The Scientist - USA (2021-02)

18 THE SCIENTIST | the-scientist.com

Notebook

COURTESY OF KATHERINE RAINES

Radioactive

Bees

A few years ago, on one of her first visits

to Chernobyl, Katherine Raines went to

the Red Forest, a radioactive cemetery of

pine trees scorched by the nuclear accident

in 1986. She was curious to see if there

were bees living in the area. Research on

the effect of chronic exposure to ionizing

radiation on insects is limited, and some

of the findings are controversial, but most

experts support the idea that bees and

other invertebrates are relatively resilient

to radioactive stress.

Raines, a radioecologist at the University

of Stirling in Scotland, didn’t spend long in

that forest. In one spot there, her personal

radiation dosimeter measured an environ-

mental level of ionizing radiation of 200

microsieverts (μSv) per hour; more than

a few hours of that exposure could have

increased her cancer risk. But even during

that brief visit, she did see bees. Whether they

were living there or just visiting, Raines says,

is hard to tell.

Back in the UK, Raines and colleagues

recreated the same levels of radiation in a

specialized facility. Boxes each containing

a bumble bee colony made up of a queen,

workers, and brood were placed at differ-

ent distances from a radiation source, cre-

ating a gradient where bees in each box

received a fairly steady dose of between

20 and 3,000 micrograys (μGy) per hour.

(The two kinds of units, sieverts and grays,

are essentially equivalent measures of the

amount of exposure to radiation; sieverts

factor in the type of radiation and account

for the sensitivity of the exposed tissue.

Bees at the site Raines visited in the Red

Forest would experience around 200 μGy

per hour.) The bees stayed in their artificial

homes for four weeks before being moved

outdoors into the university gardens for

around one month, until the colonies were

no longer viable—that is, once the queen

had died and only a few workers remained.

The limited lab studies previously car-

ried out by other groups had suggested that

bees and other insects should be safe below

400 μGy per hour. So, Raines says, she was

FEBRUARY 2021

GETTING A BUZZ: Researchers studied how

radiation might affect bumble bees like this

one at Chernobyl.