Clothianidin seed-treatment has no detectable negative impact on honeybee colonies and their pathogens.

Interactions between multiple stressors have been implicated in elevated honeybee colony losses. Here, we extend our landscape-scale study on the effects of placement at clothianidin seed-treated oilseed rape fields on honeybees with an additional year and new data on honeybee colony development, swarming, mortality, pathogens and immune gene expression. Clothianidin residues in pollen, nectar and honeybees were consistently higher at clothianidin-treated fields, with large differences between fields and years. We found large variations in colony development and microbial composition and no observable negative impact of placement at clothianidin-treated fields. Clothianidin treatment was associated with an increase in brood, adult bees and Gilliamella apicola (beneficial gut symbiont) and a decrease in Aphid lethal paralysis virus and Black queen cell virus - particularly in the second year. The results suggest that at colony level, honeybees are relatively robust to the effects of clothianidin in real-world agricultural landscapes, with moderate, natural disease pressure.

Seasonal Effects and the Impact of In-Hive Pesticide Treatments on Parasite, Pathogens, and Health of Honey Bees.

Honey bee, Apis mellifera (L.; Hymenoptera: Apidae), populations are in decline and their losses pose a serious threat for crop pollination and food production. The specific causes of these losses are believed to be multifactorial. Pesticides, parasites and pathogens, and nutritional deficiencies have been implicated in the losses due to their ability to exert energetic stress on bees. While our understanding of the role of these factors in honey bee colony losses has improved, there is still a lack of knowledge of how they impact the immune system of the honey bee. In this study, honey bee colonies were exposed to Fumagilin-B, Apistan (tau-fluvalinate), and chlorothalonil at field realistic levels. No significant effects of the antibiotic and two pesticides were observed on the levels of varroa mite, Nosema ceranae (Fries; Microsporidia: Nosematidae), black queen cell virus, deformed wing virus, or immunity as measured by phenoloxidase and glucose oxidase activity. Any effects on the parasites, pathogens, and immunity we observed appear to be due mainly to seasonal changes within the honey bee colonies. The results suggest that Fumagilin-B, Apistan, and chlorothalonil do not significantly impact the health of honey bee colonies, based on the factors analyzed and the concentration of chemicals tested.

An Inert Pesticide Adjuvant Synergizes Viral Pathogenicity and Mortality in Honey Bee Larvae.

Honey bees are highly valued for their pollination services in agricultural settings, and recent declines in managed populations have caused concern. Colony losses following a major pollination event in the United States, almond pollination, have been characterized by brood mortality with specific symptoms, followed by eventual colony loss weeks later. In this study, we demonstrate that these symptoms can be produced by chronically exposing brood to both an organosilicone surfactant adjuvant (OSS) commonly used on many agricultural crops including wine grapes, tree nuts and tree fruits and exogenous viral pathogens by simulating a horizontal transmission event. Observed synergistic mortality occurred during the larval-pupal molt. Using q-PCR techniques to measure gene expression and viral levels in larvae taken prior to observed mortality at metamorphosis, we found that exposure to OSS and exogenous virus resulted in significantly heightened Black Queen Cell Virus (BQCV) titers and lower expression of a Toll 7-like-receptor associated with autophagic viral defense (Am18w). These results demonstrate that organosilicone spray adjuvants that are considered biologically inert potentiate viral pathogenicity in honey bee larvae, and guidelines for OSS use may be warranted.

Identification of genes involved in taura syndrome virus resistance in litopenaeus vannamei.

Abstract The goal of the present research was to identify the genes that are differentially expressed between two lineages of Pacific white shrimp Litopenaeus vannamei displaying different susceptibilities to Taura syndrome virus (TSV) and to understand the molecular pathways involved in resistance to the disease. An oligonucleotide microarray was constructed and used to identify several genes that were differentially expressed in the two L. vannamei lineages following infection with TSV. Individual L. vannamei from either resistant or susceptible lineages were exposed via injection to TSV. Individuals were removed at 6 and 24 h postinfection, and gene expression was assessed with the in-house microarray. The microarray data resulted in the selection of a set of 397 genes that were altered by TSV exposure between the different lineages. Significantly differentially expressed genes were subjected to hierarchical clustering and revealed a lineage-dependent clustering at 24 h postinoculation, but not at 6 h postinoculation. Discriminant analysis resulted in the identification of a set of 11 genes that were able to correctly classify Pacific white shrimp as resistant or susceptible based on gene expression data. Received June 21, 2013; accepted October 24, 2013.

Inactivation of a non-enveloped RNA virus by artificial ribonucleases: honey bees and acute bee paralysis virus as a new experimental model for in vivo antiviral activity assessment.

RNA-containing viruses represent a global threat to the health and wellbeing of humans and animals. Hence, the discovery of new approaches for the design of novel vaccines and antiviral compounds attains high attention. Here we describe the potential of artificial ribonucleases (aRNases), low molecular weight compounds capable to cleave phosphodiester bonds in RNA under mild conditions, to act as antiviral compounds via destroying the genome of non-enveloped RNA viruses, and the potential of utilizing honey bee larvae and adult bees (Apis mellifera) as a novel experimental system for the screening of new antiviral compounds. Pre-incubation of an Acute bee paralysis virus (ABPV) suspension with aRNases D3-12, K-D-1 or Dp12F6 in a concentration-dependent manner increased the survival rate of bee larvae and adult bees subsequently infected with these preparations, whereas incubation of the virus with aRNases ABL3C3 or L2-3 had no effect at all. The results of RT-PCR analysis of viral RNA isolated from aRNase-treated virus particles confirmed that virus inactivation occurs via degradation of viral genomic RNA: dose-dependent inactivation of ABPV correlates well with the cleavage of viral RNA. Electron microscopy analysis revealed that the morphology of ABPV particles inactivated by aRNases remains unaffected as compared to control virus preparations. Altogether the obtained results clearly demonstrate the potential of aRNases as a new virus inactivation agents and bee larvae/ABPV as a new in vivo system for the screening of antiviral compounds.

Large-scale field application of RNAi technology reducing Israeli acute paralysis virus disease in honey bees (Apis mellifera, Hymenoptera: Apidae).

The importance of honey bees to the world economy far surpasses their contribution in terms of honey production; they are responsible for up to 30% of the world's food production through pollination of crops. Since fall 2006, honey bees in the U.S. have faced a serious population decline, due in part to a phenomenon called Colony Collapse Disorder (CCD), which is a disease syndrome that is likely caused by several factors. Data from an initial study in which investigators compared pathogens in honey bees affected by CCD suggested a putative role for Israeli Acute Paralysis Virus, IAPV. This is a single stranded RNA virus with no DNA stage placed taxonomically within the family Dicistroviridae. Although subsequent studies have failed to find IAPV in all CCD diagnosed colonies, IAPV has been shown to cause honey bee mortality. RNA interference technology (RNAi) has been used successfully to silence endogenous insect (including honey bee) genes both by injection and feeding. Moreover, RNAi was shown to prevent bees from succumbing to infection from IAPV under laboratory conditions. In the current study IAPV specific homologous dsRNA was used in the field, under natural beekeeping conditions in order to prevent mortality and improve the overall health of bees infected with IAPV. This controlled study included a total of 160 honey bee hives in two discrete climates, seasons and geographical locations (Florida and Pennsylvania). To our knowledge, this is the first successful large-scale real world use of RNAi for disease control.