Dosdall: Determining Arthropod Biodiversity in Canola Cropping Systems as a Key to Enhancing Sustainability of Production
Date: April 2013
Term: 3 years
Status: Completed
Researcher(s): Lloyd Dosdall, University of Alberta, Edmonton AB, Hector Carcamo, Agriculture and Agri-Food Canada, Lethbridge AB, John Spence, University of Alberta, Edmonton AB, J. Broatch, Alberta Agriculture and Rural Development, Lacombe AB
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
Canola cropping systems harbour a diverse fauna of arthropods (insects, spiders, mites, and their relatives) at several trophic levels, and understanding their biodiversity can improve the ability to enhance the long-term sustainability of canola production. As a result of a three-year project co-led by the University of Alberta and Agriculture and Agri-Food Canada, researchers have produced a database for members of the canola industry of the diversity of species of beetles, anthomyiid flies, hymenopteran parasitoids, true bugs, spiders, and butterflies and moths commonly found in canola. A better understanding of the role of predators in canola cropping systems is needed to better understand the ecosystem function and economic benefits of these species and to guide growers on possible insecticide interventions when insect pest attack occurs.
Canola cropping systems harbour a diverse fauna of arthropods (insects, spiders, mites, and their relatives) at several trophic levels, and understanding their biodiversity can improve the ability to enhance the long-term sustainability of canola production. Although the major species of economically important insect herbivores that occur in canola are reasonably well known, species of lesser economic importance are poorly known, and many species essential to some vital ecosystem processes are virtually unknown. Without foundation knowledge of the full extent of canola arthropod biodiversity and their ecology, it is not possible to determine how various cropping regimes affect their role in ecosystem function.
A three-year project co-led by the University of Alberta and Agriculture and Agri-Food Canada in Lethbridge was conducted to develop a new database of information on arthropod biodiversity in canola cropping systems that can assist other realms of canola integrated crop management. Researchers wanted to determine the species of arthropods in canola cropping systems that have been recorded, as well as those that are known to exist in various regional insect collections but have not been previously documented in canola. They also wanted to identify gaps in the knowledge of taxonomy and biology of insect arthropods in canola, and to determine how arthrodpods respond to variations in vegetational diversity in terms of weed:crop plant densities and variations in rotational strategies in canola cropping systems.
The research project included multiple studies ranging from literature searches to various field studies in southern and central Alberta. In 2011, field sampling studies were conducted at twenty sites in southern Alberta to gain understanding of the parasitoid fauna that attacks lepidopteran (moth and butterfly) pests in canola. From 2010 to 2012, several canola fields in southern Alberta were sampled weekly with sweep nets from early flower to the pod ripening stage to collect and document some of the arthropod species present in those sites. In 2012, the predator complex of canola lepidopteran larvae in southern Alberta was also investigated.
In 2011 and 2012 at Lacombe and Edmonton, a pitfall trap study was established in plots to see how arthropods respond to variations in vegetation diversity. Treatment combinations included crop types and rotation (canola, wheat, barley and pea), herbicide treatments (0%, 50% and 100% herbicide rate), and seeding rates (recommended seed rate, and two times the recommended seeding rate).
As a result of the project, researchers have produced a database for members of the canola industry of the diversity of species of beetles, anthomyiid flies, hymenopteran parasitoids, true bugs, spiders, and butterflies and moths commonly found in canola. The study showed that canola fields vary in the biodiversity of their arthropod faunas, depending on location, crop species, seeding rate, and pesticide applications.
The study showed that a more biodiverse fauna was achieved with some background weed populations. Therefore, sequential herbicide applications to control late-emerging weeds should be avoided so that small weedy backgrounds in canola are maintained. The negative effect of these weeds on crop yield may be minimal, and the study indicates that small weedy backgrounds have the potential to enhance arthropod biodiversity, especially of predatory ground beetles.
The dominant predators in canola cropping systems included ground beetles, rove beetles, and spiders. The study found that high mortality occurred to diamondback moth larvae, primarily from ground beetles and spiders climbing into the canola foliage to attack the larvae. Several ground predators also fed on diamond back moth larvae when they fell to the ground during an experiment that simulated heavy showers.
The insect pest fauna is reasonably well known in canola cropping systems, but significant gaps still exist in understanding the biodiversity of predators, parasitoids, and soil macroinvertebrates. Further studies are recommended to investigate the structure and function of these arthropod communities. A better understanding of the role of predators in canola cropping systems is needed to better understand the ecosystem function and economic benefits of these species and to guide growers on possible insecticide interventions when insect pest attack occurs.
Scientific Publications.
Cárcamo H., J. Pinzón, R. Leech, and J. Spence. 2014. Spiders (Arachnida: Araneae) of the Canadian Prairies. In Arthropods of Canadian Grasslands (Volume 3): Biodiversity and Systematics Part 1. Edited by H. A. Cárcamo and D. J. Giberson. Biological Survey of Canada. Chapter 4, pp. 75-137.
Hummel, J.D., L.M. Dosdall, G.W. Clayton, K.N. Harker, and J.T. O’Donovan. 2012. Ground beetle (Coleoptera: Carabidae) diversity, activity density, and community structure in a diversified agroecosystem. Environmental Entomology 41: 72-80.
Mauduit, L.A. First assessment of predation by the arthropod natural enemy complex on the insect pests of canola-cropping systems in Southern Alberta in Canada: example of the diamondback moth (Plutella xylostella). Thesis of Final year of studies (Master designation in France) Institut Polytechnique LaSalle Beauvais. Co-supervised with Dr. Lloyd Dosdall, University of Alberta and Dr. David Grandgirard of LaSalle Beavais.
Full Report PDF: n/a