Do local environmental variables differently influence the visitation of effective and ineffective pollinators to highbush blueberry flowers?

Abstract

Floral visitors adapt their foraging behavior through time and space, focusing their efforts to maximize floral resource collection. They are therefore vulnerable to variations in local environmental conditions. However, most studies focusing on understanding insect sensitivity to environmental variables are based on taxonomic identity rather than their role as pollinators. Consequently, frequent visits by neutral and antagonistic species can obscure the interactions between plants and effective pollinators unless their contributions to pollination are distinguished. Here, we investigated whether local environmental variables differentially influence the daily visitation frequency of effective pollinators compared to ineffective pollinators of cultivated highbush blueberry in southern Chile. Flower visitation was recorded alongside temperature, light intensity, and wind speed. Effective pollinators were defined as those that deposited more conspecific pollen on stigmas per visit than unvisited flowers, as opposed to ineffective pollinators. Our findings demonstrate that the dominant floral visitors in Chilean highbush blueberry crops are not necessarily the most effective pollinators. Although honeybees accounted for most floral visits, their pollination effectiveness was comparatively low. While light intensity positively influenced the frequency of all visitors (effective and ineffective pollinators) to blueberry flowers, wind speed had a negative effect. Although exotic managed bees may mask the visitation patterns of native insects, our results showed that they respond similarly to environmental variables. This suggests that, despite significant differences in pollination outcomes for the blueberry crops, all functional groups exhibit similar environmental sensitivity. Blueberry flower reward may interact with environmental variables to influence flower visitation patterns.