Field and Cage Tests with Polyhedrosis Viruses for Control of the Cabbage Looper123

A nuclear polyhedrosis virus isloated from Trichoplusia ni (Hübner) that has virions singly occluded in the polyhedral matrix; a nuclear polyhedrosis virus isolated from the alfalfa looper, Autographa californica (Speyer), that has virions grouped in bundles in the polyhedral matrix; and a cytoplasmic polyhedrosis virus isolated from the cabbage looper were tested in the field and in field cages as controls for the cabbage looper. Looper populations were reduced when the 3 viruses were applied alone or in combination, and in several treatments the degree of control compared favorably with that obtained with chemical treatments of naled or Monitor® (O, S-dimethyl phosphoroamidothioate). The cytoplasmic polyhedrosis virus reduced the total number of loopers and the pupal weights in caged populations. The virus of the alfalfa looper used at rates of application ranging from 1.5×1013 to 3.6×109 polyhedra per acre often reduced the number of loopers in treated plots below the number in plots treated with the cabbage looper virus.