Six years without any treatment against Varroa using the bottom board and LEGRIS tubes

INTRODUCTION

In October 1993, I received three anti-Varroa bottom boards from Mr. Legris, they were sent to me to try out in my hives. I ordered them after reading the interesting description given by Veterinary Doctor Louis Leclerc in "L’Abeille de France et l’Apiculteur" (issue No 782). He indicated that numerous wild bee colonies survived without any anti-Varroa treatment, very likely because a certain amount of Varroa mites fall out of the cluster to disappear under the colony in places unvisited by the bees. Conversely, in traditional hives, the Varroa mites are easily recycled through contact with bees.

The Legris bottom board, which was presented by its inventor in issue No 784 of the same journal immediately struck me as being the ideal system for my hives. Don't forget that this bottom board consists of a frame with a tube placed under each brood box frame, the 3.5 mm space between each tube ensures that all the space between the tubes is situated precisely where the hive waste is evacuated and where the Varroa mites fall. In this way waste evacuation openings are situated exactly where they are needed.

Later on, Mr. Legris stopped manufacturing them so I had to make myself a few extra bottom boards. They were relatively expensive to produce but the savings made in time and chemical treatment have more than compensated for this extra cost.

Once my hives were fitted out, I skipped the autumn treatment and only treated in spring. It was a first step towards testing the bottom board's efficacy. The result was completely satisfactory. Then in 1997, I took another step and left two hives out of six without any treatment. During the following season, every sunny day saw the appearance of a few dozen crawling bees with atrophied wings. At first glance this might appear alarming. However, this number is insignificant compared to the thousands of bees which emerge every day, and, in practical terms, there was no difference between the amount harvested by the two non-treated hives and the rest of the apiary. Furthermore, at the end of the following winter, the state of these two hives was totally satisfactory. As a result they were left untreated.

ENVIRONMENT

Rueil-Malmaison, a suburban town less than 10 km north-west of Paris, is a favorable region for beekeeping. The region is made up of small gardens which provide nectar for the workers practically all year round. Even in December, on mild days, the bees are able to bring pollen back to the hive. Along the banks of the Seine, the linden trees produce a honey flow even in dry conditions and a certain number of acacia trees bring an added touch of quality to the honey. Since my beekeeping debut in 1993, I have never encountered the slightest problem with intoxication due to badly controlled spraying such as is experienced in agricultural zones. At least, it was true until a night in the beginning of June 2003 when a treatment against cochineal was made on trees in the streets. Linden trees were in bloom and flowers in gardens were also contaminated by the insecticide flow, told to be safe for bees. It is to be expected it will be possible to avoid that in the future and come back to an healthy environment.

So, no feeding is required in autumn. On the contrary since autumn 2002, to prevent swarming, I have harvested 4 frames in September from most of the hives and replaced them with new foundation. During the preceding years, before the first spring visit, the queen lacked laying space, a situation which generated double and triple swarming a few weeks later.

My apiary is made up of 6 Dadant 12-frame hives. Three other hives are used for any swarms from my apiary or elsewhere. It is probable that wild swarms live in Saint Cucufa wood as it is within the Rueil-Malmaison council area. A lot of collected swarms are found around there. Next spring I pass on any excess colonies to interested beekeepers.

OBSERVATIONS

It is easy to count the fallen Varroa by placing a sheet of glass under the hive. It is, however, a tedious business, which I don't systematically do. The figures listed in the diagrams below are, nevertheless, a rich source of information.

At the beginning of the 1997 season, I had 6 hives, numbered 1 to 6, whilst the hives numbered 7 to 9 were made up during the season from swarms. On the 22nd February, Apistan strips were placed in the
hives numbered 2 to 5 and the total number of Varroa found under each one during the treatment varied from 700 to 1,200, a fairly low count and a favorable augur. In the two untreated hives, the number of fallen Varroa rose in March and started dropping in April. Due to multiple swarming, the harvest produced the average result of 182 kg. Individual production can be estimated by the number of frames harvested at the beginning of July. Hive number 6 had an appreciably higher harvest than hive number 1, which had the highest number of fallen Varroa.

In 1998 we observed the following: the number of bees with atrophied wings seemed significantly lower than the previous year. In addition to that, the only Varroa count carried out came up with much lower figures than in 1997, which did not call for a close follow up. The honey harvest remained stable for the same reasons.

In 1999, more regular Varroa counts showed that fallen Varroa numbers dropped off in April and May and practically disappeared during summer. I can remember having difficulty in finding a single fallen Varroa under my hives to show to novice beekeeping friends. As for the honey harvest, it more than doubled compared to previous years, rising to 383 kg.

In 2000, the counts were reduced to a strict minimum, like in 1998, but with an even lower overall average. The harvest dropped to 180 kg again.

In 2001, no count was done. The harvest produced 299 kg.

On 28th April 2002, the rate of Varroa infestation was tested according to the method set out in Varroa and Varroatose (p 86 and 87). This method consists of removing between 200 to 500 bees from several brood combs and dropping them into 70°-proof alcohol. The Varroa fall off the bees, and both bees and Varroa can be counted. In this way you get an approximate idea of the degree of infestation. The colony is considered to be lightly infested with up to 5% of Varroa and at this stage does not require any treatment.

The samples were taken from one of the stronger hives, hive number 4, which had already half-filled a second super, and from a rather weak hive, number 2, which only had one half-filled super.

A capped brood comb provided 304 bees and 16 drones in hive number 4. Nine Varroa were found. Two uncapped brood combs were used to remove 253 bees from hive number 2. Four Varroa were found.
The respective degree of infestation was 3% (without counting the drones) and 1.6%, well below the above-mentioned limit.

In 2002, swarming level was very high, three swarm exits having even been observed on some hives. However, honey harvest was very good and produced 312 kg. Hive numbered 5 itself filled 5 supers with more than 100 kg honey. Only two hives among three made up of swarms did not produce anything. Two Varroa counts carried out in September on hives numbered 2, 3 and 5 showed again the difference in mites falls from a hive to another without any relationship with honey harvest.

Year 2003 began like year 2002 except that after swarming, treatment against cochineal was made on trees in the streets. As a result, bees population remained at a low level and filling of supers stopped. A colony even died. Harvest was the one it would have been at the end of May, that is to say 155 kg.

ANALYSIS

The following experiment was not carried out following scientific protocol. If it is excessive to draw conclusions, there are, however, certain facts that can be reported:
Bee colonies in hives fitted with a Legris anti-Varroa bottom board developed, swarmed and produced very good honey harvests without any treatment of any sort for six years;
These colonies were not specially selected and came from swarms found within the surrounding area, which in turn came from other apiaries or wild colonies.

Therefore, it is unlikely that a similar experiment carried out in another apiary would fail. It is perfectly reasonable to think that comparable results would be attained in many different areas. After this, it would be up to bee breeders to multiply the colonies most suited to beekeeping, the lowest rate of infestation cannot be considered as the only important criterion for honey production.

Furthermore, the self-cleaning properties of the Legris bottom board and the moderate airflow it brings into the hive are health factors for the bees, mean less work for the beekeeper as well as stronger colonies, surely enough to justify its use in apiaries.

AVAILABILITY

The initial manufacture of the bottom board turned out to be a fairly costly venture for Mr. Legris. In fact, the decision to hold the tubes in place by fitting their two extremities into holes in the frame meant using highly priced rigid, rectilinear tubes. The new series is using polyethylene tubes held in place by three struts, one close to each extremity and the third in the middle to keep the tubes parallel. The struts will clip into grooves cut along the frame sides to hold everything in place. So, the tube and strut section will be able to be easily removed.

This new model costs much less than the first and has been available in France since October 2002. After a first trial order, many beekeepers have equipped all remaining hives, being particularly happy of the permanent cleanness of the floor, a token of health for the colony. It was also reported that 20 fallen Varroa mites had been found each hour, immediately after replacement of mesh bottom boards by tubes bottom boards.

Distributors of many countries have been contacted and it is hoped that it will be widely available within less than a year.

• Jean-Pierre LE PABIC, October 2003

• Varroa count, Year 1998
  No treatment applied
  Date :		13th/4
  Count duration :		8 days
  Hive n° 1 (no treatment since 2 years) :
  Hive n° 2 :
  Hive n° 3 :		95
  Hive n° 4 :		84
  Hive n° 5 :		44
  Hive n° 6 (no treatment since 2 years) :		39

• Varroa count, Year 1997
  Apistan treatment applied on 22nd/2, hives n° 2, 3, 4, 5.
  Date :		2nd/3	8th/3	15th/3	23rd/3	31st/3	27th/4
  Count duration :		7 days	6 days	7 days	8 days	8 days	7 days
  Hive n° 1 (no treatment) :		43	150	170	233	203	183
  Hive n° 2 :		940	248	10	0
  Hive n° 3 :		680	468	30	0
  Hive n° 4 :		800	25	8	25
  Hive n° 5 :		190	283	166	25
  Hive n° 6 (no treatment) :		37	78	106	121	164	115

• Varroa count, Year 1999
  No treatment applied
  Date :	20th/12	24th/1	11th/4	18th/4	25th/4	16th/5	12th/9	19th/9	26th/9
  Count duration :	8 days	7 days	7 days	7 days	7 days	7 days	14 days	7 days	7 days
  Hive n° 1 :
  Hive n° 2 :	90	38	31	31	7	1	49	22	114
  Hive n° 3 :	45	38					7	13	13
  Hive n° 4 :	61	57	0	2	0	0	176	132	125
  Hive n° 5 :	280	112	4	5	4	1	3	7	52
  Hive n° 6 :	94	126	14	16	20	2	98	47	74

Varroa count, Year 2000
No treatment applied
Date :	27th/2
Count duration :	7 days
Hive n° 1 :
Hive n° 2 :	78
Hive n° 3 :	26
Hive n° 4 :	11
Hive n° 5 :	53
Hive n° 6 :	84

Varroa count, Year 2002
No treatment applied
Date :	22nd/9	29th/9
Count duration :	7 days	7 days
Hive n° 1 :
Hive n° 2 :	52	86
Hive n° 3 :	3	4
Hive n° 4 :
Hive n° 5 :	60	65

Download the Versoul Trial Report on Happykeeper bottom boards.