The addition of Fluorescent brighteners al 0.1% concentration to Spodoptera
littoralis nucleopolyhedrovlrus (SpIIMNPV) increased the susceptibility of S. littora/is
larvse to virus. The highest rates of enhancement among the six tested optical
brighteners were obtained in case of Blankophor BBH, TIn opal UNPA-GX and
Blankophor HRS. LC5O'S values were sharply reduced from 1.9x10" to 2.3x1 0²,
2.4x10 and 4.94x10²PIB's/ml diet by 82.6, 78.2 and 38.7fold, respectively. Whereas,
Blankophor RKH, Blankophor P167 and Blankophor BSU exhibited less effect than
the previous three products. Also, a reduction In the time required for killing 50% of the tested population
(L T 50) was recorded with a value of 2.23 fold in case of Tinopal UNPA-GX. Effects on
the larval weight, duration of larval stage, duration of pupal stage and the sex ratio of
emerged moths were studied. The reduction In larval weight was correlated with a
high rate of enhancement effect. The duration of the larval stage was longer in case of
the brightener treatments especially with those effectiVe products. No effect could be
detected on the duration of the pupal stage and sex ratio. The present study suggests
the potential use of Blankophor BBH and TInopal UNPA-GX to improve the effect of
SpliMNPV formulation.