Exploring Monticola — Efforts to Find an Acceptable Varroa-Resistant Honey Bee

Article of Am. BEE Journal 1991


Exploring Monticola — Efforts to Find an Acceptable Varroa-Resistant Honey Bee

Published by
Am.  Bee J.  (1991) 131: 49-56
PI 5062B
S-69400 Hallsberg, Sweden


The beekeeping world is shouting for a Varroa-resistant bee.  And the search is going on.  There are good reports in this respect.  We do know that Apis cerana can handle the mite.  We also know that there are Apis mellifera strains that can live together with Varroa jacobsoni without perishing.  Apis m. capensis can do it according to different reports.  Apis m. scutellata in South America is another one1.  Apis m. lamarckii is a third one2.  Recently we have also seen reports that North African A. m. intermissa can develop a resistance.  Several research projects on breeding bees resistant to the Varroa mite are going on.  Reports of a Carniolan strain from Yugoslavia with resistant traits have also been printed.

Common Traits in African Bees

There are hopes that African races have something in common that in make them show resistant traits.  One interesting trait in this respect is the high infertility rate of the Varroa females capped worker brood (if in dronebrood, too, we don’t know).  This may indicate some sort of different chemistry in the bodyfluid or a brood development time difference.

Varroa in Sweden

Thus far no Varroa mites have been found on the mainland of Sweden.  However, Varroa is giving beekeepers on the Island Gotland in the Baltic big problems.  There are only a few who believe we are not going to get it on the mainland.  Gotland is the only Swedish territory where the Varroa mite is found.  In some ways we are lucky.  We have the possibility to study beekeeping with the mite under “secure” conditions.  The aim has been to try to use only biological methods and organic acids, such as formic acid.  This work has been led by Ingemar FRIES from the University of Agriculture in Uppsala (SLU).  In short, it is possible to use these “natural” methods without any loss of the yield, but they require a lot of work.  Recently, the authorities have allowed Perizin to be used by beekeepers on Gotland after education.

Breeding for Resistance

Of course, there are beekeepers in Sweden, too, looking at the possibilities of finding a good commercial strain that is resistant to “The” pest.  There have been many bad reports about the possibilities of finding a resistant bee among the European bee races.  The Yugoslavian strain could be an exception.  The philosophy of Brother ADAM is that you can’t breed for a trait that is extinct in a strain.  You must get it from another strain and breed it into your own.  That’s a philosophy that has made him famous all over the world.  Why not try it in this case, too?

Since A m. scutellata do show variation in temper, this indicates a possibility to breed for better temper through selection.  It might even be easier with introduced “gentle” genes from, for example, A m. ligustica by crossing and then selection.  That is confirmed by Bob and Barry MEISE in the American Bee Journal4,5.

If there is a relatively gentle African strain that has strong resistant traits, it would, of course, be easier to succeed with the crossing and selection.

Monticola in Africa

Apis mellifera monticola is a bee of the rain forests of the mountains in East-Africa living at altitudes of 2,000-3,000 m, according to literature.  The mean annual temperature of this area is measured to be around 11°C.  Our experience in the mountains in Kenya give us the impression that this is true, at least, for the higher altitudes with rain forests.  Dense fog and clouds often cover this type of zone which most likely give longer periods without flight activity6,7.  The bees are described as medium-sized and larger than all other races of tropical Africa6.  The monticola race is described as being very gentle in contrast to the common view of African bees8,9

The monticola bee consists of an unknown population that is completely isolated since individual mountain monticola niches are surrounded by the now infamous Apis mellifera scutellata — the probable origin of the AHB in South America and North America.  It is isolated by ecological factors, living at high altitudes and most likely “protected” by the mountain rain forests and its harsher climate.  Earlier findings say that hybridization between monticola and scutellata seems to be sparse.  Therefore, the conclusion has been drawn that there may also be some kind of reproductive isolation, perhaps differences in mating behavior.  This could be correct, but we saw several colonies which we could call hybrids, due to color, size and temper.  We saw also, though, colonies, especially on Mt.  Kenya, which we judged to be very pure monticola, which existed in the same apiary as colonies with traits which we could call scutellata traits, in regard to color and temper.

The different populations of monticola bees are probably relicts of a larger population connected to each other during the last glacial period and separated from each other several thousand years ago10.

Looking for the Monticola Bee

Brother ADAM searched the homeland of A. m. monticola in Tanzania in 1987.  Inspired by his findings, a new expedition was planned for March 1989 — this time to Kenya.  One of the four safari members, Erik BJÖRKLUND, secretary of the Swedish Beekeeping Association, has good contacts on Mt.  Elgon in western Kenya.  Michael van der ZEE from Holland has good contacts around Mt.  Kenya and also has experiences from similar expeditions, for example, to Tanzania 1987.  Bert THRYBOM from Sweden is a medical doctor (very handy to have around), experienced in bee breeding and instrumental insemination.  Erik ÖSTERLUND from Sweden is editor of the Swedish bee journal “Bitidningen” and a sideliner with 200 colonies.

In Kenya

In the beginning of March we arrived at the airport of Nairobi.  The Kenya we met was a nice country with friendly people.

We hired a cheap Landrover from the 1950’s.  “The Old Lady“, as we called her, took us through stony creeks up the rain forest to 3,500 m (10,500 feet) on Mt.  Elgon; through half a meter of mud for miles on our way to Mt.  Kenya; up to 4,000 m (12,000 feet) on Mt.  Kenya and back to Nairobi.  Of course, the flat tires waited until we came among the wild animals in a Wild Life Park.

Our aim in Kenya was not to do any scientific research, but simply to look at bee colonies and bring semen and eggs of A. m. monticola back to Sweden for experiments.

Mt.  Elgon

This kind of trip is no holiday.  It is hard work and sometimes dangerous.  The moment we were just a fraction from eternity we certainly won’t forget.  We were on our way down from the high slopes of Mt.  Elgon.  The afternoon rains had made the red soil slippery as soap.  We were 12 people in the heavy “Old Lady,” of whom four were armed lifeguards.  The wheels lost their grip and the “Lady” slid slowly down towards a 20 m deep ravine.  The silence was heavy upon us; only the engine and rain was heard.  In the last fraction of a second our great Caretaker made the wheels go the right way again.  Thank God!

It is difficult to choose the right season to undertake such a task as ours.  We wanted a good season ahead of us in Sweden to work with the material we eventually were going to bring home.  Of course, we also wanted the right season for good drones.  We knew we were just ahead of the rainy season after a period of dry weather.  This indicated a low level of drones.  On the other hand, where we were going, to the slopes of the mountains, there were afternoon rains now and then, even during the dry season.  So, we hoped there would be drones present in the colonies.

On our way up Mt.  Elgon we passed through elephantland in the misty mountain rain forest.  At 3,000 m (9,000 feet) we stopped and searched for bees.  It was 10 a.m. and the sun began to break through the mist.  The temperature began to rise and we could hear bees beginning the work of the day.  One of the 12 in the car told us he had been at this place a year or so ago together with people from a University of California.

3,500 m (10,500 Feet)

We were not satisfied with what we found and went on up to just under the timber line on about 3,500 m. We had to hurry now.  Usually the afternoon rains here start at 3 p.m.

Up there we found what we were looking for.  Log hives up in the trees.  We soon learned it was not drone season.  But we were lucky, in one of the colonies there were drones.  Actually, they were in the first colony up there.  We found the queen.  She looked in rags with both wings looking as they were clipped.  There were about five cell cups in the hive, which was full of beautifully built combs, with no brace-comb, just straight combs.  And we weren’t aware of any propolis.  No cell cups had eggs in them.  Obviously, the colony were planning for supersedure.  The hive had a lot of honey and a couple of healthy and beautifully filled brood combs.  We could readily search the hive bare-handed without any great risk of being stung.  After a while, we also could take off our veils.  The bees were uniformly black and bigger than bees found lower down the slopes.

Colony number two had a younger queen.  The hive was packed with bees and honey and some fine brood combs, but no drones and no cell cups..

We were lucky.  The afternoon rain didn’t start until half past 4 this day.  That was the time we started for.  home.  We had worked hard and hadn’t had time for lunch.  Now we just wanted to get back as soon as possible.  It took us three hours up and a little shorter time down to just under 2,000 m (6,000 feet) where had camped — but only after some slippery adventures which I mentioned earlier.

Preparations for Sweden

We arrived back with the boxes containing the collected drones to where we had camped lower down on Mt.  Elgon in the evening.  We had no access to electricity, so we had to collect drone semen by the light of torches.  And, we had no way to keep the semen at the most favorable temperature.  It had to be kept at the ambient temperature of this tropical area for two weeks.  The capillaries containing semen were put into test-tubes wrapped with wet paper.

In preparation for the journey back to Sweden, queens were put into queen-rearing boxes.  Just before departure, pieces of combs with eggs were cut out, wrapped in wet damp paper and put in plastic bags.  Both these bags and the semen were carried as cabin luggage.  We were not allowed to bring live bees to Sweden.  Only genetic material from the Mt. Elgon population of monticola has been used in Sweden.

Searching the Slopes

During the following days after the first successful day, we went searching the Kenyan slopes of Mt. Elgon.  At one place at about 3,000 m, which had been deforested since the beginning of this century, we found an interesting colony.  The bees were quite big, but very yellow.  And, they were very defensive, real followers, apparently influenced by scutellata.  An interesting observation was that in the same tree was another colony with smaller bees, but black, and not at all as aggressive as the other one; actually you could describe them as relatively good-tempered.

In general, the bees were bigger, the higher up they lived.  Also we saw a similarity with the comb.  At 3,500 m (10,000 feet) the worker cells were slightly smaller than European.  Combs from colonies at about 1,600 m (5,000 feet) showed very small worker cells.  They were more than 10 % smaller than European worker cells made on commercial foundation.  These findings correspond with information in the literature11.

In general, the hives were more filled with wax combs, the higher up the slopes they were placed.  We draw the conclusion that this indicated a higher inclination for swarming lower down the slopes.

Our conclusion is that the bees at 3,500 m were closest to the descriptions of monticola in literature, and that the rain forest is extremely important in protecting it from hybridization.

Mt. Kenya

Then, we traveled to Mt. Kenya.  It was a long ride back to the central part of Kenya.  The last part of the ride was a muddy one.

We didn’t find any great amount of rain forest on Mt. Kenya.  And the climate there was not at all as misty as on Mt. Elgon.  It seemed dryer and with a higher average temperature.  On Mt. Kenya we didn’t find any place where all colonies consisted of uniform black bees.  We did find some colonies with a low percentage of workers that had a few yellow stripes and which were good tempered.  Actually some of the colonies on Mt. Kenya seemed to be at least as gentle as the best on Mt. Elgon, maybe even calmer.  On the same spot where we found these, we also found colonies that differed a lot in color and temper.  The worst tempered ones followed us, but not for more than about 50 m.  The colonies were smaller in size than the biggest on Mt. Elgon.  No colony had bees as big as the biggest on Mt. Elgon.  There seemed to be many colonies on Mt. Kenya.  We even saw flying swarms there.  In some hives the bees had just started to build combs.  It was probably an absconding season there since we were approaching the end of the dry season.  We saw no signs of absconding on the slopes we searched on Mt. Elgon.

We had the opportunity to study a colony in a cliff high above the timberline at about 4,000 m (12,000 feet).  Unfortunately, these bees were small, many of them yellow-striped and very defensive.  Some years ago a big part of the forest on Mt. Kenya was accidentally burnt down.  Probably this made it easier for lowland-bees to move higher.

Deforestation and Reforestation

Apparently, the rain forest is very important for the survival of the monticola bee.  A positive sign is that the authorities were working hard to reforest deforested areas around the mountains.  They know the value of the forest for the economy of their country — an example to other countries in situations similar to Kenya.  Hopefully, that also means that the mountain rain forests will continue to exist for the benefit of Apis m. monticola as well as other wildlife.


We returned to Sweden March 19, 1989.  The pieces of combs with eggs were put into colonies that had been carefully prepared for this and fed diluted honey and pollen substitute.  The weather conditions were very unfavorable, frost in the nights and + 2°C in the days.  We were happy, however, to secure a couple of queens.  When mature, they were inseminated by Dr. THRYBOM with the pure monticola semen we brought from Mt. Elgon.

A necessity for the success of the insemination with this semen was a new diluent developed by Dr. THRYBOM that vitalizes the semen after such a long and unfavorable storage.  It is a composition of amino acids, carbohydrates and electrolytes that correspond to that of the bee semen12.

From these pure monticola queens, a new generation pure monticola queens were reared and inseminated with Swedish drone semen from gentle Italian and gentle Buckfast colonies, giving progeny with 50 % monticola inheritance.  Also, Swedish queens, Italian and Buckfast, were inseminated with the original monticola semen in order to get the reciprocal mating.  F1-queens were then reared and inseminated with Swedish drone semen, gentle Italian and Buckfast, producing progeny with a theoretical 25 % monticola inheritance.

Different pheromones?

There have been considerable difficulties in rearing monticola queens in Italian colonies.  These have shown a very low interest in and acceptance of monticola larvae.  Of those pure larvae that were accepted, always a part of the resulting queens showed signs of being underdeveloped as when one has used larvae that are too old.  Of those queens that emerged, a part of them were ignored by the bees in the nucleus.  In a week or so they were found dead on the bottom.  Buckfast colonies and mongrel bee colonies showed a higher degree of acceptance.  The conclusion is near at hand that the monticola queens have some kind of different chemistry in their pheromones and perhaps a different composition in the body fluid of the larvae.

The pure monticola queens emerge about 1.5 days earlier than Italian and Buckfast queens.  The post-capping stage for monticola workers has not yet been fully studied, but development time from egg to emerged bee is thought to be shorter than in our European races.

The monticola drones are all uniformly black as are the workers and the queens of the material we brought to Sweden.  The queens also have long legs.  The wings show a dark tinge.  The cubital index of workers are 2.37 (n=50).  Cubital index of monticola workers is 2.35 (n = 9), according to RUTTNER7.

Observations under security

Some beekeepers, but they are few in Sweden, think all bees in Africa are the same.  But since this is not true when it comes to European bees, why should it be the case when it comes to African? When those critical people heard we had brought African bees to Sweden, they were afraid the result would be AHB-bees of the same type as those in South America.  To hinder unwanted hybridization, all queens have had their wings clipped, the brood-chambers have been equipped with queen/drone excluders on top and bottom of the boxes and the colonies have been managed early in the morning to avoid flight of drones.  The response to this project from the beekeepers has been great.  Actually, the trip wouldn’t have been possible if different beekeepers in northern Europe and organizations and equipment manufacturers had not contributed money.

Our starting point in this project has been that all living creatures, in this special case, Apis mellifera, follow the same genetic laws.  That means that we could gain from the knowledge we have obtained from breeding experiences with our European races of Apis mellifera.  Experiences of Brother ADAM with bees with different temper and origin13,14 and those of Bob and Barry MEISE4,5 concerning Africanized honey bees (AHB) and European honey bees (EHB) are in correspondence with this.  Since we started with a relatively calm African race, we expected a good result quicker than if we had began with AHB.

There have been no signs of absconding.  And, there have also been no signs of swarming, not even from those colonies that have been allowed to develop normally.  In the “control” colonies of Italian and Buckfast a small percentage have had queen cells during 1990 , but none in the monticolas and their crosses.  That is surprising.  It will be interesting to see what happens the following seasons.

The behavior of the pure monticola bees in Sweden is comparable with the behavior of relatively good-tempered Swedish mongrel bees.  They will sting you if you don’t smoke them.  When the monticola colonies were managed in late autumn, they did show a tendency to follow for 10-15 m (yards) from the hive.

The pure monticola colonies have been located 7-8 m from a path where members of the Thrybom family have been passing every day and nobody has been stung so far.

Another observation is that monticola workers have a greater tendency to drift than our European bees have.

The crosses with gentle Swedish drones mainly produce a gentle progeny and the progeny in the F2-colonies (theoretical 25 % monticola inheritance in workers) are often very docile.  In the season of 1989 such F-2 colonies, in general, produced around 30 % more honey on the late flow than pure Italian colonies of comparable sizes did.  During the season of 1990, which has been a very poor one, the monticola crosses that have been allowed to develop normally have given a crop that is average or above.

The monticola and their crosses have shown a tendency to wait for a continuous availability for food before they let eggs develop into brood.  It is probably because of that that most of these colonies have built up relatively slowly in spring.  In summer and autumn the population of the monticola crosses that have been allowed to grow normally, often have been very huge.

African Traits

You can still see some typical African traits in the progeny of the F2-colonies, for instance their way of flying in a quick zigzag like pattern, especially in front of the entrance of the hive.  This pattern was still more clearly seen in the “low-land” bees (scutellata) we saw in Kenya.  And instead of landing in front of the hive before entering it, the bees often seem to enter directly into the entrance.  They also fly earlier in the morning and later in the evening than our bees.  Dr.  THRYBOM has an interesting observation from late autumn 1989.  The outdoor temperature was +5°C; sunset was at 5:30 p.m.  The pure monticola colonies, F1- and F2-colonies were flying until 6:15 p.m.  The Italian colonies had stopped flying by 4:30 p.m.

The monticola bees show a lack of “cold avoidance behavior“, in that the flight activity is not blocked very strongly by cold weather on bright winter days.  During the first of winter in Sweden, –10°C, bright sunshine and the ground covered with snow, the pure monticola bees did fly out, but not all were able to return to the hive.

The two pure monticola colonies left survived the very mild Swedish winter of 1989-90; very low temperatures only in November 1989 and cleansing flight weather in early January 1990.  But one of the queens was underdeveloped and had a lot of drone brood already in the autumn.  The other one for some reason had stopped her egg laying totally when spring came.  A new strain was established during 1990 through re-crossings due to the fact that pure drones were still available.

It is important to keep in mind that the number of colonies in this project, so far, is restricted and the conclusions must therefore be handled with care.

Resistance to Varroa jacobsoni?

The purpose of this project is to see if it is possible to breed for resistance to Varroa jacobsoni.  During the summer of 1990 there has been a preliminary test of this character under the guidance of Dr.  THRYBOM on the island of Gotland in the Baltic.

The figures from this preliminary test are not completed yet, but interesting facts have been observed.  The population dynamics of the Varroa mite on monticola crosses are different than on the Italian control colonies, in more than one aspect.  Therefore, a complementary test is planned for next season to discover if these findings will have any practical consequences for the beekeepers.

Even if the monticola bees never have any great influence on the strains of bees in Sweden, there is one important and outstanding impression for the future.  The monticola and its combinations with good representatives of Italians and Buckfast bees can in no way be compared to the highly defensive AHB.


I gratefully thank Dr. Bert THRYBOM for his kind sharing of facts concerning Apis mellifera monticola and for his valuable comments on this manuscript.


1.  von Posern, Hubertus.  1990.  Brazilian Apimondia ’89 — Impressions of a participant.  Am. Bee J130:312.

2.  Rosenkranz, Peter.  1988.  Varroa symposium at the University of Agriculture, Uppsala, Sweden.

3.  Arnold, Gérard.  1990.  Current and Recent Research on Varroa in Europe.  Am. Bee J.  130:257.

4.  Meise.  Bob and Barry.  1989.  African Honey Bees — We Have a Story of Success! Am. Bee J.  129:600-602.

5.  Meise, Bob and Barry.  1990.  Another View on African Honey Bees and Their Effects on North American Beekeeping.  Am. Bee J.  130:649-652,

6.  Ruttner, F.  1988.  Biogeography and Taxanomy of Honey bees.

7.  Rinderer, T.  ed.  1986.  Bee Genetics and Breeding.

8.  Smith, F.  G.  1961.  The Races of Honey Bee in Africa.

9.  Drescher, W.  1975.  Bienennutzung in Tanzania.  ADIZ 1975:117-122.

10.  Meixner, M., Ruttner, F., Koeniger, N., Koeniger,.  G.  1989.  The Mountain Bees of the Kilimanjaro Region and Their Relation to Neighbouring Bee Populations.  Apidologie 201:165-174.

11.  Crane, Eva.  1989.  Bees and Beekeeping.

12.  Thrybom, Bert, 1990.  En ny diluent för “single-drone” inseminationer med homogent blandad sperma.

13.  Adam, Brother.  1983.  In Search of the Best Strains of Bees.  163-205. 

14.  Adam, Brother.  1987.  Breeding the Honeybee.  96-113.