Alberta Insect Pest Monitoring
Portions of this article are taken directly from the ‘Alberta Pest Monitoring Network Manual’
The goal of IPM surveys is to develop an early warning system for field crop pests in Alberta that is easy to access, timely and informative. Some of pests surveyed in Alberta are bertha armyworm, diamondback moth, cabbage seedpod weevil, wheat midge, grasshoppers, wheat stem sawfly, cutworms, fusarium headblight, fusarium wilt, clubroot and blackleg. For pests that have a short amount of lead-time, the Prairie Pest Monitoring Network provides a dynamic web-based system that updates the risk information on a daily basis. As the surveying is done and the information entered, the pest risk map changse to reflect that information. Pest forecast maps are available for viewing at AAFRD’s Ropin’ the Web site. Being forewarned means that producers and agronomists can be watching for specific pests so that timely scouting and control operations can be carried out before crop losses occur. The dynamic nature and timeliness of the information available to the agriculture industry would be a valuable addition to enhance decision making for producers, industry agronomists and researchers.
- To participate in a complete pest monitoring program for Alberta
- To ensure the best, most current pest information is extended in a timely, appropriate manner for Northeast Alberta producers
- To participate in a coordinated network of survey gatherers providing up-to-the-minute information for Alberta crop producers, media, industry, and professionals
- Meet international trade demand
Bertha armyworm is one of the most significant insect pest of canola in Canada. It occurs throughout Manitoba, Saskatchewan, Alberta and into the interior of BC. Severe infestation can occur throughout most of this area but are usually limited to the parkland area of the Prairies and the Peace River region of BC and Alberta. Infestation was severe in 2012, especially in the County of St. Paul. A lot of insecticide was applied in an effort to prevent losses, but some fields were still severely damaged by the worms. Infestations also seemed patchy, with fields just west of Highway 41 in the MD of Bonnyville seeing large armyworm numbers, while the fills at LARA only had a very few. Armyworms can overwinter in the soil, so it is likely that the mild winter 2011-2012 contributed in part to the outbreak in 2012.
In most years, populations are kept low by unfavorable weather condition such as cold winters and cool wet weather, and by parasites, predators and diseases. But when these natural regulators fail, population can increase dramatically, creating the potential for widespread damage to a variety of broad leaved crops. In extreme situations, infestations of more than 1000 larva per square metre have been reported while densities of 50 to 200 larvae per square metre may be common.
Infestations may be localized or spread over millions of acres. Widespread crop losses can be minimized with insecticides if the infestation is detected early. However, failure to detect infestations early may result in insufficient time to apply the chemicals before severe damage is done. Also, there may be temporary insecticide shortages if suppliers are not aware of the potential outbreak.
Bertha armyworm surveys were conducted in canola fields using pheromone traps. These traps were set up on the edge of the fields. The bertha armyworm adult is a moth, and the traps are designed to attract them. Moth counts were taken once a week. Moth numbers are correlated to armyworm numbers. The bertha armyworm traps were checked from June-August.
Diamondback moth was introduced into North America from Europe about 150 years ago. It is now found throughout North America, wherever host plants are grown. Diamondback moth larvae feed on all plants in the mustard family (canola, mustard), cole crops (broccoli, cabbage) and on several greenhouse plants. In Western Canada, canola and mustard are primary targets.
Although the diamondback moth occurs each year throughout the Canadian prairies and north central United States, the severity of the infestation varies considerably from year to year. An infestation of diamondback moths cannot be predicted based on the previous years’ population because very few, if any, pupae survive the long, cold Canadian winters. Instead, the severity of the infestation in any given year depends on two factors – overwintering population to the south and strong south winds to transport the moths north into Manitoba, central Saskatchewan and eastern Alberta in the spring.
In years when conditions are right for the moths – that is, when the moths arrive on the wind in large numbers in early May and summer temperatures are hot – diamondback moth infestations can cause millions of dollars of damage.
Diamondback surveys were conducted in canola fields using pheromone traps. These traps were set up on the edge of the fields and checked once a week and counts taken. Diamondback surveys took place from May-July 2012.
The wheat midge (Sitodiplosis mosellana) is found in most areas around the world wherever wheat is grown. In recent years, significant damage to wheat crops has been reported in Alberta, Saskatchewan, Manitoba, and southern British Columbia.
Infestations of wheat midge can reduce crop yields and lower the grade of the harvested grain. Midge may exist at low population levels for several years before they become a significant problem. But if conditions become favourable, populations can reach epidemic proportions quickly. Producers inexperienced with wheat midge infestations often mistake the symptoms of damage and report that frost or drought was responsible for reduced wheat yields or grain quality.
Crop damage occurs during the larval stage. After hatching, the midge larvae feed on the developing wheat kernel, causing it to shrivel, crack and become deformed. As there are no visible, external changes in colour, size or shape of the affected wheat head, the damage to the crop is not readily apparent. Damage can only be detected by inspecting the developing seed within the glumes. Damage to wheat kernels will vary within a single head. A few kernels may be aborted entirely. Others will not fully develop and will be so small and light, they will pass through the combine with the chaff during harvest. Still others may be only slightly damaged. Some kernels may not be affected at all. Careful, regular monitoring of wheat fields between heading and flowering is necessary both to identify a wheat midge infestation and to take the appropriate action.
Research indicates that wheat heads are most susceptible to damage when egg laying occurs during heading. Kernel damage due to wheat midge declines by 15 to 25 fold between later stages of heading and early flowering or anthesis (first yellow anthers appear on wheat head). Therefore, fields should be inspected daily from the time wheat heads emerge from the boot leaf until anthers are visible on the heads.
The orange wheat blossom midge survey was conducted by LARA in fall and 10 soil samples were taken from the Lakeland area. About 10, 1” diameter soil samples, to a depth of 6 inches, were taken from each location and mixed and then sub-sampled. These subsamples were then sent to Brooks where they were tested for the cocoon of the orange wheat blossom midge.
Pest surveys are very important to producers, and the province. With the information that is obtained, proper and accurate forecasting maps can be displayed to inform producers of possible outbreaks. These pest and diseases have a significant impact on crop production. It is important to know proper times of the year when scouting is effective and to know exactly what to look for when out in the fields. Also, crop rotations, varieties, and weather play a great role in determining possible outbreaks. The goal of pest surveys is to help prevent an outbreak from occurring through the collection of this data and to prepare producers so they can manage any possible outbreaks.
Agriculture Research and Extension Council of Alberta
Alberta Agriculture and Rural Development
Lac La Biche County
County of St. Paul
MD of Bonnyville
Smoky Lake County
University of Alberta
Agriculture and Agri-Food Canada
Alberta Innovates Technology Futures
Alberta Research Council
Western Committee on Crop Pests
Stats Branch/Crop Diversification