Worldwide insect pollinators greatly influence fruit production of economically valuable crops and native plants. Insects are essential for pollination of 100 economically valuable crops in the U.S. (Xerces Society 2019). Bee populations are declining worldwide (Klein 2006) potentially impacting both ecology and economics. Huckleberries (Vaccinium sp.) have cultural, economic, and ecological importance with fruits critical for both people (Minore 1972, Richard and Alexander 2006) and wildlife (Tirmenstein 1990) in the Pacific Northwest; including communities of Montana (Richard and Alexander 2006). Native bumblebees are the primary pollinator of huckleberry flowers (Dolan 2016, Lichtenberg unpublished). Because pollinators are shown to be crucial to fruit development (Garibaldi et al 2013), it is important to know how much change is seen when pollinators are excluded from the flowers of food plants. We explore the effects of pollinator exclusion on berry set and sugar content of huckleberries placed in four pollination treatments to examine importance of pollinators on fruit development in Montana.
Evenly spaced Huckleberry plants (n=120) were selected in each of four treatments with stratification along transects. Exclusion netting was used on 50% of the plants to restrict natural pollination prior to flowering. Hand pollination with wands was applied to 60 plants atleast 3 times per week throughout flowering. This resulted in 4 cross-wise treatments; (natural, hand, hand + natural, hand-natural). Exclusion netting was removed from plants after flowering. Plants were tracked throughout berry development. Ripe berries were collected every 2 days until depletion. Berries were counted, weighed, and placed in a freezer for further laboratory analysis of sugar content. Berries prepared for analysis using the solvents MeOH, EtOH, heat, and deionized water. A Brix microplate reader will be used to measure sugar content for comparisons among treatment groups.
Results/Conclusions
Pollination significantly influenced berry counts (P<0.05; 650 berries) compared to Control (545 berries), Human-pollinated only (365 berries), and Restricted pollination (63 berries). This information is important for understanding the importance of bumble bees to huckleberry fruit set. Laboratory results will add to knowledge of the potential influence of pollination for berry sugar content. We are currently conducting experiments to analyze sugar content. We will examine how treatments affect berries when these lab tests are completed.