SEASONAL CHANGES IN MITE (TROPILAELAPS CLAREAE) AND HONEYBEE (APIS MELLIFERA) POPULATIONS IN APISTAN TREATED AND UNTREATED COLONIES

Beekeepers in Pakistan in 1992 repeatedly complained of heavy losses of honey and honeybee colonies owing to the disease problem mainly caused by Tropilaelaps clareae, Asian parasitic brood mite. Despite frequently treating their colonies with low-cost chemicals, like sulphur, tobacco and camphor (naphthalene), many colonies were still found infested. In order to achieve a better control of the parasite, it was essential to understand the biology and behaviour of mite. This paper describes the development of T. clareae infestation in the Apistan treated and untreated A.mellifera colonies having brood and foraging through the year under Islamabad and Chakwal conditions in Pakistan covering a period of 14 months since October 1993. The study was carried out using A.mellifera colonies in group A and B that were naturally infested with T. clareae. Group A: A set of four low-infested colonies treated with Apistan. Group B: A set of four highly infested colonies remained untreated. Observations on T. clareae population fluctuations in eight colonies were recorded by regular monitoring of weekly hive debris. Mean infestation level in bees and brood (mites/100 bees and mites /100 brood cells) were determined bimonthly. The colonies have mostly remained in Islamabad except for moving them once to Chakwal for a period of 6 weeks for the third honey crop during September-October 1994. The highest mite density was recorded in debris for untreated group B in March 1994 followed by sudden decrease in April and gradual decrease reaching minimum in September. The mite infestation in brood peaks in May and October coinciding with increased brood rearing activity in A. mellifera colonies in Islamabad and Chakwal. T. clareae re-infests the treated colonies during the active honey flow periods, that is during April and in October. These observations helped to explain differences in the level of damage with least and heavy infestations caused to beekeeping with A. mellifera in Pakistan.