COMPARATIVE POPULATION DYNAMICS OF TROPILAELAPS CLAREAE AND VARROA JACOBSONI MITES ON HONEYBEES J. WOYKE 1

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1 Journal of Apicultural Research 26(3) : (1987) COMPARATIVE POPULATION DYNAMICS OF TROPILAELAPS CLAREAE AND VARROA JACOBSONI MITES ON HONEYBEES J. WOYKE 1 F AO Representation, Kabul, Afghanistan and Hanoi, Vietnam. Revised typescript received for publication 25 August 1986 Summary A high infestation rate of honeybee (Apis mellifera) colonies by Tropilaelaps clareae mites was found in Afghanistan and southern Vietnam and a low rate in northern Vietnam. The rate of infestation by Varroa jacobsoni was low in both parts of Vietnam. The ratios of brood: worker infestation by T. clareae ranged from 13'5-16'0 in Afghanistan and southern Vietnam and 26'1-36'9 in northern Vietnam. The corresponding ratios for V. jacobsoni were 0'8 in southern Vietnam and 2'9-8'2 in the north. These data suggest that in the colder areas V. jacobsoni mites remain outside sealed brood for a shorter time, resulting in a more rapid population increase there. Some measures of population for T. clareae mites in honeybee colonies with low (26%) and high (72%) rates ofinfestation were as follows: l'3 and 2'3 females were found on average per brood cell, 18 and 7'3% of females were infertile, one female produced an average of 1'3 and 1'9 descendants, and the mean overall numbers of mites per brood cell were 2'9 and 5'I. The population oft. clareae increases at a geometrically greater rate than that of V. jacobsoni, owing mainly to the fact that mites of the former species remain outside sealed brood cells for only a small fraction of the time spent outside by the latter. The ratio of males to females for all T. clareae mites, old and young, present in brood cells was 1:4. On the average one old female produced 0'6 males and 1'4 females. In the offspring the ratio of males to females was 1 : 2'3. The mean infestation rate of drone brood by V, jacobsoni was 5'1 times that of worker brood, whereas for T. clareae the rate was l'5 times as great for worker brood. Thus it would be practically useless to remove drone brood from honeybee colonies as a control measure for T. clareae. Introduction Populations of the parasitic bee mite V. jacobsoni increase very rapidly in some regions such as Europe but remain at a low level in some tropical countries (De Jong et al., 1984; Ruttner et al., 1984) resulting in great differences in damage to beekeeping. Differences due to climate in infestation of honeybee colonies by the other parasitic mite, T. clareae, have not been previously recorded. Accordingly, infestation of colonies by the latter has now been compared for different areas. Other parameters in addition to low or high rates of brood or adult infestation have been investigated. These may help to explain differences in the levels of damage with light or heavy infestation caused to beekeeping with Apis mellifera. Understanding the parameters may help in the control of the mite and also indicate which parameters are responsible for the more rapid buildup of populations of T. clareae compared with V. jacobsoni and consequently for the more serious damage caused by the former in areas where both species occur. Materials and Methods The investigations were carried out in Kabul, Afghanistan in 1984 and near Ho-Chi-Minh City, in southern Vietnam and near Hanoi, in northern Vietnam, in Determination of infestation The degree of brood infestation was ascertained by opening sealed cells and recording the numbers containing mites. Adult infestation was estimated by brushing workers from brood combs into a container of petrol (in Afghanistan) or hot water (Vietnam). The bees were stirred thorougwy in the fluid for a while and then individually shaken out, still in the fluid, with the aid of forceps. Numbers of bees removed and numbers of mites remaining in the container were recorded. I Present address: Bee Division, Agricultural University, Warszawa, Nowoursynowska 166, Poland.

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