暖地二期作馬鈴薯の採種に関する研究 : 第I報 暖地におけるジャガイモアブラムシの寄生および飛翔活動, 並びにそれと馬鈴薯ウイルス病伝染との関係

抄録

I. Fluctuations in population of the alatae and the apterae of Myzus persicae (SULZER), Aphis gossypii GLOVER and Aulacorthum solani (KALTENBACH) were Surveyed, sticky traps of BROADBENT style being used with regard to their flight, in experimental potato-field-blocks which were planted at nine different times successively throughout from spring to autumn in Himeji from 1955 to 1958. The results are as follows: (1) The appearance of those aphids has three seasons, marked off by the disappearance and the diminution periods on host and flight, which are relatively stable but without connection with plant growth. (2) M. persicae appears most abundantly in the early and middle part of the first season (from April to June), and also in the middle and late part of the third season (from Octover to December), but scarcely in the second season (from July to mid September); A. gossypii exceedingly in the second season, and also in the middle and late part of the first season, and in the early and middle of the third season; the counts of A. solani is always the smallest. (3) Though the aphid population varies markedly with dats of potato sprouting, the seasonal fluctuation curve of parasitic activity in each species is obtainable by the line connecting the highest value of the aphid population among blocks of each planting date. Such fluctuation curves in different years and aphid species were discussed with regard to flight fluctuation. II. On a virus free potato row planted in a victoria lawn tunnel, adjacent to an alternate open row of diseased poatoes infected with virus Y and leafroll virus, was allowed natural inoculation by opening the tunnel for one week at definite time, in Himeji from 1955 to 1957. The results are: (1) the fluctuation observed in virus transmission in years, seasons and with the dates of sprouting revealed close connection with activities, especially with flight, of the aphids which inoculated the diseases, i.e. virus Y being associated with A. gossypii or plus M. persicae, and leafroll virus with M. persicae or plus A. solani. However, in un-caged blocks, transmission of leafrall and virus Y were rather correlated with the index-value for the whole season infestation of alate aphids, with the relation of M. parsicae plus A. solani to leafroll and A. gossypii plus A. solani to virus Y, the index-value being obtainable by summing up all countings made on every tenth day by the line of parasitic activity. The reason for the affecting of A. solani to the transmission of virus Y must be owing to the abnormal appearance of the species in autumn 1956. (2) The number of days for virus diseases to flow down from inoculated leaves to tubers varied in connection with the aphid population; in relatively shorter period of time the tubers seemed to be infected, if much of inoculations have been occured by many aphids.