Emerging infectious diseases (EIDs) pose a risk to human welfare, both directly and indirectly, by affecting managed livestock and wildlife that provide valuable resources and ecosystem services, ...such as the pollination of crops. Honeybees (Apis mellifera), the prevailing managed insect crop pollinator, suffer from a range of emerging and exotic high-impact pathogens, and population maintenance requires active management by beekeepers to control them. Wild pollinators such as bumblebees (Bombus spp.) are in global decline, one cause of which may be pathogen spillover from managed pollinators like honeybees or commercial colonies of bumblebees. Here we use a combination of infection experiments and landscape-scale field data to show that honeybee EIDs are indeed widespread infectious agents within the pollinator assemblage. The prevalence of deformed wing virus (DWV) and the exotic parasite Nosema ceranae in honeybees and bumblebees is linked; as honeybees have higher DWV prevalence, and sympatric bumblebees and honeybees are infected by the same DWV strains, Apis is the likely source of at least one major EID in wild pollinators. Lessons learned from vertebrates highlight the need for increased pathogen control in managed bee species to maintain wild pollinators, as declines in native pollinators may be caused by interspecies pathogen transmission originating from managed pollinators.
Global warming may have a significant negative impact on insects in the tropics due to an increase in the frequency and intensity of heat waves. Heat waves may have a particularly harsh impact on the ...relatively sessile juvenile stages of holometabolous insects, such as larvae and pupae. The honey bee (
Apis
mellifera
L.) is an important tropical holometabolous insect whose queens and drones may also be negatively impacted by heat waves during their development, leading to reduced reproductive capacity. However, we have little information on the thermal tolerance of honey bee subspecies in tropical regions. To address this knowledge gap, we evaluated the effect of simulated heat waves during development on drones and queens of Africanized
A.
mellifera
in terms of the size, shape, and symmetry of their forewings, as well as their reproductive traits such as sperm concentration and viability in drones, and ovariole number and spermatheca volume in queens. Drones raised at high temperatures were more asymmetric in forewing size but not in shape, and had a smaller body size and reduced sperm concentration and viability compared to those raised at normal hive temperatures. In contrast, no effect of an elevated temperature regime during development was seen in queens in terms of the size and symmetry of the forewing, the number of ovarioles, and the volume of the spermatheca. Our results support the notion that males of insects are more susceptible to high temperatures compared to females. We discuss the implications of our findings for the reproductive fitness of honey bee colonies in tropical regions.
Insects of the order Hymenoptera are biologically and economically important
members of natural and agro ecosystems and exhibit diverse biologies, mating
systems, and sex pheromones. We review what ...is known of their sex pheromone
chemistry and function, paying particular emphasis to the Hymenoptera Aculeata
(primarily ants, bees, and sphecid and vespid wasps), and provide a framework
for the functional classification of their sex pheromones. Sex pheromones often
comprise multicomponent blends derived from numerous exocrine tissues,
including the cuticle. However, very few sex pheromones have been definitively
characterized using bioassays, in part because of the behavioral sophistication
of many Aculeata. The relative importance of species isolation versus sexual
selection in shaping sex pheromone evolution is still unclear. Many species
appear to discriminate among mates at the level of individual or kin/colony,
and they use antiaphrodisiacs. Some orchids use hymenopteran sex pheromones to
dupe males into performing pseudocopulation, with extreme species
specificity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Lactic acid bacteria (LAB) are well recognized beneficial host-associated members of the microbiota of humans and animals. Yet LAB-associations of invertebrates have been poorly characterized and ...their functions remain obscure. Here we show that honeybees possess an abundant, diverse and ancient LAB microbiota in their honey crop with beneficial effects for bee health, defending them against microbial threats. Our studies of LAB in all extant honeybee species plus related apid bees reveal one of the largest collections of novel species from the genera Lactobacillus and Bifidobacterium ever discovered within a single insect and suggest a long (>80 mya) history of association. Bee associated microbiotas highlight Lactobacillus kunkeei as the dominant LAB member. Those showing potent antimicrobial properties are acquired by callow honey bee workers from nestmates and maintained within the crop in biofilms, though beekeeping management practices can negatively impact this microbiota. Prophylactic practices that enhance LAB, or supplementary feeding of LAB, may serve in integrated approaches to sustainable pollinator service provision. We anticipate this microbiota will become central to studies on honeybee health, including colony collapse disorder, and act as an exemplar case of insect-microbe symbiosis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Wild and managed bees are essential for global food security and the maintenance of biodiversity. At present, the conservation of wild bees is hampered by a huge shortfall in knowledge about the ...trends and status of individual species mainly due to their large diversity and variation in life histories. In contrast, the managed Western honey bee
Apis mellifera
is one of the best studied and monitored insects in existence. Since similar drivers may be relevant for the decline of wild bees and losses of managed honey bees, this raises the possibility that monitoring of honey bees may help to detect threatened regions for wild bees, thereby fostering urgently required conservation measures. However, this possible relationship has not yet been explicitly tested for. Moreover, research currently focused on honey bees as a model species may yield important insights into wild insect susceptibility to stressors and vice versa. Here we use the bees of Europe as a model to show that managed honey bees are not suitable surrogates for detecting declines in wild bees. A direct comparison of the response of wild bees and honey bees to the same threats (nutritional deficiencies, parasites and pathogens, pesticides, and a changing climate) shows that, whilst some of their responses may be similar at the individual level, when considered at the reproductive level (individuals versus colonies), many of their responses diverge. These results reinforce the need for basic research into wild bee biology, the need for national monitoring schemes for wild bee populations, and the call for conservation actions tailored to the individual ecologies of wild bee species.
Mammalian cells proteolytically release (shed) the extracellular domains of many cell-surface proteins. Modification of the cell surface in this way can alter the cell's responsiveness to its ...environment and release potent soluble regulatory factors. The release of soluble tumour-necrosis factor-alpha (TNF-alpha) from its membrane-bound precursor is one of the most intensively studied shedding events because this inflammatory cytokine is so physiologically important. The inhibition of TNF-alpha release (and many other shedding phenomena) by hydroxamic acid-based inhibitors indicates that one or more metalloproteinases is involved. We have now purified and cloned a metalloproteinase that specifically cleaves precursor TNF-alpha. Inactivation of the gene in mouse cells caused a marked decrease in soluble TNF-alpha production. This enzyme (called the TNF-alpha-converting enzyme, or TACE) is a new member of the family of mammalian adamalysins (or ADAMs), for which no physiological catalytic function has previously been identified. Our results should facilitate the development of therapeutically useful inhibitors of TNF-alpha release, and they indicate that an important function of adamalysins may be to shed cell-surface proteins.
Effective population size (Ne) is one of the most important parameter in population genetics and conservation biology. It translates census sizes of a real population into the size of an idealized ...population showing the same rate of loss of genetic diversity as the real population under study.
•We measured, in irrigated cotton, root-rainwater uptake using stable isotopes of water.•The measurements were done under field conditions before and after a rain event.•Stable isotopes can be used ...to discriminate between rainwater and irrigation transpired by cotton.
The natural rate of recharge for some groundwater systems, such as the Southern Ogallala Aquifer in the central United States, is smaller than the rate of annual withdrawals for irrigation. As aquifer depletion continues, efficient management of the water budget gains importance. Of interest is the use of rainwater by irrigated crops during the course of the growing season, as rain can account for an important amount of the water input in the semi-arid climate of the Texas High Plains. We tested the suitability of stable isotopes of water as a method to determine the source of water in the transpiration of field-grown cotton (Gossypium hirsutum L.) plants from either rain or irrigation-water. We selected this method because irrigation water from the Ogallala Aquifer has a stable isotopic signature that can either be enriched or depleted when compared to the isotopic signature of water from any rain event. Cotton petioles were sampled before two rain events of 33mm, and after every 2h for two days. The water in the cotton petioles was extracted using cryogenic vacuum distillation and was analyzed for its isotopic signature. The results showed a shift of 29% from −7 (‰) to −5 δ18O (‰), which is similar to the isotopic signature of the rainwater (−4.2 δ18O (‰)). These results suggest that it is possible to use water stable isotopes to differentiate between rainwater and irrigation transpired by cotton under field conditions.
Considerable interspecific diversity exists among bees in the rendezvous sites where males search for females and in the behaviours employed by males in their efforts to secure matings. I present an ...evolutionary framework in which to interpret this variation, and highlight the importance for the framework of (i) the distribution of receptive (typically immediate post-emergence) females, which ordinarily translates into the distribution of nests, and (ii) the density of competing males. Other than the highly polyandrous honey bees (Apis), most female bees are thought to be monandrous, though genetic data with which to support this view are generally lacking. Given the opportunity, male bees are typically polygamous. I highlight intraspecific diversity in rendezvous site, male behaviour and mating system, which is in part predicted from the conceptual framework. Finally, I suggest that inbreeding may be far more widespread among bees than has hitherto been considered the case.
In this letter we present the first two‐dimensional observations of sub‐auroral ion drift (SAID) variability within the sub‐auroral polarization stream (SAPS) using a new mid‐latitude SuperDARN radar ...located at Wallops Island, VA. The radar data are complemented with observations from the DMSP F15, TIMED, and NOAA‐18 spacecraft to confirm that a backscatter feature observed at the equatorward edge of the auroral oval is a manifestation of SAPS/SAID. During a several hour long period on August 6, 2005, the velocity data indicate that significant changes in the SAPS flow occurred on time scales of a few minutes. The Wallops HF radar observations demonstrate that the SAPS phenomenon is a source of small‐scale irregularities extending over many hours of MLT and that the electric fields associated with SAID in particular are highly variable.
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