Abstract:
Norway was early in starting to produce bumblebees for use in tomato cultivation in commercial greenhouses. This niche production is relatively complicated and therefore requires good knowledge and precise work. The Department for Agriculture was concerned that importing bumblebees could lead to importing of sicknesses and to genetic pollution of native Norwegian bumblebees. This article describes the start of bumblebee production in Norway and gives a technical description of the process of bumblebee rearing.

Keywords:
bumblebee – breeding – Norway – beekeeping – pollination

In Norway there are 35 species of bumblebee, out of a total of around 250 species worldwide. Bumblebees belong to the family of bumblebees and other bees, called Apidae. It is the large earth bumblebee (or buff-tailed bumblebee), Bombus terrestris, which dominates in commercial bumblebee rearing, both in Norway and internationally.

It started in 1989

The idea and enthusiasm for starting up commercial rearing of Norwegian-produced bumblebees came from The Norwegian Beekeeping Society’s General Secretary, Trond Gjessing together with Rogaland County Council’s Chief Agronomist, Ketil Fuglestad. Due to their positions, the pair acted as coordinators, assistants and initiative takers, but they did not provide technical assistance; this was provided by biologist Atle Mjelde.

It started with a public body, The Bee Sickness Committee, of which Trond Gjessing was secretary. They received a request from The Department for Agriculture with respect to the importing of bumblebees to Norway. They were particularly concerned with the problem of taking insects over the border, and the effects this would have on the genetic heredity of Norway’s native population.

In 1991 The Norwegian Beekeeping Society arranged a meeting inviting key people to attend. They had arranged for a Dutch speaker to hold a presentation on this niche area of production: the commercial rearing of bumblebees. The speaker was Ard de Ruijter, Director of The Research Center for Insect Pollination and Beekeeping. Ketil Fuglestad, Rogaland County Council’s Chief Agronomist, took part in the meeting and says himself that he was excited by the possibility of Norwegian bumblebee production, and that Ruitjer was very inspiring. Ruitjer’s experience from Holland, was that it was beekeepers who were most successful at rearing queens. Some in the professional community believed that it was easier for beekeepers to take care of the bumblebees, because they understood how sensitive they are. One must learn the signals given by the bumblebees and be able to interpret their behaviour.

Pollinering Service Company

In 1991 beekeepers Karl Ivar Stangeland and Egil Fosse established the company “Pollinering Service ANS” and thereby started Norwegian bumblebee production. They were the only company in Norway engaged in bumblebee rearing up until the year 2000. At that time two new companies started up, and all three of them were based in Jæren in Rogland.

Pollination in Norwegian commercial greenhouses has gone from manual pollination to Norwegian production of bumblebee colonies. This change has meant that tomatoes have become a much better commodity. Tomatoes have many seeds, and if the tomatoes are to swell to be round and even, they must be pollinated evenly inside the flower – this is the job of the bees. Bumblebee production has meant that several different growers have been able to use bees for pollination, and this has lead til a reduction in the use of chemical spraying in fruit and berry production.

Ban on import of bumblebees to Norway.

Since as early as 1991 it has been forbidden to import bumblebees in to Norway. There were two important reasons given by professionals in the field, for not allowing the import of bumblebees. The first was the risk of importing disease and parasites and the second was the danger of genetic pollution. The latter problem was a particular concern for The Department for Agriculture. The initiative to start up rearing of bumblebees in Norway came from Rogaland County Council and The Norwegian Beekeeping Society.

How is the bumblebee colony produced?

To understand the challenges of rearing bumblebees, you need to have a good understanding of ecology and not least a good understanding of bumblebee biology.

The large earth bumblebee comes out of hibernation in the spring

After pairing, the large earth bumblebee queen goes in to hibernation for the winter. She digs a hole in the earth in autumn to protect her from the frost, but she makes sure that the hole will not be in full sunlight. That is to say, she finds a place where spring will not come too early.

After coming out of hibernation the bumblebee queen is alone at first and is therefore very busy. First she has to find a site for a nest. She builds herself up by gathering nectar. She makes circular honey pots from wax for storing nectar, pollen and eggs. When the store of nectar and pollen is big enough, she lays the first egg.

Bumblebees can’t eat dry pollen: they need extra nectar to moisten it. Unlike other bees, bumblebees do not have salivary glands. They therefore chew a mixture of pollen and nectar, swallow it and then regurgitate the mixture as food for the larvae. The queens, drones and workers all die before the winter; only the queens that have mated and that have dug themselves down under the earth, survive the winter.

How is this done in commercial rearing?

A new colony is started with a queen in a starting case, which is about 5 cm x 10 cm in size. To get the queen to lay eggs, live drone pupae are used. The drone pupae are taken from a larger bumblebee colony. The bumblebee queen will warm up and brood the pupae. When she has eaten enough pollen, she will start to lay eggs. The queen is given fresh pollen every third day, and it is the new pollen that stimulates her to lay eggs. After the first pupae have hatched, the worker bees start to feed the larvae and from there the colony usually develops quickly.

The best way that has been found to get the bumblebee queen to lay eggs, is to mate them in autumn and winter. Thereafter they are put in to hibernation for four months at a temperature of +4°C.

Bumblebee queens are cooled to + 4°C

When the case containing the queens is taken out of the cold room, following 4 months of hibernation, the queens are fed with pollen and a sugar solution, and they soon come back to life. Their ovaries start to grow and the queens must be separated within a couple of days. If not, they get angry and start to attack each other.

Breeding

To avoid in-breeding it is important to constantly renew the breeding stock. If there are several queens that are to be fertilised all from one nest, it is important to use drones from a nest that is not related. It is important to take the queens out from the cold room at exactly the right time, so that they can be mated with the right drones.

To make sure that the queens being used for breeding don’t start to stagnate, the newly born queens need to be taken out each day and fed with pollen and sugar solution, for a period of five days, before they are put together with the drones for mating.

Life in the bumblebee colony is dynamic.

The queen uses pheromones to exercise full control over the worker bees in the first weeks. The more eggs the queen lays in this period, the stronger the colony will be. At a set point in the development of the colony, activity goes over to the production of gendered individuals, that is drones and queens. After this point the queens reduce the production of pheromones that hinder egg laying by the worker bees. Some of the workers start to lay eggs, but the queens eat most of the eggs laid by the workers. If the queen is strong enough to lay enough eggs to keep the worker bees occupied with feeding only larva hatched from them, the colony will last longer.

If the queen shows signs of weakness, which is to say she lays too few eggs, the workers can kill the queen and take over control of the nest. The dominant workers stress the others, fighting, killing and threatening. In this phase, before the ranking within the workers has been established, the nest should not be sold, as the workers will not be effective.

The nest is ready for the greenhouse.

When a nest is delivered to the greenhouse, it contains between 200 and 400 worker bees. Some greenhouses buy a new nest every month. Despite the fact that a nest can last from 7 to 8 weeks, they want to have a period of overlapping. This means that they have several nests simultaneously. It is important to make sure that the colonies are not too large in relation to the greenhouse, as the workers can be too hard on the pollen anther and style, causing them damage.

Author:

Knut G. Austad
Jaermuseet
PB 250, 4367 Nærbø
kga@jaermuseet.no