Approximately one-third of our food globally comes from insect-pollinated crops. The dependence on pollinators has been linked to yield instability, which could potentially become worse in a changing climate. Insect-pollinated crops produced via hybrid breeding (20% of fruit and vegetable production globally) are especially at risk as they are even more reliant on pollinators than open-pollinated plants. We already observe a wide range of fruit and seed yields between different cultivars of the same crop species, and it is unknown how existing variation will be affected in a changing climate. In this study, we examined how three hybrid carrot varieties with differential performance in the field responded to three temperature regimes (cooler than the historical average, average, and warmer that the historical average). We tested how temperature affected the plants' ability to set seed (seed set, pollen viability) as well as attract pollinators (nectar composition, floral volatiles). We found that there were significant intrinsic differences in nectar phenolics, pollen viability, and seed set between the carrot varieties, and that higher temperatures did not exaggerate those differences. However, elevated temperature did negatively affect several characteristics relating to the attraction and reward of pollinators (lower volatile production and higher nectar sugar concentration) across all varieties, which may decrease the attractiveness of this already pollinator-limited crop. Given existing predictions of lower pollinator populations in a warmer climate, reduced attractiveness would add yet another challenge to future food production.

Cultivated cranberry (Vaccinium macrocarpon Aiton) relies on insect pollination for berry production. Honeybees (Apis mellifera L.) have historically provided this service, but their recent decline has underscored the need for additional pollinators. The objective of this study was to determine the richness and abundance of native bees in the cranberry-growing area of southern coastal Oregon and compare foraging behaviors of honeybees and native bees. In a 2-year study, we collected over 27 native bee species in traps set out during and after bloom (mid-May to mid-June). During 67 2-min observations, honeybees (68.1%) and three species of bumble bees (Bombus spp.; 31.6%) comprised 99.7% of foragers. The dominant bumble bee was Bombus vosnesenskii Radoszkowski (56.0%). Multivariate regression of temperature and wind speed data indicated that both were significantly predictive of honeybee and bumble bee foragers (P < 0.001). The interquartile range for foraging was 18.3 to 22.2 °C for bumble bees and 21.1 to 26.7 °C for honeybees. Over 75% of honeybees were seen foraging above the average observed temperature (19.5 °C). Bumble bee pollen loads had a greater dry mass (6.8 ± 12.9 mg) than those of honeybees (2.0 ± 3.6 mg; P < 0.001), and the latter were observed collecting nectar but no pollen more often (during 37.2% of visits) than bumble bees (11.3% of visits). Based on our results, bumble bees in general, and B. vosnesenskii in particular, may be providing significant pollination services for Oregon cranberry farms. However, to maintain current native bumble bee populations, conservation efforts are recommended.

Avocado (Persea americana) flowers are primarily diurnal, however low minimum overnight temperatures can delay in the opening of female-phase flowers such that the flowers open late in the day and remain open overnight. To determine whether moths are important visitors to avocado flowers at night, we trapped moths in the Bay of Plenty, New Zealand, and examined the pollen moths carried. 11.5% of moths carried avocado pollen grains, and 50.4% of all moths were found to carry pollen grains from other plant species. Moth species diversity was highly variable between orchards, but Ichneutica mutans, Ichneutica ustistriga, Epyaxa rosearia, Rhapsa scotosialis, Phrissogonus laticostatus were observed at all sites and Ichneutica steropastis at three sites, with avocado pollen grains found on 10%-33% of these individual species. We suggest that these species may be the most important pollinating moth species because of their abundance, proportion of individuals carrying avocado pollen, and the number of pollen grains per individual. This exploratory study has shown that moths are capable of carrying avocado pollen grains and may be providing a background pollination service to complement that of honey bees (Apis mellifera). To better understand moth contribution to pollination, fruit set needs to be assessed.

Mutualistic plant-pollinator interactions are critical for the functioning of both non-managed and agricultural systems. Mathematical models of plant-pollinator interactions can help understand key determinants in pollination success. However, most previous models have not addressed pollinator behavior and plant biology combined. Information generated from such a model can inform optimal design of crop orchards and effective utilization of managed pollinators like western honey bees ( Apis mellifera ), and help generate hypotheses about the effects of management practices and cultivar selection. We expect that the number of honey bees per flower and male to female flower ratio will influence fruit yield. To test the relative importance of these effects, both singly and simultaneously, we utilized a delay differential equation model combined with Latin hypercube sampling for sensitivity analysis. Empirical data obtained from historical records and collected in kiwifruit ( Actinidia chinensis ) orchards in New Zealand were used to parameterize the model. We found that, at realistic bee densities, the optimal orchard had 65-75% female flowers, and the most benefit was gained from the first 6-8 bees/1000 flowers, with diminishing returns thereafter. While bee density significantly impacted fruit production, plant-based parameters-flower density and male:female flower ratio-were the most influential. The predictive model provides strategies for improving crop management, such as choosing cultivars which have their peak bloom on the same day, increasing the number of flowers with approximately 70% female flowers in the orchard, and placing enough hives to maintain more than 6 bees per 1000 flowers to optimize yield.

Pollination by insects is critical for the production of many crops worldwide. Crop cultivars vary in a number of traits, but their differing pollination requirements are often overlooked. Kiwifruit (Actinidia chinensis) is reliant on pollen movement between male and female plants, but there has been disagreement in the literature about what its pollination requirements are. Additionally, there is little information about how time-of-day might affect fruit and seed set, and how this may alter the efficacy of pollination management strategies. In this study, we compare the pollination requirements of A. chinensis var. deliciosa 'Hayward' (a hexaploid green-fleshed variety) and A. chinensis var. chinensis 'Zesy002' (a tetraploid gold-fleshed variety). We find that 'Zesy002' requires fewer pollen grains than 'Hayward' for full seed set. Kiwifruit appears to be equally able to set fruit at any time of the day, meaning that insects which forage outside the peak hours of 0900-1500 h may play an important supporting role in fruit production, and that artificial pollination could profitably be applied into the evening hours rather than being limited to the period of peak pollinator activity.