The effect of alkane-growth induction of the entomopathogenic fungus Beauveria bassiana on the ability to kill the bean weevil Acanthoscelides obtectus was tested. Adult insects were sprayed with an 0.01% Tween 20 aqueous suspension of 4 x 106 conidia/ml. The performance of fungi grown in complete agar medium containg glucose as carbon source (FS0) was compared to that of alkane-grown fungi (FS1). Mortality increased (p <0.05) from 22 ± 4.5% to 44 ± 11.4% at day 7, and from 26 ± 5.5% to 60 ± 7.1% 14 days after treatment with FS0 or FS1 respectively. The insect hydrocarbons were analysed by capillary gas chromatography (CGC), major components were saturated hydrocarbons, 27 to 29 carbons length. Oleic, linoleic and palmitic acids accounted for almost 88% of the fungal fatty acids. These results indicate that alkane supplementation of culture media might be a tool to improve the virulence of some mycoinsecticides.