American scientists have found that the infection of bees by the Israeli
virus of acute paralysis alters their social interactions,therefore,
the infected bees become less popular in their own colony, but
more popular in another. As suggested by the authors of the article in the Proceedings of the National Academy of Sciences, this may be the consequence of the evolutionary strategy of the virus to spread
between the colonies.
Parasites often alter the behavior of their hosts for the benefit of themselves.
For example, parasitic worms make ants less aggressive, which leads
to capture the anthill outsiders and contributes to the spread of parasites. Scientists
found out that something similar occurs with bees infected with Israeli
the acute paralysis virus (IAPV — Israeli acute paralysis virus).
This virus, which has already led to the deaths of many bees in bee farms
Israel and the United States, typically in a colony with varroa mites, but can
transmitted by contact between bees. The researchers suggested that the infected
bees easily penetrate into neighboring colonies and, thus, contribute to
the spread of the virus.
Scientists from the state University of Iowa and
University of Illinois at Urbana infecting bees with IAPV virus and compared
their behavior with the behavior of Bumble bees and bees that had been injected with double-stranded
RNA to run a nonspecific antiviral response in the body.
The researchers found a system of automatic monitoring
three bee colonies and observed for five days for social
interactions artificially infected bees. It turned out that people
bees are less likely to participate in mutual feeding (trophallaxis) with other members
the colony, despite the fact that moving more.
Inside the colony bees are actively cooperating with
aerials (antennae) and can detect chemical markers on the surface of the cuticle other
bees. A set of chemicals unique to each colony, and in addition,
depends on the age and social status of the insect. Thus, for example,
bee-guards who are on duty at the entrance of the hive, recognize stray bees, and
try not to let them inside.
In the experimental hives surrounding the bees ignored the sick bees
quite, but refused to engage in closer contact after the inspection.
Likely, this contributed to changes in the chemical composition of the cuticle
infected insects. Chromatographic analysis really showed
a significant change in the chemical profile of the cuticle after exposure. For example,
they were characterized by a reduced amount of octacosane that is associated with
reduced aggression toward such bees.
In a laboratory experiment, scientists have shown that bees
infected with IAPV, but not
control cause less aggression in foreign bees, therefore, they
it would be more likely to penetrate a foreign colony. A field experiment in which
infected bees were released at the entrance to the alien hive, really showed that
security guards are twice as likely to let them in, than, for example, bees with
stimulated non-specific immunity (30 percent vs. 15). In addition
after the entrance of strangers often engaged in trophallaxis with new neighbors,
probably also contributed to the spread of the virus.
Despite a reliable “navigation system” in
the nature of bees sometimes make mistakes and not return to the colony and into another. It is assumed,
that diseased bees get lost more often, and thus can contribute
the spread of the pathogen. In the nature of bee colonies are low
density, but in the beekeeping hives are very tight, which greatly increases
the rate of infection. So, in 2015 in the US for some strange reason
had destroyed 42 percent of all bees.