Evaluate entomopathogenic nematodes as biological control agents for root weevil management in outdoor ornamental nursery production
Project Code PRR19-020
Anne Marie Fortier, Phytodata
To improve root weevil control in outdoor ornamental nursery production in Canada by evaluating commercially available entomopathogenic nematode products
Insect pests of outdoor ornamentals were identified as a high priority issue through stakeholder consultation and a systematic assessment of pesticide risk reduction potential. Many of these pests are being managed by repetitive applications of chemical insecticides. Many insecticides are registered to control insects and mites on various nursery plants, including organophosphates (for example malathion) and neonicotinoids (for example imidacloprid). Apart from representing a high environmental pesticide load, repeated use of these products increases the probability that the target pests will become resistant. The development and adoption of reduced-risk pest management approaches is therefore required to help to diversify the toolbox available to growers and to reduce the use of insecticides while maintaining effective control of those key pests that are considered a threat to the industry.
Field trials showing the potential of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) against root weevils in ornamental pot and field cultivation have been conducted. However, trials evaluating a range of efficacy measures are needed to increase confidence and adoption of these alternative controls by industry. In this project, applications of entomopathogenic nematodes will be aimed at controlling strawberry root weevil larvae (Otiorhynchus ovatus) and black vine weevil (O. sulcatus) both of which can cause significant damage in ornamental nurseries by attacking the roots and crown of producing plants. These insects have several hosts including spruce (Picea spp.), azaleas and rhododendrons (Rhododendron spp.), lilacs (Syringa spp.), cedars (Thuja spp.), vines (Vitis spp.) and several other perennial plants. Efficacy measures to be evaluated in this project include: pest mortality, damage to the crop, and the survival of the beneficial nematodes. Soil temperature and humidity will also be assessed as environmental factors affecting nematode survival and efficacy. A cost-benefit analysis will be conducted taking into account input and labour costs, crop yield and value to compare the economics of conventional root weevil management practices with the use of beneficial nematodes and determine the feasibility of implementation of these practices on a commercial scale.
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