Providing evidence to improve practice

Individual study: Treatment with carbon dioxide induces egg-laying in captive buff-tailed bumblebee queens Bombus terrestris; a laboratory study in Würzburg, Bayern, Germany

Published source details

Röseler P.F. (1985) A technique for year-round rearing of Bombus terrestris (Apidae, Bombini) colonies in captivity. Apidologie, 16, 165-170

Background

Bumblebees Bombus spp. are declining in Europe and America, and captive rearing followed by re-introduction is planned for one species in the UK. This laboratory study carried out in Würzburg, Bayern (Bavaria), southern Germany documents a technique to break hibernation and induce egg-laying in mated bumblebee queens, either caught from the wild or overwintered in captivity.

Action

46 young mated buff-tailed bumblebee queens Bombus terrestris from laboratory-reared colonies were subjected to CO2 narcosis one day after mating. They were placed in a glass jar and treated with a CO2 stream until they became still. They were left in the closed jar for 30 minutes, then allowed to fly in a gauze cage. The process was repeated the following day.

48 young mated buff-tailed bumblebee queens were 'over-wintered' by placing them in jars lined with moist soft paper (replaced monthly) and storing them between 5° C and 10° C for between three weeks and six months. After hibernation, the queens were activated with a soft stream of CO2, kept at 15°C overnight, allowed to fly in a cage at room temperature, then subjected to CO2 narcosis twice as above.
Two to six days after the CO2 narcosis, single queens were confined in nest boxes provided with 50:50 honey:water solution and fresh pollen, along with larvae or freshly pupated workers from another colony and 2-5 newly emerged workers. The nest boxes were kept in a controlled climate room at 28-30°C. The workers were replaced every five days until the new brood emerged.

Consequences

After CO2 narcosis without hibernation, 33 of the 46 queens (72%) began egg-laying within one week. After CO2 narcosis and hibernation, 39 of the 48 queens (81%) began egg-laying within one week. All the queens treated this way eventually laid eggs, some after more than 10 days of confinement.

Colonies developed normally, except that the first brood sometimes contained some males. The technique makes it possible to rear bumblebees all year round, rather than annually.

 

Note: If using or referring to this published study, please read and quote the original paper, the abstract of which is available at: http://www.apidologie.org