Husbandry and Life Cycle


Husbandry and Life Cycle

Sciara are grown on agar in glass vials. A food mixture of yeast, mushroom powder and ground straw is manually deposited in the vials three times per week during larval stages of Sciara. Larvae are grown at 18-21℃, but their growth can be slowed down at a cooler temperature (eg, 12℃) or temporally arrested at 4℃.

Sciarid fly stocks can be decimated by microsporidian infection (Pavan and Basile 1966; Roberts et al. 1967; Diaz et al. 1969). These are noticed by sac-like structures within the lumen of the salivary glands. Since we frequently prepare salivary gland polytene chromosome preparations from our stocks, such an infection would be readily noticed. This occurred in the early 1970s and we discarded the infected stocks to prevent spread of the infection. To minimize microsporidian or viral infections, disposable gloves are worn when we add autoclaved food to the Sciara vials three times each week.

Over the past decades we have had three cases of mite infestation; this is readily noticed by dissecting microscope observation of the mites on the adult Sciara when we are mating the flies. These rare occurrences of mite problems are overcome by selecting adult Sciara without mites adhering to them for crosses. Unlike Drosophila, chemicals cannot be used to overcome mite infestations of Sciara, so we are extremely diligent to not store Sciara near Drosophila (that might have mites), to not allow houseplants (that could carry mites) in the lab, to wash all Sciara vials soon after adults have emerged, and to autoclave the vials, agar and food used for Sciara maintenance.

Since the life cycle of Sciara is 5 weeks, we maintain multiple lines of each stock by doing independent crosses during 3 or more of the 5 week cycle of weekly crosses. In addition, a line of each stock is maintained in the cold room and they are brought to room temperature and grown up after 6 months and new crosses (to prevent bottle-necking) of each line are then deposited back into the cold room.

Life Cycle of Sciara
The life cycle of Sciara is about five weeks. Seven to ten days after egg-laying, the embryos emerge as larvae. There are four larval instars that last about three weeks, with the fourth instar lasting seven to ten days. During the last several days of the fourth instar, “eyespots” appear at the anterior end of the larvae --- these are the anlage to the adult eyes. DNA puff amplification in salivary gland polytene chromosomes occurs during the later eyespot stages. After a few days in pupation (when meiosis occurs), the adult flies emerge and live for about a week.