either directly or indirectly.

Cereal leaf beetle

Cereal leaf beetle (Oulema melanopus) - As of June 14, 2020, cereal leaf beetle (CLB) simulations indicate that oviposition is almost complete with 30% of the population in the egg stage (Table 1).  

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 14, 2020).

Across the prairies, first instar larvae are predicted to be most abundant (prairie average; Fig. 1).  This week, fourth instar larvae may begin to occur.  The following three maps illustrate larval development of first (Fig. 1), second (Fig. 2) and third instar (Fig. 3) stages across the prairies. Based on the simulation, development is greatest across southern Manitoba and southern Saskatchewan.

Figure 2. Predicted percent of cereal leaf beetle (Oulema melanopus) population at first instar stage across the Canadian prairies (as of June 14, 2020).  

Figure 3. Predicted percent of cereal leaf beetle (Oulema melanopus) population at second instar stage across the Canadian prairies (as of June 14, 2020).  

Figure 4. Predicted percent of cereal leaf beetle (Oulema melanopus) population at third instar stage across the Canadian prairies (as of June 14, 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. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

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.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Model output indicates that hatch is almost complete with less than 5% of the population predicted to still be in the egg stage (prairie average; Table 1). Across the prairies, populations are predicted to be 12, 45, 29 and 10% in first, second, third and fourth instars, respectively.  

Table 1.  Predictive model output estimates for Hypera postica development (% of total population for each location) at selected sites across the Canadian prairie as of June 14, 2020.

Larval populations in the Peace River region are expected to be mostly in the second instar (Fig. 1).  Last week, the presence of third instar larvae was limited to areas southeast of Saskatchewan and extended into Manitoba (Fig. 2).  This week third instar larvae should be occurring across southern and central regions of the prairies (Fig. 3).  Fourth instar larvae should be abundant across southern Manitoba and southeastern Saskatchewan.

Figure 1. Predicted percent of populations of alfalfa weevil (Hypera postica) in the second instar stage across

the Canadian prairies as of June 14, 2020. 

Figure 2. Predicted percent of populations of alfalfa weevil (Hypera postica) in the third instar stage across

the Canadian prairies as of June 14, 2020. 

Figure 3. Predicted percent of populations of alfalfa weevil (Hypera postica) in the fourth instar stage across

the Canadian prairies as of June 14, 2020. 

Monitoring

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 3, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Cereal leaf beetle

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).

Figure 1. Predicted cereal leaf beetle phenology at Regina SK.
Values are based on model simulations (April 1-June 7, 2020).

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. 

Figure 4.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

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.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9 °C are produced to predict the development of Alfalfa weevil (AAW) across the prairies.  The model is updated weekly to help growers time their in-field scouting for second-instar larvae. 

As of June 7, 2020, model output indicates that hatch of alfalfa weevil eggs is almost complete, as only 20% of the population is expected to currently be in the egg stage (prairie average). Prairie populations are predominantly in the first (29%) or second (36%) instar larval stages (Fig. 1) and approximately 15% are predicted to be third instar larvae (Table 1; Fig. 2). Developmental rates should be greatest across southern Manitoba and southeastern Saskatchewan.

Table 1.  Predictive model output estimates for Hypera postica development (% of total population for each location) at selected sites across the Canadian prairie as of June 7, 2020.

Figure 1. Predicted percent of populations of alfalfa weevil (Hypera postica) in the second instar stage across

the Canadian prairies as of June 7, 2020. 

Figure 2 Predicted percent of populations of alfalfa weevil (Hypera postica) in the third instar stage across

the Canadian prairies as of June 7, 2020. 

Monitoring

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 3, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Cereal leaf beetle

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 May 31, 2020, simulations for cereal leaf beetle (CLB) development indicate that oviposition continues and that first instar larvae are beginning to appear (Table 1). The graph for Saskatoon illustrates occurrence of first instar larvae (Fig. 1). The second graph demonstrates that development is slower at Lethbridge (Fig. 2) compared to Saskatoon. 

Table 1. Predictive model output estimates for O. melanopus at selected sites across the Canadian prairies (as of May 31, 2020).

Figure 1. Predicted cereal leaf beetle phenology at Saskatoon SK.
Values are based on model simulations (April 1-May 31, 2020).

Figure 2. Predicted cereal leaf beetle phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 31, 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. 

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 4). 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 4. 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. 5).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 5.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

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.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9 °C are produced to predict the development of Alfalfa weevil (AAW) across the prairies.  The model is updated weekly to help growers time their in-field scouting for second-instar larvae. 

As of May 31, 2020, model output indicates that hatch is well underway and both first and second instar larvae may be occurring in alfalfa fields across southern Manitoba and Saskatchewan (Table 1). The following graphs compare development for Winnipeg (Fig. 1) and Swift Current (Fig. 2). At Winnipeg (Fig. 1), AAW populations are predicted to be primarily in the second instar. Weevil populations near Swift Current (Fig. 2) are expected to consist mostly of first instar larvae. If present, the model predicts that populations in the southern Peace River region would primarily still be in the egg stage (Table 1).  

Table 1.  Predictive model output estimates for Hypera postica populations at selected sites across the Canadian prairie as of May 31, 2020.

Figure 1. Predicted alfalfa weevil (Hypera postica) phenology at Winnipeg MB.
Values are based on model simulations (April 1-May 31, 2020).

Figure 2. Predicted alfalfa weevil (Hypera postica) phenology at Swift Current SK.
Values are based on model simulations (April 1-May 31, 2020).

The map below (Fig. 3) indicates areas where populations should have second instar larvae (% of total population).

Figure 3. Predicted development of populations of alfalfa weevil (Hypera postica) across

the Canadian prairies as of May 31, 2020. 

Monitoring

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 3, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Alfalfa weevil

Alfalfa Weevil (Hypera postica) – Degree-day maps of base 9 °C are produced to predict the development of Alfalfa weevil (AAW) across the prairies.  The model is updated weekly to help growers time their in-field scouting for second-instar larvae. 

As of May 25, 2020, the model output indicates that oviposition is well underway and initial hatch has begun in some locations. The following graphs compare development for Winnipeg (Fig. 1) and Lethbridge (Fig. 2).  At Winnipeg, first instar larvae are expected to occur already (Fig. 1) while first instar larvae should begin to appear later this week in southern AB (Fig. 2). 

Figure 1. Predicted alfalfa weevil (Hypera postica) phenology at Winnipeg MB.
Values are based on model simulations (April 1-May 25, 2020).

Figure 2. Predicted alfalfa weevil (Hypera postica) phenology at Lethbridge AB.
Values are based on model simulations (April 1-May 25, 2020).

Based on the alfalfa weevil degree day model (Soroka et al. 2020), AAW development is most advanced across southern SK (Fig. 3). The second map (Fig. 4) presents occurrence of first instar larvae (% of total population). 

Figure 3. Predicted development of populations of alfalfa weevil (Hypera postica) across

the Canadian prairies as of May 25, 2020. 

Figure 4. Predicted percent of alfalfa weevil (Hypera postica) at first instar stage across

the Canadian prairies as of May 25, 2020. 

Monitoring

The larval stage of this weevil feeds on alfalfa leaves in a manner that characterizes the pest as a “skeletonizer” (Fig. 3, lower left).  The green larva featuring a dorsal, white line down the length of its body has a dark brown head capsule and will grow to 9 mm long (Fig. 3, upper right).  

Figure 3.  Developmental stages of the alfalfa weevil (Hypera postica); overwintered adult (upper row L-R), eggs, larvae, larva feeding or "skeletonizing" alfalfa leaf (lower row L-R), pupa within lacey cocoon, pupa, and newly emerged adult.

Alfalfa growers are encouraged to check the Alfalfa Weevil Fact Sheet prepared by Dr. Julie Soroka (AAFC-Saskatoon).  Additional information can be accessed by reviewing the Alfalfa Weevil Page extracted from the "Field crop and forage pests and their natural enemies in western Canada - Identification and management field guide" (Philip et al. 2018). The guide is available as an English-enhanced or French-enhanced version.

Cereal leaf beetle

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 May 25, 2020, CLB simulations indicate that oviposition continues and that first instar larvae are beginning to appear (Table 1).  The graph for Winnipeg illustrates occurrence of 1st instar larvae (Fig. 1).

Table 1. Predictive model output estimates for O. melanopus at selected sites across the Canadian prairies (as of May 25, 2020).

Figure 1. Predicted cereal leaf beetle phenology at Winnipeg MB.
Values are based on model simulations (April 1-May 25, 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. 

Lifecycle and Damage:

Adult: Adult cereal leaf beetles (CLB) have shiny bluish-black wing-covers (Fig. 4). 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 4. 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. 5).  When the larva completes its growth, it drops to the ground and pupates in the soil. 

Figure 5.  Larval stage of Oulema melanopus with characteristic feeding 
damage visible on leaf (Photo: M. Dolinski).

Pupa: Pupal colour varies from a bright yellow when it is first formed, to the colour of the adult just before emergence. The pupal stage lasts 2 - 3 weeks. Adult beetles emerge and feed for a couple of weeks before seeking overwintering sites. There is one generation per year.

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.