Seasonal Variation in Ectoparasitic Mite Tropilaelaelaps mercedesae Anderson and Morgan, 2007 in Apistan Treated and Untreated Colonies of Apis mellifera in Kathmandu, Nepal

Abstract

This study carried out for a period of six months from May 2017 to October 2017 describes the development of T. mercedesae infestation in the brood and foraging adults along with debris of A. mellifera honey bee colonies in Kathmandu, Nepal. A. mellifera colonies were divided into two groups: group A (treated with Apistan) and group B (untreated) that were naturally infested with T. mercedesae. Fortnightly observation of mites by "Sugar shake" method on adult bees and by opening the capped cells from the honey comb for broods was done. To inspect the number of dead mites in debris, formica sheets were placed at the bottom of hives. Group A colonies showed fluctuation in number of mites within study period with highest rate of infestation during October month (0.625% in adults, 8.375% in brood and 25.75 in debris) while the least rate of infestation during May (0% in adult, 2% in brood and 3.25 in debris). In Group B colonies, the highest infestation was observed in October in adult and debris (2.5% and 67.625 respectively) while it was 21.75% in brood in September while the least infestation was observed in May (0.5625% in adult, 2.75% in brood and 3.25 in debris). The difference between the mean values of the mites in broods of two colonies wasn't found to be significant with p value 0.089 (df, 6). The Apistan was found to be effective in controlling the mites in adult bees with p-value 0.0067 (df, 6). The population of the T. mercedesae mites was found to be positively correlated with humidity while it was found to be negatively correlated with the temperature. Therefore, during summer season, the number of mites remained low while the number increased during autumn when there was much brood rearing.