The rate at which bees are disappearing from their hives does not bode well for the future of such plants. The colony collapse disorder (CCD) continues to mystify scientists and beekeepers alike. The cause is still unknown. A team from the University of Illinois perused the guts of healthy and infected bees for some answers.

Entomologist May R Berenbaum and colleagues collected healthy bees from Illinois and infected bees from the east coast and the west coast of the US. Damaged genetic fragments were evident in the guts of infected bees. The fragments, called ribosomal RNA (RRNA), form cell components called ribosomes, protein manufacturing units.

Parasites find it easier to attack a bee’s body by penetrating its gut wall. This explains why the team examined the bees’ guts. The rest of the insect’s digestive tract is covered on the inside by a thick, protective layer called the cuticle. After entering the body, the parasites take over the cellular machinery to achieve the replication of their own genes. The first step towards this is protein production. Hence the team concluded that the RRNA litter in the infected bee guts was from a pathogen overload. The next step was to confirm the connection between parasitic destruction and CCD. From the gut matter, the team detected and identified genetic markers of eight parasites linked to the disorder: five viruses, one bacterium, one fungus and a single-celled protozoan. The parasites’ distribution varied between the infected bees from the east coast and the west coast. The common point was that the litter of RRNA was missing only from the healthy bee guts.

“But CCD is not caused by a single agent,” said Berenbaum. Other factors aid and abet. For example, the bee gut releases detoxification enzymes that help fortify its immunity. But if the pathogens can still turn it into a haven of their own, it means the bee has low immunity. It might be malnourished. The parasite’s job is easier then. Exposure to harmful chemicals is another example.

The researchers hope to use the genetic fragments as a diagnostic tool for sick bees. “This is a marker that predicts the bees will soon face trouble. We hope that someone could connect this to a precise cause that can be treated,” said Jay D Evans from the US Department of Agriculture’s Bee Research Lab, a partner in the study.
Diya Das
Down To Earth Feature Service

Tales whiskers tell
Every whisker tells a story. That is the thinking behind a study of the migration patterns and foraging strategies of Antarctic fur seals. Whiskers, like human hair, are made primarily of the protein keratin and grow from the base. Keratin is stable, so whatever atoms it incorporates as the whisker grows, from whatever the animal breathes, drinks and eats, are locked in place. So a whisker can be a linear archive of information about the animal's foraging habits.

Yves Cherel of the Chize Center for Biological Studies in France and colleagues took whiskers from 10 male Antarctic fur seals that breed on the Crozet Islands in the southern Indian Ocean and chopped them into equal segments, each about one-eighth of an inch long. (The longest whisker was about 13 inches, yielding 111 segments.) Then they analysed them for ratios of isotopes of carbon and nitrogen.
Changes in the carbon isotope ratio can reflect where the animal has travelled, from subtropical zones to Antarctic waters, while changes in the nitrogen isotope ratio reflect a change in eating habits depending on the animal's ecological niche.
As reported in Biology Letters, the isotopic signatures in the whiskers showed a distinct yearly pattern, with the seals migrating between the subtropics and the high Antarctic, and shifting from a diet of krill in the Antarctic to fish in sub-Antarctic and subtropical waters.
But there was significant diversity among the individual seals: Some remained only in sub-Antarctic waters, for example, never venturing to higher latitudes.
Henry Fountain
NYT News Service