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RNA viruses in hymenopteran pollinators: evidence of inter-Taxa virus transmission via pollen and potential impact on non-Apis hymenopteran species.

Singh R, Levitt AL, Rajotte EG, Holmes EC, Ostiguy N, Vanengelsdorp D, Lipkin WI, Depamphilis CW, Toth AL, Cox-Foster DL - PLoS ONE (2010)

Bottom Line: Although overall pollinator populations have declined over the last couple of decades, the honey bee (Apis mellifera) malady, colony collapse disorder (CCD), has caused major concern in the agricultural community.This finding further expands the viral host range and implies a possible deeper impact on the health of our ecosystem.Notably, in cases where honey bee apiaries affected by CCD harbored honey bees with Israeli Acute Paralysis virus (IAPV), nearby non-Apis hymenopteran pollinators also had IAPV, while those near apiaries without IAPV did not.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, The Pennsylvania State University, Pennsylvania, United States of America.

ABSTRACT
Although overall pollinator populations have declined over the last couple of decades, the honey bee (Apis mellifera) malady, colony collapse disorder (CCD), has caused major concern in the agricultural community. Among honey bee pathogens, RNA viruses are emerging as a serious threat and are suspected as major contributors to CCD. Recent detection of these viral species in bumble bees suggests a possible wider environmental spread of these viruses with potential broader impact. It is therefore vital to study the ecology and epidemiology of these viruses in the hymenopteran pollinator community as a whole. We studied the viral distribution in honey bees, in their pollen loads, and in other non-Apis hymenopteran pollinators collected from flowering plants in Pennsylvania, New York, and Illinois in the United States. Viruses in the samples were detected using reverse transcriptase-PCR and confirmed by sequencing. For the first time, we report the molecular detection of picorna-like RNA viruses (deformed wing virus, sacbrood virus and black queen cell virus) in pollen pellets collected directly from forager bees. Pollen pellets from several uninfected forager bees were detected with virus, indicating that pollen itself may harbor viruses. The viruses in the pollen and honey stored in the hive were demonstrated to be infective, with the queen becoming infected and laying infected eggs after these virus-contaminated foods were given to virus-free colonies. These viruses were detected in eleven other non-Apis hymenopteran species, ranging from many solitary bees to bumble bees and wasps. This finding further expands the viral host range and implies a possible deeper impact on the health of our ecosystem. Phylogenetic analyses support that these viruses are disseminating freely among the pollinators via the flower pollen itself. Notably, in cases where honey bee apiaries affected by CCD harbored honey bees with Israeli Acute Paralysis virus (IAPV), nearby non-Apis hymenopteran pollinators also had IAPV, while those near apiaries without IAPV did not. In containment greenhouse experiments, IAPV moved from infected honey bees to bumble bees and from infected bumble bees to honey bees within a week, demonstrating that the viruses could be transmitted from one species to another. This study adds to our present understanding of virus epidemiology and may help explain bee disease patterns and pollinator population decline in general.

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Comparison of viral presence in pollen pellets and their corresponding forager with her body dissected into two regions with or without salivary glands, to determine if salivary secretions of the forager are associated with virus in pollen pellets.Incoming foragers with pollen pellets were collected in 2005; pollen pellets removed, tagged with identifier, and frozen at −80°C. Some foragers (1–8) were kept for 24 hrs at 34°C, 50% relative humidity and fed sugar water; others (9–12) were frozen immediately upon collection. After freezing, all foragers were divided into two regions, head plus prothorax that have salivary glands (H/T1) and the remainder of body lacking salivary glands (T2,3/A). Pollen pellets and forager body regions were extracted for detection of deformed wing virus (DWV), sacbrood virus (SBV), and actin mRNA (forager only). Actin mRNA was used as an internal control for methods and loading. Red box indicates three foragers that lack detections of DWV but had pollen pellets with detectable DWV. The red star (lane 3) indicates a forager with heavy DWV infection in Head/Prothorax but no detectable DWV in her pollen pellets. Size of DWV reaction = 424 bp, SBV reaction = 693 bp and Actin reaction = 514 bp.
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pone-0014357-g001: Comparison of viral presence in pollen pellets and their corresponding forager with her body dissected into two regions with or without salivary glands, to determine if salivary secretions of the forager are associated with virus in pollen pellets.Incoming foragers with pollen pellets were collected in 2005; pollen pellets removed, tagged with identifier, and frozen at −80°C. Some foragers (1–8) were kept for 24 hrs at 34°C, 50% relative humidity and fed sugar water; others (9–12) were frozen immediately upon collection. After freezing, all foragers were divided into two regions, head plus prothorax that have salivary glands (H/T1) and the remainder of body lacking salivary glands (T2,3/A). Pollen pellets and forager body regions were extracted for detection of deformed wing virus (DWV), sacbrood virus (SBV), and actin mRNA (forager only). Actin mRNA was used as an internal control for methods and loading. Red box indicates three foragers that lack detections of DWV but had pollen pellets with detectable DWV. The red star (lane 3) indicates a forager with heavy DWV infection in Head/Prothorax but no detectable DWV in her pollen pellets. Size of DWV reaction = 424 bp, SBV reaction = 693 bp and Actin reaction = 514 bp.

Mentions: Of the 12 initial honey bee pollen foragers analyzed for SBV and DWV and either kept for 24 hrs after removing their pollen pellets or directly frozen, there were no detectable differences in the prevalence of the viruses in these two groups. This suggests that the supply of virus associated with either the salivary glands or digestive tract was not reduced in those assayed immediately after collection as compared to those kept for 24 hrs. All foragers were dissected into two regions prior to virus analysis, the head and first thoracic segment containing the salivary glands and the remainder of the body. Three of the foragers were found to have detectable DWV in their pollen loads, without any detectable viral infections in the head/thoracic segments and two of these did not have any detectable infections anywhere (Figure 1) indicating that the salivary secretions of the forager were not a likely source of viral contamination on the pollen. One forager had a high level of DWV in her head/thoracic segment but there was no detectable DWV in her pollen load. SBV was detected in most of the pollen pellets as well as in the abdomen/thorax of the foragers, but few of the foragers had detectable virus in their heads/thoracic segments. These data therefore suggest that there is an alternative source of bee bread contamination.


RNA viruses in hymenopteran pollinators: evidence of inter-Taxa virus transmission via pollen and potential impact on non-Apis hymenopteran species.

Singh R, Levitt AL, Rajotte EG, Holmes EC, Ostiguy N, Vanengelsdorp D, Lipkin WI, Depamphilis CW, Toth AL, Cox-Foster DL - PLoS ONE (2010)

Comparison of viral presence in pollen pellets and their corresponding forager with her body dissected into two regions with or without salivary glands, to determine if salivary secretions of the forager are associated with virus in pollen pellets.Incoming foragers with pollen pellets were collected in 2005; pollen pellets removed, tagged with identifier, and frozen at −80°C. Some foragers (1–8) were kept for 24 hrs at 34°C, 50% relative humidity and fed sugar water; others (9–12) were frozen immediately upon collection. After freezing, all foragers were divided into two regions, head plus prothorax that have salivary glands (H/T1) and the remainder of body lacking salivary glands (T2,3/A). Pollen pellets and forager body regions were extracted for detection of deformed wing virus (DWV), sacbrood virus (SBV), and actin mRNA (forager only). Actin mRNA was used as an internal control for methods and loading. Red box indicates three foragers that lack detections of DWV but had pollen pellets with detectable DWV. The red star (lane 3) indicates a forager with heavy DWV infection in Head/Prothorax but no detectable DWV in her pollen pellets. Size of DWV reaction = 424 bp, SBV reaction = 693 bp and Actin reaction = 514 bp.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3008715&req=5

pone-0014357-g001: Comparison of viral presence in pollen pellets and their corresponding forager with her body dissected into two regions with or without salivary glands, to determine if salivary secretions of the forager are associated with virus in pollen pellets.Incoming foragers with pollen pellets were collected in 2005; pollen pellets removed, tagged with identifier, and frozen at −80°C. Some foragers (1–8) were kept for 24 hrs at 34°C, 50% relative humidity and fed sugar water; others (9–12) were frozen immediately upon collection. After freezing, all foragers were divided into two regions, head plus prothorax that have salivary glands (H/T1) and the remainder of body lacking salivary glands (T2,3/A). Pollen pellets and forager body regions were extracted for detection of deformed wing virus (DWV), sacbrood virus (SBV), and actin mRNA (forager only). Actin mRNA was used as an internal control for methods and loading. Red box indicates three foragers that lack detections of DWV but had pollen pellets with detectable DWV. The red star (lane 3) indicates a forager with heavy DWV infection in Head/Prothorax but no detectable DWV in her pollen pellets. Size of DWV reaction = 424 bp, SBV reaction = 693 bp and Actin reaction = 514 bp.
Mentions: Of the 12 initial honey bee pollen foragers analyzed for SBV and DWV and either kept for 24 hrs after removing their pollen pellets or directly frozen, there were no detectable differences in the prevalence of the viruses in these two groups. This suggests that the supply of virus associated with either the salivary glands or digestive tract was not reduced in those assayed immediately after collection as compared to those kept for 24 hrs. All foragers were dissected into two regions prior to virus analysis, the head and first thoracic segment containing the salivary glands and the remainder of the body. Three of the foragers were found to have detectable DWV in their pollen loads, without any detectable viral infections in the head/thoracic segments and two of these did not have any detectable infections anywhere (Figure 1) indicating that the salivary secretions of the forager were not a likely source of viral contamination on the pollen. One forager had a high level of DWV in her head/thoracic segment but there was no detectable DWV in her pollen load. SBV was detected in most of the pollen pellets as well as in the abdomen/thorax of the foragers, but few of the foragers had detectable virus in their heads/thoracic segments. These data therefore suggest that there is an alternative source of bee bread contamination.

Bottom Line: Although overall pollinator populations have declined over the last couple of decades, the honey bee (Apis mellifera) malady, colony collapse disorder (CCD), has caused major concern in the agricultural community.This finding further expands the viral host range and implies a possible deeper impact on the health of our ecosystem.Notably, in cases where honey bee apiaries affected by CCD harbored honey bees with Israeli Acute Paralysis virus (IAPV), nearby non-Apis hymenopteran pollinators also had IAPV, while those near apiaries without IAPV did not.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, The Pennsylvania State University, Pennsylvania, United States of America.

ABSTRACT
Although overall pollinator populations have declined over the last couple of decades, the honey bee (Apis mellifera) malady, colony collapse disorder (CCD), has caused major concern in the agricultural community. Among honey bee pathogens, RNA viruses are emerging as a serious threat and are suspected as major contributors to CCD. Recent detection of these viral species in bumble bees suggests a possible wider environmental spread of these viruses with potential broader impact. It is therefore vital to study the ecology and epidemiology of these viruses in the hymenopteran pollinator community as a whole. We studied the viral distribution in honey bees, in their pollen loads, and in other non-Apis hymenopteran pollinators collected from flowering plants in Pennsylvania, New York, and Illinois in the United States. Viruses in the samples were detected using reverse transcriptase-PCR and confirmed by sequencing. For the first time, we report the molecular detection of picorna-like RNA viruses (deformed wing virus, sacbrood virus and black queen cell virus) in pollen pellets collected directly from forager bees. Pollen pellets from several uninfected forager bees were detected with virus, indicating that pollen itself may harbor viruses. The viruses in the pollen and honey stored in the hive were demonstrated to be infective, with the queen becoming infected and laying infected eggs after these virus-contaminated foods were given to virus-free colonies. These viruses were detected in eleven other non-Apis hymenopteran species, ranging from many solitary bees to bumble bees and wasps. This finding further expands the viral host range and implies a possible deeper impact on the health of our ecosystem. Phylogenetic analyses support that these viruses are disseminating freely among the pollinators via the flower pollen itself. Notably, in cases where honey bee apiaries affected by CCD harbored honey bees with Israeli Acute Paralysis virus (IAPV), nearby non-Apis hymenopteran pollinators also had IAPV, while those near apiaries without IAPV did not. In containment greenhouse experiments, IAPV moved from infected honey bees to bumble bees and from infected bumble bees to honey bees within a week, demonstrating that the viruses could be transmitted from one species to another. This study adds to our present understanding of virus epidemiology and may help explain bee disease patterns and pollinator population decline in general.

Show MeSH
Related in: MedlinePlus