Pakistan J. Zool., vol. 44 (4), pp. 985-989, 2012. Control of Ectoparasitic Mites in Honeybee (Apis mellifera L.) Colonies by Using Thymol and Oxalic Acid Rashid Mahmood, 1 Elizabeth Stephen Wagchoure, 1 Atta ul Mohsin, 2 Shazia Raja 1 and Ghulam Sarwar 1 1 Honeybee Research Institute, National Agricultural Research Centre, Islamabad, Pakistan 2 Department of Entomology, PMAS University of Arid Agriculture, Pakistan Abstract.- A study was carried out to determine the effects of thymol (powdered form) with 3.2% oxalic acid (OA) on two ectoparasitic mites, Varroa destructor Anderson and Trueman (Acari:Varroidae) and Tropilaelaps clareae Delfinado and Baker (Laelapidae: Acrina) populations in honeybee Apis mellifera linguistica (Hymenoptera: Apidae) colonies in the fall. Thymol 2, 4 and 6 g with 3.2% OA applied to twenty honeybee colonies thrice on different dates, showed 26, 41, 36% mortality in T. clareae and 93, 99 and 94% mortality in V. destructor, respectively. The results showed that 3.2% OA with 4g thymol was the best treatment for controlling these mites. No queens were lost, and there was no adult honeybee mortality in any of the colonies during the experiment. Key words: Honeybee, Varroa destructor, Laelapidae, mites, thymol, oxalic acid, trickling. INTRODUCTION Honey bee colonies are subject to infestation by mites, insects and diseases. Ecto- parasitic mites attack honeybees and cause low yield of honey, absconding and swarming of bee colonies. The two mite species Tropilaelaps clareae (Laelapidae: Acrina) and Varroa destructor (Varroidae: Acrina) are considered to be the cause of continued destruction of Apis mellifera colonies in Asia (De Jong et al., 1982). Each year many honeybee colonies are damaged by mites. A. mellifera colonies must, therefore, be treated several times in a year with acaricides to prevent unlimited growth of mites’ populations and the death of colonies (Khan et al., 1987). The mite, T. clareae, is a parasite on bee brood causing brood malformation, death of the bees and subsequent colony decline or absconding (Hosamani et al., 2006). Development requires about one week and mites are dispersed on bees. T. clareae occurs on 5 species of bee - Apis cerana, A. dorsata, A. florea, A. laboriosa and A. mellifera. T. clareae is known to have a wide distribution in Asia extending eastwards from Iran to Papua New Guinea (Matheson, 1995). The greatest infestation ______________________________ * Corresponding author: rashid_ento1@yahoo.com 0030-9923/2012/0004-0985 $ 8.00/0 Copyright 2012 Zoological Society of Pakistan. occurred in February, March and April with a decline from May to August (Camphor et al., 2005). Poor management of bee colonies, hive microclimate, strength of the colony increased the prevalence of T. clareae in bee colonies (Mahavir and Gupta, 1999). T. clareae caused 30-70% colony loss of A. mellifera with reduced honey production (Woo and Lee, 1997). The V. destructor mite always has been associated with A. cerana in Pakistan. With the introduction of A. mellifera in Pakistan in 1977-78, this mite become a serious pest and destroyed a large number of colonies (Ahmad, 1988). Varroa mites feed on the developing honeybee larvae, pupae and the adult bees. Heavily infested colonies usually have large numbers of unsealed brood cells. Dead or dying newly emerged bees with malformed wings; legs, abdomen and thoraxes may be present at the entrance of affected colonies. Colonies heavily infested by Varroa produce little or no honey (Ritter, 1981). The beekeepers have been forced to use unapproved chemicals such as chlorobenzilate, phenothiazine, sulphur, amitraz or different pyrethroids to control the mite infestation. Uncontrolled use of these agents led to the development of resistance, resurgence of the infestation and the risk of residues in the honey which might pose a risk for human consumption. Keeping in view the importance of safe and non-contaminated control methods to suppress mite