A granulovirus of Pandemis leafroller was discovered in Wenatchee that can produce high natural levels of infection at low dosages. Bioassays of the virus against Pandemis leafroller were conducted on artificial media with five virus concentrations ranging from 1 to 5000 virus granules/mm2 that produced mortality in neonates and older instars ranging from 20 to 90%. Additionally, groups of 45 neonate Pandemis larvae were exposed to approximate LC95 dosages of the Pandemis virus in the manner prescribed above and monitored daily to track the progression of mortality over a 21 day observation period. The results of tests that investigated the effect of Pandemis larval age on susceptibility to PpGV revealed that fourth instars were as susceptible to the virus as were neonates, although the onset of mortality was slower. The increased mortality at lower dosages observed in the fourth instars was probably a function of the large amount virus consumed with diet. The onset of mortality is both a function of larval age and dosage. Even moderately low dosages (5 and 50 virus granules/mm2) result in high mortality when the observation period is extended to 3 weeks. Examination of tissues from moribund larvae using light and electron microscopy revealed a broad range of tissues infected with large amounts of virus production taking place in the fat body.
Species 1: Lepidoptera Tortricidae Pandemis pyrusana (Pandemis leafroller)
Keywords: microbial control, granulovirus
Back to Display Presentations, Subsection Ce. Insect Pathology and Microbial Control
Back to Posters
Back to The 2002 ESA Annual Meeting and Exhibition