Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 12, 1996
Publication Date: N/A
Interpretive Summary: The beet armyworm is an important agricultural pest which is difficult to control due to its resistance to registered insecticides. A new commercial formulation of a nuclear polyhedrosis virus that is pathogenic to beet armyworm larvae was tested with and without a fluorescent brightener which had enhanced infectivity of fall armyworm nuclear polyhedrosis virus. The fluorescent brightener enhanced infectivity of the beet armyworm virus approximately 20-fold and reduced variability of the insect's susceptibility to the virus. Thus, the fluorescent brightener might increase the reliability of the virus for control of beet armyworm in the field.
Technical Abstract: The beet armyworm, Spodoptera exigua (Hubner), is an important pest which is difficult to control due to its resistance to registered insecticides. A new commercial formulation of a nuclear polyhedrosis virus that is pathogenic to beet armyworm larvae, SPOD-X, was tested with and without a fluorescent brightener, Tinopal LPW, which had enhanced infectivity of fall armyworm NPV to the fall armyworm, Spodoptera frugiperda. The effects on larvae from six colonies of the beet armyworm which had recently been established from field collections in Georgia and Alabama were compared with a laboratory colony which had been maintained in the laboratory for 2 years. The LC50 was lower in all bioassays with SPOD-X in 0.25% Tinopal LPW than with SPOD-X in water, although in 3 of 12 bioassays the difference was not significant based on overlapping 95% confidence intervals. The mean LC50 for SPOD-X in water was 376 polyhedral occlusion bodies per cup (surface area 800 mm sq). The mean LC50 for SPOD-X in 0.25% Tinopal LPW was 30 polyhedral occlusion bodies per cup.