Technical adaptations of instant medium for Drosophila. Bizzo, L.,1,2 T. Vanderlinde,1 B. Wildemann,1,2 and D.C. De Toni1. 1Laboratório de drosofilídeos, sala 304C, Departamento de Biologia Celular, Embriologia e Genética, Universidade Federal de Santa Catarina. Campus Universitário Trindade, 88040-900, Florianópolis,Santa Catarina, Brasil; e-mail: email@example.com; 2Programa de Pós-Graduação em Biologia Celular e do Desenvolvimento - Centro de Ciências Biológicas, Universidade Federal de Santa Catarina.
Like all holometabolous insects, Drosophila occupy two very different habitats during their life cycle. Females lay their eggs on a soft substrate that is suitable for larval development. After the larvalstage, the pupal stage sets in, inciting the imagos to emerge. The length of the life cycle varies from one species to another and is dependent on environmental factors such as temperature, type of substrate, and humidity (Powell, 1997). The ease with which species can be cultured in the laboratory varies considerably. There is a clear correlation between the ease of culturing and the breadth ofniche species, as well as with adaptation to be human commensals (Powell, 1997). Domestic species, including the most studied model, D. melanogaster, have a broad range of habitat preferences and do not have particularly narrow nutritional requirements (Powell, 1997). However, there are species of this genus, that, due to the irrestricted ecology, have no reported studies concerning theirbiological and behavioral features, precisely because of the difficulty of keeping these species in a laboratory environment (Hofmann et al., 1984). Drosophilids can live and forage on many types of substrates, such as flowers, fruit, leaves, sap, cactus, fungus, and also in decomposing organic matter. In a laboratory these substrates are replaced by culture medium in order to facilitate the maintenanceand cut costs. In species from the cardini group that occupy a narrow niche, the culture medium may be a reason for the limited population growth. The length of each genaration of the cardini group species is estimated to be 15 days (Markow, 2006). We were able to maintain our stock on standard agaryeast-cornmeal medium; however, our strains of D. polymorpha did not develop properly, taking morethan 25 days to complete their life cycle. Moreover, these conditions enabled some fungi to emerge, and the offspring also became considerably reduced, leading to the loss of many lines. Therefore, we decided to search for a culture medium more suitable for species from this group. We reviewed the culture media used in stock centers and made some adjustments. We looked for an instant medium with asimilar recipe to 4-24 from Carolina Biological. Therefore, we chose potato flakes, which are easily prepared because they do not require cooking, and only need the adding of the liquid portion. However, the liquid portion has to be enriched in order to ensure that the medium has all the essential components for the successful development of flies and also for yeast that eventually comes togetherwith wild flies. To this purpose, sugar, proteins, and minerals were added to the water, after which eventually an antifungal can beaded in. Because of the mixture’s simplicity, independently we obtained a very similar recipe as proposed by Kliethermes et al. (2011). We chose molasses as a source of sugar due to its greater diversity and quantity of sugar compared to regular sugar and honey. Yeastswere also added in, as a source of proteins and minerals. Propionic acid was chosen as an antifugal instead of nipagin (methylparaben), which is insoluble in water. The quantity of each ingredient is listed below:
Dros. Inf. Serv. 95 (2012)
400 ml water 20 g molasses 6 g yeast (Saccharomyces cerevisiae) 1 ml propionic acid Firstly, we recommend dissolving the...