EFFECT OF OPTICAL BRIGHTENERS ON THE EFFICACY OF GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) NUCLEAR POLYHEDROSIS-VIRUS IN FOREST PLOTS WITH HIGH OR LOW-LEVELS OF NATURAL VIRUS
Re. Webb et al., EFFECT OF OPTICAL BRIGHTENERS ON THE EFFICACY OF GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) NUCLEAR POLYHEDROSIS-VIRUS IN FOREST PLOTS WITH HIGH OR LOW-LEVELS OF NATURAL VIRUS, Journal of economic entomology, 87(1), 1994, pp. 134-143
Doses of a standard formulation of Gypchek (gypsy moth NPV) containing
the sunscreen Orzan and a sticker were evaluated against gypsy moth,
Lymantria dispar (L.), along with experimental aqueous formulations of
Gypchek in which Orzan was replaced by stilbene disulfonic acid optic
al brighteners, Phorwite AR (1991) or Blankophor BBH (1992), that had
acted as potentiating agents for the virus in laboratory tests. The tr
eatments were applied to gypsy-moth-infested small (0.02 ha) forest pl
ots where preliminary studies had demonstrated high (1991) or low (199
2) levels of natural gypsy moth NPV. In 1991, treatments included two
lower concentrations of Gypchek with the formulation containing Orzan
as well as the formulation containing Phorwite AR. In 1992, treatments
were the lower dose of Gypchek with two levels of Blankophor BBH, one
dose of cell-culture-produced gypsy moth NPV with one level of Blanko
phor BBH, Blankophor BBH alone, and untreated control plots. The 1991
treatments containing Phorwite AR had significantly higher levels of g
ypsy moth larval mortality and significantly reduced LT50s compared wi
th equivalent treatments containing Orzan. The Phorwite AR increased t
he mortality of gypsy moths (caused by the natural virus) to that of t
he high dose of applied virus without Phorwite AR. In 1992, all treatm
ents containing Blankophor BBH with the low dose of virus had levels o
f gypsy moth larval mortality equal to or higher than the standard for
mulation with the higher dose of virus, significantly higher levels of
gypsy moth larval mortality than the standard formulation with the lo
wer dose of virus, and significantly reduced LT50s compared with eithe
r of the treatments containing Orzan. Natural gypsy moth NPV levels re
mained low in the control plots, and Blankophor BBH applied alone sign
ificantly increased the mortality of gypsy moths.