Method of holding survey of the two wild host plants, Pharbitis congesta and Ipomoea pes-caprae, of Cylas formicarius (Fabricius)

摘要

Stems (1 m in length) of two wild host plants of Cylas formicarius (Pharbitis congesta and Ipomoea pes-caprae) were dissected in order to detect individuals of immature stages on the day of sampling when collected from the field (control) in Japan and after holding for 10 and 20 days. After dissection the number of detected individuals and developmental stages were recorded. The tested stems, except controls, were held at 27deg C and 70% RH with and without water. The number of detected individuals per stem gradually increased as holding periods became longer. First-instar larvae were detected in 10-day holding plots, but were not detected in 20-day holding plots. The results indicated that individuals in stems developed during the holding period. Therefore, holding stems was considered an effective method to reduce the number of eggs and young larvae.