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Identifying agronomic practices that conserve and enhance natural enemies Open Access


Other title
Natural Enemies
Root Maggots
Type of item
Degree grantor
University of Alberta
Author or creator
Subramaniam, Ravindran
Supervisor and department
Dosdall, Lloyd (Department of Agricultural, Food and Nutritional Science)
Examining committee member and department
O'Donovan, John (Agri-Food Canada, Lacombe Research Station)
Keddie, Andrew (Department of Biological Science)
Spaner, Dean (Department of Agricultural, Food and Nutritional Science)
Department of Agricultural, Food, and Nutritional Science

Date accepted
Graduation date
Master of Science
Degree level
Yield losses from infestations of root maggots (Delia spp.) (Diptera: Anthomyiidae) can be severe in canola crops in central Alberta. Studies were undertaken in central Alberta, Canada to manipulate agronomic practices that have potential to affect crop yield, root maggot infestations, and the survival and abundance of Aleochara bilineata (Coleoptera: Staphylinidae), which is an important natural enemy of root maggots. I investigated tillage regime (conventional versus zero tillage), row spacing, and seeding rate to assess effects on Delia spp. and A. bilineata populations. In general I observed greater root maggot incidence and damage, and greater activity density of A. bilineata, in plots subjected to a conventional tillage regime than in a zero tillage regime. I found relatively greater parasitism of root maggot puparia by A. bilineata in plots subjected to a zero tillage regime than a conventional tillage regime. No consistent effects were observed on A. bilineata activity in relation to seeding rate and row spacing. In this study, there is no evidence to conclude that tillage regime had a significant effect on canola seed yield. Seed yields in relation to seeding rate and row spacing were variable. In the context of integrated pest management in canola cropping systems, I suggest that canola growers utilize zero tillage in conjunction with adopting the currently recommended seeding rates of between 5.6 to 9.0 kg per ha and row spacing of 30 cm because this can bring advantages in terms of improved management of root maggots and other important canola pests like flea beetles and weeds.
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