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 jaco bsoni and the fungi Ascosphaera apis in collapsing honey bee (Apis mellifer a 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 stag e and 11 honey bee colonies from the same apiaries showing a population dev elopment of 6-8 combs of brood and high number of adult bees were considere d as normal colonies. Collapsing and normal colonies were treated with a commercial miticide (Bay varol (R)) for 42 days and the number of Varroa mites and chalkbrood mummie s mere collected in bottom board traps. The results showed that collapsing colonies presented a higher number of to tal 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 trap s in collapsing colonies mas higher (253.9+/-86.5) and statistically differ ent (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 com parison 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 wi th the mite V. jacobsoni, may enter a collapsing stage in association with chalkbrood disease in this region of Yucatan, Mexico.