Abstract
AbstractExclusion netting systems are effective in various contexts and are increasingly used to control crop pests. However, factors affecting pollination management under nets are poorly known. The pollination effectiveness of commercial bumble bee hives ofBombus impatiensCresson (Hymenoptera: Apidae) was studied for apple production under exclusion netting systems in a research orchard located in Quebec, Canada during 2016–2017. Sixteen single-row plots of apple trees (plot length: 18.5 m, cultivar GingerGold) were subjected to one of the following four treatments during bloom: (1) introduction of a bumble bee hive placed at the end of the row, under nets; (2) introduction of a bumble bee hive placed in the middle of the row, under nets; (3) negative control with no pollinators, under nets and (4) agronomic control with nearby bee hives (<50 m), without nets. Resulting post-harvest fruit quality (e.g., fruit weight, size, number and distribution of seeds) was evaluated, as well as correlations between bumble bee visitation rates and fruit quality parameters were evaluated. Results suggest that bumble bees provided adequate pollination under exclusion netting systems and that resulting fruit quality was equivalent to that of apple fruit conventionally pollinated by honey bees and wild bees community (bumble bees and other bees) in the orchard environment. Positioning bumble bee hives in the middle of the row provided better fruit load homogeneity in pollinated trees. Additional discussion on bumble bees as apple pollinators and on pollen distribution methods is also included.
Highlights
Apple is among the most important fruits grown in northeastern North America, yet apple growing can be arduous due to the diversity and abundance of pests and diseases that can attack the trees and the fruit (Vincent and Roy, 1992; Vincent and Bostanian, 1998)
We found that bumble bees provided sufficient pollination services which allows adequate yield and fruit quality and that it was equivalent to conventional pollination provided by honey bees and wild bees community
Our study demonstrated that bumble bees are effective pollinators for apple production under exclusion netting systems
Summary
Apple is among the most important fruits grown in northeastern North America, yet apple growing can be arduous due to the diversity and abundance of pests and diseases that can attack the trees and the fruit (Vincent and Roy, 1992; Vincent and Bostanian, 1998). In a typical commercial orchard in Quebec, for example, over 14 pesticide applications are needed during the growing season to limit production losses (Morin and Chouinard, 2001). Exclusion systems have been developed and used to prevent pest damage and reduce economic losses in many organic crops (Granatstein et al, 2016). In Quebec apple orchards, exclusion netting systems are generally installed in a row-by-row design and are closed above the base of the trunks with clips (Chouinard et al, 2016, 2017). Nets are installed before bud break to protect trees against early season pests [e.g., tarnished plant bug (Lygus lineolaris)]. While these nets exclude pests, they prevent pollinators from reaching the flowers
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