The presence of Varroa jacobsoni mite and Ascosphaera apis fungi in collapsing and normal honey bee (Apis mellifera L.) colonies in Yucatan, Mexico

A study was conducted to evaluate the possible role of the mite Varroa jacobsoni and the fungi Ascosphaera apis in collapsing honey bee (Apis mellifera L.) colonies in Yucatan, Mexico. Eleven honey bee colonies showing an abnormal population development (small number of adult bees and brood areas) were considered in a collapsing stage and 11 honey bee colonies from the same apiaries showing a population development of 6-8 combs of brood and high number of adult bees were considered as normal colonies. Collapsing and normal colonies were treated with a commercial miticide (Bayvarol (R)) for 42 days and the number of Varroa mites and chalkbrood mummies mere collected in bottom board traps. The results showed that collapsing colonies presented a higher number of total dead mites collected during the treatment period (3173+/-1528) compared with the normal colonies (1812+/-511); however, this differences were not statistically significant (P=0.103). The total number of chalkbrood mummies collected from the bottom board traps in collapsing colonies mas higher (253.9+/-86.5) and statistically different (P=0.007) from those in normal colonies (67.5+/-13.0). A high but not significant correlation was observed between number of mites and chalkbrood collected from collapsing colonies (r=0.46; P=0.158) in comparison with the correlation coefficient observed between both variables in normal colonies (r=0.12; P=0.716). These results suggest that honey bee Apis mellifera L. colonies infested with the mite V. jacobsoni, may enter a collapsing stage in association with chalkbrood disease in this region of Yucatan, Mexico.