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Insulin receptors (InR) are an integral component of the insulin/insulin‐like growth factor signaling pathway, which plays a vital role in insect development, lifespan, reproduction, and olfactory sensitivity. However, whether InR participate in the peripheral olfactory system of insects remains unclear. Recently, we found that 2‐heptanone (2‐HT) affects AcerInR expression, the gene for an InR protein, in Apis cerana cerana. We then examined the spatiotemporal expression profile of the gene in A. cerana cerana. The mRNA of AcerInR was primarily expressed in the antennae, wings, and legs of forager bees, which are probable chemosensory tissues. The results of fluorescence competitive binding assays, combined with site‐directed mutagenesis, demonstrated that AcerOBP6 and AcerOBP14 exhibit strong binding affinities to 2‐HT. Furthermore, after foragers were fed with double‐stranded AcerInR, the expression levels of AcerOBP6 and AcerOBP14 decreased significantly, as did the electroantennogram responsiveness to 2‐HT and some other odorants. In conclusion, our findings provide a foundation for understanding the involvement of AcerInR in the odor perception of A. cerana cerana. Moreover, they offer novel insights into the olfactory recognition mechanism in insects. [ABSTRACT FROM AUTHOR]

Strawberries are popular fruits around the world, and their yield and fruit quality rely on pollination by honey bees and bumblebee colonies. Both bee species have their own advantages in strawberry pollination. This study investigates the characteristic of strawberry (Fragaria × ananassa 'Red Face') flower volatiles and their effects on bee pollinators by (1) detecting the volatile compounds of strawberry flowers by polydimethylsiloxane (PDMS) combined gas chromatography-mass spectrometry (GC-MS), (2) determining whether Bombus terrestris or Apis mellifera showed antennae responses to certain compounds of strawberry flower volatiles by an electroantennography test (EAG), and (3) testing whether these compounds could elicit a corresponding behavioral response in bees. The results showed that (1) there were 38 chemical compounds in 'Red Face' volatiles with 7 types, most of which were known to be generally emitted by flowers but also have some compounds that have not been reported in strawberry flowers; (2) B. terrestris and A. mellifera had strong EAG responses to several compounds, respectively, especially to ethyl benzoate, (Z)-3-hexenyl propionate, (Z)-3-hexenyl acetate, benzeneacetaldehyde and melonal; and (3) both bee species showed significant avoidance behaviors to four tested compounds, especially the B. terrestris. Flower volatiles of strawberry 'Red face' were different from other strawberry varieties that have been reported; some of these electrophysiologically active compounds could cause antennal potential responses in bees, as well as behavioral responses. Our study supports the idea that strawberry flower volatiles are one of the factors influencing bee foraging decisions and provides a reference for formulating more reasonable bee pollination to improve strawberry fruit quality. [ABSTRACT FROM AUTHOR]

Temperature and humidity are important factors affecting the honeybees physiological metabolism. When honeybees are stressed by high temperature and high humidity, various physiological stress mechanisms evolved by bees are activated in response to injury. The accumulation of some sugars, polyols, and free amino acids can effectively protect cell structure stability and resist temperature stress. In this study, the changes of glucose, trehalose, cholesterol, sorbitol, sorbitol dehydrogenase, mannitol, and free amino acids content of worker honeybees [ Apis cerana cerana Fabricius and Apis mellifera Ligustica (Hymenoptera: Apidae)] under different temperature and humidity conditions were measured. Our research results show that high temperature has an important impact on the metabolism of honeybees. Heat stress can cause the accumulation of various antistress substances in worker. The contents of sugars, polyols, and some free amino acids accumulated in high temperature were significantly higher than those in the control, while the influence of high humidity was less. Although high humidity was improved compared with the control, the difference was not obvious. It provides a theoretical basis for exploring the physiological mechanism of individual heat resistance of honeybees. [ABSTRACT FROM AUTHOR]

The findings of this study revealed that honey bees and bumble bees had different EAG responses to tomato flower volatiles, and the two bee species showed different behavioral choices to the same compound. It has been widely known that bumble bees are effective bee pollinators of tomato as they are capable of buzz pollination to vibrate tomato anthers in order to release pollen grains, and only one visit is sufficient for full tomato pollination [[43]]. Keywords: Apis mellifera; Bombus terrestris; EAG; behavior; tomato flower volatiles EN Apis mellifera Bombus terrestris EAG behavior tomato flower volatiles 987 12 11/17/22 20221101 NES 221101 1. Bees play an important role in the pollination of tomatoes, yet the relationship between foraging choices and olfactory cues is unclear because of the difference in foraging behavior between honey bees and bumble bees on tomato flowers. [Extracted from the article]

Keywords: Apis mellifera; Bombus terrestris; flower volatiles; electroantennography (EAG); olfactory behavior; melon EN Apis mellifera Bombus terrestris flower volatiles electroantennography (EAG) olfactory behavior melon 973 19 11/17/22 20221101 NES 221101 1. EAG Recording The standard compounds for EAG recording were determined according to the identification results of volatile compounds in female and male flowers of melon. The contents and types of volatile compounds in melon flowers of these varieties are different, which may be due to the genotypes, or environmental factors such as temperature and humidity, soil, water conditions, analysis conditions of volatile compounds, and precision of GC-MS instruments [[26]]. When the antennae of bees were stimulated by the same volatiles, the EAG response induced by some volatiles was stronger in I B. terrestris i than in I A. mellifera i , while others were just the opposite. [Extracted from the article]

The interactions between plants and pollinators are complex. Flower volatiles as special olfactory cues could influence the foraging choices of pollinators. Here, we conducted bioassays to evaluate the role of flower volatiles on the attraction of honey bees (native Apis cerana and exotic Apis mellifera) to pears (native Pyrus bretschneideri and exotic Pyrus communis). Chemical and electrophysiological approaches were used to determine flower volatiles and evaluate the antennal responses of honey bees to volatiles from pear flowers. Bioassays demonstrated that flower volatiles were crucial for the attraction of honey bees to pear flowers; honey bees preferred to forage on P. communis flowers (p > 0.05), with approximately 64.37 ± 0.02% (A. mellifera) and 62.10 ± 0.02% (A. cerana) foraging on P. communis. Flowers of P. communis and P. bretschneideri yielded 27 and 31 compounds, respectively, with 17 of them being common. Honey bee antennae responded to 16 chemicals, including 5 contained in both pear species: 1-nonanol, linalool, methyl 2-hydroxy-3-methylpentanoate, methyl L-isoleucinate, and α-farnesene. In addition, there were 8 electrophysiologically active compounds in P. bretschneideri: methyl L-valine ester, benzaldehyde, 6-methyl-5-hepten-2-one, isophorone, 2-methyl octane, longicyclene, longifolene, and caryophyllene; and 3 electrophysiologically active compounds in P. communis: β-ocimene, 4-oxoisophorone and lilac alcohol D. In conclusion, our study demonstrated the significant impact of pear flower volatiles on honey bee foraging choices. This knowledge provides a basis for the selection of honey bees for pear pollination and lays a foundation for further study of the chemical communication of pear attractiveness to honey bees. [ABSTRACT FROM AUTHOR]

Abnormal temperature will affect the normal physiological activities of bees. Similarly, heat stress can also affect the immune system of bees. However, the changes that occur in immune system in bees that are exposed to heat stress remain unclear. We want to understand the impact of heat stress on the immune system of social insects (Apis cerana and Apis mellifera), so we analyzed the expression patterns of three antimicrobial peptide genes (Defensin, Abaecin, Hymenoptaecin) at different temperatures and different treatment times. Our results provide information on the expression patterns of Defensin, Abaecin and Hymenoptaecin at high temperatures. The expression of these genes was found to be increasingly affected by an increase in temperature and treatment time. Heat stress seems to have activated immunity and this early activity may prevent infection under stressful conditions. Our findings provide a basis for determining the mechanisms by which bees immune system adapt to high temperatures. [ABSTRACT FROM AUTHOR]

The malvolio (mvl) gene plays an important role in the transition from nursing to foraging in honeybees (Apis mellifera). Apis cerana cerana (A. c. cerana) is a subspecies of the eastern honeybee, well-known for its pollinator role throughout China. Although A. c. cerana shares many characteristics with A. mellifera, it is unclear whether Acmvl plays a similar role to Ammvl in foraging behavior. In this study, Acmvl expression was quantified during the transition from nursing to foraging in A. c. cerana. Acmvl protein production was also characterized in different tissues in bees from three behavioral groups. Finally, in situ hybridization was used to describe Acmvl expression patterns in forager bee brains. Acmvl expression was low early in life but then showed a major peak, which suggests its role in labor division. Examination of tissue type revealed that Acmvl expression was highest in the thoraxes of nurse bees and the heads of forager bees. In bee brains, Acmvl was selectively expressed in the somata of Kenyon cells in the mushroom bodies, optic lobes and antennal lobes. Taken together, these findings suggest that Acmvl plays a role in the nurse–forager transition of A. c. cerana. [ABSTRACT FROM AUTHOR]

Correct gustatory recognition and selection of foods both within and outside the hive by honey bee workers are fundamental to the maintenance of colonies. The tarsal chemosensilla located on the legs of workers are sensitive to nonvolatile compounds and proposed to be involved in gustatory detection. However, little is known about the molecular mechanisms underlying the gustatory recognition of foods in honey bees. In the present study, RNA-seq was performed with RNA samples extracted from the legs of 1-, 10-, and 20-d-old workers of Apis cerana cerana Fabricius, a dominant indigenous crop pollinator with a keen perception ability for phytochemicals. A total of 124 candidate chemosensory proteins (CSPs), including 15 odorant-binding proteins (OBPs), 5 CSPs, 7 gustatory receptors (GRs), 2 sensory neuron membrane proteins (SNMPs), and 95 odorant receptors (ORs), were identified from the assembled leg transcriptome. In silico analysis of expression showed that 36 of them were differentially expressed among the three different ages of A. c. cerana workers. Overall, the genes encoding OBPs and CSPs had great but extremely variable FPKM values and thus were highly expressed in the legs of workers, whereas the genes encoding ORs, GRs, and SNMPs (except SNMP2) were expressed at low levels. Tissue-specific expression patterns indicated that two upregulated genes, AcerOBP 15 and AcerCSP 3, were predominately expressed in the legs of 20-d-old foragers, suggesting they may play an essential role in gustatory recognition and selection of plant nectars and pollens. This study lays a foundation for further research on the feeding preferences of honey bees. [ABSTRACT FROM AUTHOR]

The ambient temperature and relative humidity affect the metabolic and physiological responses of bees, thus affecting their life activities. However, the physiological changes in bee due to high temperature and high humidity remain poorly understood. In this study, we explored the effects of higher temperature and humidity on the epiphysiology of bees by evaluating the survival, tolerance and body water loss in two bee species (Apis cerana and Apis mellifera). We also evaluated the changes in the activity of antioxidant and detoxification enzymes in their body. We observed that under higher temperature and humidity conditions, the survival rate of A. mellifera was higher than that of A. cerana. On the other hand, a comparison of water loss between the two species revealed that A. mellifera lost more water. However, under extremely high temperature conditions, A. cerana was more tolerant than A. mellifera. Moreover, under higher temperature and humidity conditions, the activity of antioxidant and detoxification enzymes in bees was significantly increased. Overall, these results suggest that high temperatures can adversely affect bees. They not only affect the survival and water loss, but also stimulate oxidative stress in bees. However, unlike our previous understanding, high humidity can also adversely affect bees, although its effects are lower than that of temperature. [ABSTRACT FROM AUTHOR]

One important concern regarding the use of transgenic cotton expressing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) is its potential detrimental effect on non-target organisms. The honey bee ( Apis mellifera ) is the most important pollinator species worldwide and it is directly exposed to transgenic crops by the consumption of genetically modified (GM) pollen. However, the potential effects of Bt cotton on A. mellifera remain unclear. In the present study, we assessed the effects of two Bt cotton varieties; ZMSJ expressing the Cry1Ac and Cry2Ab insecticidal proteins, and ZMKCKC producing Cry1Ac and EPSPS, on A. mellifera . Feeding on pollen from two Bt cotton varieties led to detection of low levels of Cry toxins (<10 ng/g fresh weight) in the midgut of A. mellifera adults, yet expression of detoxification genes did not change significantly compared to feeding on non-Bt cotton. Binding assays showed no Cry1Ac or Cry2Ab binding to midgut brush border membrane proteins from A. mellifera adults. Taken together, these results support minimal risk for potential negative effects on A. mellifera by exposure to Bt cotton. [ABSTRACT FROM AUTHOR]

Transgenic insect-resistant cotton (Bt cotton) has been extensively planted in China, but its effects on non-targeted insect species such as the economically important honey bee (Apis mellifera) and silkworm (Bombyx mori) currently are unknown. In this study, pollen from two Bt cotton cultivars, one expressing Cry1Ac/EPSPS and the other expressing Cry1Ac/Cry2Ab, were used to evaluate the effects of Bt cotton on adult honey bees and silkworm larvae. Laboratory feeding studies showed no adverse effects on the survival, cumulative consumption, and total hemocyte count (THC) of A. mellifera fed with Bt pollen for 7 days. No effects on the survival or development of B. mori larvae were observed either. A marginally significant difference between Cry1Ac/Cry2Ab cotton and the conventional cotton on the THC of the 3rd day of 5thB. mori instar larvae was observed only at the two highest pollen densities (approximately 900 and 8000 grains/cm2), which are much higher than the pollen deposition that occurs under normal field conditions. The results of this study show that pollen of the tested Bt cotton varieties carried no lethal or sublethal risk for A. mellifera, and the risk for B. mori was negligible. [ABSTRACT FROM AUTHOR]

Simple Summary: Apis mellifera is one of the most important pollinator communities in nature. Insecticide residues in pollen and nectar, due to their wide use, may harm bees. Thus, it is crucial to provide novel insights into the effects of neonicotinoid insecticides on pollinators for protecting bees and maintaining a long-term stable ecological environment. The aim of our study was to investigate the effect and the mechanisms underlying bees impaired by dinotefuran. In the present study, for the first time, we found the mRNA expression profile of bees changes after treatment with sublethal doses of dinotefuran. Overall, our findings enhance understanding of the molecular mechanisms that underly physiological and behavioural damage for bees after dinotefuran exposure. The decreasing number of bees is a global ecological problem. With the advancement of agricultural modernisation, the large-scale use of neonicotinoid insecticides is one of the main factors leading to the decline of bees. The aim of the present study was to investigate the effect and the mechanisms underlying bees impaired by dinotefuran. Acute (48 h) oral toxicity tests showed that a 5% lethal concentration (LC5) was 0.220 mg/L, and a 20% lethal concentration (LC20) was 0.458 mg/L. The gene expression profile shows that when compared with the control group, the LC5 group induced 206 significantly upregulated, differentially expressed genes (DEGs) and 363 significantly downregulated DEGs, while the LC20 group induced 180 significantly upregulated DEGs and 419 significantly downregulated DEGs. Significantly, transcriptomic analysis revealed DEGs involved in immunity, detoxification, and the nervous system, such as antimicrobial peptides, vitellogenin, synaptotagmin-10, AChE-2, and nAChRa9. Furthermore, Gene Ontology (GO) annotation and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis revealed that DEGs were enriched in amino acid and fatty acid biosynthesis and metabolism pathways. Collectively, our findings will help clarify the deleterious physiological and behavioural impacts of dinotefuran on bees and provide a basis for future research on the mechanisms underlying bees impaired by dinotefuran. [ABSTRACT FROM AUTHOR]

Simple Summary: Pollinators adjust their foraging preference based on the pollen cues of foraging plants. Honey bees, for example, prefer to collect one type of pollen from plants that bloom at the same time. In northern China, apricot and pear trees are the two main foraging plants in the early spring. However, honey bees tend to collect pollen from apricot trees. It is interesting to understand what affects the foraging decision of honey bees regarding these two pollen types. In this study, we observed the foraging preference of Apis mellifera workers with respect to apricot and pear pollen under laboratory conditions. The effect of pollen on the development of the hypopharyngeal gland (HG) and ovary was measured. The number of visits made to apricot pollen was significantly higher than that to pear pollen. Furthermore, the response of the HG and ovary to these two pollens was different. The development of the HG was significantly affected by pollen diet treatments. However, there was no significant difference in the ovarian development of caged workers supplied with the two different pollen diets. Overall, honey bees showed a significant preference for apricot pollen over pear pollen. Compared with the ovary, the HG of honey bee workers may be more sensitive to pollen nutrition. With the availability of various plants in bloom simultaneously, honey bees prefer to collect some pollen types over others. To better understand pollen's role as a reward for workers, we compared the digestibility and nutritional value of two pollen diets, namely, pear (Pyrus bretschneideri Rehd.) and apricot (Armeniaca sibirica L.). We investigated the visits, pollen consumption, and pollen extraction efficiency of caged Apis mellifera workers. Newly emerged workers were reared, and the effects of two pollen diets on their physiological status (the development of hypopharyngeal glands and ovaries) were compared. The choice-test experiments indicated a significant preference of A. mellifera workers for apricot pollen diets over pear pollen diets (number of bees landing, 29.5 ± 8.11 and 9.25 ± 5.10, p < 0.001 and pollen consumption, 0.052 ± 0.026 g/day and 0.033 ± 0.013 g/day, p < 0.05). Both pollen diets had comparable extraction efficiencies (67.63% for pear pollen and 67.73% for apricot pollen). Caged workers fed different pollen diets also exhibited similar ovarian development (p > 0.05). However, workers fed apricot pollen had significantly larger hypopharyngeal glands than those fed pear pollen (p < 0.001). Our results indicated that the benefits conferred to honey bees by different pollen diets may influence their foraging preference. [ABSTRACT FROM AUTHOR]

Honeybees are prone to poisoning after collecting jujube nectar during the jujube flowering period ('honeybee's jujube flower disease'). To explore the mechanism of honeybee poisoning, the gut microbiota of honeybees undergoing the disease were characterised based on amplicon sequencing of the 16 S rRNA gene. Our results showed that the composition and diversity of the gut microbiota were significantly altered in diseased honeybees. We observed a decrease in the relative abundance of Proteobacteria and increased abundances of Firmicutes and Actinobacteria in the midgut and hindgut of diseased honeybees. Moreover, linear discriminant analysis (LDA) effect size revealed significantly selected enrichment of Fructobacillus and Snodgrassella in the midguts from diseased honeybees and Lactobacillus , Bifidobacterium , and Snodgrassella in the hindguts from diseased honeybees. Tax4Fun anylasis indicated that the functional potential of the diseased honeybee gut bacterial community was significantly changed relative to the healthy honeybee. Carbohydrate metabolism, nucleotides metabolism, amino acid synthesis metabolism, coenzyme and vitamins metabolism were increased, while energy metabolism and xenobiotic biodegradation and metabolism were decreased in the diseased honeybees. These results provide a new perspective for evaluating the response of honeybees to jujube flower disease based on changes in the intestinal microflora. Image 1 • The gut microbiota composition and diversity of honeybee undergoing jujube flower disease were significantly altered. • There were shifts in the community functional potential in the diseased honeybees. • These microbial imbalances or alterations may cause functional changes, eventually affect honeybee health. [ABSTRACT FROM AUTHOR]

Temperature and humidity are the most important factors affecting the growth, reproduction, and survival of bees. Apis mellifera are important pollinating bees that are widely used in agricultural systems. However, the higher temperatures and humidity in greenhouses are not conducive to the survival of bees. Although previous research has revealed the behavioral responses and physiological mechanisms of honeybees to adapt to high temperature and humidity, there are few data on the exact molecular mechanisms involved. In our study, we investigated gene expression in A. mellifera under different temperature and humidity treatments, using transcriptomic analysis to identify differentially expressed genes (DEGs) and relevant biological processes. Based on the transcriptomic results, we selected several genes with significant differences in expression, and detected the expression patterns of these genes at different temperatures or humidity or different treatment times by q-RT PCR. In the high temperature treatments, 434 DEGs were identified; in the high humidity treatments, 86 DEGs were identified; in the combined high temperature and humidity treatments, 266 DEGs were identified. Analysis results showed that DEGs were enriched in pathways related to amino acid and fatty acid biosynthesis and metabolism under each treatment. In addition, heat shock proteins, zinc finger proteins, serine/threonine-protein kinases, and antioxidase were differentially expressed between the different treatments. The results of the q-RT PCR showed that the expression levels of these genes increased with increasing temperature and over treatment time. Our findings provide a general expression profile of the adaptive expression of heat-resistance genes responding to high temperature and high humidity in A. mellifera , including the expression patterns of several DEGs. Our data provide a basis for future research on the mechanisms underlying the adaptation of insects to high temperature and humidity. Image 1 • High temperature and humidity negatively affect growth, reproduction, and survival of bees. • Differential expression of heat shock, zinc finger, and serine/threonine protein kinase genes observed. • Hsp is most sensitive to high temperature, and other genes are only highly expressed at 45 °C. [ABSTRACT FROM AUTHOR]