Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 18, 2005
Publication Date: August 7, 2005
Citation: Ugine, T.A., Wraight, S.P., Sanderson, J.P. 2005. Host plant determines efficacy of beauveria bassiana against western flower thrips. Society for Invertebrate Pathology Annual Meeting Proceedings. 38:100.
Multi-trophic interactions among the host plant, insect pest and insect pathogenic fungi are among the most important yet poorly understood biotic determinants of efficacy. Dosage-response assays evaluated the effects of rearing host plant and assay host plant, kidney bean versus garden impatiens in each instance, on efficacy of Beauveria bassiana strain GHA against the western flower thrips. Insects reared on the two host plants were exposed continuously to fungus-inoculated bean or impatiens leaf disks, and percent mortality was assessed after five days. Thrips maintained on bean foliage were 7–40 times more susceptible to B. bassiana than thrips maintained on impatiens foliage. The slopes of the probit regression lines were significantly higher for thrips maintained on beans compared to impatiens irrespective of the rearing host plant (slopes of 1.6 and 1.4 on beans versus 0.8 and 0.6 on impatiens). Additional assays were conducted to determine effects of exposure host plant and length of exposure to bean and impatiens foliage on fungal efficacy. Thrips were exposed to B. bassiana-inoculated bean or impatiens foliage and reciprocal transfers to the alternative host were made at three time intervals, 12, 24, and 48 h. Percent mortality was assessed after 5 days. There was a significant 15% reduction in percent mortality of thrips exposed to fungus on impatiens foliage, but no effect of exposure time.