Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/18/2000
Publication Date: 8/13/2000
Citation: JARONSKI, S., JARONSKI, S.T., REX, T., LUTZ, R. SCREENING DEUTEROMYCETE FUNGI FOR THE CONTROL OF LARVAL FLEAS (SIPHONAPTHERA). PROCEEDINGS OF THE ANNUAL MTG OF THE SOCIETY FOR INVERTEBRATE PATHOLOGY. 2000. Interpretive Summary:
Technical Abstract: Deuteromycete fungi from larval flea habitats and culture collections were screened for commercial potential as biocontrols of larval dog and cat fleas.Isolates were primarily Beauveria bassiana, but Metarhizium anisop- liae, Paecilomyces farinosus, and P. lilacinus were also represented. All fungi were first passed through and reisolated from larval fleas. Ninety- one isolates were evaluated in terms of spore production in a bench-scale version of Mycotech Corporation's solid substrate production system. Spore production ranged from 1x1011 to 2.25x1013 conidia / Kg substrate under i- dentical fermentation conditions. All isolates were also assessed in a two tier bioassay, in comparison with Mycotech's Strain GHA. The bioassay con- sisted of exposing flea larvae to fungal conidia incorporated into Heska's proprietary larval flea medium. Mortality was assessed after 10 days. The first tier consisted of two doses,5x107 & 4x108 conidia/gram larval sub- strate, which approximately represented the LC10 & LC50 of strain GHA. Eac isolate was bioassayed at least twice. The best 10 isolates, based on their spore production and virulence, were further bioassayed three times using five does straddling the LC50 of each isolate. The LC50's of these 10 is- olates ranged from 4.5x107 to 1.9x108 conidia per gram of medium. A subset of 24 isolates, representing satisfactory spore production and virulence were also evaluated for shelf life of unformulated conidial powders in plastic vials held at 30, 35, and 40C. Half-lives of these isolates ranged from 23 to >500 days at 30 C. 15-246 days at 35C & 7-164 days at 40C. Two soil-derived B. Bassiana, SC19 & SA8, were identified as potential commer- cial condidates based on a combination of virulence, spore production, and shelf life.