Validation of hygienic Apis mellifera L. colonies against Varroa destructor Anderson and Trueman infestation
Abstract
Varroa destructor is a major bee parasitic mite causing huge losses to Apis mellifera colonies worldwide. Apart from various chemical based strategies, hygienic behaviour is an important ecological Varroa management strategy. This trait plays an important role in imparting the colony resistance against the
V. destructor. Here, we assessed the colony level hygienic behaviour of 100 colonies using pin-killed brood method and from these 100 colonies, ten colonies (7 hygienic and 3 non-hygienic) were validated against V. destructor infestation for two seasons, autumn and spring. The worker larval brood near capping stage was inoculated with Varroa mite. In total, 21 inoculations were made in every test colony and replicated thrice. The observations were recorded at every 2 h interval till complete removal of mite. During the autumn season, in the 7 hygienic colonies, the mean of Varroa mite inoculated brood cells emptied after 2, 4 and 6 h was 1.36±0.11, 3.17±0.10 and 5.66±0.68%, and while in the non-hygienic colonies, it was 0±0.00, 0.52±0.10 and 2.11±0.53%, respectively. After 24 h a mean of 93.43±2.43% of brood cells were emptied in the hygienic colonies, while in the non-hygienic colonies, it was only 61.90±4.59%. During the spring season, in the hygienic colonies, mean mite inoculated brood cells emptied after 2, 4 and 6 h were 3.62±1.24, 6.57±0.73 and 7.25±0.47%, respectively while in the non-hygienic colonies the mean was 0±0.00%, 1.57±0.00 and 2.11±0.53%. After 24 h, it was 96.83±1.86% and 77.25±0.53% in the hygienic and non-hygienic colonies, respectively. In the autumn season, the hygienic colonies on an average took 28 h, whereas non-hygienic colonies took 50.67 h to achieve 100% uncapping and cleaning of cells. On the contrary, the hygienic colonies on an average took 25.71 h, whereas non-hygienic colonies took 47.36 h to achieve the same in the spring season. Hence, the hygienic behaviour can contribute to the colony’s resistance towards V. destructor mite inoculation in capped brood cells and result in reduced use of chemicals into the honey bee colonies.
V. destructor. Here, we assessed the colony level hygienic behaviour of 100 colonies using pin-killed brood method and from these 100 colonies, ten colonies (7 hygienic and 3 non-hygienic) were validated against V. destructor infestation for two seasons, autumn and spring. The worker larval brood near capping stage was inoculated with Varroa mite. In total, 21 inoculations were made in every test colony and replicated thrice. The observations were recorded at every 2 h interval till complete removal of mite. During the autumn season, in the 7 hygienic colonies, the mean of Varroa mite inoculated brood cells emptied after 2, 4 and 6 h was 1.36±0.11, 3.17±0.10 and 5.66±0.68%, and while in the non-hygienic colonies, it was 0±0.00, 0.52±0.10 and 2.11±0.53%, respectively. After 24 h a mean of 93.43±2.43% of brood cells were emptied in the hygienic colonies, while in the non-hygienic colonies, it was only 61.90±4.59%. During the spring season, in the hygienic colonies, mean mite inoculated brood cells emptied after 2, 4 and 6 h were 3.62±1.24, 6.57±0.73 and 7.25±0.47%, respectively while in the non-hygienic colonies the mean was 0±0.00%, 1.57±0.00 and 2.11±0.53%. After 24 h, it was 96.83±1.86% and 77.25±0.53% in the hygienic and non-hygienic colonies, respectively. In the autumn season, the hygienic colonies on an average took 28 h, whereas non-hygienic colonies took 50.67 h to achieve 100% uncapping and cleaning of cells. On the contrary, the hygienic colonies on an average took 25.71 h, whereas non-hygienic colonies took 47.36 h to achieve the same in the spring season. Hence, the hygienic behaviour can contribute to the colony’s resistance towards V. destructor mite inoculation in capped brood cells and result in reduced use of chemicals into the honey bee colonies.
Keyword(s)
European\Western honey bee; Bee colony; Brood cells; Mite resistance
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