Number of SHB in the colonies and colony defensiveness

Small hive beetles (SHB), Aethina tumida, are free-flying parasites, which
actively seek and invade honeybee host colonies. It seems as if SHB may
prefer colonies in the shade. Further, it has been stated that SHB invade
any colony with equal impunity. However, the impact of colony
aggressiveness on SHB infestation levels has never been quantified. Here,
we confirm significantly higher SHB infestation levels in shaded colonies
and further suggest that host colony aggression is of minor importance
only. In the state of Rio de Janeiro, Brazil, local Africanized honeybee
colonies at a sunny (N=10) and at a shaded apiary (N=11) were tested for
aggression and visually screened for SHB infestations using standard
methods. Both colony aggression and infestation levels were variable, but
not significantly correlated. The results confirm that infestation levels
are significantly higher in the shaded apiary compared to the sun-exposed
one. Further, host colony aggression is unlikely to interfere with SHB
infestation levels of colonies. Instead, SHB seem to remain even in
aggressive colonies. The underlying mechanisms for the significant
differences in colony infestation levels due to sun exposure remain
unknown. Beekeepers are advised to prefer sun-exposed apiary locations in
regions, where SHB are a pest of concern.