ARS | Publication request: Does the removal of mite-infested brood facilitate grooming?

Submitted to: American Bee Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 11, 2013
Publication Date: N/A

Technical Abstract: The relationship between the removal of mite-infested brood and mite drop was compared using Russian (RHB, n = 9) and Italian (IHB, n = 9) honey bee colonies. A cloake board was used to isolate test brood frame on the top hive body and the metal sheet served as a varroa trap. Inoculum mites were collected from newly sealed larvae and each was marked using correction fluid (Kirrane et al., 2012 J. Apic. Res. 51: 212-213). Brood cells randomly received one of the following groups: 1) brood inoculated with one female varroa, 2) brood with capping opened and closed without mite inoculation (o/c), and 3) undisturbed brood cells as control. Brood removal and mite drop were determined every day for eight days. Both stocks removed more mite-inoculated brood than o/c or control groups (P <0.0001). RHB (87.9 ± 2.0%) significantly removed more inoculated brood than IHB (61.9 ± 7.3%) (P = 0.0001). Increased removal of frozen brood by RHB has also been demonstrated (de Guzman et al., 2002 Am. Bee J. 141: 58-60). Although both stocks removed brood every day, brood removal peaked during the first four days for IHB and during the first two days for RHB colonies. Overall, the RHB (2.5 ± 0.1 days) removed brood faster than the IHB (3.0 ± 0.1 days) colonies (P = 0.014). Fallen marked mites were collected from traps every day with peaks observed during the first three days coinciding with the peak of brood removal. Overall, about 35% of the introduced mites dropped from the RHB compared to 24% for IHB. A similar observation was reported by Rinderer et al. (2001 Apidologie 32: 381-394). Regardless of stock, the number of dropped mites increased with an increase in brood removal (r = 0.089, P = 0.0001) (see figure). Brood removal may be one of the major causes of high mite drop in honey bee colonies.