Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2003
Publication Date: 8/15/2003
Citation: UGINE, T.A., WRAIGHT, S.P., SANDERSON, J.P. THE EFFECT OF CHANGING APPLICATION RATE, VOLUME, AND INTERVAL ON ACQUISITION OF BEAUVERIA BASSIANA CONIDIA BY WESTERN FLOWER THRIPS AND RESULTING CONTROL IN GARDEN IMPATIENS. PROCEEDINGS OF THE ANNUAL MEETING OF THE SOCIETY FOR INVERTEBRATE PATHOLOGY. 2003. v. 36. p. 35.
Technical Abstract: The western flower thrips (WFT), Frankliniella occidentalis, causes significant economic losses to many greenhouse crops via feeding damage and virus transmission. Its ability to rapidly develop resistance to insecticides and its high level of susceptibility to Beauveria bassiana (strain GHA) in the laboratory (LD50s for adult female and second-instar nymphs of 5 and 47 conidia/insect, respectively) make this pest a promising candidate for microbial control. A greenhouse crop of garden impatiens infested with WFT was sprayed with 1lb/100 gal/acre of the B. bassiana-based biopesticide BotaniGard 22WP once a week for three weeks. This protocol did not result in adequate control of the population. In an attempt to improve efficacy of the product, a series of independent experiments were conducted which varied three spray parameters: application interval, application rate and application volume. Applications of BotaniGard were made (1) at a rate of 1 lb/100 gal/acre at spray intervals of 3, 5 and 7 days, (2) at application rates of 1, 2, 4 and 6 lb/100 gal/10,000 square feet, and (3) at a rate of 1 lb/10,000 square feet in volumes of 25, 50, and 100 gal. Application rate and volume treatments were applied weekly for three weeks. Samples of pollen- bearing impatiens flowers were taken twice weekly to estimate thrips population density, and adult female and second-instar thrips were collected 24 h post-inoculation for determination of dose (conidia/insect). Increasing application interval and volume resulted in slight reductions in the rate of population growth, but varying spray parameters did not lead to significant levels of control in any of the experiments. Conidia/insect increased linearly with increasing application interval and volume. Unexpectedly, however, the number of conidia/insect was not affected by application rate.