Effect of different narcosis procedures on initiating oviposition of pre-diapausing Bombus terrestris queens

Published source details (1994) Effect of different narcosis procedures on initiating oviposition of pre-diapausing Bombus terrestris queens. Entomologia experimentalis et applicata, 72, 273-279.
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Summary

Bumblebees Bombus spp. are declining in Europe, and captive rearing could be used to augment or re-establish populations. This study tests the effect of different rearing procedures on egg-laying in buff-tailed bumblebee queens Bombus terrestris, in a laboratory study at the French National Institute for Agricultural Research (INRA), Lusignan, Poitou-Charentes, France.

Five days after mating, 200 laboratory-reared B. terrestris queens (not hibernated) were cooled to 3-4°C, then anaesthetized in plastic boxes with 99.9% CO₂for two periods of 10 minutes, 24 hours apart. Between the periods of ‘narcosis’ queens were kept at 23-24°C.

After treatment, queens were introduced to wooden boxes (11.3 x 4.5 x 4.3 cm) with one B. terrestris worker. 73% sugar solution and freshly frozen pollen collected by honey bees Apis mellifera (renewed daily) were supplied, and a 3cm diameter plastic lid coated with beeswax.

Queens were kept in darkness at 28-29° C and 65% relative humidity, and observed daily under red light.

Experimental treatments varied the regime as follows: 44 queens were kept at 34°C for four to six days after narcosis, before rearing; 29 queens were given narcosis 30 days after mating instead of five; 103 queens were reared in eight hours light, 16 hours darkness; of these, 13 queens were given no narcosis; nine were given two five-minute periods; 36 were given the standard 10 minute periods of narcosis.

The only experimental treatment that increased the chances of a queen laying eggs, and made her lay more quickly, was eight hours of artificial light during rearing.

Queens exposed to light were more likely to survive and lay eggs (73%) than those kept in the dark (67%) and laid eggs more quickly (21.1 days on average, compared to 38.9 days to lay eggs in the dark).

A period of high temperature, narcosis at a greater age, or for a shorter time did not affect the percentage of queens that laid eggs (65-68%) or the amount of time before egg-laying (36-40 days), compared to the standard treatment.

Without narcosis, 7 of 13 queens (53%) survived and laid eggs, but took a similar amount of time to lay eggs as queens given 10 minutes of narcosis (average 17.3 – 19.8 days). There was no significant difference between the proportion of queens surviving and the time taken to lay eggs, between the five and 10 minute narcosis treatments.

Note: If using or referring to this published study, please read and quote the original paper, the abstract of which is available at: http://www3.interscience.wiley.com/journal/117984720/home