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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>http://www.economist.com/node/21543469<o:p></o:p></span></font></p>
<h2><b><font size=5 face="Times New Roman"><span style='font-size:18.0pt'>Colony
collapse disorder<o:p></o:p></span></font></b></h2>
<h3><b><font size=4 face="Times New Roman"><span style='font-size:13.5pt'>Bee
off<o:p></o:p></span></font></b></h3>
<h1><b><font size=6 face="Times New Roman"><span style='font-size:24.0pt'>A
possible explanation of why beehives sometimes vanish<o:p></o:p></span></font></b></h1>
<p class=ec-article-info><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>Jan 28th 2012 | from the print edition <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><img width=290 height=417 id="_x0000_i1030"
src="cid:image001.jpg@01CCECA4.82C0D910" title=""
class="imagecache imagecache-290-width"><span class=caption>Looking for the
cause</span> <o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>HONEYBEES
are sensitive creatures. From time to time a hive simply gives up the ghost and
vanishes. Colony collapse disorder, as this phenomenon is known, has been
getting worse since 2006. Some beekeepers worry that it may make their trade
impossible, and could even have an effect on agriculture—since many crops
rely on bees to pollinate them. Climate change, habitat destruction, pesticides
and disease have all been suggested as possible causes. Nothing, though, has
been proved. But the latest idea, reported in <em><i><font
face="Times New Roman">Naturwissenschaften</font></i></em> by Jeff Pettis of
the Bee Research Laboratory in <st1:place w:st="on"><st1:City w:st="on">Beltsville</st1:City>,
<st1:State w:st="on">Maryland</st1:State></st1:place>, suggests that this may
be because more than one factor is involved.<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>Dr Pettis
and his colleagues knew from previous reports that exposure to a pesticide
called imidacloprid has a bad effect on honeybees’ ability to learn
things and wondered whether it might be causing other, less noticeable, damage.
Since one thing common to colonies that go on to collapse seems to be a greater
variety and higher load of parasites and pathogens than other colonies, they
wondered in particular whether it might be weakening the insects’ immune
systems, and thus allowing infections to spread through a hive.<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>To find
out, they gave 20 hives protein food (a substitute for pollen, which is fed to
developing larvae) that had been spiked with imidacloprid. In ten cases the
dose was five parts per billion (ppb); in the other ten it was 20 ppb. Previous
experiments have shown that neither dose perceptibly harms bees. A further ten
hives were given unspiked food as a control. Then, when the young bees emerged
a few weeks later, Dr Pettis collected them and fed them with spores of a
fungal parasite called <em><i><font face="Times New Roman">Nosema</font></i></em>.
Twelve days later, he killed them and estimated the extent of their
infestation.<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>Both of
the groups that had been exposed to imidacloprid harboured an average of
700,000 parasite spores in each bee. Bees from the control colonies, by
contrast, harboured fewer than 200,000 spores in their bodies. The insecticide,
in other words, was exposing bees to infestation, and thus to a much greater
chance of dying prematurely.<o:p></o:p></span></font></p>
<p><font size=3 face="Times New Roman"><span style='font-size:12.0pt'>Whether
this is actually the reason for colonies collapsing remains to be determined.
But it is a plausible hypothesis, and is likely to get beekeepers buzzing with
interest.<o:p></o:p></span></font></p>
<p class=ec-article-info><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'>from the print edition | Science and technology <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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