Co-ordinated monitoring, forecasting and risk warning for insect pests of field crops in Canada

Project Summary

Summary

This 3-year project led by Dr. Olfert was established to keep the agriculture industry informed of the risks to crop production from insect pests. When insect pest outbreaks occur in one area their impact is eventually felt across the entire canola growing region. A regional pest monitoring program is vital to keeping the agriculture industry informed of the risks to crop production from insect pests. Timely and accurate forecasts and risk warnings are a priority for decision-making and for implementation of commodity-specific risk reduction strategies. 

Overall insect pest populations have begun to increase above economic levels for parts of the Prairies in 2006. Two canola pests, bertha armyworm and cabbage seedpod weevil, required some chemical intervention to protect crops in select locations. Population levels of these two pests were greater in several restricted areas than in 2005. Pests of concern to cereal grain growers in 2006 were wheat stem sawfly and wheat midge. Monitoring of pea leaf weevil (Sitona lineatus) indicated that the pest has significantly expanded its range level of damage; damaging field peas and faba beans in Alberta. It was first recorded damaging peas in 2000 and, by 2006, approximately 10,000 acres were sprayed for pea leaf weevil in Alberta. Climate matching models, developed for canola pollen beetle, cabbage seedpod weevil and cereal leaf beetle were utilized to assess the potential impact of these invasive species under climate change. The results indicated that risks associated with these species will likely become more intense, both in terms of severity and in their ability to become established in areas where they do not yet occur.

Objectives

This project aims to develop a co-ordinated pest monitoring program designed to keeping the canola industry informed of the risks to crop production from insect pests. The specific objectives are to:

a) monitor existing/emerging pest populations (including, but not restricted to, bertha armyworm, diamondback moth, wheat midge, cabbage seedpod weevil).

b) forecast pest damage potential, and quantify the potential of new invasive species to establish in Canada.

c) produce timely risk warnings.

Results

Monitoring Work Plan 2006

a) Bertha armyworm.  Collaborators monitored approximately 300 canola fields in AB, SK and MB by installing pheromone traps in mid-June to determine the time, distribution and density of moth flight.  The network of traps indicated that the bertha armyworm populations increased across much of the Prairies in 2006. There were an increased number of pockets of high moth counts, especially in Saskatchewan and Alberta, and less so in Manitoba.  It is anticipated that crops (canola, flax) in these areas will be more at risk in 2007 than elsewhere in the Prairies because bertha armyworm does over-winter in the soil.

b) Diamondback moth.  Approximately 50 sentinel sites were established across the Prairies by installing pheromone traps in canola fields to determine the time, distribution and density of moth migrations from the USA.  Wind trajectory model output, purchased from Environment Canada was analysed on a daily basis beginning in May to assist in predicting moth migrations from southern USA and Mexico.  The complaints in 2005 about ineffective pheromone lures resulted in a research project at the U. of Alberta in 2006 to re-examine the chemical makeup of the pheromone in relation to current moth populations.

c) Cabbage Seedpod Weevil.  Due in part to the improvement of moisture conditions, cabbage seedpod weevil population density has again increased in 2006. In Saskatchewan, higher numbers of weevils were recorded in sweep samples in the southwest, extending from the Alberta border to Maple Creek and to south of Moose Jaw, and as far north as Kindersley. Producers in these areas were made aware that both types of canola (Polish and Argentine) are susceptible to weevil damage. Brown mustard (Brassica juncea) is also at risk. Crops of white mustard (Sinapis alba, or mustard with hairy pods) and non-cruciferous crops (wheat, barley, corn, potatoes, sugar beet) are resistant to cabbage seedpod weevil.

d) Wheat midge.  Approximately, 190 wheat fields were sampled in fall in SK to determine the distribution, density and rates of parasitism of midge cocoons in the soil.  The trend in increase of wheat midge densities over the past two years has continued. This increased distribution of wheat midge is based on cocoons present in soil samples collected in a 2006 fall survey. Although a number of factors influence over-wintering survival of the midge, the survey and map provide a general picture of existing densities and the potential for infestation in 2007. Climatic conditions – mainly temperature and moisture – will ultimately determine the extent and timing of midge emergence during the growing season. The survey indicated that midge population levels have further increased over last year in the eastern half of SK. The most severe infestations are predicted to occur in a diagonal line southeast of Regina and extending west to the Alberta border, south of Lloydminster. As a result, monitoring susceptible wheat fields will be important during 2007.

e)  Grasshoppers.  The impact of grasshopper infestations was again relatively low throughout much of the crop land across the Prairies. However, there were several isolated locations in Alberta and Manitoba, where warm temperatures and light soil contributed to an increase in grasshopper populations. For the most part, the Prairies experienced cooler spring temperatures that resulted in a slow start of the grasshopper hatch and the cool, wet growing conditions in June and July further retarded their development and feeding activity. In 2007, the highest levels of grasshopper infestations are expected to occur in isolated regions of Alberta and Manitoba.

f)  Wheat stem sawfly.  A survey of wheat fields conducted in AB in 2006 indicated that the pest continues to be distributed throughout much of the wheat-growing area of Alberta in fairly high numbers. Producers were encouraged to grow resistant cultivars and/or crops in the heavily-infested areas.  If wheat is in the current rotation, solid stem wheat varieties (AC Eatonia, AC Abbey) was recommended as they are significantly more resistant to sawfly than hollow-stem cultivars. All broadleaf crops such as canola, flax and alfalfa are resistant to wheat stem sawfly.

g)  Pea leaf weevil. Pea leaf weevil is European in origin and is a pest of field peas and faba beans.  It is common in these pulse crops in northwestern USA and was first recorded in Alberta in 2000. Subsequent surveys revealed considerable range expansion and increased damage and by 2006, approximately 10,000 acres were sprayed to control this pest.  A major project has been initiated (Lead – Dr. H. Carcamo). The project objective is to enable pea growers to implement an integrated pest management plan for pea leaf weevil. A wide range of basic and applied studies will be conducted to ensure that all the necessary elements of IPM are covered; seasonal biology and habitat use which are key elements to support any pest management action.  Spatial distribution studies at the field and geographic scale will establish the rate of the pest spread and provide data to model its future range expansion.  Insect-plant-soil fertility interaction studies will establish the plant damage and economic thresholds and we will develop both chemical and cultural control methods.

h)  Additional Pest Species. One suction trap was operated throughout the summer and fall of 2006 near Consul, SK, to monitor Russian wheat aphid. High numbers of aphids were collected in early fall, 2006, resulting in fairly extensive field infestations. However, spring surveys determine that populations were unable to overwinter successfully in large numbers. Cereal leaf beetle, discovered in several counties near Lethbridge in 2005, will again be the target of surveys in 2007 throughout southern AB and SK to determine the extent of the new infestation.

Risk Warnings Work Plan – 2006

All data relating to insect populations were compiled on a weekly basis during the growing season. The annual insect population data were directly incorporated into the insect population trend data base for analysis of factors influencing population increase and decrease. Spatial analysis systems were developed to accurately summarize the distribution and density of the pest populations.  Technology transfer was in map format (prairie-wide, provincial and regional) accompanied with interpretive text.

Near real-time weather was obtained from Environment Canada on a weekly basis and degree-days for bertha armyworm, wheat midge and grasshoppers were accumulated daily.  Spatial analysis systems were then used to transform weather data to a spatial format compatible with modeling insect population dynamics.

Mathematical models for pest population establishment and growth were designed, validated and implemented on the basis of the near real-time weather data to develop risk warnings related to crop damage potential.  The risk warnings were released at intervals appropriate to the pest – crop situation.

Field sampling was conducted at sentinel sites to validate forecasts.  Pest and crop data, collected at approximately weekly intervals during June and July, were used to enhance the accuracy of risk warnings.

Weather data on wind movement was again evaluated in relation to diamondback moth originating from crucifer-growing areas in the southern US and Mexico and migrating to canola growing regions of Canada.  Backward trajectory data will be generated from areas and dates where immigration occurs, and the trap and back trajectory data will be used to substantiate the accuracy of the forecast maps.  New in 2006, the potential for plant disease transmission (via leafhoppers, aphids) and pollen distribution from regions in central and north western USA were also investigated. Climate-matching models, developed for grasshoppers, pollen beetle, cabbage seedpod weevil and cereal leaf beetle were utilized to assess the potential impact of these invasive species under climate change.  The results indicated that risks associated with these species will likely become more intense, both in terms of severity and in their ability to become established in areas where they do not yet occur. Also, a bioclimatic model for swede midge (currently present in eastern Canada) was developed to assess the risk of successful establishment in the Prairie ecoregion and assess the potential for successful establishment of biocontrol agents.

Related Publications

• Olfert, O. & R.M. Weiss.  2006.  Impact of climate change on potential distributions and relative abundances of Oulema melanopus, Meligethes viridescens and Ceutorhynchus obstrictus in Canada.  Agriculture, Ecosystems and Environment: 113: 295-301.
• Kuhlmann, U.,  P.G. Mason, H.L. Hinz, B. Blossey, R.A. De Clerck-Floate, L.M. Dosdall, J.P.
• McCaffrey, M. Schwarzlaender, O. Olfert, J. Brodeur, A. Gassmann, A.S. McClay & R. N. Wiedenmann.  2006.  Avoiding conflicts between insect and weed biological control: selection of non-target species to assess host specificity of cabbage seedpod weevil parasitoids.  Journal of Applied Entomology: 130: 129-141.
• Olfert, O.& R. M. Weiss.  2006.  Bio-climatic model of Melanoplus sanguinipes (Fabricius) (Orthoptera: Acrididae) populations in Canada and the potential impacts of climate change.  Journal of Orthoptera Research 15: 65-77.
• Olfert O, Hallett R. Weiss RM, Soroka J, & Goodfellow S.  2006.  Potential Distribution and Relative Abundance of Swede Midge Contarinia nasturtii (Diptera: Cecidomyiidae), an Invasive Pest in Canada. Entomologia experimentalis et applicata 120: 221-228.
• Carcamo, H., L. Dunn, L. Dosdall & O. Olfert. 2006.  Managing cabbage seedpod weevil in canola using a trap crop – a farm-scale study in western Canada.  The Canadian Entomologist: (in press)
• Olfert, O., D. Giffen & S. Hartley.  2006.  Analysis of grasshopper (Orthoptera: Acrididae) populations in Saskatchewan: 1972-2004.  The Canadian Entomologist 138: 875-887.