Exclusion 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 of Bombus impatiens Cresson (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.

中文翻译：

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商业大黄蜂 (Bombus impatiens) 蜂巢在排除网系统下用于果园苹果授粉

排除网系统在各种情况下都有效，并且越来越多地用于控制作物害虫。然而，影响网下授粉管理的因素却鲜为人知。商业大黄蜂蜂箱的授粉效果凤仙花2016 年至 2017 年期间，在位于加拿大魁北克的一个研究果园中，研究了 Cresson（膜翅目：蜜蜂科）在排除网系统下的苹果生产。在开花期间，对 16 棵单行苹果树（地块长度：18.5 m，栽培品种 GingerGold）进行以下四种处理之一：（1）在网下引入放置在行尾的大黄蜂蜂箱；(2) 引入一个大黄蜂蜂巢，放置在行的中间，网下；(3) 没有传粉媒介的负控制，网下和 (4) 附近蜂箱 (<50 m) 的农艺控制，没有网。评估了收获后的果实质量（例如，果实重量、大小、种子数量和分布），并评估了大黄蜂访问率与果实质量参数之间的相关性。结果表明，大黄蜂在排网系统下提供了足够的授粉，并且由此产生的果实质量相当于果园环境中蜜蜂和野生蜜蜂群落（大黄蜂和其他蜜蜂）常规授粉的苹果果实的质量。将大黄蜂蜂箱放置在行的中间可以在授粉树中提供更好的果实负载均匀性。还包括关于大黄蜂作为苹果授粉媒介和花粉分布方法的额外讨论。将大黄蜂蜂箱放置在行的中间可以在授粉树中提供更好的果实负载均匀性。还包括关于大黄蜂作为苹果授粉媒介和花粉分布方法的额外讨论。将大黄蜂蜂箱放置在行的中间可以在授粉树中提供更好的果实负载均匀性。还包括关于大黄蜂作为苹果授粉媒介和花粉分布方法的额外讨论。