Effects of a fluorescent brightener on the activity of Anagrapha falcifera (Lepidoptera: Noctuidae) nuclear polyhedrosis virus to four noctuid pests

The influence of Calcofluor white M2R (=Tinopal LPW = fluorescent brightener 28), a fluorescent brightener, on the laboratory activity of a nuclear polyhedrosis virus (AfMNPV) isolated from the celery looper Anagrapha falcifera (Kirby) was determined. The species challenged with and without M2R included Heliothis virescens (Fabricius), Helicoverpa zea (Boddie), Spodoptera exigua (Hubner), and Trichoplusia ni (Hubner), all economically important pest species of a number of food and fiber crops. Levels of enhancement as determined by LC(50) values varied from 2.9- to 13.6-fold, whereas levels of LC(95) values ranged from 3.7- to 16-fold, depending on the species. The greatest enhancement occurred among T. ni larvae. LT(50) values were significantly affected particularly when lower concentrations of polyhedra were fed. The presence of M2R reduced LT(50) values up to 2.1-fold among the species tested. The optimum concentrations for M2R enhancement were between 0.25 and 1% (wt/vol). Choice tests between water- and M2R-treated diet showed that larvae preferred non-M2R-treated diet. The implications of these data for use of M2R as an adjuvant for AfMNPV and other baculoviruses are discussed. (C) 1996 Academic Press, Inc.