Animal stock maintenance
Stocks of Drosophila virilis (Cambridge Fly Facility StrainvS-4,
isolated in 1991), were kept in a temperature-controlled room at 23°C,
12:12 L:D and ambient humidity. Although a long term laboratory stock,
this stock was included in a recent analysis of upper thermal limits
from 36 Drosophila species that found no significant association
between time in culture and any upper thermal limit (Parratt et
al. 2021), suggesting it is a reasonable model for the species. Stocks
were maintained at moderate density (50 – 100 flies per 300ml bottle
culture) on ‘Propionic’ medium (10g agar, 20g yeast extract, 70g
cornmeal, 10g soya flour, 80g malt extract, 22g molasses, 14ml 10%
nipagin, 6ml propionic acid, 1000ml H2O). Ovipositing
adults were tipped to new food every week to prevent overlapping
generations and were replaced with fresh sexually mature adult flies
every 4-6 weeks.