B-liners: Some thoughts about the Tracheal mite resistance in honey bees. In recent years, we have learned about mechanisms of honey bee resistance to varroa mites, Thanks to Apis cerana and to Peng et al. 1987's study in China. A contrast comparative study showed that the hygienic mechanism is an effective method of keeping varroa mites under control in the Asian bee colonies. Several studies followed this study and shed more lights on other mechanisms of resistance to varroa. On the other hand, there are few studies which have focused on resistance to tracheal mites. These studies are not as advanced as the varroa study due to several factors: 1. There is no race or line of bees known for resistance as we have in the case of cerana bees. All the known resistant bees such as the Buckfast bees or tracheal mite resistant bred bees were recently confirmed as resistant bees using sophisticated bioassay tests. In addition, we need to test the bee lines to make sure that they are resistant before conducting any study. Thus, any study will take more time and will cost more money to conduct. Who is going to pay the bill? 2. The microscopic size of tracheal mites and the nature of the parasite as an internal obligatory parasite cause difficulty in handling the mites and conducting this type of detailed study. Although the above mentioned difficulties, there are several reports about possible mechanisms for tracheal mite resistance in honey bees. Several studies (Lee 1963, Gary and Page,1987, Gary et al. 1989, Nasr et al. (Unpublished data) and others reported differences in abundance and prevalences of mites in honey bees. These tested bees had different relative attractiveness to tracheal mite as they age. Tracheal mites preferentially infest bees <24 h-old and the frequency of infestation declines quickly thereafter; Bees >4 days old were rarely infested. Bees of mite resistant lines could be attractive to mites for a relatively shorter period of time than susceptible lines or bees of mite resistance could be less attractive to mites during that window of time in their age than the susceptible lines. The end result in both cases is that fewer migratory female mites migrate into their tracheae over the four day period when bees are attractive to mites. There is recent unpublished research showed that tracheal mite resistant bees are less attractive to infestation by tracheal mites during that window of their age than susceptible bees. Based on the deferential attractiveness of honey bees to tracheal mites, we (Ontario Bee breeders, Canada) are using a bioassay test to identify bees less attractive to mites within the first 7 days of their life. The identified lines are then subjected to a breeding system to increase the frequency of the criteria in the subsequent generations. There was also an early study showed that the presence of spiracular hairs had no effect on mite infestation. Recently, some researchers restudied this mechanism. Early results showed that bees with hairy spiracles had less mites! Researching the mechanisms of resistance to tracheal mites will progress and advance in the coming years. More focus will be on the biology of bees (population dynamics, broodless periods, etc.) in relation to mite population. In addition physiological, physical, and behavioural mechanisms to explain the resistance to tracheal mites will be investigated. Medhat Nasr, Ph.D. Ontario Beekeepers' Association Ontario, Canada > > > > > On 30 Jan 97 > at 18:13, Stan Sandler wrote: mechanisms of tracheal mite > tolerance > > > > > The interesting discussion about varroa mite resistance / tolerance has me > > > curious about tracheal mites now. In the types of bees that have shown > > > greater tolerance what mechanisms contribute to this? > > > > We have been working with Dr.Nasr and the Ontario Breeding program for a > > number of years now. They can tell us wether our strain of bees are > > resistant or tolerant to T-mites, but not a word about the mechanisms. It > > has been known, for a long time, that the mature mite moves out and looks > > for a new host under 4 days old. Beyond that, nothing. > > It is thought that the mites don't like the taste of the new host and > > move back out, as there is record of bite marks in some tracheae but no > > mites. > > > > ********************************************************* > > The Bee Works, 9 Progress Drive Unit 2, Orillia, > > Ontario, Canada. L3V 6H1 > > David Eyre, Owner. Phone/Fax 705 326 7171 > > Dealers for E.H.Thorne & B.J.Sherriff UK > > http://www.muskoka.net/~beeworks > > ********************************************************* > > >