Week In Science

In the past few months important studies have been published about honey bees. Some address the American problem of colony collapse which concerns farmers throughout the United States. Others have identified specific genes and proteins with honey bee development and behavior.

The Making of a Queen: TOR Pathway Is a Key Player in Diphenic Caste Development is the title of a paper published in PLOS One and is authored by Avani Patel, M. Kim Fondrk, Osman Kaftanoglu, Christine Emore, Greg Hunt, Katy Frederick and Gro V. Amdam.

It has long been understood that the diphenic development of honey bees (Apis mellifera) is linked to the feeding of female larvae. A moderate diet produces worker bees and more nourishment yields queens. Less well understood was the actual signaling pathway linked to the development of queen and worker bees. The authors suspected that a kinase enzyme known as target of rapamycin (TOR) controlled the growth of the developing larvae.

TOR is found in signaling pathways of eukaryotic organisms. These pathways have cell regulatory and organismal growth functions. Growth is related to nutrition. The specific nutritional variation that differentiates queens from worker bees entails a diet rich in royal jelly for the developing queen and a moderate amount of less nutritious jelly for workers.

Researchers succeeded in implicating Apis mellifera TOR (amTOR) in the differentiation of queens and workers. Gene knockdown through the utilization of RNAi (RNA interference) was employed to demonstrate that a reduction in amTOR activity correlates to the blockage of the pathway to a queen and the resultant development of workers.

A paper entitled A Single Gene Coordinates the Social Life of Honeybees by Liza Gross appeared in PLOS Biology. Liza Gross documented the critical role of the vitellogenin protein in regulating the social behavoir of the honey bee. Regulated by this protein are the division of labor and foraging preference which are elements of the honey bees' organizational structure. Levels of vitellogenin control when bees begin foraging as well as what they forage. It even affects life expectency. Bees having lower levels of vitellogenin tend to forage for nectar while those with higher levels early in their lives forage for pollen.

More data, less clarity in bee colony collapse, an article by John Timmer, touches on the troublesome demise of bee colonies that has become a concern throughout the United States. An article in Science was cited and a possibly helpful finding was made. There was a 95 per cent correlation documented between colony collapse and a virus known as the Israeli acute paralysis virus. The problem though was that the source of the virus- Australia- which exported bees to the United States has not experienced problems with its bees. This indicates there should be other factors contributing to the problem in the USA. Pehaps parasitic mites or chemicals are culprits but the investigation continues.

Another PLOS Biology article What's Killing American Honey Bees? by Benjamin P. Oldroyd, explores the mystery previously alluded to. The author notes that honey bees are afflicted by a large number of pathogenic organisms which include fungi and mites to go along with viruses and unicellular organisms. He gets specific in naming different species but rules out most candidates.

Benjamin Oldroyd concludes by hypothesizing that colony collapse might be caused simply by inadaquate incubation. He suggests that the test for this involves incubating broods at different temperatures and then observing to see if the colonies raised in sub-optimal temperatures experienced colony collapse.