BEHAVIORAL RHYTHMS OF DROSOPHILA SUZUKII AND DROSOPHILA MELANOGASTER

Drosophila suzukii and Drosophila melanogaster feed on various fruits, causing great eco- nomic losses. In order to find the optimum time for controlling D. suzukii and D. melano- gaster, the daily rhythms of oviposition, egg hatch, pupation, adult eclosion, copulation, and feeding of these two pests were studied. We found the circadian rhythm of D. suzukii oviposi- tion to have a single pattern with a peak from 20:00-24:00, while the peak oviposition of D. melanogaster was from 16:00-4:00 (the next day). Neither D. suzukii nor D. melanogaster showed a daily pattern of egg hatch; the single peak of egg hatch for D. suzukii occurred 24- 32 h after oviposition, while that for D. melanogaster followed a bimodal pattern, with the first peak of egg hatch from 0-4 h after oviposition and the second from 32-36 h after oviposi- tion. Pupation in D. suzukii showed a single peak from 8:00~16:00, while in D. melanogaster pupation followed a bimodal pattern, with peaks from 4:00-8:00 and 12:00-20:00. Eclosion of of D. suzukii adults followed a unimodal pattern, and generally took place from 0:00-8:00, while that of D. melanogaster also showed a single peak, generally from 0:00-12:00. Mean- while copulation of D. suzukii, which showed a bimodal pattern, was concentrated from 0:00- 12:00 and 20:00-24:00 (the next day), while copulation of D. melanogaster showed a single peak, generally from 0:00-12:00. Both D. suzukii and D. melanogaster had a preference for feeding in light, and in a 24 h photoperiod the percentages of feeding insects were 80.8and 81.1, respectively.