The role of disease in bee foraging ecology

Diseases have important but understudied effects on bee foraging ecology. Bees transmit and contract diseases on flowers, but floral traits including plant volatiles and inflorescence architecture may affect transmission. Diseases spill over from managed or invasive pollinators to native wild bee species, and impacts of emerging diseases are of particular concern, threatening pollinator populations and pollination services. Here we review how parasites can alter the foraging behaviour of bees by changing floral preferences and impairing foraging efficiency. We also consider how changes to pollinator behaviours alter or reduce pollination services. The availability of diverse floral resources can, however, ameliorate bee diseases and their impacts through better nutrition and antimicrobial effects of plant compounds in pollen and nectar

Spectrophotometric analysis of ternary uranyl systems to replace tri-N-butyl phosphate (TBP) in used fuel reprocessing

In this report, the interaction of monoamide/diamide and monoamide/diglycolamide mixtures with UO2+2 are investigated in pH = 1 methanolic nitric acid media. These monoamides include N,N-dimethylacetamide (DMAA), N,N-diethylacetamide (DEAA), N,N-dibutylacetamide (DBAA) and N,N-dibutylbutanamide (DBBA). N,N,N′N′-tetraethylmalonamide (TEMA) and N,N,N′,N′-tetraethyldiglycolamide (TEDGA), which were chosen as model diamides and diglycolamides, respectively. Complex stability constants for each ligand were modelled using the Stability Quotients Using Absorbance Data program using UV–visible data. Complex stoichiometry of ligand mixtures was determined using Job plots and UV–Vis spectrometry. Monoamides were confirmed to produce only disolvate complexes with UO2+2 in solution. The log10(K) values for monoamides were found to be independent of amine-side chain length, but were slightly dependent on the carbonyl-side chain length. TEDGA was found to produce multiple uranyl complexes in solution. Job plot data indicated that the uranyl cation strongly prefers to bond either only with the monoamide or diamide in ternary monoamide–diamide–UO2 systems. Monoamide–diglycolamide–UO2 systems were more complicated, with Job plot data indicating the potential for multiple ternary species being present is dependent on the monoamide structure

Newly emerged bumblebees are highly susceptible to gut parasite infection

One factor that can affect infection susceptibility is host age, the effects of which vary in a range of ways. For example, susceptibility may increase with age, due to senescence or decrease with age as a result of maturation of the immune system. If certain ages are more susceptible to infection, populations with contrasting demographics, such as same-age cohorts versus a mixture of ages, will exhibit differing disease prevalence. We use the bumblebee, Bombus terrestris, and its interaction with the gut trypanosome Crithidia sp. as a model system to investigate age-related susceptibility in a social insect. Crithidia sp. are widespread and prevalent parasites of bumblebees that are spread between colonies via faeces on flowers when foraging, and within colonies via contact with infected bees and contaminated surfaces and resources. In the field, Bombus spp. live for approximately three weeks. Here, we inoculated bumblebees at 0, 7, 14 and 21 days of age and measured their infection after one week. We also measured the level of gene expression of two antimicrobial peptides important in the defence against Crithidia bombi in bumblebees. We found that younger bumblebees are more susceptible to infection by Crithidia sp. than their older siblings. Specifically, individuals inoculated on their first day of emergence had infection intensities seven days later that were four-fold higher than bees inoculated at 21 days of age. In contrast, the gene expression of two AMPs known to protect against the trypanosome, abaecin and defensin, did not significantly vary with age. These results suggest that age does affect susceptibility to Crithidia sp. infection in B. terrestris. The higher susceptibility of callows may have implications for the susceptibility of colonies at different stages of their lifecycle, due to the contrasting age demography of workers in the colony

"‘Inert’ Ingredients Are Understudied, Potentially Dangerous to Bees and Deserve More Research Attention

Agrochemical formulations are composed of two broad groups of chemicals: active ingredients, which confer pest control action, and ‘inert’ ingredients, which facilitate the action of the active ingredient. Most research into the effects of agrochemicals focusses on the effects of active ingredients. This reflects the assumption that ‘inert’ ingredients are non-toxic. A review of relevant research shows that for bees, this assumption is without empirical foundation. After conducting a systematic literature search, we found just 19 studies that tested the effects of ‘inert’ ingredients on bee health. In these studies, ‘inert’ ingredients were found to cause mortality in bees through multiple exposure routes, act synergistically with other stressors and cause colony level effects. This lack of research is compounded by a lack of diversity in study organism used. We argue that ‘inert’ ingredients have distinct, and poorly understood, ecological persistency profiles and toxicities, making research into their individual effects necessary. We highlight the lack of mitigation in place to protect bees from ‘inert’ ingredients and argue that research efforts should be redistributed to address the knowledge gap identified here. If so-called ‘inert’ ingredients are, in fact, detrimental to bee health, their potential role in widespread bee declines needs urgent assessment

Parasite resistance and immunity across female castes in a social insect

[EN] Living in a social group increases the risks of parasitism, especially in highly-related groups. In homogenous groups, with no reproductive division of labour, the impact of parasitism is unlikely to vary with host identity. Many social systems, however, do exhibit division of reproductive labour, most famously in social insects with their reproductive queens and generally infertile workers. In such systems, the impact of parasitism will differ for each group. Consequently, we predict that susceptibility to parasites will vary to reflect such differential impact. We tested this prediction using a trypanosome-bumble bee system, where Crithidia bombi infects both gynes and workers of Bombus terrestris. We studied both susceptibility to the parasite and relevant measures of the immune function. As predicted, gynes were significantly less susceptible to the parasite than workers, but while gynes and workers expressed different immune profiles, how these link to differential susceptibility remains unclear. In conclusion, our results suggest that differential selection pressures exerted by parasites may produce multiple phenotypes from a single genotype in order to maximise fitness in a social group context. Significance statement Social insect colonies dominate terrestrial ecology, and as such are targets for parasites. How they defend themselves against such threats is a key question. Here, we show that bumble bee gynes - the reproductive individuals that overwinter and found colonies in this annual social system - are more resistant to a parasite that disproportionately affects reproductive fitness than their sister workers. Differential patterns of susceptibility may help to explain the success of these social insects.This study was supported by an Enterprise Ireland grant to M. J. F. B., a Ulysses grant to M. J. F. B. and Y. M., and Y. M. was supported by the Centre National de la Recherche Scientifique (C.N.R.S.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.Ruiz-González, MX.; Kelly, M.; Moret, Y.; Brown, MJF. (2022). Parasite resistance and immunity across female castes in a social insect. Behavioral Ecology and Sociobiology. 76(4):1-8. https://doi.org/10.1007/s00265-022-03162-01876