Treesearch

Field research since 1978 using different formulations, dosages, and spray volumes of Bacillus thuringiensis Berliner (Bt) against the gypsy moth are reviewed. Problems associated with inconsistent results are discussed, with an emphasis on timing of application. Recommendations for proper use of Bt are presented along with suggestions for further studies on the use of Gypchek and development of better spray technology for both Bt and Gypchek.

The increased use of B. thuringiensis as an alternative to chemical insecticides has stimulated the search for more potent strains. Presently over 1100 strains have been isolated from worldwide sources. Some of these appear to be more effective than the commercially developed HD-1 strain against both the gypsy moth and spruce budworm. One strain in particular, when prepared as a standardized formulation was more effective than HD-1 against the eastern spruce budworm when compared under laboratory and field operational conditions. Laboratory bioassay data also indicates that against gypsy...

Screening of 402 strains of more than 18 varieties of Bacillus thuringiensis showed chitinase to be inducible in virtually every serovar tested. Though the chitinase titre varied among strains, there was a strong correlation between enhanced lethality to spruce budworm, Choristoneura fumiferana (Clemens), and an increase in chitinase titre within the serovar. Strains grown in chitinase inducing medium gave a more rapid and higher kill than those grown in sporulation medium, and a faster kill than the currently used commercial strain.

Recent advances in genetics and molecular biology make possible the cloning and genetic manipulation of genes for insecticidal activities from natural insect pathogens. Using recombinant DNA methods and site-directed mutagenesis of specific gene regions, production of new and improved biorationals should be possible.

Biochem Products is part of a large industrial and scientific family - the Solvay Group. Solvay, headquartered in Brussels, Belgium is a multinational company with 46,000 employees worldwide. In the U.S., our working partners include a large polymer manufacturer, a peroxygen producer and a leading poultry and animal health products company. Biochem Products is a division of the latter - Salsbury Laboratories, Inc. Biochem Products in the U.S. was started in 1979. It is committed to research, development and marketing of microbial products for insect pest management. Our first product was...

Reuter Laboratories announces additions to its line of microbial insecticides with the 1984-85 introduction of a Bacillus thuringiensis, Berliner, variety Kurstaki (HD-1, H-3A3B) wettable powder formulation. Gypsy moth nucleopolyhedrosis virus, in experimental production since 1982, is scheduled for commercial introduction as a wettable powder in the 1985-86 season.

The parasite Cotesia melanoscelus attacks small gypsy moth larvae more successfully than large ones, and Bacillus thuringiensis retards the growth of caterpillars it does not kill. Together, both factors lead to higher parasitism by C. melanoscelus in areas sprayed with B. thuringiensis than elsewhere.

The development of the gypsy moth nucleopolyhedrosis virus product Gypchek, and strategies for its use, have been largely patterned after conventional pesticide technology. Prior to Gypchek registration with the Environmental Protection Agency in 1978, several field tests involving variations in virus product, application hardware, dose rates, timing and formulation were conducted. Further tests since 1978 have been promising, but nonconclusive, and 6 years after registration, Gypchek is not in commercial production. It is clear that if this product is to be seriously considered as either...

Recent testing in the eastern U. S. has led quickly to the adoption of 12 BIU/acre as the best operational dosage rate, with operational spray emission rates reduced to a quart or less per acre. Some recent work suggests that older larval instars of the budworm are highly susceptible to B.t. sprays, and the effective "spray window" can be broadened when budworm populations are moderate. New studies on second-year benefits of B.t. treatments are producing negative results.

Field tests were conducted in 1980, 1981, and 1982 with a new Bacillus thuringiensis formula called Futura. Tests were conducted with a Grumman AgCat aircraft on 40 ha forest blocks and with a DC-4G aircraft on larger forested areas. Futura which is able to disperse the required 20 x 109 I.U./ha for spruce budworm control in 2.5 L/ha proved to be physically and bacteriologically stable and easy to mix. Also it assured a deposit of up to 80% emitted volume, a larval mortality in the range of 70 to 90%, and a foliage protection of about 70%. Because of its low-volume dispersion property and...