Photo shows a
bumblebee (Bombus melanopygus) in flight towards a pansy flower.
Photo credit: Kathy
Keatley Garvey, UC Davis.
Study by UC Riverside entomologist and colleagues shows
flowers serve as parasite-dispersing hubs
(August 5, 2015) Despite
their beauty, flowers can pose a grave danger to bees by providing a platform
of parasites to visiting bees, a team of researchers has determined.
“Flowers are hotspots for parasite spread between and within
pollinator populations,” said Peter Graystock, a postdoctoral researcher in the
Department of Entomology at the University of California, Riverside and a
member of the research team. “Both the flower and bee species play a role in
how likely parasite dispersal will occur.”
The study, published online in the Proceedings of the Royal
Society B, is the first to show that not only can bees disperse parasites
around the environment but also that flowers are platforms for a host of
pollinator parasites subsequently dispersed onto visiting bees.
“By showing that visits from parasite-carrying bees can turn
flowers into parasite platforms, we can say that it is likely that heavily
visited flowers may become more ‘dirty’ with bee parasites,” said Graystock,
the research paper’s first author.
“Planting more flowers would provide bees with more options, and
parasite spread may thus be reduced.”
Photo shows a honey
bee (Apis mellifera) and a bumblebee (Bombus spp.) foraging
on a purple
coneflower. PHOTO CREDIT: KATHY KEATLEY GARVEY, UC DAVIS.
The researchers found four common honey bee and bumblebee
parasites dispersed via flowers: Nosema apis (causes a honey bee disease), Nosema
ceranae (causes an emergent disease in honey bees and bumblebees), Crithidia
bombi (causes a bumblebee disease) and Apicystis bombi (mostly found in
bumblebees). These parasites are known to cause, lethargy, dysentery, colony
collapse, and queen death in heavily infected bees.
Photo shows a honey
bee (Apis mellifera) foraging on a pansy flower.
PHOTO CREDIT: KATHY
KEATLEY GARVEY, UC DAVIS.
Currently, bees are frequently transported across state and
international territories. Quarantine
and parasite screening usually cover only the screening of host-specific
diseases. But bumblebees can transport
honey bee parasites, and vice versa, the research team has now shown, and
proposes that increased screening protocols be employed to protect pollinator
diversity.