晩秋期におけるダイズサヤタマバエ(双翅目,タマバエ科)の齢構成と生存率

Abstract

The soybean pod gall midge, Asphondylia sp., is one of the serious pests of soybean, particularly in southwestern Japan. In summer and autumn, the larvae of the species inhabit the pods of cultivated soybean and of wild leguminous plants, repeating at least two generations on these plants. However, life cycles and host plants in other seasons are still unknown, and this species has been left unnamed. In order to examine the possibility of hibernation in the host pods, age structure and survival rate of the species were investigated by dissecting the pods sampled twice in November and once in December, 1979 from a soybean field in Kagoshima City. Most of the adults had already emerged by the 9th of November, and thereafter, the adults could not be considered to emerge continuously, because there was no significant difference among the three samples in the rate of adults emerging. The third instar larvae remaining in the pods developed successively into the late stage of pupa, but they died at this stage due to withering of the pods. This indicates that the species can not hibernate in the pods of herba leguminous plants under natural conditions because a large majority of the plants wither in winter. In addition, there was no evidence that the larvae escaped from the pods to spine cocoons in the soil. To clarify the annual life cycle of the species, the possibility that the plants other than Leguminosae are utilized as hosts in winter and spring should be taken into consideration, and dispersal ability of the adult midges should be assessed.