Use of almond mesocarp for production of the entomopathogenic fungus Verticillium lecanii

Almond mesocarp (AM) has been evaluated for production of Verticillium leca nii. Microbial flora of AM has been studied. After ground AM dilution plati ng, 5.3 x 10(5) +/- 2.6 x 10(4) fungal CFU.g(-1) of dry AM were found. Comm on fungal saprophytes (Rhizopus sp. and Alternaria spp.) were found in more than 80% of the samples. Aspergillus sp. and yeasts were found less common ly Rhizopus sp., Alternaria spp., and Aspergillus sp. inhibited growth of s everal V. lecanii; therefore, AN was treated with sterilization agents to e liminate endogenous mycoflora. Small samples (10 g) of AM saturated in dist illed water treated with steam (120 degrees C and 100 kPa) were completely sterilized after 15 min. Ground AM incorporated on agar increased the bioma ss of V. lecanii compared with controls. This suggested AM as suitable subs trate for the production of the fungus. In petri dishes, 9.7 x 10(7) +/- 2. 9 x 10(7) conidia.g(-1) of dry AM were produced after inoculating 10 conidi a.g(-1) of AM and incubating for 2 weeks. Viability of conidia produced was more than 90%. These conidia (5 x 10(4) conidia per larvae) caused Galleri a mellonella mortality, calculated as median lethal time (LT50 5.3 +/- 1.6 days), that was significantly higher (F = 10.93; P < 0.05) than untreated c ontrols (LT50 11.3 +/- 1.1 days). Larger scale tests have to be optimized b efore mass production.