LC and LD50’s of Bacillus thuringiensis serovar japonensis strain Buibui toxin to oriental beetle and northern masked chafer larvae (Coleoptera: Scarabaeidae)

ABSTRACT Bacillus thuringiensis serovar japonensis strain Buibui has the potential to be an important control agent for pest scarabs. LC and LD50’s of Bacillus thuringiensis serovar japonensis strain Buibui toxin and spores were determined by four different bioassays for the oriental beetle, Anomala orientalis (Waterhouse) and Northern masked chafer, Cyclocephala borealis Arrow. Oriental beetle larvae were bioassayed in autoclaved and non-autoclaved soil from where they were collected (Kingston, RI=native), in non-autoclaved soil from where the Northern masked chafer larvae were collected (Groton, CT=foreign), and per os. Northern masked chafer larvae were bioassayed in autoclaved and non-autoclaved soil from where they were collected (Groton, CT=native), in non-autoclaved soil from where the oriental beetle larvae were collected (Kingston, RI=foreign) and per os. LC50’s of 3.93 µg toxin /g autoclaved native soil, 1.80 µg toxin /g non-autoclaved native soil, 0.42 µg toxin / g non-autoclaved foreign soil, and an LD50 of 0.41 µg per os were determined at 14 days for A. orientalis. LC50’s of 588.28 µg toxin /g autoclaved native soil, 155.10 µg toxin /g non-autoclaved native soil, 265.32 µg toxin /g non-autoclaved foreign soil, and LD50 of 5.21 µg per os were determined at 14 days (soils) and 10 days (per os) for C. borealis. There were significant differences in LC50’s for oriental beetles in autoclaved, non-autoclaved native soil and non-autoclaved foreign soil. There were significant differences in LC50’s for Northern masked chafers in autoclaved and non-autoclaved native soil.