Pollen products collected from honey bee hives experiencing minor stress have altered fungal communities and reduced antimicrobial properties.

Fungi are increasingly recognized to play diverse roles within honey bee hives, acting as pathogens, mutualists, and commensals. Pollen products, essential for hive nutrition, host significant fungal communities with potential protective and nutritional benefits. In this study, we profile the fungal communities and antifungal properties of three pollen products from healthy and stressed hives: fresh pollen collected by forager bees from local plants; stored pollen packed into the comb inside the hive; and bee bread, which is stored pollen following anaerobic fermentation used for bee and larval nutrition. Using amplicon sequencing, we found significant differences in fungal community composition, with hive health and sample type accounting for 8.8% and 19.3% of variation in beta diversity, respectively. Pollen and bee bread extracts had species-specific antimicrobial activity and inhibited the fungal hive pathogens Ascosphaera apis, Aspergillus flavus, and Aspergillus fumigatus, and the bacterial hive pathogen Paenibacillus larvae. Activity was positively correlated with phenolic and antioxidant content and was diminished in stressed hives. The plant source of pollen determined by amplicon sequencing differed in stressed hives, suggesting altered foraging behaviour. These findings illustrate the complex interplay between honey bees, fungal communities, and hive products, which should be considered in hive management and conservation.

Nurse bees regulate the larval nutrition of developing workers (Apis mellifera) when feeding on various pollen types.

Nutrition has been identified as a key driver of colony health and productivity. Yet, in honey bees, relatively little is known about how the vast variety of natural pollen sources impact larval development. The impact of the nutritional quality of 4 naturally occurring pollen sources, of importance to the Western Australian beekeeping industry, was tested on honey bee (Apis mellifera L.) development. Bee packages consisting of 800 g of bees and a mated sister queen were assigned to 40 nucleus hives and randomly allocated to one of the 4 feed treatments (10 colonies each) of marri (Corymbia calophylla Lindl.), jarrah (Eucalyptus marginata Sm.), clover (Trifolium repens L.), and canola (Brassica napus L.) pollen. Emerging bees were collected once the first bees started hatching on the assigned feed sources. Newly emerging bees were weighed individually, and body composition was measured in batches according to the feed treatment groups. Food consumption was recorded for the duration of the experiment. Nurse bees successfully raised young adult workers from the larval stage until emergence when fed with one of 4 pollen patties with different nutritional qualities. There was no difference in the body composition or weight of emerging bees fed on the different pollen types. However, the body weight of bees increased over time, most likely related to colony size and structure. With the type of pollen patties having little impact on larval development, the availability of pollen may be more important than its composition, providing bees have access to all essential nutrients.

Protein-Level Interactions as Mediators of Sexual Conflict in Ants.

All social insects with obligate reproductive division of labor evolved from strictly monogamous ancestors, but multiple queen-mating (polyandry) arose de novo, in several evolutionarily derived lineages. Polyandrous ant queens are inseminated soon after hatching and store sperm mixtures for a potential reproductive life of decades. However, they cannot re-mate later in life and are thus expected to control the loss of viable sperm because their lifetime reproductive success is ultimately sperm limited. In the leaf-cutting ant Atta colombica,, the survival of newly inseminated sperm is known to be compromised by seminal fluid of rival males and to be protected by secretions of the queen sperm storage organ (spermatheca). Here we investigate the main protein-level interactions that appear to mediate sperm competition dynamics and sperm preservation. We conducted an artificial insemination experiment and DIGE-based proteomics to identify proteomic changes when seminal fluid is exposed to spermathecal fluid followed by a mass spectrometry analysis of both secretions that allowed us to identify the sex-specific origins of the proteins that had changed in abundance. We found that spermathecal fluid targets only seven (2%) of the identified seminal fluid proteins for degradation, including two proteolytic serine proteases, a SERPIN inhibitor, and a semen-liquefying acid phosphatase. In vitro, and in vivo, experiments provided further confirmation that these proteins are key molecules mediating sexual conflict over sperm competition and viability preservation during sperm storage. In vitro, exposure to spermathecal fluid reduced the capacity of seminal fluid to compromise survival of rival sperm in a matter of hours and biochemical inhibition of these seminal fluid proteins largely eliminated that adverse effect. Our findings indicate that A. colombica, queens are in control of sperm competition and sperm storage, a capacity that has not been documented in other animals but is predicted to have independently evolved in other polyandrous social insects.

Parasitized honey bees are less likely to forage and carry less pollen.

Research into loss of pollination capacity has focused primarily on documenting pollinator declines and their causes with comparatively little attention paid to how stressors may affect pollinating behavior of surviving pollinators. The European honey bee, Apis mellifera is one of the world's most important generalist pollinators, and Nosema apis is a widespread microsporidian gut parasite of adult A. mellifera. We individually fed 960 newly eclosed A. mellifera workers either a sucrose solution or 400 N. apis spores in a sucrose solution and tagged them with a unique radio frequency identification (RFID) tag to monitor their foraging behavior. We found spore-fed bees were less likely to forage than those fed sugar only. Those that did forage started foraging when they were older and stopped foraging when they were younger than bees fed sugar only. However, inoculated and non-inoculated bees did not significantly differ in the number of foraging trips taken per day, the total hours foraged over their lifetime, or homing ability. Inoculated returning foragers were 4.3 times less likely to be carrying available pollen than non-inoculated returning foragers and the number of pollen grains carried was negatively correlated with the number of N. apis spores. In an arena of artificial flowers, inoculated bees had a tendency (p=0.061) to choose sugar flowers over pollen flowers, compared to non-inoculated bees which visited pollen and sugar flowers equally. These results demonstrate that even a relatively low dose of a widespread disease of A. mellifera may adversely affect bees' ability to pollinate.