Continued loss of natural habitats with native prairies and wildflower patches is eliminating diverse sources of pollen, nectar and phytochemicals therein for foraging bees. The longstanding plant-pollinator mutualism reiterates the role of phytochemicals in sustaining plant-pollinator relationship and promoting honey bee health. We studied the effects of four phytochemicals—caffeine, gallic acid, kaempferol and p-coumaric acid, on survival and pathogen tolerance in the European honey bee, Apis mellifera (L.). We recorded longevity of worker bees that were provided ad libitum access to sugar solution supplemented with different concentrations of phytochemicals. We artificially infected worker bees with the protozoan parasite, Nosema ceranae. Infected bees were provided access to the same concentrations of the phytochemicals in the sugar solution, and their longevity and spore load at mortality were determined. Bees supplemented with dietary phytochemicals survived longer and lower concentrations were generally more beneficial. Dietary phytochemicals enabled bees to combat infection as seen by reduced spore-load at mortality. Many of the phytochemicals are plant defense compounds that pollinators have evolved to tolerate and derive benefits from. Our findings support the chemical bases of co-evolutionary interactions and reiterate the importance of diversity in floral nutrition sources to sustain healthy honey bee populations by strengthening the natural mutualistic relationships.

A plant investing in reproduction partitions resources between flowering and seed production. Under resource limitation, altered allocations may result in floral trait variations, leading to compromised fecundity. Floral longevity and timing of selfing are often the traits most likely to be affected. The duration of corolla retention determines whether fecundity results from outcrossing or by delayed selfing-mediated reproductive assurance. In this study, the role of pollination schedules and soil water availability on floral longevity and seed production is tested in Collinsia heterophylla (Plantaginaceae). Using three different watering regimes and pollination schedules, effects on floral longevity and seed production were studied in this protandrous, flowering annual. The results reveal that soil water status and pollination together influence floral longevity with low soil water and hand-pollinations early in the floral lifespan reducing longevity. However, early pollinations under excess water did not extend longevity, implying that resource surplus does not lengthen the outcrossing period. The results also indicate that pollen receipt, a reliable cue for fecundity, accelerates flower drop. Early corolla abscission under drought stress could potentially exacerbate sexual conflict in this protandrous, hermaphroditic species by ensuring self-pollen paternity and enabling male control of floral longevity. While pollination schedules did not affect fecundity, water stress reduced per-capita seed numbers. Unmanipulated flowers underwent delayed autonomous selfing, producing very few seeds, suggesting that inbreeding depression may limit benefits of selfing. In plants where herkogamy and dichogamy facilitate outcrossing, floral longevity determines reproductive success and mating system. Reduction in longevity under drought suggests a strong environmental effect that could potentially alter the preferred breeding mode in this mixed-mated species. Extrapolating the findings to unpredictable global drought cycles, it is suggested that in addition to reducing yield, water stress may influence the evolutionary trajectory of plant mating system.

Aim Determine the impact of beneficial phytochemicals on diversity and abundance of the gut microbiome in the honey bee (Apis mellifera). Methods and Results Eight-day-old honey bee workers were fed 25 ppm of phytochemical (caffeine, gallic acid, p-coumaric acid or kaempferol) in 20% sucrose. Guts of bees collected at 3 and 6 days were excised and subjected to next-generation sequencing for bacterial 16S and fungal ITS regions. Although phytochemical supplementation fostered gut microbial diversity and abundance, the patterns differed between phytochemicals and there was a temporal stabilization of the bacterial community. While bacterial and fungal communities responded differently, all phytochemical treatments displayed increased abundance of the most represented bacterial genera, Snodgrassella sp. and Lactobacillus sp. Conclusions Phytochemical supplementation improves gut microbial diversity and abundance, reiterating the need for diverse habitats that provide bees with access to pollen and nectar rich in these micronutrients. Diverse gut microbiota can provide a strong line of defense for bees against biotic stressors while improving worker bee lifespan. Significance and Impact of the Study This is the first report on the impact of phytochemical supplementation on gut microbiota in honey bees and these findings have implications for strategic hive management through standardization of effective phytochemical and probiotic feed supplements.

Ongoing climatic changes have altered growing conditions for plants by limiting water availability and inducing unprecedented temperature increases, eliciting plant functional responses that compromise floral trait expression, reduce pollen production and promote early self‐pollination. In a controlled greenhouse study, plants of Collinsia heterophylla, an annual mixed‐mated hermaphrodite, were grown under temperature and water stresses. Floral trait responses and related effects on plant reproductive success were recorded. Plants grown under temperature and water stresses were shorter and had fewer leaves at flowering than control plants. Temperature‐stressed plants flowered earlier and had smaller flowers that produced fewer per capita pollen grains than control and water‐stressed plants. While lifetime flower production in plants experiencing temperature stress alone or water stress alone was similar to control plants, those receiving combined temperature and water stresses had significantly lower lifetime flower production. Abiotic stress did not affect investment in female traits such as ovule number per flower, but impacted male traits seen as fewer pollen grains per flower. In plants experiencing abiotic stress, an increase in autonomous self‐pollination was facilitated through a compromise in herkogamy, a sexual interference mechanism that promotes cross‐pollination. Spatial separation between stigma and anther, a measure of herkogamy was zero or negative in stressed plants. Thus, abiotic stress responses in plants did not compromise plant reproductive success as autonomous selfing was augmented. In nature, such responses will likely reduce available nutrition for pollinators through decreased flower and pollen production.