Effects of CO ₂ Narcosis and Cold Storage on Colony Success of Artificially Inseminated Bumblebee Queens

ABSTRACT

Bumblebees are vital pollinators for both agricultural crops and natural plants. Among the various bumblebee species, Bombus terrestris (Hymenoptera: Apidae) is available commercially for pollination purposes. To develop reliable artificial insemination techniques for bumblebees, we examined the effects of different carbon dioxide (CO ₂ ) treatments and cold storage after insemination on colony success of bumblebee queens. CO ₂ treatments were applied to queens as follows: CO2‐1 (CO ₂ narcosis once during insemination) and CO2‐2 (CO ₂ narcosis twice during insemination and 3 days after insemination). Queens inseminated under CO2‐1 conditions were subjected to cold storage at 2.5°C for 4, 8, and 12 weeks. In the experiments, the insemination and survival rates of queens after insemination were almost 100%. In the CO ₂ treatments, oviposition by inseminated queens and adult emergence rates exhibited similar patterns in the CO2‐1 and CO2‐2 conditions but declined gradually as cold storage duration increased. Among the bumblebee species examined, the efficiency of artificial insemination, as measured by adult emergence, was the highest in B. terrestris , followed by B. ignitus and B. hypocrita sapporoensis . To evaluate the suitability of B. terrestris queens for artificial insemination with semen from different Bombus species, queens were inseminated with semen from B. ignitus and B. hypocrita sapporoensis , and B. terrestris males were produced in all treatments. The results provide a basis for artificial insemination in bumblebees and could have various applications.