Dietary and olfactory effects of fermenting apple juice on reproductive diapause in <scp> <i>Drosophila moriwakii</i> </scp> (Diptera: Drosophilidae)

Abstract Drosophila moriwakii (Diptera: Drosophilidae) generally has one generation in a year and enters summer–winter reproductive diapause in early summer in Sapporo, northern Japan, but a small fraction of the population produces the second generation in mid‐summer at places where breeding resources are abundantly provided. In the laboratory experiments, flies were revealed to enter diapause under moderately low temperatures and short daylengths. Under long daylengths, they enter diapause when reared in cages in which they are able to fly freely but do not when reared in small vials in which they are prevented from flying. However, the effect of diet on diapause has not been investigated in the laboratory. In this study, we address this issue by using artificially prepared breeding resources made of Drosophila medium, apple juice and dry yeast. In the results, females of this species were prevented from entering diapause not only when they were fed with these resources but also when they were exposed only to the odor of fermenting apple juice.