Success rates for instrumental insemination of carbon dioxide and nitrogen anaesthetised honey bee (Apis mellifera) queens

This study assessed the usefulness of CO2/N-2 mixtures for anaesthetising queen bees (Apis mellifera) in instrumental insemination. Of 98 instrumentally inseminated queens, 31 were anaesthetised with 40% CO2 and 60% N-2, 32 with 60% CO2 and 40% N-2, and 33 with 100% CO2. The gas composition did not affect the proportion of queens starting oviposition, which were: 85.3% for 40% CO2 and 60% N-2; 87.9% for 60% CO2 and 40% N-2; and 83.9% for 100% CO2. On average, queens started oviposition significantly earlier in the treatments using 60% CO2 and 40% N-2 (at 7.2 +/- 4.0 days after insemination) and 100% CO2 (at 8.1 +/- 4.2 days) than those treated with 40% CO2 and 60% N-2 (at 10.3 +/- 4.1 days).