FIELD-BASED ESTIMATES OF DOSE RESPONSES OF THREE GYPSY MOTH VIRUS STRAINS WITH AND WITHOUT THE VIRUS ENHANCER, BLANKOPHOR BBH.

Authors: Thorpe, Kevin; PODGWAITE, J. - USDA, FS; SLAVICEK, J. - USDA, FS; Webb, Ralph; Fuester, Roger; PEIFFER, R. - DELAWARE STATE UNIV; VALENTI, M. - DELAWARE DEPT. AGRIC; Taylor, Philip

Submitted to: United States Department of Agricultural Interagency Gypsy Moth Research Forum
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In vitro production of gypsy moth nucleopolyhedrosis virus (LdMNPV) can potentially reduce costs and encourage commercial production of this biological control agent. An in vitro- produced virus strain developed by the USDA, Forest Service produces viral polyhedral occlusion bodies (PIB) that are smaller and contain less virions than those of virus produced in living insects. This study was conducted to provide information on the dose responses of gypsy moth virus strains 2031a1c (in vivo), 122b1a (in vitro) and Gypchek (in vivo). Gypchek is currently produced by the USDA Forest Service for operational gypsy moth control. Gypsy moth larvae were caged on treated foliage for 1 week, and mortality and speed of kill for each strain was determined with and without the viral enhancer, Blankophor BBH, at 0.5% (W:V). Without enhancer, 10(12) PIB/100 gallons caused >90% mortality with the in vivo-produced strains and 66% mortality with the in vitro-produced strain. With enhancer, mortality exceeded 95% with both of the in vivo-produced strains and was 82% with the in vitro-produced strain at 10(10) PIB/100 gallons. The presence of Blankophor BBH decreased the LD(50) values of the in vivo-produced strains by about 3 logs (= 1000-fold) and that of the in vitro-produced strain by 3.75 logs (= 5,600-fold). The enhancer increased the speed of kill of the in vivo-produced strains, but not that of the in vitro-produced strain, at 10(11) PIBs/100 gallons.