Charles P. Milne Jr, John P. Phillips And Peter J. Krell
A simple, quick and reliable microinjection technique was developed for use with the early honeybee (Apis mellifera L.) embryo. Newly laid eggs were taken from a colony, placed on double-sided 'Scotch' tape, covered with light paraffin oil and injected at the posterior end with a fine glass needle (tip diameter = 2-5 µm). Development continued at 35°C under oil. Injection was visualized for this study by injecting a heavy paraffin oil that formed a droplet in the aqueous egg protoplasm. The volume of the injected oil was 0.2-0.4 nl and represented about 0.2% of the egg volume. It is likely that more could have been injected into the embryo. Development of a single injected embryo was photographed till hatching, and the oil droplet could be clearly seen in the newly hatched larva. With practice, about 100 eggs could be injected per hour. Twenty-one percent of the embryos injected with paraffin oil survived till hatching. Development of injected embryos was slightly retarded; 16 injected eggs required 80.0 ± SE 4.6 h to hatch, which was significantly (P<0.05) longer by an analysis of variance than eggs under oil (77.6 ± 2.7 h, n = 23) or in a comb (76.7 ± 2.1 h, n = 63).