TOXICITY OF PURIFIED FUNGAL TOXIN HIRSUTELLIN-A TO THE CITRUS RUST MITE PHYLLOCOPTRUTA-OLEIVORA (ASH.)

A toxic protein, hirsutellin A, isolated from culture filtrate during liquid fermentation of the fungal mycelia of Hirsutella thompsonii, wa s tested using contact/residual and residual leaf bioassay methodologi es at concentrations of 0, 10, 32, 56, and 100 mu g/ml against adult c itrus rust mite, Phyllocoptruta oleivora. P. oleivora is the natural h ost of the parasitic fungus, H. thompsonii. Mite mortality increased w ith an increase in hirsutellin A concentration, reaching virtually 100 % at 100 mu g/ml using both leaf assay methods. The number of eggs fou nd on leaf disk bioassays within a 3-day period decreased significantl y with an increase in hirsutellin A concentration, suggesting that fec undity was affected prior to the death of the host. (C) 1998 Academic Press.