Systemic Spread and Propagation of a Plant-Pathogenic Virus in European Honeybees, Apis mellifera

Li, Ji Lian; Cornman, R. Scott; Evans, Jay D.; Pettis, Jeffery S.; Zhao, Yan; Murphy, Charles; Peng, Wen Jun; Wu, Jie; Hamilton, Michele; Boncristiani, Humberto F.; Zhou, Liang; Hammond, John; Chen, Yan Ping

For assessing the effects of viruses on honeybees, the seasonal prevalence of virus infections was determined in ten colonies for a period of 1 year starting in March and finishing in February of the following year. Bee colonies were classified as strong or weak based on the size of adult populations, amount of sealed brood, and presence of food stores, as previously described (60) . Bee colonies that had more than ten frames covered with adult workers and more than six frames filled with brood and food stores were defined as strong colonies, while bee colonies that had a small number of foraging bees flying in and out, fewer than ten frames of adult bees, fewer than six combs with brood, and small patches of food stores were defined as weak colonies. For each colony, samples of 20 adult workers were collected every month and stored at Ϫ80°C until subsequent RNA isolation for virus analysis.