Varroa destructor is an ectoparasitic pest of honeybees, and a threat to the survival of the
apiculture industry. Several studies have shown that unlike European honeybees, African
honeybee populations appear to be minimally affected when attacked by this mite. However,
little is known about the underlying drivers contributing to survival of African honeybee populations
against the mite. We hypothesized that resistant behavioral defenses are responsible
for the survival of African honeybees against the ectoparasite. We tested this hypothesis
by comparing grooming and hygienic behaviors in the African savannah honeybee Apis mellifera
scutellata in Kenya and A. mellifera hybrids of European origin in Florida, USA against
the mite. Grooming behavior was assessed by determining adult mite infestation levels,
daily mite fall per colony and percentage mite damage (as an indicator of adult grooming
rate), while hygienic behavior was assessed by determining the brood removal rate after
freeze killing a section of the brood. Our results identified two additional undescribed damaged
mite categories along with the six previously known damage categories associated
with the grooming behavior of both honeybee subspecies. Adult mite infestation level was
approximately three-fold higher in A. mellifera hybrids of European origin than in A. m. scutellata,
however, brood removal rate, adult grooming rate and daily natural mite fall were
similar in both honeybee subspecies. Unlike A. mellifera hybrids of European origin, adult
grooming rate and brood removal rate did not correlate with mite infestation levels on adult
worker honeybee of A. m. scutellata though they were more aggressive towards the mites
than their European counterparts. Our results provide valuable insights into the tolerance
mechanisms that contribute to the survival of A. m. scutellata against the mite.
S1 Table. Primers used for molecular analysis for identification of Varroa species and haplotype.
Amplified gene fragment, product size base pairs (bp) and annealing temperatures
(Ta) are indicated .