Pathogenic Bacteria of Aphids

II. Characteristics of Insecticidal Activity

Abstract

When the liquid culture of bacterial isolate (HS870031) showing toxic activity against aphids was centrifuged into the supernatant and pellet, only the supernatant caused high mortality in the foxglove aphid, Aulacorthum solani. However, the pellet did induce low mortality. Spraying with the supernatant of HS870031 cultured for 16 h resulted in high mortality of A. solani nymphs and the supernatant cultured for 20 h induced high mortality in adults. When sucking time become longer and inoculum dose was more concentrated, the number of living cells in aphids increased with the peroral inoculation of the bacterial isolate (HP890972). When HP890972 cells were perorally inoculated to aphids, the survival period of aphids was decreased depending on the dose concentration. HP890972 cells were constantly recovered from dead aphids at approximately 10⁷ cfu/aphid regardless of dose concentration.