Submitted to: Proceedings of Workshop on Global Int Org Biocontrol (IOBC) Working Group
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 1997
Publication Date: N/A
Adult cabbage root flies were exposed to dry conidia of Beauveria bassiana, Metarhizium anisopliae or Paecilomyces fumosoroseus. Flies were exposed to the fungi by placing 5 flies in a centrifuge tube containing conidia scraped directly from culture plates, then released into small screened plastic cages. Mortality was assessed after 48, 120 and 160h. Dead flies were incubated to confirm infection by identifying fungal sporulation on the cadaver. Isolate P89 (B. bassiana) caused mortality in the most flies after 48h. It was also the only isolate that gave 100% mortality and 100% infection. Isolate L90 (B. bassiana) & one M. anisopliae isolate also caused fatal infection in more than 50% of the flies. In further experi- ments comparing the commercial B. bassiana product Mycotrol (Mycotech Corp) to isolate P89, both gave 100% mortality in adult flies. The commercial product was chosen for autodissemination studies as it was readily avail- able. Newly emerged flies were exposed to a dry powder formulation contain ing B. bassian by placing the flies in a small container with Mycotrol on the bottom. The flies were removed to small screened cages containing un- treated flies. When the flies died, they were incubated to confirm sporul- ation of the fungus. This experiment confirmed the ability of flies to pass inoculum to other flies. In a similar experiment, one treated fly was placed in each cage with one untreated fly. When each fly died, 1 untreated fly was added to each cage after the dead fly was removed. This study showed that fly to fly transfer of fatal doses of inoculum was possible for a chain of at least six flies, beginning with 1 treated fly. Further studies are being conducted to develop a system where flies attracted to a trap will be inoculated with the fungus & spread it to a field population.