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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Subtropical Insects and Horticulture Research » Research » Publications at this Location » Publication #173503
Title: EFFECT OF BEAUVERIA BASSIANA ON LOBATE LAC SCALE INFESTING ORNAMENTALS

Author
item McKenzie, Cindy
item MANNION, CATHARINE - UNIV OF FLORIDA, TREC

Submitted to: Arthropod Management Tests
Publication Type: Other
Publication Acceptance Date: 4/1/2005
Publication Date: 10/1/2005
Citation: McKenzie, C.L., Mannion, C. 2005. Effect of Beauveria bassiana on Lobate lac scale infesting ornamentals,2004. Arthropod Management Tests 30: G43 2 pp. htty:www.entsoc.org/protected/AMT/AMT30/AMT30.aspx?Report=G43.htm (report).

Interpretive Summary: BotaniGard® ES mycoinsecticide (Beauveria bassiana) was evaluated for efficacy against lobate lac scale on two susceptible ornamental hosts, southern wax myrtle and co-co plum. Mortality in the untreated control plants increased during the trial period for both life stages and host plants evaluated. Percent mortality in the BotaniGard® ES treatments were corrected according to the Henderson-Tilton formula and mortality did increase overtime for both life stages and host plants evaluated. However, no sporolation of Beauvaria bassiana entomopathogenic fungi was observed during the trial. The BotaniGard® ES formulation does contain petroleum distillates in the inert ingredients which may have contributed to lobate lac scale mortality, but further testing needs to be conducted.

Technical Abstract: BotaniGard® ES mycoinsecticide (Beauveria bassiana) was evaluated for efficacy against lobate lac scale on two susceptible ornamental hosts, southern wax myrtle and co-co plum. Lobate lac scale were field collected from multiple sites and various host plants across south Florida by cutting infested twigs into 8-10' length segments for easy storage in emergence containers. Twigs were held and monitored for crawler emergence. When crawlers were noted, twigs were divided into 2' lengths and placed at the base of each test plant so that crawlers would independently transfer and settle on the test plant naturally for mycoinsecticide evaluations. Speedling trays of southern wax myrtle and co-co plum were obtained from a local nursery and examined for contamination (pest or disease). Clean transplant cells were broken up into single plants and planted into Ray Leach 'Cone-tainer' single cell systems. Cone-tainers were placed in half racks so that the rack could be placed in a water holding tub. All plants received the same water and fertilizer amounts at the same time by filling up the holding tub above the bottom of the cone tubes. Water was siphoned from the holding tub after watering (~2-3 hrs), but kept to a 1' inch level remaining in the tub to insure humidity was kept at an acceptable level for proliferation of LLS. Soil and nutritional requirements were satisfied by standard ProMix Bx potting medium and fertilized weekly with Peter's Professional General Purpose FLA Special 20-10-20. Two age groups of lobate lac scale were evaluated on each of the ornamental hosts. Large lobate lac scales were seeded between 9 Mar and 3 May and small lobate lac scales were seeded between 21 June and 9 July. BotaniGard® ES mycoinsecticide was applied according to the label as a rooted cutting dip at the recommended high rate (1 oz per gallon water) and compared to an untreated control (dipped in water only) using the cone-tainer plants. Test plants were kept in environmental growth chambers at 27º C, 12:12 L: D photoperiod and relative humidity of ~50%. Applications were made on 14 and 25 Oct. Plants infested with LLS were counted pretreatment under a microscope and mortality was assessed at 4, 7 and 10 d after the first application and 4, 7, 14, and 21 d after the second application. No phytotoxic effect was noted for any of the treatments and data were subjected to GLM and means separated with Ryan-Einot-Gabriel-Welsch multiple range test (P = 0.05). Mortality in the untreated control plants increased during the trial period for both life stages and host plants evaluated. Percent mortality in the BotaniGard® ES treatments were corrected according to the Henderson-Tilton formula and mortality did increase overtime for both life stages and host plants evaluated. However, no sporolation of Beauvaria bassiana entomopathogenic fungi was observed during the trial. The BotaniGard® ES formulation does contain petroleum distillates in the inert ingredients which may have contributed to lobate lac scale mortality, but further testing needs to be conducted.