Small hive beetle infestation levels correlate with sun exposure but not aggression of honeybee host colonies

Small hive beetles (SHB), Aethina tumida, are free-flying parasites, which actively seek and invade honeybee host colonies. Previous research suggests that SHB prefer colonies in the shade. Further, it has been stated that SHB invade any colony with equal impunity. Though, 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 than in the sun-exposed one. However, 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.