Kazuo Kawada

Apterous males and holocyclic reproduction of Lipaphis erysimi in Japan

KAZUO KAWADA & TAMOTSU MURAI~: Apterous males and holocyclic reproduction ofLipaphis erysimi in Japan. The turnip aphid, Lipaphis erysimi Kaltenbach is a destructive pest of cruciferous crops. However, the complete life cycle of this aphid has not yet been described. Apterous males, oviparous females and fundatrices of L. erysimi have been reported in Europe (Bodenheimer & Swirski, 1957, Mfiiler, 1955). In India, oviparous females have been recorded from Cherrapunji and Kalimpong (Basu et al., 1970), and a single alate male has been found in the Kashmir region (Verma & Mathur, 1966). In New Zealand, a single oviparous female was discovered in Auckland (Cottier, 1953). In Japan, oviparous females and fundatrices were previously found in Ise (Sorin & Shinohara, 1972) and oviparous females in Kyoto (Takada, 1976). In this paper we report the observation of holocyclic L. erysimi in the field in Japan, and laboratory rearing of all morphs. We also provide the first detailed description of apterous males of this aphid. We started field surveys in October 1975. In the Kurashiki district (34.36°N, 133.43°E) some 250 km W of Ise and Kyoto, turnip aphids were found to reproduce parthenogenetically throughout the year, and even in the cold winter, viviparous females were seen on radish leaves in the field, but no sexual forms were observed. In the Saigo area (36.12°N, 133.19°E) of the Oki Islands about 180 km NW of Kurashiki, oviparous females and apterous males were found on field radish leaves on October 14, 1976. A few days after mating, eggs were found on the leaves usually along veins. Fundatrix larvae hatching from eggs that had overwintered were first observed on April 5, 1977. The fundatrix adults began to produce offspring toward the end of April, and parthenogenetic reproduction lasted until September or in some cases October. In our laboratory fundatrix larvae hatching from eggs that had overwintered in the field in Saigo were first observed on March 3, 1977, and they were used to initiate our laboratory culture. The apterous fundatrigeniae produced by these apterous fundatrices were isolated until birth of the next third generation, their offspring were isolated in turn, and the process repeated until the line ended. Rearing was carried out under a short photoperiod of 8 hr light per diem at a constant temperature of 15 ° with fresh radish leaves every 5th day. Under these conditions a succession of apterous viviparae was reared for eight generations. Alate viviparae were produced in other culture lines in which the aphids were crowded. Apterous sexuparae appeared in the ninth generation, and oviparous