Abstract
Population density estimates and yield data were used to assess the effect of an integrated pest management (IPM) package, host plant resistance, companion cropping, and Bacillus thuringiensis Berliner, on cabbage looper (CL) [Trichoplusia ni (Hubner)] and diamondback moth (DBM) [Plutella xylostella (L.)] larval infestation of cabbage, and in protecting beneficial arthropods. Compared with the IPM package, the standard (susceptible) cabbage variety grown by farmers and treated with a pyrethroid insecticide had a significantly higher number of DBM larvae and fewer predators (although not significant in all cases), but the number of CL larvae was not significantly different. Parasitoids did not emerge from field-collected DBM larvae reared in the laboratory. Yield and value of marketable cabbage were highest in the resistant variety plus B. thuringiensis treatment. In contrast, the standard variety treated with a pyrethroid insecticide had the lowest marketable yield and value and the highest loss of marketable yield. lntercropping was not reliable in controlling DBM, but an economic justification for planting the companion crop was demonstrated. These results provide evidence that host plant resistance complemented by B. thuringiensis are suitable components in an IPM programme for CL and DBM management in Jamaica.
