Greater wax moth control in apiaries can be improved by combining Bacillus thuringiensis and entrapments.

The greater wax moth (GWM), Galleria mellonella (Lepidoptera: Pyralidae), is a major bee pest that causes significant damage to beehives and results in economic losses. Bacillus thuringiensis (Bt) appears as a potential sustainable solution to control this pest. Here, we develop a novel Bt strain (designated BiotGm) that exhibits insecticidal activity against GWM larvae with a LC50 value lower than 2 µg/g, and low toxicity levels to honey bee with a LC50 = 20598.78 µg/mL for larvae and no observed adverse effect concentration = 100 µg/mL for adults. We design an entrapment method consisting of a lure for GWM larvae, BiotGm, and a trapping device that prevents bees from contacting the lure. We find that this method reduces the population of GWM larvae in both laboratory and field trials. Overall, these results provide a promising direction for the application of Bt-based biological control of GWM in beehives, although further optimization remain necessary.

Acute and chronic effects of sublethal neonicotinoid thiacloprid to Asian honey bee (Apis cerana cerana).

Pesticide pollution is one of the most important factors for global bee declines. Despite many studies have revealed that the most important Chinese indigenous species，Apis cerana, is presenting a high risk on exposure to neonicotinoids, the toxicology information on Apis cerana remain limited. This study was aimed to determine the acute and chronic toxic effects of thiacloprid (IUPAC name: {(2Z)-3-[(6-Chloro-3-pyridinyl)methyl]-1,3-thiazolidin-2-ylidene}cyanamide) on behavioral and physiological performance as well as genome-wide transcriptome in A. cerana. We found the 1/5 LC50 of thiacloprid significantly impaired learning and memory abilities after both acute and chronic exposure, nevertheless, has no effects on the sucrose responsiveness and phototaxis climbing ability of A. cerana. Moreover, activities of detoxification enzyme P450 monooxygenases and CarE were increased by short-term exposure to thiacloprid, while prolonged exposure caused suppression of CarE activity. Neither acute nor chronic exposure to thiacloprid altered honey bee AChE activities. To further study the potential defense molecular mechanisms in Asian honey bee under pesticide stress, we analyzed the transcriptomes of honeybees in response to thiacloprid stress. The transcriptomic profiles revealed consistent upregulation of immune- and stress-related genes by both acute or chronic treatments. Our results suggest that the chronic exposure to thiacloprid produced greater toxic effects than a single administration to A. cerana. Altogether, our study deepens the understanding of the toxicological characteristic of A. cerana against thiacloprid, and could be used to further investigate the complex molecular mechanisms in Asian honey bee under pesticide stress.

Interaction of chlorothalonil and Varroa destructor on immature honey bees rearing in vitro.

Under realistic environmental conditions, bees are often exposed to multiple stressors, especially Varroa destructor and pesticides. In this study, the effects of exposure to NOAEC of chlorothalonil during the larval stage, in the presence or absence of V. destructor, was examined in terms of survival, morphological and transcriptional changes. The interaction between chlorothalonil and V. destructor on the survival of honey bee was additive. V. destructor are the dominant factor in the interaction for survival and transcriptome alternation. The downregulation of the genes related to tissue growth and caste differentiation may directly link to the mortality of honey bees. Either chlorothalonil or V. destructor induces the irregular morphology of trophocytes and oenocytes in the fat body. In addition to irregular shapes, oenocytes in V. destructor alone and double-stressor treatment group showed altered nuclei and vacuoles in the cytoplasm. The interaction of V. destructor and chlorothalonil at the larval stage have potential adverse effects on the subsequent adult bees, with up-regulation of genes involved in lipid metabolism and detoxification/defense in fat body tissue. Our findings provide a comprehensive understanding of combinatorial effects between biotic and abiotic stressors on one of the most important pollinators, honey bees.

Thiacloprid impairs honeybee worker learning and memory with inducing neuronal apoptosis and downregulating memory-related genes.

Neonicotinoids are among the most widely used insecticides in the world and are recognized as a potential cause of pollinator decline. Previous studies have demonstrated that the neonicotinoid thiacloprid has adverse effects on foraging and memory behaviors. However, there is no direct evidence linking thiacloprid-induced neuronal cell damage in the brains of honeybees to learning and memory dysfunction. Adult honeybee (Apis mellifera L.) workers were chronically exposed to sub-lethal concentrations of thiacloprid. We discovered that thiacloprid negatively affected their survival, food consumption, and body weight. In addition, sucrose sensitivity and memory performance were impaired. We evaluated the apoptosis of honeybee brain cells using TUNEL (Terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP-biotin nick-end labeling) and Caspase-3 assays, which revealed that thiacloprid increases the dose-dependent apoptosis of neurons in the mushroom bodies (MB) and antennal lobes (AL). We also determined the abnormal transcripts of multiple genes, including vitellogenin (Vg), immune system genes (apidaecin and catalase), and memory-associated genes (pka, creb, Nmdar1, Dop2, Oa1, Oa-2R, and Oa-3R). These results indicate that exposure to sublethal concentrations of thiacloprid cause abnormal expression of memory-related genes and apoptosis of brain cells in the AL and MB, which may contribute to the memory disorder induced by thiacloprid exposure.

Acute oral toxicity, apoptosis, and immune response in nurse bees (Apis mellifera) induced by flupyradifurone.

The potential toxicity of flupyradifurone (FPF) to honey bees has been a subject of controversy in recent years. Understanding the effect of pesticides on nurse bees is important because the fitness of nurse bees is critical for in-hive activities, such as larval survival and performing hive maintenance. In order to evaluate the acute oral toxicity of flupyradifurone on nurse bees, flupyradifurone at five different concentrations was selected to feed both larvae and nurse bees. Our results showed that nurse bees were more sensitive to flupyradifurone than larvae (LD50 of the acute oral toxicity of flupyradifurone was 17.72 µg a.i./larva and 3.368 µg a.i./nurse bee). In addition, the apoptotic rates of neurons in mushroom bodies of nurse bees were significantly induced by flupyradifurone at sublethal concentrations (8 mg/L, 20 mg/L, and 50 mg/L) and the median lethal concentration LC50 (125 mg/L). The expression of immune-related genes (Hsp90, Toll-8/Tollo, and defensin) was significantly changed in exposed nurse bees at the field-realistic concentration of flupyradifurone. However, three detoxifying enzyme genes (CYP9Q1, -2, and -3) were not affected by pesticide exposure. Our data suggest that although flupyradifurone had a relatively lower acute oral toxicity than many other common pesticides, exposures to the field-realistic and other sublethal concentrations of flupyradifurone still have cytotoxicity and immune-responsive effects on nurse bees. Therefore, flupyradifurone should be considered for its application in crops.

Exposure of chlorothalonil and acetamiprid reduce the survival and cause multiple internal disturbances in Apis mellifera larvae reared in vitro.

Background: Chlorothalonil and acetamiprid are chemical pesticides commonly used in agricultural production and have been shown to have negative effects on bee's fitness. Despite many studies have revealed that honey bee (Apis mellifera L.) larvae are posting a high risk on exposure to pesticides, but the toxicology information of chlorothalonil and acetamiprid on bee larvae remain limited. Results: The no observed adverse effect concentration (NOAEC) of chlorothalonil and acetamiprid for honey bee larvae were 4 µg/mL and 2 µg/mL, respectively. Except for CarE, the enzymic activities of GST and P450 were not influenced by chlorothalonil at NOAEC, while chronic exposure to acetamiprid slightly increased the activities of the three tested enzymes at NOAEC. Further, the exposed larvae showed significantly higher expression of genes involved in a series of different toxicologically relevant process following, including caste development (Tor (GB44905), InR-2 (GB55425), Hr4 (GB47037), Ac3 (GB11637) and ILP-2 (GB10174)), immune system response (abaecin (GB18323), defensin-1 (GB19392), toll-X4 (GB50418)), and oxidative stress response (P450, GSH, GST, CarE). Conclusion: Our results suggest that the exposure to chlorothalonil and acetamiprid, even at concentrations below the NOAEC, showed potentially effects on bee larvae's fitness, and more important synergistic and behavioral effects that can affect larvae fitness should be explored in the further.

Combined transcriptome and metabolite profiling analyses provide insights into the chronic toxicity of carbaryl and acetamiprid to Apis mellifera larvae.

Despite many studies have revealed that developing honey bee (Apis mellifera) larvae are posting a high risk on exposure to insecticides, the toxicology information on bee larvae remain limited. The present study demonstrated the first assessment of the effects of no observed adverse effect concentration (NOAEC) of carbaryl (CR) and acetamiprid (ACE) on transcriptome and metabolome in honeybee larvae reared in vitro. Chronic exposure to carbaryl caused transcriptional disorders associated with oxidative stress. In addition, a series of metabolic homeostasis were disrupted by carbaryl stress, such amino acid metabolism, purine and pyrimidine metabolism and flavone and flavonol biosynthesis. The activities of enzymic biomarkers including GST, P450, CAT, AChE and SOD were not influenced by ACE stress, while the CR exposure slightly decreased the activity of CAT and SOD. Our results clearly show that ACE and CR display different potential to modulate transcriptome and metabolome associated with their different toxicity against bee larvae.

Genomics and proteomics of Apis mellifera filamentous virus isolated from honeybees in China.

Apis mellifera filamentous virus (AmFV) is a large DNA virus that is endemic in honeybee colonies. The genome sequence of the AmFV Swiss isolate (AmFV CH-C05) has been reported, but so far very few molecular studies have been conducted on this virus. In this study, we isolated and purified AmFV (AmFV CN) from Chinese honeybee (Apis mellifera) colonies and elucidated its genomics and proteomics. Electron microscopy showed ovoid purified virions with dimensions of 300-500 â€‹× â€‹210-285 â€‹nm, wrapping a 3165 â€‹× â€‹40 â€‹nm filamentous nucleocapsid in three figure-eight loops. Unlike AmFV CH-C05, which was reported to have a circular genome, our data suggest that AmFV CN has a linear genome of approximately 493 â€‹kb. A total of 197 ORFs were identified, among which 36 putative genes including 18 baculoviral homologs were annotated. The overall nucleotide similarity between the CN and CH-C05 isolates was 96.9%. Several ORFs were newly annotated in AmFV CN, including homologs of per os infectivity factor 4 (PIF4) and a putative integrase. Phylogenomic analysis placed AmFVs on a separate branch within the newly proposed virus class Naldaviricetes. Proteomic analysis revealed 47 AmFV virion-associated proteins, of which 14 had over 50% sequence coverage, suggesting that they are likely to be main structural proteins. In addition, all six of the annotated PIFs (PIF-0-5) were identified by proteomics, suggesting that they may function as entry factors in AmFV infection. This study provides fundamental information regarding the molecular biology of AmFV.

Chlorothalonil alters the gut microbiota and reduces the survival of immature honey bees reared in vitro.

BACKGROUND: Chlorothalonil is a nonsystemic fungicide, and it is one of the most widely detected pesticides in bee hives. The effect of chlorothalonil on the survival, weight, and gut microbiota of immature Apis mellifera L. reared in vitro was studied. RESULTS: Larvae were fed 1, 2, 4, 8, and 16 µg/mL chlorothalonil and compared with larvae fed the negative control (diet without any additives), positive control (45 mg/L dimethoate), and solvent control (2% acetone). Compared with the control groups, the survival of the 2, 4, 8, and 16 µg/mL chlorothalonil treatments was significantly reduced. The no-observed-adverse-effect concentration of chlorothalonil was 1 µg/mL. Chlorothalonil had no significant effect on larval weight. The gut bacterial community composition of newly emerged bees was determined by PacBio 16S rDNA gene sequencing. linear discriminant analysis effect size (LEFSe) analysis showed that Pseudomonadales and Burkholderiales were affected by exposure to chlorothalonil. CONCLUSION: Chlorothalonil reduced the survival of honey bee larvae and altered the gut microbiota of newly emerged bees. The risk of pesticides to honey bees is related to their toxicity and exposure dose.

Exposure of Larvae to Sublethal Thiacloprid Delays Bee Development and Affects Transcriptional Responses of Newly Emerged Honey Bees.

Understanding the cause of honey bee (Apis mellifera) population decline has attracted immense attention worldwide in recent years. Exposure to neonicotinoid pesticides is considered one of the most probable factors due to the physiological and behavioral damage they cause to honey bees. However, the influence of thiacloprid, a relatively less toxic cyanogen-substituted form of neonicotinoid, on honey bee (Apis mellifera L.) development is not well studied. The toxicity of sublethal thiacloprid to larvae, pupae, and emerging honey bees was assessed under laboratory conditions. We found that thiacloprid reduced the survival rate of larvae and pupae, and delayed the development of bees which led to lower bodyweight and size. Furthermore, we identified differentially expressed genes involved in metabolism and immunity though RNA-sequencing of newly-emerged adult bees. GO enrichment analysis identified genes involved in metabolism, catalytic activity, and transporter activity. KEGG pathway analysis indicated that thiacloprid induced up-regulation of genes related to glutathione metabolism and Toll-like receptor signaling pathway. Overall, our results suggest that chronic sublethal thiacloprid can affect honey bee colonies by reducing survival and delaying bee development.

Nano-La2O3 Induces Honeybee (Apis mellifera) Death and Enriches for Pathogens in Honeybee Gut Bacterial Communities.

Honeybees (Apis mellifera) can be exposed via numerous potential pathways to ambient nanoparticles (NPs), including rare earth oxide (REO) NPs that are increasingly used and released into the environment. Gut microorganisms are pivotal in mediating honeybee health, but how REO NPs may affect honeybee health and gut microbiota remains poorly understood. To address this knowledge gap, honeybees were fed pollen and sucrose syrup containing 0, 1, 10, 100, and 1000mgkg-1 of nano-La2O3 for 12days. Nano-La2O3 exerted detrimental effects on honeybee physiology, as reflected by dose-dependent adverse effects of nano-La2O3 on survival, pollen consumption, and body weight (p<0.05). Nano-La2O3 caused the dysbiosis of honeybee gut bacterial communities, as evidenced by the change of gut bacterial community composition, the enrichment of pathogenic Serratia and Frischella, and the alteration of digestion-related taxa Bombella (p<0.05). There were significant correlations between honeybee physiological parameters and the relative abundances of pathogenic Serratia and Frischella (p<0.05), underscoring linkages between honeybee health and gut bacterial communities. Taken together, this study demonstrates that nano-La2O3 can cause detrimental effects on honeybee health, potentially by disordering gut bacterial communities. This study thus reveals a previously overlooked effect of nano-La2O3 on the ecologically and economically important honeybee species Apis mellifera.

IAPV-Induced Paralytic Symptoms Associated with Tachypnea via Impaired Tracheal System Function.

Although it had been reported that Israeli acute paralysis virus (IAPV) can cause systemic infection in honey bees, little is known about how it establishes this infection and results in the typical symptoms, paralysis and trembling. Here, we used our previously constructed IAPV infectious clone to investigate viral loads in different tissues of honey bees and further identify the relation between tissue tropism and paralytic symptoms. Our results showed that tracheae showed a greater concentration of viral abundance than other tissues. The abundance of viral protein in the tracheae was positively associated with viral titers, and was further confirmed by immunological and ultrastructural evidence. Furthermore, higher viral loads in tracheae induced remarkable down-regulation of succinate dehydrogenase and cytochrome c oxidase genes, and progressed to causing respiratory failure of honey bees, resulting in the appearance of typical symptoms, paralysis and body trembling. Our results showed that paralysis symptoms or trembling was actually to mitigate tachypnea induced by IAPV infection due to the impairment of honey bee tracheae, and revealed a direct causal link between paralysis symptoms and tissue tropism. These findings provide new insights into the understanding of the underlying mechanism of paralysis symptoms of honey bees after viral infection and have implications for viral disease prevention and specific therapeutics in practice.

Microplastic Polystyrene Ingestion Promotes the Susceptibility of Honeybee to Viral Infection.

Microplastics (MPs) are an emerging threat to ecological conservation and biodiversity; however, little is known of the types and possible impacts of MPs in pollinators. To examine whether MPs were present in honeybees, we analyzed the honeybee samples collected in fields from six provinces in China. Four types MPs were identified in honeybee including polystyrene (PS) by Raman spectroscopic analysis, and these plastic polymers were detected in 66.7% bee samples. Then, we assessed the physical and biological impacts of PS of three sizes (0.5, 5, and 50 µm) on bees for 21 days. Next, we measured how the presence of PS affected the Israeli acute paralysis virus proliferation, a small RNA virus associated with bee colony decline. Experimental evidence showed that a large mass of PS was ingested and accumulated within the midgut and enhanced the susceptibility of bees to viral infection. Not only histological analysis showed that PS, especially 0.5 µm PS, damaged the midgut tissue and was subsequently transferred to the hemolymph, trachea, and Malpighian tubules, but also qPCR and transcriptomic results indicated that genes correlated with membrane lipid metabolism, immune response, detoxification, and the respiratory system were significantly regulated after PS ingestion. Our results highlight neglected MP contamination to the bees, a pollination ecosystem stressed by the anthropogenic pollution, and have implications for human health via ingestion of bee products.

Tropilaelaps mercedesae parasitism changes behavior and gene expression in honey bee workers.

Tropilaelaps mercedesae is one of the most problematic honey bee parasites and has become more threatening to the beekeeping industry. Tropilaelaps can easily parasitize immature honey bees (larvae and pupae) and have both lethal and sublethal effects on the individual worker bees. Our study for the first time experimentally assessed the effects of T. mercedesae on olfactory learning, flight ability, homing ability as well as transcriptional changes in parasitized adult honey bees. T. mercedesae infestation had negative impacts on olfactory associated function, flight ability, and homing rate. The volume of the mushroom body significantly increased in infested honey bees, which may be correlated to the lower sucrose responsiveness as well as lower learning ability in the infested bees. The gene expression involved in immune systems and carbohydrate transport and metabolism were significantly different between infested bees and non-infested bees. Moreover, genes function in cell adhesion play an essential role in olfactory sensory in honey bees. Our findings provide a comprehensive understanding of European honey bees in response to T. mercedesae infestation, and could be used to further investigate the complex molecular mechanisms in honey bees under parasitic stress.

Host Species and Geography Differentiate Honeybee Gut Bacterial Communities by Changing the Relative Contribution of Community Assembly Processes.

Honeybee gut microbiota modulates the health and fitness of honeybees, the ecologically and economically important pollinators and honey producers. However, which processes drive the assembly and shift of honeybee gut microbiota remains unknown. To explore the patterns of honeybee gut bacterial communities across host species and geographical sites and the relative contribution of different processes (i.e., homogeneous selection, variable selection, homogeneous dispersal, dispersal limitation, and an undominated process) in driving the patterns, two honeybee species (Apis cerana and Apis mellifera) were sampled from five geographically distant sites along a latitudinal gradient, followed by gut bacterial 16S rRNA gene sequencing. The gut bacterial communities differed significantly between A. cerana and A. mellifera, which was driven by the interhost dispersal limitation associated with the long-term coevolution between hosts and their prokaryotic symbionts. A. mellifera harbored more diverse but less varied gut bacterial communities than A. cerana due to the dominant role of homogeneous selection in converging A. mellifera intestinal communities. For each honeybee species, the gut bacterial communities differed across geographical sites, with individuals from lower latitudes harboring higher diversity; also, there was significant decay of gut community similarity against geographic distance. The geographical variation of honeybee gut bacterial communities was mainly driven by an undominated process (e.g., stochastic drift) rather than variable selection or dispersal limitation. This study elucidates that variations in host and geography alter the relative contribution of different processes in assembling honeybee gut microbiota and, thus, provides insights into the mechanisms underlying honeybee gut microbial shifts across evolutionary time. IMPORTANCE Honeybees provide crucial pollination services and valuable apiarian products. The symbiotic intestinal communities facilitate honeybee health and fitness by promoting nutrient assimilation, detoxifying toxins, and resisting pathogens. Thus, understanding the processes that govern honeybee gut bacterial communities is imperative for better managing gut microbiota to improve honeybee health. However, little is known about the processes driving the assembly and shift of honeybee gut bacterial communities. This study quantitatively deciphers the relative importance of selection, dispersal, and undominated processes in governing the assembly of honeybee gut bacterial communities and explores how their relative importance varies across biological and spatial scales. Our study provides new insights into the mechanisms underlying the maintenance and shift of honeybee gut microbiota.

The Effects of Exposure to Flupyradifurone on Survival, Development, and Foraging Activity of Honey Bees (Apis mellifera L.) under Field Conditions.

Flupyradifurone (FPF) is a novel systemic nAChR agonist that interferes with signal transduction in the central nervous system of sucking pests. Despite claims that FPF is potentially "bee-safe" by risk assessments, laboratory data have suggested that FPF has multiple sub-lethal effects on individual honey bees. Our study aimed to expand the studies to the effects of field-realistic concentration of FPF. We found a statistically significant decrease in the survival rate of honey bees exposed to FPF, whereas there were no significantly negative effects on larvae development durations nor foraging activity. In addition, we found that the exposed foragers showed significantly higher expression of ApidNT, CYP9Q2, CYP9Q3, and AmInR-2 compared to the CK group (control group), but no alteration in the gene expression was observed in larvae. The exposed newly emerged bees showed significantly higher expression of Defensin and ApidNT. These results indicate that the chronic exposure to the field-realistic concentration of FPF has negligible effects, but more important synergistic and behavioral effects that can affect colony fitness should be explored in the future, considering the wide use of FPF on crops pollinated and visited by honey bees.

Effects of a commercially formulated glyphosate solutions at recommended concentrations on honeybee (Apis mellifera L.) behaviours.

Glyphosate, the active ingredient of the most widely used commercial herbicide formulation, is extensively used and produced in China. Previous studies have reported sublethal effects of glyphosate on honeybees. However, the effects of commercially formulated glyphosate (CFG) at the recommended concentration (RC) on the chronic toxicity of honeybees, especially on their behaviours, remain unknown. In this study, a series of behavioural experiments were conducted to investigate the effects of CFG on honeybees. The results showed that there was a significant decline in water responsiveness at 1/2 × , 1 × and 2 × the RC after 3 h of exposure to CFG for 11 days. The CFG significantly reduced sucrose responsiveness at 1/2 × and 1 × the RC. In addition, CFG significantly affected olfactory learning ability at 1/2 × , 1 × , and 2 × the RC and negatively affected memory ability at 1/2 × and 1 × the RC. The climbing ability of honeybees also significantly decreased at 1/2 × , 1 × and 2 × the RC. Our findings indicated that, after they were chronically exposed to CFG at the RC, honeybees exhibited behavioural changes. These results provide a theoretical basis for regulating field applications of CFG, which is necessary for establishing an early warning and notification system and for protecting honeybees.

A combination of Tropilaelaps mercedesae and imidacloprid negatively affects survival, pollen consumption and midgut bacterial composition of honey bee.

Tropilaelaps mercedesae is not only a major threat to honey bees in Asia but also a potential risk to global apiculture due to trade. Imidacloprid is a systemic insecticide that negatively affects individual bees. Moreover, the health of honey bees may be threatened by imidacloprid exposure and T. mercedesae infestation. We studied the effects of T. mercedesae and imidacloprid on the survival, food consumption and midgut bacterial diversity of Apis mellifera in the laboratory. Illumina 16S rRNA gene sequencing was used to determine the bacterial composition in the honey bee midgut. T. mercedesae decreased survival in parasitized honey bees compared with nonparasitized honey bees, but there was no significant difference in food consumption. The imidacloprid 50 µg/L diet significantly decreased syrup consumption of A. mellifera compared with the control diet. The combination of T. mercedesae infestation and imidacloprid 50 µg/L exposure reduced survival and increased pollen consumption of A. mellifera. T. mercedesae infestation or a combination of T. mercedesae infestation and exposure to 25 µg/L imidacloprid affected the midgut bacterial composition of honey bees. T. mercedesae infestation and imidacloprid exposure may reduce the survival and affect honey bee health.

Flupyradifurone reduces nectar consumption and foraging but does not alter honey bee recruitment dancing.

Foraging is essential for honey bee colony fitness and is enhanced by the waggle dance, a recruitment behavior in which bees can communicate food location and quality. We tested if the consumption of nectar (sucrose solution) with a field-realistic concentration of 4 ppm flupyradifurone (FPF) could alter foraging behavior and recruitment dancing in Apis mellifera. Foragers were repelled by FPF. They visited the FPF feeder less often and spent less time imbibing sucrose solution (2.5 M, 65% w/w) with FPF. As a result, bees feeding on the FPF treatment consumed 16% less nectar. However, FPF did not affect dancing: there were no effects on unloading wait time, the number of dance bouts per nest visit, or the number of dance circuits performed per dance bout. FPF could therefore deter bees from foraging on contaminated nectar. However, the willingness of bees to recruit nestmates for nectar with FPF is concerning. Recruitment can rapidly amplify the number of foragers and could overcome the decrease in consumption of FPF-contaminated nectar, resulting in a net inflow of pesticide to the colony. FPF also significantly altered the expression of 116 genes, some of which may be relevant for the olfactory learning deficits induced by FPF and the toxicity of FPF.

Effects of Bt Cry78Ba1 Toxin on Larvae and Adults of Apis mellifera (Hymenoptera: Apidae).

Cry78Ba1 is Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt) protein found with high insecticidal activity against the piercing-sucking insect Laodelphax striatellus Fallén (Homoptera: Delphacidae) and has broad application prospects for control of the rice planthopper. As honey bees may be exposed to Bt Cry78Ba1 rice pollen by feeding, we evaluated the risk of Bt Cry78Ba1 toxin to Apis mellifera L. workers. A dietary exposure experiment was conducted on worker larvae and adults under controlled laboratory conditions to examine the effects of Cry78Ba1 toxin on honey bees. Worker bee larvae were fed a diet containing Cry78Ba1 toxin (0.01, 0.1, 1, and 10 mg/liter) on day 2 through day 5 after grafting, and adults were exposed to syrup containing Cry78Ba1 for up to 16 d. Negative control (no test substance added), solvent control (1 mM Tris-HCl), and positive control (dimethoate 45 mg/liter for the larva test, 1 and 45 mg/liter for the adult test) groups were established. Compared with the negative control, larvae and adults that consumed food containing Cry78Ba1 toxin exhibited no significant differences in survival, larval weight, or pollen or syrup consumption. This result indicates that chronic oral exposure to Cry78Ba1 toxin has no negative effects on honey bees at the maximum tested concentration.