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Ants are ubiquitous and eusocial insects that exhibit frequent physical contact among colony members, thereby increasing their susceptibility to diseases. Some species are often found in beehives and in their surroundings, where they exploit the food resources of honey bees. This intricate relationship may facilitate the interspecific transmission of honey bee pathogens to ants, although ants themselves may contribute to spillback phenomena. The objective of this study was to assess the presence and abundance of honey bee pathogens in ants sampled from Italian apiaries. A total of 37 colonies within 24 apiaries across 7 regions were monitored. In total, 6 pathogens were detected in adult ants and 3 in the brood. In particular, the study revealed a high prevalence of honey bee pathogens in ants, with DWV, BQCV, and CBPV being the most commonly encountered. The brood also tested positive for the same viruses. Notably, all analyzed viruses were found to be replicative in both adult ants and ant broods. Furthermore, co-infections were prevalent, suggesting complex pathogen interactions within ant populations. Statistical analysis indicated significant differences in pathogen prevalence and abundance among ant species and sample types. The findings highlight active infection in both the ants and the brood, suggesting a potential role of ants as reservoir hosts and vectors of honey bee pathogens emphasizing the need for further research to understand the implications of interspecific pathogen transmission on ant and bee health.

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BACKGROUND: The yellow-legged hornet (Vespa velutina nigrithorax) is a predatory species native to South-East Asia. The hornet is invasive in Europe, spreading to several countries and becoming a pest for Apis mellifera due to its behaviour of preying in front of apiaries. The aim of this study was (i) to investigate the presence of honey bee pathogens within the developmental stages of V. velutina after neutralizing a nest in Bologna province (Emilia-Romagna, Italy) and (ii) to analyze the mitochondrial DNA to determine if the population derived from the population initially introduced in Europe. RESULTS: The results indicated that deformed wing virus (82.76%) and Nosema ceranae (67.28%) were the most prevalent pathogens. Deformed wing virus, N. ceranae and sacbrood virus were found in all investigated stages, while chronic bee paralysis virus and Kashmir bee virus were exclusively found in foraging adults. All detected viruses were found to be replicative, highlighting active infection in the hosts. The mtDNA analysis demonstrated that the origin derived from the invasive population arrived in France. CONCLUSION: This study underscores the importance of further research to understand the effect of interspecific transmission, especially concerning the potential role of these pathogens as a biocontrol for the invasive V. velutina nigrithorax. © 2024 Society of Chemical Industry.

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Honey bees (Apis mellifera) play a crucial role in agriculture through their pollination activities. However, they have faced significant health challenges over the past decades that can limit colony performance and even lead to collapse. A primary culprit is the parasitic mite Varroa destructor, known for transmitting harmful bee viruses. Among these viruses is deformed wing virus (DWV), which impacts bee pupae during their development, resulting in either pupal demise or in the emergence of crippled adult bees. In this study, we focused on DWV master variant B. DWV-B prevalence has risen sharply in recent decades and appears to be outcompeting variant A of DWV. We generated a molecular clone of a typical DWV-B strain to compare it with our established DWV-A clone, examining RNA replication, protein expression, and virulence. Initially, we analyzed the genome using RACE-PCR and RT-PCR techniques. Subsequently, we conducted full-genome RT-PCR and inserted the complete viral cDNA into a bacterial plasmid backbone. Phylogenetic comparisons with available full-length sequences were performed, followed by functional analyses using a live bee pupae model. Upon the transfection of in vitro-transcribed RNA, bee pupae exhibited symptoms of DWV infection, with detectable viral protein expression and stable RNA replication observed in subsequent virus passages. The DWV-B clone displayed a lower virulence compared to the DWV-A clone after the transfection of synthetic RNA, as evidenced by a reduced pupal mortality rate of only 20% compared to 80% in the case of DWV-A and a lack of malformations in 50% of the emerging bees. Comparable results were observed in experiments with low infection doses of the passaged virus clones. In these tests, 90% of bees infected with DWV-B showed no clinical symptoms, while 100% of pupae infected with DWV-A died. However, at high infection doses, both DWV-A and DWV-B caused mortality rates exceeding 90%. Taken together, we have generated an authentic virus clone of DWV-B and characterized it in animal experiments.

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Viral infections can be detrimental to the foraging ability of the western honey bee, Apis mellifera. The deformed wing virus (DWV) is the most common honey bee virus and has been proposed as a possible cause of learning and memory impairment. However, evidence for this phenomenon so far has come from artificially infected bees, while less is known about the implications of natural infections with the virus. Using the proboscis extension reflex (PER), we uncovered no significant association between a simple associative learning task and natural DWV load. However, when assessed through a reversal associative learning assay, bees with higher DWV load performed better in the reversal learning phase. DWV is able to replicate in the honey bee mushroom bodies, where the GABAergic signalling pathway has an antagonistic effect on associative learning but is crucial for reversal learning. Hence, we assessed the pattern of expression of several GABA-related genes in bees with different learning responses. Intriguingly, mushroom body expression of selected genes was positively correlated with DWV load, but only for bees with good reversal learning performance. We hypothesise that DWV might improve olfactory learning performance by enhancing the GABAergic inhibition of responses to unrewarded stimuli, which is consistent with the behavioural patterns that we observed. However, at higher disease burdens, which might be induced by an artificial infection or by a severe, natural Varroa infestation, this DWV-associated increase in GABA signalling could impair associative learning as previously reported by other studies.

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In La Réunion, the established honeybee subspecies Apis mellifera unicolor, an endemic subspecies of African lineage, is facing considerable challenges. Since the introduction of the Varroa destructor mite in 2017 high colony losses have been recorded. We investigated the dynamics of V. destructor and two viruses, the Deformed Wing Virus (DWV), known to be transmitted by the mite, and the Chronic Bee Paralysis Virus (CBPV), in A. m. unicolor. Colonies from two apiaries located at 300 and 900 m a.s.l were monitored twice for one year without any acaricide treatment. The brood area, V. destructor infestation rates, DWV and CBPV prevalence and load were recorded monthly. A. m. unicolor maintained brood rearing throughout the year. Varroa destructor infestation resulted in high colony mortality (up to 85 %) and high phoretic mite rates (up to 52 mites per hundred bees). The establishment of DWV in colonies occurred after that of V. destructor and the mite infestation rate had a significant effect on the virus prevalence and load. CBPV appeared only transiently throughout the surveys. The data showed that, in tropical colonies with permanent brood rearing, V. destructor and DWV can reach high levels, but are still subject to seasonal variations that appear to be influenced by environmental conditions. This suggests that beekeeping practices could be adapted by favouring sites and periods for transhumance or acaricide treatment.

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The ectoparasitic mite Varroa destructor transmits and triggers viral infections that have deleterious effects on honey bee colonies worldwide. We performed a manipulative experiment in which worker bees collected at emergence were exposed to Varroa for 72 h, and their proteomes were compared with those of untreated control bees. Label-free quantitative proteomics identified 77 differentially expressed A. mellifera proteins (DEPs). In addition, viral proteins were identified by orthogonal analysis, and most importantly, Deformed wing virus (DWV) was found at high levels/intensity in Varroa-exposed bees. Pathway enrichment analysis suggested that the main pathways affected included peroxisomal metabolism, cyto-/exoskeleton reorganization, and cuticular proteins. Detailed examination of individual DEPs revealed that additional changes in DEPs were associated with peroxisomal function. In addition, the proteome data support the importance of TGF-ß signaling in Varroa-DWV interaction and the involvement of the mTORC1 and Hippo pathways. These results suggest that the effect of DWV on bees associated with Varroa feeding results in aberrant autophagy. In particular, autophagy is selectively modulated by peroxisomes, to which the observed proteome changes strongly corresponded. This study complements previous research with different study designs and suggests the importance of the peroxisome, which plays a key role in viral infections.

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Insect behavior is coordinated mainly by smell through the diverse odor-binding proteins (OBP) that allow them to identify and recognize their environment. Sensory information collected through smell is then analyzed and interpreted in the brain, allowing for correct insect functioning. The behavior of honeybees (Apis mellifera L.) can be affected by different pathogens, such as deformed wing virus (DWV). In particular, the DWV variant A (DWV-A) is capable of altering olfactory sensitivity and reducing the gene expression of different OBPs, including those associated with nursing behavior. The DWV is also capable of replicating itself in the sensory lobes of the brain, further compromising the processing of sensory information. This study evaluated the behavioral response of nurse honeybees exposed to a pheromone compound and the alterations in the gene expression of the pre- and post-synaptic neuronal genes neuroxins-1 and neurogilin-1 in the bee heads and OBP proteins in the antennae of nurse bees inoculated with DWV-A. The behavioral response of nurse bees exposed to the larval pheromone compound benzyl alcohol was analyzed using a Y-tube olfactometer. The viral load, the gene expression of OBP5 and OBP11 in antennae, and neuroxins-1 and neurogilin-1 in the bee heads were analyzed via qPCR. High viral loads significantly reduced the ability of 10- and 15-day-old nurse honeybees to choose the correct pheromone compound. Also, the gene expression of OBP5, OBP11, neuroxin-1, and neurogilin-1 in nurse honeybees decreased when they were highly infected with DWV-A. These results suggest that a DWV-A infection can disturb information processing and cause nursing honeybees to reduce their activity inside the hive, altering internal cohesion.

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A major threat to honey bee (Apis mellifera Linnaeus, Hymenoptera: Apidae) health continues to be parasitism by the mite Varroa destructor, which has been linked to high colony losses worldwide. Besides feeding on developing and adult bees, Varroa is also a prolific vector of honey bee-associated viruses. Because they live in unmanaged conditions, wild honey bee colonies are not treated against Varroa, which has enabled the natural selection of more mite-tolerant bees. To date, few studies have explored the prevalence of viruses in unmanaged colonies. The Welder Wildlife Refuge (WWR) in Texas is a unique site to study the viral landscape of unmanaged honey bees in the United States. The goals of this study were to identify and quantify viruses in wild colonies at the WWR, to examine changes in the prevalence of viruses in these colonies over time, and to compare the presence and titers of viruses between wild colonies at the WWR and those from the nearest managed apiary. We collected bees from colonies at the WWR in 2013, 2016, and 2021, and analyzed selected viruses for their presence and titers via quantitative polymerase chain reaction. In 2021, we also sampled bees from the nearest managed apiary for comparison. We found low average virus titers in all wild colonies sampled, and no difference in virus titers between colonies at the WWR and those from the managed apiary. Our study indicates that virus titers in wild colonies at the WWR are similar to those found in nearby colonies, and that these titers fluctuate over time.

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The deformed wing virus (DWV) belongs to the genus Iflavirus and the family Iflaviridae within the order Picornavirales. It is an important pathogen of the Western honey bee, Apis mellifera, causing major losses among honey bee colonies in association with the ectoparasitic mite Varroa destructor. Although DWV is one of the best-studied insect viruses, the mechanisms of viral replication and polyprotein processing have been poorly studied in the past. We investigated the processing of the protease-polymerase region at the C-terminus of the polyprotein in more detail using recombinant expression, novel serological reagents, and virus clone mutagenesis. Edman degradation of purified maturated polypeptides uncovered the C- and N-termini of the mature 3C-like (3CL) protease and RNA-dependent RNA polymerase (3DL, RdRp), respectively. Autocatalytic processing of the recombinant DWV 3CL protease occurred at P1 Q2118 and P1' G2119 (KPQ/GST) as well as P1 Q2393 and P1' S2394 (HAQ/SPS) cleavage sites. New monoclonal antibodies (Mab) detected the mature 3CL protease with an apparent molecular mass of 32 kDa, mature 3DL with an apparent molecular mass of 55 kDa as well as a dominant 3CDL precursor of 90 kDa in DWV infected honey bee pupae. The observed pattern corresponds well to data obtained via recombinant expression and N-terminal sequencing. Finally, we were able to show that 3CL protease activity and availability of the specific protease cleavage sites are essential for viral replication, protein synthesis, and establishment of infection using our molecular clone of DWV-A.

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The Oriental hornet (Vespa orientalis) is one of the major predators of honey bees. It has been demonstrated that adults of V. orientalis can harbor honey bee viruses, however the transmission route of infection is still not clear. The aim of this study was to study the possible presence of honey bee viruses in V. orientalis larvae and honey bees collected from the same apiary. Therefore, 29 samples of V. orientalis larvae and 2 pools of honey bee (Apis mellifera). samples were analyzed by multiplex PCR to detect the presence of six honeybee viruses: Acute Bee Paralysis Virus (ABPV), Black Queen Cell Virus (BQCV), Chronic Bee Paralysis Virus (CBPV), Deformed Wing Virus (DWV), Kashmir Bee Virus (KBV) and Sac Brood Virus (SBV). Biomolecular analysis of V. orientalis larvae revealed that DWV was present in 24/29 samples, SBV in 10/29, BQCV in 7/29 samples and ABPV in 5/29 samples, while no sample was found positive for CBPV or KBV. From biomolecular analysis of honey bee samples DWV was the most detected virus, followed by SBV, BQCV, ABPV. No honey bee sample was found positive for CBPV or KBV. Considering the overlapping of positivities between V.orientalis larvae and honey bee samples, and that V.orientalis larvae are fed insect proteins, preferably honey bees, we can suggest the acquisition of viral particles through the ingestion of infected bees. However, future studies are needed to confirm this hypothesis and rule out any other source of infection.

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Widespread native honey bee species in South and East Asia (Apis cerana, Apis dorsata and Apis florea) and the imported western honey bee (Apis mellifera) share habitats and potentially also share pathogens. Chief among the threats facing A. mellifera in Europe and North America is deformed wing virus (DWV), including its two principal genotypes: A and B (DWV-A and DWV-B respectively). Though DWV-A has been recorded in Asia's native Apis species, it is not known if DWV-B, or both DWV-A and DWV-B, are currently widespread in Asia and, if so, whether viral transmission is primarily intraspecific or interspecific. This study aims to fill these knowledge gaps by (i) determining the DWV genotype in four co-occurring Apis host species using qPCR and (ii) inferring viral transmission between them using nucleotide sequences of DWV from Apis host species collected at three independent localities in Northern Thailand. We found DWV-A and -B in all four Apis species, the exotic A. mellifera and the native A. cerana, A. dorsata and A. florea. That DWV-A sequences were identical across Apis species at the same locality, with a similar pattern for DWV-B sequences, suggests that DWV's epidemiology is largely driven by ongoing interspecific transmission (spillover) of DWV across co-occurring native and exotic Apis species. Both genotypes of DWV represent a serious threat to Asia's exotic and native honey bee species.

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Varroa destructor is an ectoparasitic mite of honeybees which vectors a range of pathogenic viruses, the most notable being Deformed wing virus (DWV). Mites parasitise bees during pupal development and male honeybees, drones, have a longer development cycle than female workers (24 versus 21 days), allow for more progeny mites to develop per foundress (1.6-2.5 compared to 0.7-1.45). How this longer exposure time influences evolution of the transmitted virus population is unknown. Using uniquely tagged viruses recovered from cDNA we investigated the replication, competition and morbidity of DWV genotypes in drones. Assays examining virus replication and morbidity revealed drones are highly susceptible to both predominant genotypes of DWV. In virus passage studies using an equimolar inocula of major DNA genotypes and their recombinants, the recombinant form dominated but did not reach 100% of the virus population within 10 passages. Using an in-silico model of the virus-mite-bee system we examined bottlenecks during virus acquisition by the mite and subsequent injection of viruses into the host, which may play a significant role in shaping virus diversity. This study furthers our understanding of the variables influencing DWV diversity changes and provides insight into areas of future research in the mite-virus-bee system.

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Nutritional stress, especially a dearth of pollen, has been linked to honey bee colony losses. Colony-level experiments are critical for understanding the mechanisms by which nutritional stress affects individual honey bee physiology and pushes honey bee colonies to collapse. In this study, we investigated the impact of pollen restriction on key markers of honey bee physiology, main elements of the immune system, and predominant honey bee viruses. To achieve this objective, we uncoupled the effects of behavior, age, and nutritional conditions using a new colony establishment technique designed to control size, demography, and genetic background. Our results showed that the expression of storage proteins, including vitellogenin (vg) and royal jelly major protein 1 (mrjp1), were significantly associated with nursing, pollen ingestion, and older age. On the other hand, genes involved in hormonal regulation including insulin-like peptides (ilp1 and ilp2) and methyl farnesoate epoxidase (mfe), exhibited higher expression levels in young foragers from colonies not experiencing pollen restriction. In contrast, pollen restriction induced higher levels of insulin-like peptides in old nurses. On the other hand, we found a strong effect of behavior on the expression of all immune genes, with higher expression levels in foragers. In contrast, the effects of nutrition and age were significant only the expression of the regulatory gene dorsal. We also found multiple interactions of the experimental variables on viral titers, including higher Deformed wing virus (DWV) titers associated with foraging and age-related decline. In addition, nutrition significantly affected DWV titers in young nurses, with higher titers induced by pollen ingestion. In contrast, higher levels of Black queen cell virus (BQCV) were associated with pollen restriction. Finally, correlation, PCA, and NMDS analyses proved that behavior had had the strongest effect on gene expression and viral titers, followed by age and nutrition. These analyses also support multiple interactions among genes and virus analyzed, including negative correlations between the expression of genes encoding storage proteins associated with pollen ingestion and nursing (vg and mrjp1) with the expression of immune genes and DWV titers. Our results provide new insights into the proximal mechanisms by which nutritional stress is associated with changes in honey bee physiology, immunity, and viral titers.

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Honey bees play an important role in the pollination of crops and wild plants and provide important products to humans. Pathogens and parasites are the main factors that threaten beekeeping in South Korea. Therefore, a nationwide detection of 14 honey bee pathogens, including parasites (phorid flies, Nosema ceranae, and Acarapis woodi mites), viruses, bacteria, and fungal pathogens, was conducted from 2017 to 2021 in the country. The infection rate and the trend of detection of each pathogenic agent were determined. A total of 830 honey bee samples from Apis cerana (n = 357) and A. mellifera (n = 473) were examined. N. ceranae (35.53%), deformed wing virus (52.63%), sacbrood virus (SBV) (52.63%), and black queen cell virus (55.26%) were the most prevalent honey bee pathogens, and their prevalence rapidly increased from 2017 to 2021. The prevalence of Paenibacillus larvae, Israeli acute paralysis virus, Ascosphaera apis, A. woodi, Melissococcus plutonius, and chronic bee paralysis virus remained stable during the surveillance period, with infection rates ranging from 5.26% to 16.45% in 2021. Other pathogens, including acute bee paralysis virus, phorid flies, Kashmir bee virus, and Aspergillus flavus, had low infection rates that gradually declined during the detection period. The occurrence of honeybee pathogens peaked in July. SBV was the most common pathogen in A. cerana, whereas N. ceranae was predominant in A. mellifera. This study provides information regarding the current status of honey bee pathogens and presents the trend of the occurrence of each pathogen in South Korea. These data are important for predicting outbreaks of honey bee diseases in the country.

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Deformed wing virus (DWV) is a widespread pathogen of Apis mellifera honey bees, and is considered a major causative factor for the collapse of infected honey bee colonies. DWV can be horizontally transmitted among bees through various oral routes, including via food sharing and by interactions of bees with viral-contaminated solid hive substrates. Cold plasma ionized hydrogen peroxide (iHP) is used extensively by the food production, processing and medical industries to clean surfaces of microbial contaminants. In this study, we investigated the use of iHP to inactivate DWV particles in situ on a solid substrate. iHP-treated DWV sources were ~105-fold less infectious when injected into naïve honey bee pupae compared to DWV receiving no iHP treatment, matching injected controls containing no DWV. iHP treatment also greatly reduced the incidence of overt DWV infections (i.e., pupae having >109 copies of DWV). The level of DWV inactivation achieved with iHP treatment was higher than other means of viral inactivation such as gamma irradiation, and iHP treatment is likely simpler and safer. Treatment of DWV contaminated hive substrates with iHP, even with honey bees present, may be an effective way to decrease the impacts of DWV infection on honey bees.

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The health of the western honeybee, Apis mellifera, the most crucial pollinator, has been challenged globally over the past decades. An ectoparasitic mite, Varroa destructor, together with the viruses it vectored, is generally regarded as the vital pathogenic agent. Although the poor health status of A. mellifera compared to its eastern counterpart, Apis cerana, has been broadly identified, the underlying mechanism remains poorly understood and comparison between susceptible and resistant hosts will potentially ameliorate this predicament. Here, we investigated the impacts of two widespread viruses-deformed wing virus type A (DWV-A) and Israeli acute paralysis virus (IAPV), mediated by V. destructor mite, on the capped developing honeybee brood, in the absence of adult workers, of A. mellifera and A. cerana, with positive and negative controls. Our results demonstrated that the endogenous viruses imposed limited damage on the hosts even if the brood was wounded. In contrast, the exogenous viruses introduced by ectoparasites triggered variable mortality of the infested brood between host species. Intriguingly, death causes of both honeybee species presented a similar trend: the acute IAPV generally causes morbidity and mortality of late larvae, while the chronic DWV-A typically leads to brood mortality during and after pupation. Notably, the susceptible immature A. cerana individuals, supported by higher observed mortality and a lower virus tolerance, serve the interests of the colony and foster the overall survival of a resistant honeybee superorganism. These results improve our understanding of the interactions between viruses carried by ectoparasites and their developing hosts, and the novel insight of weak individuals fostering strong colonies may promote breeding efforts to mitigate the indefensible colony losses globally.

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Air distribution is an effective engineering measure to fight against respiratory infectious diseases like COVID-19. Ventilation indices are widely used to indicate the airborne infection risk of respiratory infectious diseases due to the practical convenience. This study investigates the relationships between the ventilation indices and airborne infection risk to suggest the proper ventilation indices for the evaluation of airborne infection risk control performance of air distribution. Besides the commonly used ventilation indices of the age of air (AoA), air change effectiveness (ACE), and contaminant removal effectiveness (CRE), this study introduces two ventilation indices, i.e., the air utilization effectiveness (AUE) and contaminant dispersion index (CDI). CFD simulations of a hospital ward and a classroom served by different air distributions, including mixing ventilation, displacement ventilation, stratum ventilation and downward ventilation, are validated to calculate the ventilation indices and airborne infection risk. A three-step correlation analysis based on Spearman's rank correlation coefficient, Pearson correlation coefficient, and goodness of fit and a min-max normalization-based error analysis are developed to qualitatively and quantitatively test the validity of ventilation indices respectively. The results recommend the integrated index of AUE and CDI to indicate the overall airborne infection risk, and CDI to indicate the local airborne infection risk respectively regardless of the effects of air distribution, supply airflow rate, infectivity intensity, room configuration and occupant distribution. This study contributes to airborne transmission control of infectious respiratory diseases with air distribution.

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The recent decades witnessed the collapse of honey bee colonies at a global level. The major drivers of this collapse include both individual and synergic pathogen actions, threatening the colonies' survival. The need to define the epidemiological pattern of the pathogens that are involved has led to the establishment of monitoring programs in many countries, Italy included. In this framework, the health status of managed honey bees in the Emilia-Romagna region (northern Italy) was assessed, throughout the year 2021, on workers from 31 apiaries to investigate the presence of major known and emerging honey bee pathogens. The prevalence and abundance of DWV, KBV, ABPV, CBPV, Nosema ceranae, and trypanosomatids (Lotmaria passim, Crithidia mellificae, Crithidia bombi) were assessed by molecular methods. The most prevalent pathogen was DWV, followed by CBPV and N. ceranae. Trypanosomatids were not found in any of the samples. Pathogens had different peaks in abundance over the months, showing seasonal trends that were related to the dynamics of both bee colonies and Varroa destructor infestation. For some of the pathogens, a weak but significant correlation was observed between abundance and geographical longitude. The information obtained in this study increases our understanding of the epidemiological situation of bee colonies in Emilia-Romagna and helps us to implement better disease prevention and improved territorial management of honey bee health.

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This study was conducted to analyze the effect of genotype and climate on the resistance of honey bee (Apis mellifera) colonies to parasitic and viral diseases. The prevalence and intensity of parasitism by Varroa destructor, or infection by Nosema spp., and four honey bee viruses were determined in 365 colonies of predominantly European or African ancestry (descendants of A. m. scutellata) in subtropical and temperate regions of Mexico. Varroa destructor was the most prevalent parasite (95%), whilst N. ceranae was the least prevalent parasite (15%). Deformed wing virus (DWV) and black queen cell virus (BQCV) were the only viruses detected, at frequencies of 38% and 66%, respectively. Varroa destructor was significantly more prevalent in colonies of European ancestry (p < 0.05), and the intensity of parasitism by V. destructor or infection by DWV and BQCV was also significantly higher in colonies of European descent than in African descent colonies (p < 0.01), although no genotype−parasite associations were found for N. ceranae. Additionally, significant and positive correlations were found between V. destructor and DWV levels, and the abundance of these pathogens was negatively correlated with the African ancestry of colonies (p < 0.01). However, there were no significant effects of environment on parasitism or infection intensity for the colonies of both genotypes. Therefore, it is concluded that the genotype of honey bee colonies, but not climate, influences their resistance to DWV, BQCV, and V. destructor.

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Honey bees are economically important insects for crop pollination. They play a significant role as pollinators of wild plants and agricultural crops and produce economical products, such as honey, royal jelly, wax, pollen, propolis, and venom. Despite their ecological and economical importance, the global honey bee population is in decline due to factors including pathogens, parasites, intensive agriculture, and pesticides. Moreover, these factors may be interlinked and exacerbate the loss of honey bees. This study aimed to investigate the interaction between a pesticide, thiamethoxam, and deformed wing virus type A (DWV-A) to honey bees and the effects on survival rate, wing characteristics, and expression of immune and apoptosis genes in Apis mellifera. We described the potential interaction between thiamethoxam and DWV-A on honey bee wing characteristics, DWV-A loads, and the expressions of immune (defensin, abaecin, and hymenoptaecin) and apoptosis genes (buffy, apaf1, caspase3-like, caspase8-like, and caspase9-like). Honey bee larvae were fed with three different thiamethoxam doses (0.001, 1.4, and 14.3 ng/µL of the diet). Then, thiamethoxam-treated white-eyed pupae were injected with 107 copy numbers/honey bee of the DWV-A genome. The interaction between thiamethoxam and DWV-A caused a high mortality rate, crippled wings in newly emerged adult honey bees (100%), and resulted in induced expression of hymenoptaecin gene compared to the control group, while downregulation of caspase8-like, caspase9-like genes compared to the DWV injection group. Therefore, the potential interaction between thiamethoxam and DWV-A might have a deleterious effect on honey bee lifespan. The results from this study could be used as a tool to combat DWV-A infection and mitigate pesticide usage to alleviate the decrease in the honey bee population.