Susceptibility of small honey bee colonies to invasion by the small hive beetle, Aethina tumida (Coleoptera, Nitidulidae)

Weak and small honey bee colonies are supposed to be more susceptible to infestations by the small hive beetle [Aethina tumida, small hive beetle (SHB)]. To test this, we established 24 nucleus colonies [12 with and 12 without previous SHB removal (= screening)]. Four weeks later, we compared beetle numbers and the occurrence of SHB reproduction to the corresponding full-sized colonies. Full-sized colonies with no screening were infested with significantly more SHBs than all other groups (mean +/- standard deviation = 46.9 +/- 26.7). Regardless of this, none of the full-sized colonies showed damage or evidence of SHB reproduction. In contrast, five nucleus colonies collapsed and SHB larvae were found in an additional seven colonies. Our study demonstrates that SHB infestation levels which are harmless to full-sized colonies may have a negative impact on small nucleus colonies.