Journal of Economic Entomology (1998) 91, 86-93
P. Tamez-Guerra, R. Castro-Franco, H. Medrano-Roldán, M.R. McGuire, L.J. Galán-Wong and H.A. Luna-Olvera (1998)
Laboratory and field comparison of strains of Bacillus thuringiensis for activity against noctuid larvae using granular formulations (Lepidoptera)
Journal of Economic Entomology 91 (1), 86-93
Abstract: The toxicity of 6 strains of Bacillus thuringiensis representing 4 serovars, aizawai, galleriae, kurstaki, and kumamotoensis, were evaluated in laboratory and field studies for activity against 3 lepidopteran crop pests, Heliothis virescens (F.), Spodoptera exigua (Hübner), and Trichoplusia ni (Hübner). Results of laboratory tests showed that some B. thuringiensis strains isolated from Mexico (GM-7 and GM-10), were sufficiently toxic to warrant further investigation as potential bioinsecticides for lepidopteran control. Nixtamalized corn flour was used to create a B. thuringiensis granule formulation that remained toxic for at least 2 yr. Field tests were conducted in 1994 and 1995 on corn plots in a semiarid region in central Mexico. Granular formulations were made with 2% (wt:wt) or 4% (wt:wt) of a spore-crystal B. thuringiensis concentrate and tested with carbaryl and Dipel 2X. In 1994, the corn yields obtained from plots treated with 2 strains from the Howard Dulmage collection (HD-187 and HD-193-kurstaki and galleriae, respectively) and 1 Mexican strain (GM-10, aizawai) at 2% were significantly higher than from plots treated with Dipel2X or the untreated control. Formulations of 4% containing strains GM-7, GM-10, HD-187, HD-193, and HD-263 provided better insect control than formulations made with C-4. These tests indicated that B. thuringiensis survived in the nixtamalized flour matrix complex and was effective in causing pest reduction. In the 1995 field test, the 3 most toxic strains were evaluated individually or by mixing 2 in the same granular formulation at a total dose of 3%. The highest yields of corn were obtained from plots treated with strain HD-263 (kurstaki), which had originally shown the highest efficacy in laboratory bioassays, and with strain GM-10 (aizawai), formulated 2 yr earlier. These data suggest that the product can be produced and retain shelf life suitable for commercialization.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Patricia Tamez-Guerra, Michael R. McGuire
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
evaluation - screening - selection
