shocked when she found that even those col-
onies exposed to lower rates showed signs of
a negative effect of radiation, especially on
reproduction. Bumble bee colonies experienc-
ing just 100 μGy per hour, for example, had
reduced their production of queens by almost
half, dramatically impairing the chances of
successfully founding new colonies. Accord-
ing to the study, the overall effect was stronger
than the one-fourth reduction observed in col-
onies exposed to a popular pesticide.This work “sheds new light on the
importance of chronic low-dose radiation
exposure in a nonmodel species [with] pro-
found relevance for the natural world,” says
Timothy Mousseau, an ecological genet-
icist at the University of South Carolina
who was not involved in this research. But
he adds that it is hard to determine how
some of these results, based on experimen-
tal manipulations in an artificial setting,
can translate “to what’s actually going on in
Chernobyl” for these important pollinators.
Mousseau and his colleague Anders
Pape Møller (now at CNRS in France)
have been doing field studies since 2000
to assess the abundance of wildlife popu-
lations living in the Chernobyl Exclusion
Zone (CEZ), a 2,600 square-kilometer
area surrounding the nuclear power
plant. Their results have shown a neg-
ative correlation between radiation lev-
els—which vary a great deal within the
zone—and wildlife abundance. Insects
were no exception: the team observed
fewer bumble bees in the most contami-
nated areas, a relationship that held even
within a range of extremely low radia-
tion levels (from 0.01 to 1 μGy per hour).
Those studies have been criticized,
partly over the accuracy of their estimations
of radiation levels. Mousseau and Møller
have collaborated with some of their critics
to reanalyze some of their data, and main-tain that there has been wildlife reduction
in the CEZ due to radiation. But Jim Smith,
an environmental scientist at the University
of Portsmouth in the UK, is one of several
scientists who still has doubts about the
studies, telling The Scientist that the obser-
vations don’t align with findings from other
surveys in the region. For example, Smith,
who has been visiting Chernobyl since the
1990s but is not involved in Raines’s or
Mousseau’s work, failed to find evidence
that either the abundance or the diversity
of aquatic insects and other macroinver-
tebrates was reduced by radiation in any
of the eight natural lakes that he and his
colleagues analyzed in the CEZ in 2011,
despite measuring external dose rates of
between 0.1 and 30 μGy per hour.
Smith—who, along with Raines,
belongs to a UK research program par-
tially funded by the Environment Agency
and its safe disposal contractor, RadioactiveWaste Management—says that Raines’s
bee study provides “interesting new data
on a species that hasn’t really been stud-
ied [and] that is potentially more radio-
sensitive than we thought.” But he is skeptical
about the wider relevance of studying the
effect of radiation levels rarely encountered
in nature. Chernobyl’s radiation levels are
a consequence of “the worst nuclear acci-
dent in history,” he says. And even within
the CEZ, very few spots reach the radiation
levels explored in this paper.
Raines says that although she did
not detect any negative effect in colonies
exposed to less than 50 μGy per hour—close
to 200 times what humans experience, on
average, from natural radiation sources—
she didn’t have enough colonies at that level
to conclude that bumble bees are unaffected.
Her team had not designed its experiment
to explore bees’ responses to such low lev-
els, having assumed they wouldn’t see anyBumble bee colonies
experienc ing just 100 ȝGy
per hour had reduced their
production of queens by
almost half.ANDRZEJ KRAUZE
VOL. 35 ISSUE 2 | THE SCIENTIST 19