Results of a bi-national effort were released and published this week in mBio, the online open-access journal of the American Society for Microbiology. Authors of the study included Yan Ping Chen from the U.S. Department of Agriculture's Agricultural Research Service (ARS) laboratory in Beltsville, Maryland, and lead author Ji Lian Li, at the Chinese Academy of Agricultural Science in Beijing.

Chen said routine screening of bees for frequent and rare viruses resulted in the detection of TRSV and prompted an investigation into whether the plant-infecting virus could also cause systemic infection in the bees.

"The results of our study provide the first evidence that honeybees exposed to virus-contaminated pollen can also be infected and that the infection becomes widespread in their bodies," Li said in the study. "We already know that honeybees, Apis melllifera, can transmit TRSV when they move from flower to flower, likely spreading the virus from one plant to another."

TRSV was also detected inside the bodies of Varroa mites, a vampire parasite that transmits viruses between bees while feeding on their blood. According to the study, the infected queen in a colony lays infected eggs, and this convinced scientists that TRSV could also be transmitted vertically to her offspring.

The study concluded that the increasing prevalence of TRSV in conjunction with other bee viruses is associated with a gradual decline of host populations and supports the view that viral infections have a significant negative impact on colony survival.

The other study, released by researchers at Royal Holloway University in London, was published last week in the Journal of Applied Ecology. Research team members included Gemma Baron, Dr. Nigel Raine and Professor Mark Brown, all from the School of Biological Sciences at Royal Holloway.

The study involved tracking how bee colonies grew over an extended period of time, recording their size and weight as well as monitoring the number of queens and worker bees produced by the colony.

"We already know that larger bumblebees are more effective at foraging. Our result, revealing that this pesticide causes bees to hatch out at a smaller size, is of concern as the size of workers produced in the field is likely to be a key component of colony success, with smaller bees being less efficient at collecting nectar and pollen from flowers," noted research lead Gemma Baron in the study summary.


Also of interest:

Stress may contribute to poor bee health

Casting doubt on neonicotinoid guilt

Pesticides get undue blame in honey bee decline