Sex ratio and dispersal of small hive beetles

Apis mellifera, honey bee, monitoring Journal of Apicultural Research 51(2): 216-217 (2012) © IBRA 2012 DOI 10.3896/IBRA.1.51.2.12 Small hive beetles (SHB), Aethina tumida, are parasites and scavengers of honey bee colonies and have become an invasive species with established populations in the USA and in Australia (Neumann and Ellis, 2008). They seem to have a female-biased adult sex ratio in the USA (Ellis et al., 2002a) and in Africa (Schmolke, 1974), but the latter report is based on only two infected hives in Zimbabwe. Otherwise, SHB sex ratios have only been analysed during laboratory rearing, also suggesting a bias towards females (Neumann et al., 2001a; Ellis et al., 2002b; Murrle and Neumann, 2004). We here provide the first systematic analyses of adult SHB sex ratios in Australian field populations and re-address South Africa. Since the two sexes of the SHB seem to differ in flight activity (Elzen et al., 2000), we also compared the sex ratios of newly infested colonies with those that had been infested for longer. The sex ratios were assessed in Australia in spring 2005 (37 colonies from five commercial apiaries in NSW: Richmond, Berowra, and Hawkesbury Area) and in South Africa in late summer 2005 (10 colonies from five commercial apiaries located in Grahamstown (Eastern Cape, N = 3), Port Elisabeth (Eastern Cape, N = 1), Pretoria (Gauteng, N = 1)) by sexing 7768 adult SHB (Schmolke, 1974). The sex ratios were compared to each other and to a 1:1 ratio using χ