|DIEZ IBANEZ, M|
Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2003
Publication Date: 7/26/2003
Citation: Fargues, J., Smits, N., Vidal, C., Meikle, W.G., Mercadier, G., Vega, F., Quimby, P.C., Durand, A., Diez Ibanez, M., Issaly, N. 2003. Influence of submerged cultivation additives and formulation ingredients on the tolerance of blastospores of metarhizium anisopliae var. acridum to thermic stress under fluctuating regime. Society for Invertebrate Pathology Annual Meeting.
Technical Abstract: Because of severe climate conditions prevailing in areas targeted for locust control, influence of both fungus fermentation and propagule formulation was studied as a means ofr assessing blastospore quality of Metarhizium anisopliae var. acridum (isolate IMI 330189 kindly provide to Virginia Tech* by CABI Biosciences). Quality evaluation consisted of exposing stabilized propagules to daily fluctuating temperature at 13-43°C under humidity conditions regulated at 13% RH and testing viability through colony growth assays (CFU counts). The survival of Stabilize**-formulated blastospores originated from Jackson media with increasing C/N ratios (10-50) showed a significantly better tolerance to thermic stress of propagules formed in lower C/N ratio conditions. Attempts for optimizing Stabilize**-formulated propagule quality in adding ingredients during the liquid cultivation (at 96h) in Jackson medium demonstrated clearly a negative effect of glycerol alone or in combination with sucrose, Tween and corn oil. The relative loss of viability of blastospores produced with Jackson medium added with Tween and sucrose was similar, over a period of 60-day exposure, to that of blastopores produced in Jackson medium without additives. Formulation assays showed that drying temperature during the dehydration phase of fresh bastospores is a key factor for improving the robustness of dried inocula. Sucrose was tested as additive ingredient in submerged culture as 'sugar shock' according to the Stareze*** process, and as formulation ingredient during the harvesting phase of fresh fungal biomass added with hydrated silica (HiSil). In both cases, the addition of sugar did not increase the survival of dried blastospores exposed to temperature stress. Effect of talc, hydrated silica and Kraft lignin (according to a VT- improved procedure) showed a rapid decay of talc-formulated blastospores in contrast with the favorable effect of the two other formulation ingredients.