Sexual Maturity Time and Spermatheca Size of the Bumblebee Bombus ignitus at Mating for Artificial Insemination

Abstract

We investigated the mating age for sexual maturity of the bumblebee Bombus ignitus queens and males. In the mating age of sexual maturity of queen, mating rate was 1.1% at 3 days of emergence, peaked 24.7% at 20 days of emergence, and decreased thereafter. In case of mating age of sexual maturity of male, mating rate was 3.3% at just emergence and 20.0% to 43.3% at 6 days to 20 days of emergence. The colony development at aging of B. ignitus queen and male was a similar tendency to the mating age of sexual maturity. The age and copulation times of B. ignitus male were older and more, the copulation duration was longer. In case of multiple mating, B. ignitus was mated by 4 times, mating was mostly showed a peak at 9 to 11 AM, which was 70.5%. The number of ovum per ovariole in ovarium in non‐ mated and mated queens was 4.13 and 4.29, respectively at 10 days of emergence, and decreased thereafter. The number of ovum per ovariole of mated queens was a little more than that of non‐ mated queens. The size of spermatozoa of B. ignitus queen was a similar tendency to the number of ovum per ovariole. Our results indicate that period favorable for artificial insemination of B. ignitus was from 6‐10 days after emergence for queen and 9‐20 days after emergence for male.