Adult Bees Research Articles

Detection and quantification of Melissococcus plutonius in honey bee workers exposed to European foulbrood in Czechia through conventional PCR, qPCR, and barcode sequencing

Melissococcus plutonius is the causative agent of European foulbrood (EFB), an important bacterial disease of honey bee larvae, and various methods have been developed for the detection of this disease. Adult bees are not affected but spread M. plutonius among beehives and serve as a diagnostic tool to detect EFB. Melissococcus plutonius detection based on conventional polymerase chain reaction (PCR) (16S DNA), qPCR (sodA), and barcode sequencing of the 16S RNA V4 region in worker bees from colonies with and without clinical symptoms were compared. We validated these detection tools in terms of the presence/absence of clinical signs of the disease. The comparison of the PCR- and qPCR-based methods showed their usability for confirmation of the disease in both colonies with and without clinical symptoms. Our results revealed that qPCR was more suitable for the confirmation of clinical EFB than conventional PCR and that conventional PCR was better for general screening, including the screening of asymptomatic colonies, than qPCR. Redundancy analyses (tbRDAs) of the microbiome composition showed that the detection limit-based qPCR of M. plutonius revealed a greater variability in the microbiome profiles of worker bees compared with that explained by clinical signs of the disease and PCR detection as factors. The presence of “secondary invaders” (Paenibacillus alvei and Enterococcus) was positively correlated with an increase in the profile of M. plutonius in the worker bee microbiome, whereas Apibacter adventoris and Bartonella apis were negatively correlated. Both types of correlations were found among Lactobacilli.

A molecular clone of Chronic Bee Paralysis Virus (CBPV) causes mortality in honey bee pupae (Apis mellifera)

Among the many diseases compromising the well-being of the honey bee (Apis mellifera) the chronic paralysis syndrome of adult honey bees is one of the best described. The causative agent, chronic bee paralysis virus (CBPV), is a positive sense, single-stranded RNA virus with a segmented genome. Segment 1 encodes three putative open reading frames (ORFs), including the RNA-dependent RNA polymerase and other non-structural protein coding regions. Segment 2 encodes four putative ORFs, which contain the genes of supposed structural proteins. In this study, we established a reverse genetic system for CBPV by molecular cloning of DNA copies of both genome segments. CBPV rescue was studied in imago and honey bee pupae infection models. Virus replication and progeny virus production was only initiated when capped RNAs of both genome segments were injected in honey bees. As injection of these clonal RNAs caused clinical symptoms similar to wild-type CBPV infection, we conclude that the novel molecular clone fulfilled Koch’s postulates. Our virus clone will enable in-depth analysis of CBPV pathogenesis and help to increase knowledge about this important honey bee disease.

Lethal and Histological Effects of Neonicotinoids Insecticides on Apis mellifera (Hymenoptera, Apiadae)

Using of Neonicotinoids insecticides affect honeybees that visit field and horticultural crops for collecting nectar and pollen. Therefore, this investigation aimed to study the effect of three neonicotinoids insecticides (Imidacloprid, Acetamiprid and Dinotefuran,) with three (recommended, half, and quarter) doses on mortality rate of adult bees, also their effect on midgut tissues under laboratory conditions. The obtained results showed that a highly mortality% was recorded in Dinotefuran 100% after 48hr, while Acetamiprid revealed the lowest mortality% as 56, 51 and 33% with recommended, half and quarter dose, respectively. Imidacloprid recorded 81, 79 and 74% mortality for recommended, half and quarter dose, respectively. On the other hand, there was mild vacuolar degeneration with nucleus pyknosis in some cells in the lining mucosal epithelium of minimum concentration half recommended dose of Imidacloprid. Also, there was moderate proliferation of cells lining midgut with increasing number of goblet cells of the quarter recommended dose of Acetamiprid.It could be concluded that Dinotefuran is very dangerous and lethal on bees.

Exposure of honey bee larvae to thiamethoxam and its interaction with Nosema ceranae infection in adult honey bees

During their lifetime honey bees (Apis mellifera) rarely experience optimal conditions. Sometimes, a simultaneous action of multiple stressors, natural and chemical, results in even greater effect than of any stressor alone. Therefore, integrative investigations of different factors affecting honey bees have to be carried out. In this study, adult honey bees exposed to thiamethoxam in larval and/or adult stage and infected with Nosema ceranae were examined. Newly emerged bees from colonies, non-treated or treated with thiamethoxam, were organized in six groups and kept in cages. Thiamethoxam treated bees were further exposed to either thiamethoxam or Nosema (groups TT and TN), or simultaneously to both (group TTN). Newly emerged bees from non-treated colonies were exposed to Nosema (group CN). From both, treated and non-treated colonies two groups were organized and further fed only with sugar solution (groups C and TC). Here, we present the expression profile of 19 genes in adult worker honey bees comprising those involved in immune, detoxification, development and apoptosis response. Results showed that gene expression patterns changed with time and depended on the treatment. In group TC at the time of emergence the majority of tested genes were downregulated, among which nine were significantly altered. The same gene pattern was observed on day six, where the only significantly upregulated gene was defensin-1. On day nine most of analyzed genes in all experimental groups showed upregulation compared to control group, where upregulation of antimicrobial peptide genes abaecin, defensin-1 and defensin-2 was significant in groups TT and TTN. On day 15 we observed a similar pattern of expression in groups TC and TT exposed to thiamethoxam only, where most of the detoxification genes were downregulated. Additionally RNA loads of Nosema and honey bee viruses were recorded. We detected a synergistic interaction of thiamethoxam and Nosema, reflected in lowest honey bee survival.

An interaction between host and microbe genotypes determines colonization success of a key bumble bee gut microbiota member.

There has been a proliferation of studies demonstrating an organism's health is influenced by its microbiota. However, factors influencing beneficial microbe colonization and the evolution of these relationships remain understudied relative to host-pathogen interactions. Vertically transmitted beneficial microbes are predicted to show high levels of specificity in colonization, including genotype matching, which may transpire through coevolution. We investigate how host and bacterial genotypes influence colonization of a core coevolved microbiota member in bumble bees. The hindgut colonizing Snodgrassella alvi confers direct benefits, but, as an early colonizer, also facilitates the further development of a healthy microbiota. Due to predominantly vertical transmission promoting tight evolution between colonization factors of bacteria and host lineages, we predict that genotype-by-genotype interactions will determine successful colonization. Germ-free adult bees from seven bumble bee colonies (host genotypic units) were inoculated with one of six genetically distinct strains of S. alvi. Subsequent colonization within host and microbe genotypes combinations ranged from 0 to 100%, and an interaction between host and microbe genotypes determined colonization success. This novel finding of a genotype-by-genotype interaction determining colonization in an animal host-beneficial microbe system has implications for the ecological and evolutionary dynamics of host and microbe, including associated host-fitness benefits.

Flumethrin at sublethal concentrations induces stresses in adult honey bees (Apis mellifera L.)

Flumethrin is a typical pyrethroid varroacide widely used for mite control in beekeeping worldwide. Currently, information on the toxicological characteristics of flumethrin on bees at sublethal concentrations is still lacking. To fill this gap in information, we performed a 48-h acute oral and 14-day chronic toxicity testing of flumethrin in newly emerged adult honey bees under laboratory conditions. Results showed that flumethrin had high acute toxicity to honey bees with a 48-h LD50 of 0.47 µg/bee (95% CI, 0.39 ∼ 0.57 µg/bee), which is higher than that of many other commercial pyrethroid insecticides, but lower than that of tau-fluvalinate. After 14 days of chronic exposure to flumethrin at 0.01, 0.10, and 1.0 mg/L, significant antioxidant response, detoxification, immune reaction, and apoptosis were observed in the midguts. These findings indicated that flumethrin had potential risks to bees, and it can disturb the homeostasis of bees at sublethal concentrations under longer exposure conditions. Flumethrin is highly lipophilic and easy to accumulate in beeswax; thus, careless practices might pose risks to colony development in commercial beekeeping and native populations. This laboratory study can serve as an early warning, and further studies are required to understand the real residual level of flumethrin in bees and the risks of flumethrin in field condition.

Effect of Abscisic Acid (ABA) Combined with Two Different Beekeeping Nutritional Strategies to Confront Overwintering: Studies on Honey Bees' Population Dynamics and Nosemosis.

In temperate climates, beekeeping operations suffer colony losses and colony depopulation of Apis mellifera during overwintering, which are associated with biotic and abiotic stressors that impact bees’ health. In this work, we evaluate the impacts of abscisic acid (ABA) dietary supplementation on honey bee colonies kept in Langstroth hives. The effects of ABA were evaluated in combination with two different beekeeping nutritional strategies to confront overwintering: “honey management” and “syrup management”. Specifically, we evaluated strength parameters of honey bee colonies (adult bee and brood population) and the population dynamics of Nosema (prevalence and intensity) associated with both nutritional systems and ABA supplementation during the whole study (late autumn-winter-early spring). The entire experiment was designed and performed with a local group of beekeepers, “Azahares del sudeste”, who showed interest in answering problems associated with the management of honey bee colonies during the winter. The results indicated that the ABA supplementation had positive effects on the population dynamics of the A. mellifera colonies during overwintering and on the nosemosis at colony level (prevalence) in both nutritional strategies evaluated.

Acaricide efficacy and honey bee toxicity of three new formic acid-based products to control Varroa destructor

The replacement of synthetic acaricides with organic treatments is a big challenge in modern beekeeping. In summer 2015, we carried out in Central Italy a study to compare the varroacide efficacy and the toxicity on honey bees of the formic acid evaporator Nassenheider Professional® with two new formic acid-based gel formulations: MAQS® and Varterminator®. In the same apiary with 32 colonies, four homogeneous groups with eight hives each were prepared. The mean acaricide efficacy of Nassenheider Professional® was 73.2 ± 12.5%, while MAQS® and Varterminator® showed a mean efficacy of 49.3 ± 14.9 and 81.2 ± 16.0%, respectively. Colonies showed a statistically significant reduction of adult bees only after the MAQS® treatment with respect to the control group. All the treatments showed absent or quite moderate queen mortality (MAQS® and in Varterminator® groups 12.5%, Nassenheider professional®, and control groups 0%). Our study indicates that Nassenheider Professional® and Varterminator® may represent a sustainable and effective solution to control mite infestation during summer in temperate areas.

A country-wide survey of Varroa destructor, an ectoparasitic mite of honey bees, in Nigeria: a preliminary report

Through a country-wide survey, the present study aimed at investigating the extent of the spread of Varroa destructor in Nigeria. To this end, a total of 122 Apis mellifera colonies from 13 localities were sampled in regions without previous assessment of the mite. Infestation and prevalence rates were estimated using the soap washing method. Varroa mites were found in 87% of the sampled colonies with a parasitic load ranging from 0.20 to 16.35 mites per 100 adult bees per colony. Given the presence of the mite with a very high prevalence in all the sampled localities and the fact that each of the states from which the mite is not yet reported is next to at least one occupied state, it is very likely that V. destructor spread throughout Nigeria. Future molecular analyses can evaluate whether V. destructor in Nigeria stems from a single source or additional introductions.

Effectiveness of the smoke of fruits of Guazuma ulmifolia (Sterculiaceae) and vapors of Thymol for control of Varroa destructor infesting Africanized bees

Se evaluó la eficacia del humo de los frutos secos de Guazuma ulmifolia y los vapores de timol en el control del ácaro Varroa destructor infestando colonias de abejas africanizadas (Apis mellifera) de Yucatán. Se utilizaron tres tratamientos: Grupo 1 (G1), las colonias de abejas recibieron 5 a 8 bocanadas de humo de los frutos secos de G. ulmifolia dos veces por semana, durante un período de tres semanas; Grupo 2 (G2), las colonias recibieron 4-8 g de cristales de timol con tres aplicaciones cada siete días, y Grupo 3 (G3 o grupo control) las colonias no recibieron ningún tratamiento durante las tres semanas del experimento. Se colectaron 200 a 300 abejas adultas de cada colonia previo a la aplicación de los tratamientos (día 0) y a los 7, 14 y 21 días después de las aplicaciones, con la finalidad de determinar los niveles de infestación y eficacia de los tratamientos. Los resultados indican que los niveles de infestación de V. destructor en las abejas adultas disminuyeron al final del experimento (21 días) y fueron estadísticamente diferentes para los tres tratamientos, siendo menor para G2. La eficacia al final de los tratamientos fue de 41 y 69 %, para G1 y G2, respectivamente. Estos resultados corroboran que la aplicación de cristales de timol es una alternativa para el control del ácaro V. destructor en Yucatán, y que la aplicación del humo de los frutos secos de G. ulmifolia reduce los niveles de infestación de este parásito en comparación con las colonias que no recibieron ningún tipo de tratamiento (G3).

Feeding by Tropilaelaps mercedesae on pre- and post-capped brood increases damage to Apis mellifera colonies

Tropilaelaps mercedesae parasitism can cause Apis mellifera colony mortality in Asia. Here, we report for the first time that tropilaelaps mites feed on both pre- and post-capped stages of honey bees. Feeding on pre-capped brood may extend their survival outside capped brood cells, especially in areas where brood production is year-round. In this study, we examined the types of injury inflicted by tropilaelaps mites on different stages of honey bees, the survival of adult honey bees, and level of honey bee viruses in 4th instar larvae and prepupae. The injuries inflicted on different developing honey bee stages were visualised by staining with trypan blue. Among pre-capped stages, 4th instar larvae sustained the highest number of wounds (4.6 ± 0.5/larva) while 2nd-3rd larval instars had at least two wounds. Consequently, wounds were evident on uninfested capped brood (5th-6th instar larvae = 3.91 ± 0.64 wounds; prepupae = 5.25 ± 0.73 wounds). Tropilaelaps mite infestations resulted in 3.4- and 6-fold increases in the number of wounds in 5th-6th instar larvae and prepupae as compared to uninfested capped brood, respectively. When wound-inflicted prepupae metamorphosed to white-eyed pupae, all wound scars disappeared with the exuviae. This healing of wounds contributed to the reduction of the number of wounds (≤10) observed on the different pupal stages. Transmission of mite-borne virus such as Deformed Wing Virus (DWV) was also enhanced by mites feeding on early larval stages. DWV and Black Queen Cell Virus (BQCV) were detected in all 4th instar larvae and prepupae analysed. However, viral levels were more pronounced in scarred 4th instar larvae and infested prepupae. The remarkably high numbers of wounds and viral load on scarred or infested developing honey bees may have caused significant weight loss and extensive injuries observed on the abdomen, wings, legs, proboscis and antennae of adult honey bees. Together, the survival of infested honey bees was significantly compromised. This study demonstrates the ability of tropilaelaps mites to inflict profound damage on A. mellifera hosts. Effective management approaches need to be developed to mitigate tropilaelaps mite problems.

Comprehensive Survey of Area-Wide Agricultural Pesticide Use in Southern United States Row Crops and Potential Impact on Honey Bee Colonies.

Honey bees forage across a large area, continually scouting the local landscape for ephemeral food resources. Beekeepers often rely on flowering plants in and around irrigated farmland to maintain their colonies during dry seasons, despite the potential risk of pesticide exposure. Recent declines in pollinator abundance and diversity have focused attention on the role of pesticides and their effects on honey bee health. This investigation examined two types of landscapes within a two-mile (3.2 km) radius of honey bee colonies: an intensive agricultural setting and a rural setting without intensive agriculture. More than 10,000 acres of agricultural land was surveyed to quantify the area of cultivated crops and the area treated with pesticides, including seed treatments and foliar applications of insecticides. Samples of honey, bee bread (stored pollen), beeswax, and adult bees were collected from hives in both landscape types and screened for pesticide residues to determine if foraging bees were transporting pesticides to hives. Some samples of bee bread and honey did contain pesticide residues, but these were below known lethal dose (LD50) levels for honey bees. Beeswax samples contained the highest levels of contamination, but most were still relatively low. Samples were screened for 174 common agricultural pesticides and metabolites, but only 26 compounds were detected during the two-year study. These included one defoliant, one insect growth regulator, five herbicides, six fungicides, six insecticides never used in beekeeping, and five insecticides/miticides and their metabolites, which are used in beekeeping and for various other agricultural purposes, as well as two miticides exclusively used by beekeepers to control Varroa destructor. Bee colonies foraging in agricultural landscapes are potentially exposed to numerous pesticide applications. While the residues detected in this study did not pose an acute lethal risk to adult honey bees, this study did not measure sublethal effects on bee colony health or performance, which merit further investigation.

POPULATION DYNAMICS OF ORIENTAL HORNET (Vespa orientalis L.) DURING ITS ACTIVITYSEASON IN THE APIARY THROUGHOUT THE DAY PERIODS

The current experiment was carried out in the Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Qualubia governorate, during the oriental hornet active season extended from September 1st until end of December, 2015, to estimate the daily counts of the oriental hornet (Vespa orientalis L.) as well as its population dynamics during its active season. The experimental apiary was contained twenty four honeybee colonies, each contented seven frames covered with adult bees and four frames of brood. The wasp’s traps were used for capturing the wasps during the day. The data indicated that, the total numbers of wasps caught in September were 204, 394 and 114 wasps/trap in the three periods, respectively. There were significant differences between all the tested periods where the highest population of wasps caught was during the noon period (12pm – 3pm) followed by the morning period (9am – 12pm), while the afternoon and evening period (3pm – 9am of next day) recorded the lowest population of wasps caught in the traps, the same trend was recorded in October and November months. It also summarized that, the average means of wasps captured for tested months were 8.79, 21.99, 13.42 and 1.10 wasps/trap for September, October, November and December 2015, respectively. The highest population of oriental hornet captured by the traps was recorded during October month, followed by November and September; meanwhile the population captured during December was the lowest, with significant deference between them. For daily count, the mean average numbers of wasps captured by the traps were 10.20, 17.55 and 6.22 wasps/trap for the three periods (9am – 12pm, 12pm – 3pm and 3pm – 9am of next day), respectively. The highest numbers of wasps captured by the traps were recorded during the noon period (12pm – 3pm) followed by morning period (9am – 12pm), meanwhile the afternoon and evening period (3pm – 9am of next day) recorded the lowest numbers of wasps captured by the traps, with significant deference between all the tested period. Overall the highest numbers of oriental hornet captured by wasp’s traps were recorded in October month during the noon period, 12pm – 3pm and averaged (33.15 wasps/trap), followed by November month during the same period 12pm – 3pm (20.50 wasps/trap).

Black queen cell virus and drifting of honey bee workers (Apis mellifera)

Social insects may accidentally drift into foreign nests due to orientation errors. Even though pathogens have been reported to promote drifting, no data currently exist about the potential impact of titers of the widespread black queen cell virus (BQCV) on the orientation abilities of honey bee workers, Apis mellifera. Here, we investigated titers of BQCV in naturally infected drifted and non-drifted workers. The data show significantly higher virus titers in the drifted workers (Wilcoxon rank sum test, P < 0.01). Our results suggest that high BQCV loads may compromise honey bee orientation, possibly by affecting learning performance similar to other viruses. If future work demonstrates that the correlation found here represents a causal relationship between higher viral titers and drifting, this will be the first identification of clinical symptoms of BQCV in adult honey bee hosts.

Adaptive morphology of the host-seeking first-instar larva of Stylops advarians Pierce (Strepsiptera, Stylopidae), a parasite of Andrena milwaukeensis Graenicher (Hymenoptera, Andrenidae)

The morphology of the prognathous, host-seeking first-instar larvae of Stylops advarians was examined to advance our understanding of their adaptations to reach immature bee hosts, a process requiring temporal phoresy on an adult bee. Sensory structures on the larval head, including eye spots and two pairs of olfactory pits, evidently assist recognition of an adult bee and eventual detection of a permanent host within a nest cell. First-instar larvae utilize various features of their appendages to travel securely on their phoretic host. Flexible adhesive tarsi of the pro- and mesothoracic legs allow them to embark and be retained on a flying bee. The tips of the pair of caudal filaments appear modified for a similar purpose. Spinulae of two lengths, and arranged in distinct patterns, cover the posterior edges of the thoracic and abdominal segments both dorsally and ventrally. These projections can cause lodging of larvae in the plumose hairs of the phoretic host, and may lock into the exine of pollen collected by the foraging bee. Discovery of a first-instar larva partially packed into a pollen load and in the crop of Andrena milwaukeensis demonstrates that Stylops is adapted to travel with a phoretic host both externally and internally.

Expression of heat shock proteins in adult honey bee (Apis mellifera L.) workers under hot-arid subtropical ecosystems.

Heat stress elicits the expression of heat shock proteins (HSPs) in honey bee subspecies. These highly conserved proteins have significant role in protecting cells from thermal-induced stresses. Honey bees in subtropical regions face extremely dry and hot environment. The expression of HSPs in the nurses and foragers of indigenous (Apis mellifera jemenitica) and imported European (Apis mellifera ligustica and Apis mellifera carnica) honey bee subspecies after heat shock treatment were compared using SDS-PAGE. Hsp70 and Hsp82 were equally expressed in the nurses of all tested bee subspecies when exposed to 40 °C and 45 °C for 4 h. The forager bees exhibited differential expression of HSPs after heat stress. No HSPs was expressed in the foragers of A. m. jemenitica, and Hsp70 was expressed only in the foragers of A. m. ligustica and A. m. carnica at 40 °C. A prominent diversity in HSPs expression was also exhibited in the foragers at 45 °C with one HSP (Hsp70) in A. m. jemenitica, two HSPs (Hsp40 and Hsp70) in A. m. carnica, and three HSPs (Hsp40, Hsp60 and Hsp70) in A. m. ligustica. No HSPs was expressed in the control nurse and forager bees at any of the tested temperatures. These findings illustrated the differences in HSP expression among nurse and forager bees. It is obvious that the native foragers are more heat tolerant with least HSPs expression than exotic bee races. Further investigations will help to understand the potential role of HSPs in the adaptability, survival, and performance of bee subspecies in harsh climate of the subtropical regions.

Adaptations during Maturation in an Identified Honeybee Interneuron Responsive to Waggle Dance Vibration Signals.

Honeybees are social insects, and individual bees take on different social roles as they mature, performing a multitude of tasks that involve multi-modal sensory integration. Several activities vital for foraging, like flight and waggle dance communication, involve sensing air vibrations through their antennae. We investigated changes in the identified vibration-sensitive interneuron DL-Int-1 in the honeybee Apis mellifera during maturation by comparing properties of neurons from newly emerged adult and forager honeybees. Although comparison of morphological reconstructions of the neurons revealed no significant changes in gross dendritic features, consistent and region-dependent changes were found in dendritic density. Comparison of electrophysiological properties showed an increase in the firing rate differences between stimulus and nonstimulus periods in foragers compared with newly emerged adult bees. The observed differences in neurons of foragers compared with newly emerged adult honeybees suggest refined connectivity, improved signal propagation, and enhancement of response features possibly important for the network processing of air vibration signals relevant for the waggle dance communication of honeybees.

Pruned petioles of papaya as nesting sites of the leafcutting bee, Megachile laticeps Smith and its pollen fidelity

The nest selection and pollen fidelity of the leafcutting bee, Megachile laticeps was studied. Mature and nearly dry petioles of papaya were pruned to simulate hollow stems of other plants to attract females of M. laticeps for construction of its nest. The nest occupancy and adult emergence rate were 64.70% and 89.07% respectively, with an average of 12.7 ± 2.11 cells per nest. Scopal pollen loads from foraging adult female bees were removed and identified to the lowest taxonomic level possible. Pigeon pea, sunnhemp, and field bean pollen (Fabaceae) made up on an average of 54% of total pollen grains carried in the scopae of adult female bees. Nest pollen analysis indicated that Fabaceae pollen was the most prevalent in the brood provision. M. laticeps in a farm landscape utilized the pruned hollow petioles of standing papaya plant and local floral resources. This behavior shows the importance of pollinator species’ characteristics for developing conservation strategies to enhance pollination services in agro-ecosystems.

Effects of chronic dietary thiamethoxam andprothioconazole exposure on Apis mellifera worker adults and brood.

Chronic exposure of honey bees (Apis mellifera Linnaeus) to the neonicotinoid thiamethoxam and the fungicide prothioconazole is common during foraging in agricultural landscapes. We evaluated the survival and hypopharyngeal gland development of adult worker honey bees, and the survival of the worker brood when chronically exposed to thiamethoxam or thiamethoxam and prothioconazole in combination. We found that 30 days of exposure to 40 μg kg-1 of thiamethoxam significantly (P< 0.001) increased the frequency of death in worker adults by four times relative to solvent control. The worker brood required 23 times higher doses of thiamethoxam (1 mg L-1 or 909 μg kg-1 ) before a significant (P= 0.04), 3.9 times increase in frequency of death was observed relative to solvent control. No additive effects of simultaneous exposure of worker adults or brood to thiamethoxam and prothioconazole were observed. At day 8 and day 12, the hypopharyngeal gland acinar diameter was not significantly different (P> 0.05) between controls and adult workers exposed to thiamethoxam and/or prothioconazole. These results indicate that chronic exposure to field-realistic doses of thiamethoxam and/or prothioconazole are unlikely to affect the survival of adult workers and brood. © 2019 Society of Chemical Industry.

2D-DIGE proteomic analysis reveals changes in haemolymph proteome of 1-day-old honey bee (Apis mellifera) workers in response to infection with Varroa destructor mites

Varroa destructor is an external parasite of Apis mellifera and feeds on the haemolymph of pupae and adult bees, vectoring numerous viral pathogens, in particular the deformed wing virus (DWV). However, the changes in haemolymph protein composition after Varroa infestation are unknown. The objective of this study was to investigate alterations in the haemolymph proteome in relation to Varroa parasitism. Using two-dimensional difference gel electrophoresis and MALDI-TOF/TOF mass spectrometry, we identified changes in 44 haemolymph proteins in response to the parasite and one in protein originated from DWV. The following pathways were affected by Varroa infestation, including carbohydrate metabolism, detoxification and oxidative stress response, nutrient reservoir activity, oxidoreductase activity and the olfactory system. Several physiological functions of honey bees, such as energy metabolism, detoxification, metamorphosis and chemosensing, may be disrupted by Varroa.