Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 17, 2004
Publication Date: August 1, 2004
Citation: Filotas, M.J., Wraight, S.P., Sanderson, J.P. 2004. Selection of entomopathogenic fungi for microbial control of aphid pests in US greenhouses. Society for Invertebrate Pathology Annual Meeting Proceedings. 37:97.
Although numerous studies have screened fungi against aphids, most have targeted the adult stage of a single pest species. We have found that adults are a poor target because, although adult aphids are highly susceptible to most fungal strains, reproduction is not sufficiently reduced prior to death to provide effective control. Screening assays against aphids may thus be better aimed at identifying isolates effective at killing nymphal stages. We assessed the efficacy of a number of fungal isolates against the green peach aphid, Myzus persicae, and the melon aphid, Aphis gossypii, the two most common aphid pests of US greenhouse crops. As an initial screen, one-day-old first-instar M. persicae and A. gossypii were exposed to spray applications of a single dose (ca. 1000 spores/mm2) of 48 isolates of three Hyphomycete fungi (20 B. bassiana, 19 Metarhizium anisopliae and nine Paecilomyces fumosoroseus). Resulting mortalities ranged from 0.4 + 0.2 to 61.6 + 6.3 % for M. persicae and 1.3 + 1.2 to 56.9 + 10.3 % for A. gossypii. While both species of aphids were equally susceptible to B. bassiana, A. gossypii tended to be more susceptible to M. anisopliae and P. fumosoroseus. However, nymphal stages were generally not highly susceptible to most isolates, with less than 25% mortality of test insects observed for 38 of 48 isolates. This was likely due to loss of fungal spores via frequent molting of these rapidly developing insects. Nevertheless, we were able to identify some isolates that were effective against both aphid species. Five of these (two B. bassiana, two M. anisopliae and one P. fumosoroseus), as well as the Beauveria products Naturalis and BotaniGard and a commercially registered strain (F52) of M. anisopliae were selected for further study.