Laboratory menu and oviposition preference in Drosophila melanogaster

Abstract

In nature, fruit flies use volatile compounds produced by rotting fruits and vegetables to locate feeding, breeding and oviposition sites. The choice of oviposition site is very important for Drosophila melanogaster offspring survival and fitness. Females make decisions about egg-laying sites by evaluating complex information obtained from multiple sensory pathways. When choosing a place for oviposition, they carefully evaluate specific nutrients and substrate strength. The aim of this study was to investigate the oviposition preference of three D. melanogaster strains, reared for 22 years on different diets (standard cornmeal, tomato and carrot substrates). Virgin flies were kept on a neutral agarose substrate until the experiment started. Oviposition preference was tested in ten replicates, in transparent plastic boxes that contained five Petri dishes filled with cornmeal, tomato, banana, carrot and apple substrates. Twenty five individuals of each sex and strain, 4-5 days old, were placed in boxes overnight, after which the eggs were counted. Results pointed to significant differences among strains. Females from standard strain chose more often the standard substrate for laying eggs. On the other hand, females reared on tomato substrate chose the carrot substrate more often, whereas females from strain reared on carrot substrate significantly preferred tomato substrate for egg laying. The results of this study confirmed that the substrate on which the adults developed did not necessarily affect the preference for the egg-laying substrate. Further, substrates that contained carrot and tomato were previously determined as ones that enabled both the fastest development and higher egg-to-adult survival.