The grasshopper (Acrididae: Melanoplus sanguinipes) model predicts development using biological parameters known for the pest species and environmental data observed across the Canadian prairies on a daily basis. Review lifecycle and damage information for this pest. Review the historical grasshopper maps based on late-summer adult in-field counts performed across the prairies.
As of May 8, 2022, the model simulation indicates that egg development is most advanced in southern Alberta (Fig. 1). Cool conditions in Manitoba have resulted in slower development rates. Egg development is expected to range from 50 and 65 % across most of the prairies (average = 59 %). Based on climate normals data, long-term average development should be 57 % (Fig. 2).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 8, 2022.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 8 based on long-term average (climate normals) data.
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development and oviposition as of August 15, 2021. Above-average temperatures during June, July, and early August continue to result in a noticeable increase in the rates of oviposition.
Grasshoppers generally begin to lay eggs in early August. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July. Earlier oviposition can result in above-average production of eggs and increased overwintering survival of eggs. This may result in potential increased grasshopper risk for the 2022 growing season. Model runs for the 2021 growing season (April 1 – August 15) indicated that oviposition should now be occurring across most of the prairies and is predicted to be greatest in southeastern Alberta (Fig. 1).
Figure 1. Grasshopper (Melanoplus sanguinipes) oviposition index across the Canadian prairies as of August 8, 2021. Higher values indicate greater potential for oviposition.
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of August 8, 2021. Compared to average growing season temperatures, above-average temperatures during June, July, and early August continue to result in a noticeable increase in the rate of grasshopper development.
Oviposition generally begins in early August. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July. Earlier oviposition can result in above-average production of eggs resulting in potential risk for the following growing season. Climate data suggests that, as of August 8, oviposition would be expected to occur across most of the southern prairies (Fig. 1). Model runs for the 2021 growing season (April 1 – August 8) predicted that oviposition should now be occurring across most of the prairies (Fig. 2).
Figure 1. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 8 (based on climate normals data).Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 8, 2021.
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of August 1, 2021. Compared to average growing season temperatures, above-average temperatures during June and July continue to result in a noticeable increase in the rate of grasshopper development. Based on climate-normals, grasshopper populations near Saskatoon should have been in the fifth instar and adult stages on July 31 (Fig. 1).
Figure 1. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021, based on climate normals data).
Oviposition generally begins in early August. This year, the average July temperature at Saskatoon was 2.8 °C warmer than normal, resulting in advanced development of grasshopper populations. Based on a survey conducted across central, southern, and western regions of Saskatchewan, adults were observed during the first week of July. Model simulations for 2021 predicted that oviposition was expected to begin in mid-July (Fig. 2).
Figure 2. Predicted development of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan, as of August 1, 2021.
The onset of oviposition earlier in a growing season can result in above-average production of eggs leading to higher risk of grasshopper issues the following growing season (e.g., 2022). Climate data suggests that, as of August 1, oviposition would be expected to occur in localized areas across the prairies (Fig. 3). Model runs for the 2021 growing season (April 1 – August 1) predicted, as a result of above-normal temperatures, that oviposition should now be occurring across most of the prairies (Fig. 4)
Figure 3. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021 (based on climate normals data).Figure 4. Percent of grasshopper (Melanoplus sanguinipes) population in the egg stage across the Canadian prairies as of August 1, 2021.
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 11, 2021. Above-average temperatures in late June and early July have resulted in a noticeable increase in grasshopper development. Grasshopper development should be greatest across southern Manitoba where the majority of the population will be in the adult stage (Fig. 1). Adults should be present across all three provinces; more than 13.5 % of the population should be adults.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development across the Canadian prairies as of July 11, 2021.Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the adult stage across the Canadian prairies as of July 11, 2021.
The long-term average value for this week of the growing season is less than 1% of the population in the adult stage. Development, as of July 11, 2021, is well ahead of long-term average values (Fig. 3).
Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 11, based on climate normals data.
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of nymphs, adults, and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of July 4, 2021. Recent warm conditions have resulted in a noticeable increase in grasshopper development since last week. Grasshopper development, based on average instar, should be greatest across southern Manitoba and southeastern Saskatchewan (Fig. 1).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 4, 2021.
Across the prairies, more than 15 % of the population should be in the fifth instar (Fig. 2). Development, as of July 4, 2021, is well ahead of long-term average values (Fig. 3).
Figure 2. Percent of grasshopper (Melanoplus sanguinipes) population in the 5th instar across the Canadian prairies as of July 4, 2021.Figure 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of July 4, based on climate normals data.
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 27, 2021. The development of grasshopper nymphs, based on average instar, should be most advanced across southern Manitoba and southeastern Saskatchewan (Figure 1). Grasshopper populations south of Winnipeg are predicted to be mostly in the 4th and 5th instar stages. Across the prairies, nymph development, as of June 27, 2021 is well ahead of long term average values (Figure 2).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, 2021.Figure 2. Long term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 27, based on climate normals data.
The model was projected to July 13 to determine potential development at Saskatoon and Grande Prairie over the next two weeks. Results suggest that by July 13, Saskatoon populations will primarily be in the fourth and fifth instars with first appearance of adults (Figure 3). Development near Grande Prairie is predicted to be slower, with populations being mostly in the third and fourth instars (Figure 4). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.
Figure 3. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan as of June 27, 2021 (projected to July 13, 2021).Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Grande Prairie, Alberta as of June 27, 2021 (projected to July 13, 2021).
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 20, 2021. As of June 20, hatch is predicted to be underway across most of the prairies with a prairie average of 69 % (versus 45 % last week). Percent hatch was greater than 90 % across most of Manitoba, Saskatchewan, and southern Alberta. Development in the central and Peace River regions of Alberta has been significantly slower than the rest of the prairies (Fig. 1).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 20, 2021.
Development of grasshopper nymphs, based on average instar, should be greatest across southern Manitoba and southern Saskatchewan (Fig. 2). Grasshopper populations south of Winnipeg are predicted to be mostly in the 3rd and 4th instar stages. Across the prairies, nymph development, as of June 20, 2021, is well ahead of long-term average values across most of the prairies (Fig. 3).
Figure 2 Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 20, 2021.Figure 3. Long term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 20, based on climate normals data.
The model was projected to July 6 to determine potential development at Winnipeg and Lethbridge over the next two weeks. Results suggest that by July 6, Winnipeg populations will primarily be in the fourth and fifth instars with the first appearance of adults (Fig. 4). Development near Lethbridge is predicted to be slower, with populations being mostly in the third and fourth instars (Fig. 5). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.
Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Winnipeg, Manitoba as of June 20, 2021 (projected to July 6, 2021).Figure 5. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Lethbridge, Alberta as of June 20, 2021 (projected to July 6, 2021).
Grasshopper Scouting Steps: ● Review grasshopper diversity and scouting information including photos of both nymphs, adults and non-grasshopper species to aid in-field scouting and accurately apply thresholds for grasshoppers. ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss. ● More practically, the following thresholds are offered but, in the event of additional crop stress (e.g., drought), the use of “may be required” versus “control usually required” requires careful consideration:
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 13, 2021. Average development of eggs is 90 % and well ahead of the long-term average of 80 %. As of June 13, the hatch is predicted to be underway across most of the prairies with a prairie average of 45 % (versus 26 % last week). Hatch rates were greater than 75 % across southern Manitoba, Saskatchewan and Alberta. Development in central and Peace River regions of Alberta has been significantly slower than the rest of the prairies (Fig. 1).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 13, 2021.
Development of grasshopper nymphs, based on average instar, is greatest across Manitoba (Fig. 2). Above normal temperatures have resulted in the rapid development of grasshopper populations across Manitoba and Saskatchewan. Grasshopper populations south of Winnipeg are predicted to be mostly in the 3rd and 4th instar stages. Nymph development, as of June 13, 2021, is greater than long-term average values across most of the prairies (Fig. 3).
Figure 2 Predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 13, 2021.Fig. 3. Long-term average predicted grasshopper (Melanoplus sanguinipes) development, presented as the average instar, across the Canadian prairies as of June 15 based on climate normals data.
The model was projected to June 29 to determine potential development at Saskatoon and Winnipeg over the next two weeks. Results suggest that by June 29, Saskatoon populations will primarily be in the third and fourth instar with first appearance of fifth instar nymphs (Fig. 4) whereas near Winnipeg development is predicted to be faster, with populations being mostly in the fourth and fifth instars (Fig. 5). Producers are advised to monitor roadsides and field margins to assess the development and densities of local grasshopper populations.
Figure 4. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Saskatoon, Saskatchewan as of June 13, 2021 (projected to June 29, 2021).Figure 5. Predicted development, presented as the average instar, of Melanoplus sanguinipes populations near Winnipeg, Manitoba as of June 13, 2021 (projected to June 29, 2021).
Grasshopper Scouting Steps: ● Measure off a distance of 50 m on the level road surface and mark both starting and finishing points using markers or specific posts on the field margin. ● Start at one end in either the field or the roadside and walk toward the other end of the 50 m, making some disturbance with your feet to encourage any grasshoppers to jump. ● Grasshoppers that jump/fly through the field of view within a one-meter width in front of the observer are counted. ● A meter stick can be carried as a visual tool to give perspective for a one-meter width. However, after a few stops, one can often visualize the necessary width and a meter stick may not be required. Also, a hand-held counter can be useful in counting while the observer counts off the required distance. ● At the endpoint, the total number of grasshoppers is divided by 50 to give an average per meter. For 100 m, repeat this procedure. ● Compare counts to the following damage levels associated with pest species of grasshoppers: 0-2 per m² – None to very light damage 2-4 per m² – Very light damage 4-8 per m² – Light damage 8-12 per m² – Action threshold in cereals and canola 12-24 per m² – Severe damage 24 per m² – Very severe damage For lentils at flowering and pod stages, >2 per m² will cause yield loss. For flax at boll stages, >2 per m² will cause yield loss.
Model simulations were used to estimate grasshopper (Melanoplus sanguinipes) development as of June 6, 2021. Average development of eggs is 86 % and is well ahead of the long term average of 73 %. Last week’s warm conditions across southeastern SK and southern Manitoba have been responsible for advanced development of eggs near Regina, Saskatoon, Brandon, and Winnipeg. Egg development is predicted to exceed 90 % across most of the southern prairies (Fig. 1).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development (%) across the Canadian prairies as of June 6, 2021.
As of June 6, hatch was predicted to be occurring across most of the prairies (overall average was 26 %) with hatch rates approaching 30-45 % across southern Manitoba and Saskatchewan (Fig. 2). The model was projected to June 22 to determine potential development at Regina and Swift Current over the next two weeks (Figs. 3 and 4). Results suggest that by June 22, Regina populations will primarily be in the third instar, with first appearance of fourth instars. Development near Swift Current is predicted to be slower, with populations being mostly in the first and second instars.
Warm, dry conditions continue to persist across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as hatch progresses in June. Producers are advised to monitor roadsides and field margins to assess development and densities of local grasshopper populations.
Figure 2. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of June 6, 2021.Figure 3. Predicted development of Melanoplus sanguinipes populations near Regina, Saskatchewan as of June 6, 2021 (projected to June 22, 2021).Figure 4. Predicted development of Melanoplus sanguinipes populations near Swift Current, Saskatchewan as of June 6, 2021 (projected to June 22, 2021).
The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Model simulations were used to estimate grasshopper egg development as of May 30, 2021. Average development of eggs is 78 % and is well ahead of the long-term average of 67 %. Warm conditions across southeastern Saskatchewan and southern Manitoba (May 1-30) have been responsible for the advanced development of eggs near Regina, Saskatoon, Brandon and Winnipeg (Fig. 1). Egg development is predicted to exceed 80 % across most of the southern prairies (Fig. 2).
Figure 1. Predicted percent embryonic development of grasshopper eggs across the Canadian prairies as of May 30, 2021.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development (%) across the Canadian prairies as of May 30, 2021.
First hatchlings usually are observed once eggs reach 80 % development. As of May 30, hatch was predicted to be occurring across most of the prairies with hatch rates approaching 15-20 % across southern Manitoba and Saskatchewan (Fig. 3).
Figure 3. Predicted grasshopper (Melanoplus sanguinipes) hatch (%) across the Canadian prairies as of May 30, 2021.
The model was projected to June 15 to determine potential development at Saskatoon and Brandon over the next two weeks (Figs. 4 and 5). Results suggest that by June 15 hatch could be greater than 65 % at both locations and nymph populations will consist of first, second, and third instars. Drought conditions tend to favour the development of grasshopper populations while delaying crop development. If dry conditions persist, crop development may be delayed across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as hatch progresses in June. Monitor roadsides and field margins to assess the development and densities of local grasshopper populations.
Figure 4. Predicted development of M. sanguinipes populations near Saskatoon, Saskatchewan as of May 30, 2021 (projected to June 15, 2021).Figure 5. Predicted development of M. sanguinipes populations near Brandon, Manitoba as of May 30, 2021 (projected to June 15, 2021).
The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Model simulations were used to estimate grasshopper egg development as of May 23, 2021. Average development of eggs is 73 % and is well ahead of the long-term average of 62 %. Since last week, developmental rates increased at all locations. Recent warm conditions across southeastern Saskatchewan and southern Manitoba have been responsible for the advanced development of eggs near Regina, Brandon and Winnipeg (Fig. 1). The simulation predicted that development was greatest across most of the southern prairies (Fig. 2).
Figure 1. Predicted percent embryonic development of grasshopper eggs (Melanoplus sanguinipes) across the Canadian prairies as of May 23, 2021.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 23, 2021.
The model was projected to June 7 to determine potential development at Winnipeg and Lethbridge over the next two weeks (Figs. 3 and 4). Results suggest that by June 7 hatch could be at 20 % for Lethbridge and approximately 35 % near Winnipeg. Drought conditions tend to favour development of grasshopper populations while delaying crop development. If dry conditions persist, crop development may be delayed across Manitoba. This may result in conditions conducive to crop damage from grasshoppers as the hatch progresses in late May and early June.
Figure 3. Projected predicted development of M. sanguinipes populations near Winnipeg, Manitoba as of May 23, 2021 (projected to June 7, 2021).Figure 4. Projected predicted development of M. sanguinipes populations near Lethbridge, Alberta as of May 23, 2021 (projected to June 7, 2021).
The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Model simulations were used to estimate percent grasshopper egg development as of May 16, 2021. Average development of eggs is 68 % and is well ahead of the long term average of 59 %. Since last week, developmental rates have increased at all locations (Fig. 1). The simulation predicts that development is greatest in the region that includes Regina, Saskatoon and Lethbridge (Fig. 2).
Figure 1. Predicted percent embryonic development of grasshopper eggs across the Canadian prairies as of May 16, 2021.Figure 2. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 16, 2021.
Recent warm temperatures near Winnipeg have resulted in faster development rates. The model was projected to May 31 to determine potential development at Saskatoon and Regina (Figs. 3 and 4). Results suggest that initial hatch may occur in the next few days with increased hatch occurring in late May. Current drought conditions tend to favour development of grasshopper populations while delaying crop development. Crop development may be delayed across southern and central regions of Saskatchewan. This may result in conditions conducive for crop damage from grasshoppers as hatch progresses in late May and early June.
Figure 3. Projected predicted development of M. sanguinipes populations near Regina SK as of May 16, 2021 (projected to May 31, 2021).Figure 4. Projected predicted development of M. sanguinipes populations near Saskatoon SK as of May 16, 2021 (projected to May 31, 2021).
The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Model simulations were used to estimate percent grasshopper embryonic (egg) development as of May 9, 2021. The simulation predicts that development has now begun across southern areas of the Peace River region. Results indicate that egg development has been greatest for Lethbridge and Regina regions. Cool conditions in Manitoba have resulted in slower development rates (Figs. 1 and 2).
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 9, 2021. Figure 2. Predicted percent embryonic development of overwintered grasshopper eggs across the Canadian prairies as of May 9, 2021.
Grasshopper Simulation Model Output – The grasshopper simulation model will be used to monitor grasshopper development across the prairies. Weekly temperature data collected across the prairies is incorporated into the simulation model which calculates estimates of grasshopper development stages based on biological parameters for Melanoplus sanguinipes (Migratory grasshopper).
Model simulations were used to estimate percent grasshopper embryonic development as of May 2, 2021. Results indicate that egg development has begun across the southern prairies (Fig. 1) and progression estimates for sites across the prairies are presented in Figure 2.
Figure 1. Predicted grasshopper (Melanoplus sanguinipes) embryological development across the Canadian prairies as of May 2, 2021. Figure 2. Predicted percent embryonic development of overwintered grasshopper eggs across the Canadian prairies as of May 2, 2021.
As of July 12, 2020, the grasshopper model estimates that development across the prairies ranges from 1st instar stage to adults. Based on the model simulations, development has been slowest in the Peace River region where average nymph development ranges between the 2nd and 3rd instars (Fig. 1; Table 1). Across the southern prairies, the majority of the nymph population is predicted to be in the 3rd to 5th instar stages, with adults predicted to occur across southern Manitoba where populations are active (Fig. 1; Table 1). Across the prairies, populations are predicted to be 6, 6, 11, 27, 24, 21 and 5% in egg, first, second, third, fourth, fifth and adult stages, respectively.
Figure 1. Predicted average instar stages of grasshopper (Melanoplus sanguinipes) populations across the Canadian prairies (as of July 12, 2020).
Table 1 indicates that predicted development at Brandon and Winnipeg is well ahead of Lacombe and Grande Prairie. The two graphs compare grasshopper development in Saskatoon (Fig. 2) and Winnipeg (Fig. 3). Grasshopper populations near Saskatoon are predominantly in the 4th and 5th instars with first appearance of adults beginning to occur (Fig. 2). Populations near Winnipeg are expected to be primarily adults (Fig. 3).
Figure 2. Predicted grasshopper (Melanoplus sanguinipes) phenology at Saskatoon SK. Values are based on model simulations (April 1-July 12, 2020).Figure 3. Predicted grasshopper (Melanoplus sanguinipes) phenology at Winnipeg MB. Values are based on model simulations (April 1-July 12, 2020).
