EFFECTIVENESS OF STEINERNEMA SPP AND HETERORHABDITIS-BACTERIOPHORA AGAINST POPILLIA-JAPONICA IN THE AZORES

Steinernema carpocapsae (Breton strain), S. glaseri, and Heterorhabdit is bacteriophora were evaluated for their potential to control immatur e stages of the Japanese beetle, Popillia japonica, on Terceira Island (the Azores). In bioassays carried out at temperatures higher than 15 C, S. glaseri and H. bacteriophora caused 100% mortality of larvae, w hereas S. carpocapsae caused 56% larval mortality. At temperatures sli ghtly below 15 C, only S. glaseri remained effective. In field plots, in September, S. glaseri and S. carpocapsae reduced larval populations by 91% and 44%, respectively, when applied at the rate of 10(6) nemat odes/m2. In April, S. glaseri caused 31% reduction in numbers of larva e, but S. carpocapsae was ineffective. In colder months (November-Febr uary) neither steinernematids nor H. bacteriophora reduced larval popu lations. Increasing the application rate from 10(6) to 5 x 10(6) infec tive stage S. glaseri per m2 increased efficacy from 63% to 79% mortal ity.