Studies on Drosophila suzukii Mats.
AbstractDrosophila suzukii, Mats., is widely distributed in Japan, where it infests cherries and grapes severely and also occurs in fruits of apple, peach, plum and persimmon [cf. R.A.E., A 24 315]. The percentage of cherry fruits infested ranges up to 75. In a given year there are about 13 generations, but only 3 are completed by individuals produced late in the oviposition period of successive females, owing to the length of this period. The adults, which mostly emerge at 8-9 a.m., remain motionless at 5°C. [41°F.], begin to crawl at 10°C. [50°F.], are most active about 20°C. [68°F.] and show less activity at 30°C. [86°F.]. They live for 21-66 days in May-August, but those emerging from late September onwards overwinter and sometimes survive until the following July. The eggs are laid on warm days from April to November in the fruits, ripe fruits being preferred. The number of eggs laid per cherry by a single female averaged 2.7. The oviposition period lasted 10-59 days; the average number of eggs laid per female was 384 and the number per day 7-16. The egg stage lasted 2-72 hours and was completed in about a day in cherry in May and June. The adults begin to appear in early April and are most numerous in June-July and September-October. They enter hibernation in sheltered places in late November at about 5°C.
The larvae mature in about 3-13 days and the pupal stage, which is usually passed in the fruits but sometimes in the soil, lasts 3-15 days. If the fruits are decayed or very unripe, only 50 per cent, of the larvae survive to pupate. As many as 65 adults may emerge from a single cherry. The life-cycle is completed in about 21-25 days at a constant temperature of 15°C. [59°F.] and about 9-11 at 25°C. The larvae are parasitized by a Diapriid of the genus Phaenopria.