Page 11 - Bumblebee Conservation Trust Buzzword Magazine July 2020

Parasites and pathogens of bumblebees Several other microscopic parasites call
the live bodies of bumblebees home. The
tiny nematode worm Sphaerulia bombi –
related to (but a different species from) the
nematodes you can buy to treat infestations
of vine weevil or slugs – lurks in the soil
until a queen bumblebee nestles down next
Photo: Bee-grabber fly, (Sicus ferrugineus) the bee’s body and takes over. When the Photo: Bee-grabber fly,
to it for the winter. The worm sneaks inside
queen wakes up from her winter dormancy,
the worm somehow ‘switches off’ her nest-
(Sicus ferrugineus)
making instincts at the same time as laying
By Dr Richard Comont, Science Manager around 10,000 miniature eggs. These are scattered with the bee’s faeces as it
wanders the countryside, each egg with the potential to repeat the process on
a new queen the following winter.
Bumblebees, fortunately for them, aren’t susceptible to COVID-19. There’s even Larger parasites can be a threat to individual bumblebees as well, and the
been some suggestion, that they might be doing better this year, with the human Thick-headed or Bee-grabber flies of family Conopidae are some of the more
population largely confined to their homes. But they do suffer from a wide range spectacular to see in action. As adults, these species spend their time waiting
of other diseases and parasites. on flowers for a bumblebee to amble past. When one does, the fly will zoom
out, grab it in mid-air, lay an egg on it, then zip off before the bee knows what’s
Funnily enough, this doesn’t include the most frequently reported ‘parasite’, hit it. The larvae proceed to eat the bee from the inside out, before pupating
bumblebee mites. These little orange blobs, despite being in genus Parasitellus, inside the remains. But some bumblebees have managed to fight back. The
are actually just hitching a lift so that they can drop off when the bee reaches fly larvae need high temperatures to develop, but some parasitized bees have
its nest. Once there, the mites live under the bees, eating detritus and generally been seen spending nights outside the warmth of the nest, slowing the fly’s
helping out by keeping the nest clean and free of fungus growth. development or even killing it.
Bumblebees do get parasitic mites, however. These are Locustacarus buchneri,
tiny creatures not visible to the naked eye, which live in the trachaea and air sacs.
It’s not clear how much harm they do to the bees, although similar infestations
of the mite Acarapis woodi in honeybees are known to weaken the bee and,
eventually, the colony.

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Photos (left): Red-tailed bumblebee the sale of our bee range to Bumblebee Conservation Trust.
(Bombus lapidarius) carrying mites; Middle: @Bumblebeeconservationtrust 15% off your next order using code BEE15
harmless bumblebee mite; Right: Locustacarus @BumblebeeTrust www.creaturecandy.co.uk
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