Location: Bee Research LaboratoryTitle: Honey bee colonies act as reservoirs for two Spiroplasma facultative symbionts and incur complex multiyear infection dynamics) Author
Submitted to: The Open Microbiology Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/1/2014
Publication Date: 4/28/2014
Citation: Schwarz, R.S., Teixeira, E., Tauber, J.P., Birke, J.M., Martins, M., Fonseca, I., Evans, J.D. 2014. Honey bee colonies act as reservoirs for two Spiroplasma facultative symbionts and incur complex multiyear infection dynamics. The Open Microbiology Journal. DOI: 10.1002/mbo3.172. Interpretive Summary: Bacteria in the genus Spiroplasma can cause ‘May disease’ and ‘spiroplasmosis’ in honey bees, noted by neurological disorders and mortality. Two distinct species isolated from honey bees were first described in the 1980’s as infectious agents, Spiroplasma apis and Spiroplasma melliferum. Both species were found commonly in Spring but rarely, if at all, other times of the year, and their presence was closely tied to foraging on trees that served as bacterial reservoirs. Here we present a two-year study aimed at describing seasonal prevalence of both S. apis and S. melliferum populations in the U.S., using diagnostic molecular techniques described here. We show that hives carry higher levels in the Spring, as expected, but also that hives can carry these bacteria throughout the year, suggesting they threaten honey bee health throughout the year. We also describe, for the first time, the seasonality of these pathogens from honey bees in Brazil, showing high prevalence during the Spring and Fall. These results offer insights into a poorly understood pathogen of worker honey bees and can be used to help determine the roles of this bacterium in colony declines.
Technical Abstract: Approximately 30 years ago, two species of mollicute bacteria in the genus Spiroplasma were isolated and described from adult Western honey bees (Apis mellifera). Denominated for their host as Spiroplasma apis and Spiroplasma melliferum, these bacteria were uniquely isolated during springtime and have putatively been associated with neurological disease and increased mortality rates at this time of year. However, since their original description no information on the occurrence or prevalence of these species in A. mellifera has been assessed. We report novel methods to specifically detect each species using quantitative PCR (qPCR) analysis using a previously published primer to detect S. melliferum designed for multiplex PCR and a novel primer designed to detect S. apis via qPCR. These primers were used to analyze adult workers from colonies of A. mellifera for the presence/absence of each Spiroplasma species collected between 2011 and 2013 from the state of Maryland, U.S.A. and from 13 states in Brazil. We show that both species infect colonies at high frequency not only during springtime as expected from the northern hemisphere, but are also prevalent at other times of year with irregular frequency in both the U.S.A. and Brazil. We use our data to speculate on the contributing factors affecting transmission, latency, and frequency of Spiroplasma in honey bees colonies.