Susceptibility of Phthorimaoptera operculella Zeller (Lepidoptera; Gelechiidae) to its granulovirus PoGV with larvel age
1 Granulovirus PoGV is a strong candidate to substitute for chemical insecticides in integrated pest management (IPM) of the potato tuber moth Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae). Generally, susceptibility to baculoviruses decreases with increasing larval age. For effective field applications, knowledge of the age-related change in susceptibility is crucial.
2 The relative susceptibility of various instars of P. operculella larvae to PoGV was studied by leaf-disc bioassays in the laboratory at 26 °C incubation temperature. The LC50 increased from 4 × 10^6 granules/mL for neonate larvae to 1.2 × 10^7, 1.1 × 10^8, 4.4 × 10^8, and 4.2 × 10^9 granules/mL, signifying resistance ratios of 3, 29, 110, and 1051, for 5, 6, 7, and 9-day-old larvae, respectively.
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