閉鎖型環境でのイチジク栽培におけるアザミウマおよびサビダニの発生消長と果肉への加害

抄録

In a test cultivation of fig (Ficus carica L.) conducted in a closed-type plant cultivation room with artificial lighting, the damage of fruit pulp caused by thrips and eriophyid mites was investigated. Fig (cv. Masui Dauphine) trees were planted in plastic pots and continuously cultivated five times due to the renewal of bearing shoot. Pulp damage occurred in the fig fruits harvested from fourth and fifth cultivation. The overall incidence was 72% in the fourth cultivation and 85% in the fifth cultivation. The intrusion of onion thrips (Thrips tabaci Lindeman) into the fruit was detected as the cause. Many such infested fruits were observed where the adults and larvae of thrips co-existed, suggesting a high possibility of thrips generation alternation occurring inside the fruit. As thrips were hiding in the cracks of buds or in the soil, it was found that the thrips could not be eliminated from the cultivation environment by spraying pesticides and removing branches, which are the usual methods of pest management. Many cases were also observed where pulp damage occurred even though no thrips were present inside the fruit. Eriophyid mites were thought to be the main cause in this case. Eriophyid mites have been observed sporadically on the leaves, stems and surface of fruits since the first cultivation. In the fourth and fifth cultivation, many of them intruded inside the fruit and caused pulp damage similar to thrips. Thus, it can be concluded that the fate of these two types of pests in fig cultivation differs in a closed environment from that in open field cultivation; therefore it is necessary to develop new countermeasures to eliminate them.