Importance of insect pollination to cranberry: A systematic review

Cranberries (Vaccinium macrocarpon) are an economically important crop grown in North America, South America, and Europe. While some studies have shown pollination to increase yield and fruit quality, major questions remain regarding cranberry pollination requirements. We systematically reviewed the literature on cranberry pollination from 1900-2024 to answer: 1) Which insects have been documented as pollinators, flower visitors, or potential pollinators of cranberry? 2) Which metrics are used to study cranberry pollination? 3) What is the consensus on cranberries’ need for insect pollination? and 4) Where should future research into cranberry pollination focus to address existing knowledge gaps? We used Web of Science and Google Scholar to compile articles, removed duplicates, and then screened titles and abstracts for relevance. We assessed 132 full-text articles for eligibility and excluded articles that did not present new data on pollination, visitation, pollinator trapping, or pollen movement, resulting in a final data set of 63 papers. Our literature search revealed that 16 bee species pollinate cranberry, an additional 107 insects visit cranberry flowers (Diptera, Hymenoptera, Lepidoptera), and a further 182 species are potential pollinators of cranberry. Sixteen metrics have been used to study cranberry pollination, with visual observations of flower visitors and quantifying berry weight being the most common. When we compared six fruit set and quality metrics, all improved with insect pollination (on average 42-84%), suggesting that insect-mediated pollination is important to cranberry production. Future research into cranberry pollination should investigate the effects of surrounding landscape and changing weather conditions on pollination.