Apidologie最新文献

There are several honey bee (Apis mellifera) stocks with desirable traits that have been developed through selective breeding, but there are likely to be resultant trade-offs due to biological constraints or neutral evolution. The Russian honey bee (RHB) stock has higher resistance to Varroa mites (Varroa destructor) and tends to have more frequent brood rearing breaks relative to the common Italian honey bee (IHB) stock, which requires high levels of food consumption to sustain long brood rearing cycles. Here, we investigate how queens from the two stocks perform following prolonged nutritional stress in the form of chronic pollen deprivation and a 3-week recovery period. Overall, we find that IHB queens are heavier regardless of their nutritional treatment and that those that did not experience pollen dearth lay more eggs with a higher protein to egg weight ratio. While we cannot rule out the influence of external factors present in the colony setting such as pathogens, our findings suggest that IHB queen egg laying performance may be relatively higher when pollen resources are abundant, but at the same time, they have a higher level of sensitivity to nutritional stress. In addition, our results suggest that the more frequent brood rearing breaks exhibited by RHBs may not be due to reductions in queen egg laying in response to nutritional stress. We find that the best performing honey bee queen (RHB or IHB) is context dependent due to specific trade-offs in performance, which beekeepers may want to consider in the future for honey bee breeding and management.

The intensification of pesticide use is believed to be one of the main causes of the global decline in pollinators. The ability to forage resources effectively and return to the colony is crucial for individual eusocial bees and their colonies, and some pesticides are known to disturb this ability. Our study investigated the effects of the most widely used type of pesticide, glyphosate-based herbicides (GBHs), on the foraging and homing ability of the buff-tailed bumblebee, Bombus terrestris (L.) (Hymenoptera: Apidae). We conducted two experiments in which we exposed bees to field-realistic doses of GBH at colony and/or individual levels and observed their foraging activity and the homing ability of displaced bees. We found that 24-h colony-level GBH exposure increased the number of bumblebees’ foraging bouts, but it did not affect the duration of bouts or the homing ability. Regarding the homing rate, there was a marginally significant interaction between acute individual-level treatment and release distance from the colony. Even though the negligible impacts of short-term GBH exposure on homing ability are encouraging, the greater number of (possibly unnecessary) foraging bouts after colony-level GBH exposure might be costly for bumblebees.

Pollinating bees promote greater yield and quality of oilseed crops like canola. Canola acreage has grown over 300% in the past decade in the Pacific Northwest region of the US, providing seasonal pulses of nectar and pollen resources that may affect bee abundance and community structure. However, because pollination by insects does not limit canola seed production, few studies have examined the biodiversity of pollinators that use these resources, or the floral traits of canola that affect pollinators. Here, we conducted surveys at canola farms across the inland Northwest USA to assess how bee biodiversity and abundance varied based on canola production practices and floral traits of canola varieties. We show that mining bees (Adrenidae) were more abundant earlier in the season and sweat bees (Halictidae) later in the season, and that bees were more abundant on farms with less floral nectar and on those in less developed landscapes. Floral traits such as larger petal size and increased nectar were correlated with lower bee abundance and diversity. However, this may reflect that petal size was associated with canola type, and that more abundant and diverse bee communities may have been more effective at removing floral nectar. While we did not find a direct effect of canola type on bees, we did find that winter canola had larger petals but lower nectar volume, which indirectly affected bee diversity and abundance. This research provides information for canola growers and land managers interested in pollinator conservation and offers a framework for future research in pollinator management.

Pollen selection in Apis mellifera colonies is crucial for their development and productivity. Bees consume the pollen stored in the hive at early ages (mostly when they perform as nurses) but switch from consuming it to collecting it when they mature into foragers. Because of these differences in pollen use, we hypothesize that pollen preferences between young bees and foragers are not the same. In addition, we hypothesize that pollen preferences are also affected by experiences with the resource. To study differences in pollen preferences between the two groups, we compared the consumption preferences of nurse-aged workers for four monofloral pollens in the cages where they were confined, versus the foraging preferences of free-flying mature foragers for the same pollens offered in a foraging station. To study whether pollen experience affects choices, initial preferences and preferences obtained several hours after offering pollen were compared in both young bees and foragers. We observed that the pollen preferences of young bees and foragers were different and were modified by the experience. Interestingly, preferences of experienced young bees and foragers became more similar to each other than when they were naïves, a response that could be advantageous for the nutrition of early workers, who would have resources available in a proportion more similar to the one they consume.

Chordotonal organs are vital for survival, allowing insects to navigate, communicate, and detect predators or prey effectively. However, little is known about the toxic effects of chordotonal-organ-targeting insecticides (COTI) on stingless bees. Here, we evaluated the toxicity of commercial formulations of two COTIs, flonicamid and pymetrozine, on stingless bees Melipona beecheii and Nannotrigona perilampoides. After acute oral and contact exposure to field-recommended concentrations (flonicamid: 250 mg a.i./L and pymetrozine: 500 mg a.i./L), survival rates, walking speed, and flight take-off activity were assessed. Overall, the toxic effects of the insecticides were more pronounced in M. beecheii and when bees ingested the insecticides. Survival rates dropped to 23–32% in M. beecheii and 77–94% in N. perilampoides when exposed to the insecticides. In M. beecheii, oral exposure to insecticides decreased walking speed to 0.14–0.95 cm/s, compared to 3.30–3.74 cm/s for the control group. For contact exposure, only pymetrozine caused a significant reduction in walking speed (0.48–1.21 cm/s) compared to the control group (1.85–2.61 cm/s). In N. perilampoides, both oral and contact exposure to insecticides reduced walking speed to 0.43–0.49 cm/s, compared to 1.07–1.18 cm/s for the control group. The insecticides also significantly reduced flight take-off activity, with only 6.7% of M. beecheii adults and none of the N. perilampoides adults being able to fly after oral or contact exposure, compared to 70 and 80% of the bees in their respective control groups. Our findings demonstrate the vulnerability of stingless bees to COTIs, highlighting the urgent need for stricter pesticide regulations to protect pollinator health.

Honey bees play a critical role in pollination-dependent agriculture, and their colonies have been declining in various regions worldwide. Understanding the factors that influence colony health is essential. Pollen and nectar are primary sources of carbohydrates, micro-nutrients, and macro-nutrients necessary for bee survival. Floral diversity, abundance, and nutritional content significantly impact honey bee health. This study investigates how the diversity and structure of flowering plant communities, including landscape fragmentation, influence the nutritional availability reflected in the stored pollen within hives and its implications for the health of honey bees. Our study demonstrates that landscape diversity influences the protein-to-lipid ratio of pollen diets, specifically the protein-to-lipid ratio increases as the landscape diversity rises. This increase in protein-to-lipid ratio was also associated with the increased total bee density. Diverse pollen species in the diet enhance nutritional content, promoting healthier bees through resource complementarity. Bees exhibit adaptive foraging behavior, systematically diversifying their floral sources to optimize nutrient intake. The diversity in pollen reserves also correlates negatively with Varroa destructor prevalence, likely because the diversity of pollen enhances the nutrition and overall health of honey bee colonies. Our study emphasizes the value of biodiverse settings that offer a steady flow of floral supplies for the health and development of bee pollinator populations and their associated ecosystem services.

We evaluated the effect of different diluents on the preservation of cooled semen from Africanized bees at 16 °C, as a tool to enable its storage and transportation. Semen pools of 50 drones from 10 different colonies were obtained by the endophallus eversion technique. The pools were then divided into four aliquots that were diluted in Tris, Tris + yolk (EY), Collins or Ringer, in a ratio of 12:1 (diluent:semen). The samples were cooled in a biological incubator at 16 °C and evaluated for pH, motility, viability, membrane functionality and sperm morphology at 0, 24, 72 and 96 h. Ringer's extender promoted total loss of sperm motility at 24 h, while at 96 h, the highest motility values (P < 0.05) were exhibited by Tris + EY extender (25 ± 4.2%), compared to Tris (11.4 ± 2.8%) and Collins (2.6 ± 0.9%). After 96 h, the viability of samples diluted in Ringer's extender (34.4 ± 8.6%) showed a pronounced decrease compared to Tris (73.3 ± 6.8%). For sperm membrane functionality, both Tris and Ringer's extender were able to maintain values greater than 45% of functional membranes up to 96 h. For sperm morphology, Tris extender provided the highest values for normal sperm over time, especially compared to Ringer's extender (P < 0.05). In conclusion, we point out that Tris-based extenders, with or without egg yolk, are the most suitable for use in short-term storage at 16 °C of Africanized honeybee drone spermatozoa for up to 96 h.

Despite their importance to the ecosystem, global food production, and the beekeeping industry, honey bees are systematically threatened by multiple factors. Industrial agriculture plays an important role in such a process challenging both managed and wild bees. While the impacts of various insecticide classes on bees are well-documented, neonicotinoids are closely associated with colony losses, prompting their ban in several countries. Sulfoxaflor, a sulfoximine-based insecticide, has been proposed as a replacement for neonicotinoids like imidacloprid, targeting nicotinic acetylcholine receptors (nAChRs) through a distinct binding mechanism and allegedly posing lower risks to birds, mammals, and humans. This review systematically assesses sulfoxaflor’s effects on Apis mellifera, utilizing data from PubMed, Web of Science, Jstor, Scopus, Google Scholar, CORE, and the Directory of Open Access Journals (DOAJ) for studies published between 2019 and 2024. Nineteen studies were selected, excluding research on non-Apis bees or combined formulations. Findings revealed diverse sublethal impacts on honey bees, including metabolic, morphological, behavioral, and gene expression alterations. Even though sulfoxaflor is less toxic than neonicotinoids, it cannot be deemed a safe alternative for honey bees, especially once that many effects have been reported in both classes of pesticides.

Honeybees communicate the locations of profitable resources using waggle dances. Researchers have used two manual dance decoding methods to infer the spatial foraging patterns of the bees. The ‘waggle run method’ infers foraging distance from waggle duration, representing the actual distance signal of the bees, and the ‘circuit method’ infers foraging distance from the duration of complete dance circuits, including both waggle and return phases. The circuit method enables decoding dances by real-time observation and is likely quicker, but it might give inaccurate distance estimates due to variations in the return phases. Here, we decoded 200 natural waggle dances from four Apis mellifera colonies using both methods to test how well inferences about foraging locations would match and compared the time required for dance decoding. We found a high linear correlation between foraging distances inferred from waggle duration and circuit duration (R², 0.793). However, the circuit method systematically overestimated foraging distances by about 86 m. Both methods provided similar results with respect to relative differences in spatial foraging patterns between the four test colonies. Decoding the dances using the circuit method was three to four times faster than the waggle run method (2 versus 7.3 min per dance). We conclude that the circuit method can be used for many research questions that require manual dance decoding to minimize time costs. However, when aiming to maximize the accuracy of inferred foraging locations, systematic errors of the circuit method should be accounted for, or the waggle run method should be used.

The global decline of bees has raised significant concerns due to their crucial role in agroecosystems, rendering their diminishment a potential predisposing factor for a worldwide crisis in the agri-food sector and ecosystems. The use of pesticides, such as neonicotinoids, can impact non-target organisms, including bees. This study aimed to evaluate the gene expression in the heads of Apis mellifera bees in the forager phase. The analysis was conducted by examining their transcriptome to assess the effects of the neonicotinoid imidacloprid through contact bioassays, administered at both lethal and sublethal doses. The results revealed differential gene expression after 1 and 4 h of imidacloprid exposure. Differentially expressed genes were categorized based on gene ontology, revealing alterations in critical biological processes, molecular functions, and cellular components. These changes were associated with immune response, stress, neurotoxicity, and other vital functions. The study highlights the importance of considering sublethal pesticide effects and their potential long-term consequences on bee populations and ecosystem functioning.

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