Apidologie最新文献

Urban beekeeping is common and has become a permanent part of the landscape of many cities. However, there is scarce information about the health of honey bees (Apis mellifera) from apiaries in cities. Here, we present that the living environment of bees from urban apiaries is not indifferent to their total antioxidant capacity, immune system (defensin-2), and proteostasis (Hsp70). Still, the city does not always have only negative effects. Using an experimental system of genetically related bee colonies located in urban and rural environments, we found that genetic factors, environmental factors, or both impact the levels of the analyzed stress biomarkers. The response to environmental stress in the urban and rural areas was tissue-dependent and changed during the season. Our results will be valuable in discussing bee welfare in cities.

The use of fungus-based biopesticides has grown worldwide as an effective and ecologically sustainable strategy for the control of crop pests, which in turn increases the need to investigate potential harmful effects on non-target organisms in tropical agroecosystems. However, such effects of commercial formulations based on the entomopathogenic fungus Beauveria bassiana on stingless bees, the main pollinators of a wide range of flowering crops, remains largely unexplored. Here, we tested if Boveril^®WP, a commercial bioinsecticide, affects survival, cuticular hydrocarbon profile and social recognition in the stingless bee Scaptotrigona depilis. Combining exposure assay, cuticular hydrocarbon profiling, and lure presentation, we found that this mycopesticide causes the following: (1) lethal effects when topically applied on the thorax (LT₅₀ = 30 min) or abdomen (LT₅₀ = 24 h) of foragers; (2) quantitative changes in cuticular hydrocarbon profile of foragers within 12 h, containing significantly higher proportions of three linear alkanes and one methylated alkane; (3) subtle effect on social recognition by entrance guards, with lower aggression rates toward exposed foragers (nestmates or not), which may facilitate the transmission of lethal pathogens into and among colonies. This study demonstrates the potential incompatibility of a common biopesticide with a native pollinator, thus highlighting the much-needed Integrated Pest and Pollinator Management (IPPM) approaches for the best use of ecological services provided by non-target organisms.

Heteroplasmy is characterized by different mitochondrial haplotypes within the same organism. After evidence of heteroplasmy was found in mitochondrial sequences in Tetragonisca angustula—a bee species of great economic and ecological importance—the aim of this study was to confirm the presence of heteroplasmy in the species, analyse the frequency of synonymous and non-synonymous mutations, and classify them according to their impact on the protein’s tertiary structure. For this purpose, mitochondrial DNA was isolated from nuclear DNA in two T. angustula individuals, a portion of COI was amplified by PCR from pure mitochondrial DNA, and the different mitochondrial haplotypes were recovered through vector cloning in competent bacteria. Our results confirmed the presence of 11 and 17 different mitochondrial haplotypes in the first and second samples analysed, respectively. These different mitochondrial haplotypes are characterized by the predominance of synonymous mutations or mild and moderate non-synonymous mutations, meaning they have little impact on the protein’s tertiary structure. These results strongly support the presence of heteroplasmy in T. angustula and provide some insights into its characterization and inheritance.

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.