Evaluating entomopathogenic fungus-based products against the citrus red mite, Panonychus citri (Acari: Tetranychidae), with a novel leaf-disk bioassay

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Presenting Author(s)

Emily B. Duren

Laboratory technician I
University of Florida
Fort Pierce, Florida

Co-Author(s)

Emilie P. Demard

PhD Candidate
University of Florida
Winter Haven, Florida
PA

Pasco B. Avery

University of Florida
Fort Pierce, Florida
JQ

Jawwad A. Qureshi

Associate Professor
University of Florida
Immokalee, Florida
RC

Ronald Cave

University of Florida
Fort Pierce, Florida

use of entomopathogenic fungus (EPF)-based products is an environmentally friendly pest management strategy for pests that have become resistant to chemical insecticide applications including mites. This experiment determined which EPF-based product was most efficacious against a pest of Florida citrus, the citrus red mite, Panonychus citri, under laboratory conditions. EPF-based products were evaluated against the mites using a novel bioassay apparatus. Bioassays consisted of a cell culture well plate with solidified water agar (1 ml) in specific wells with a treated leaf disk placed on top of the agar. Treated disks were sprayed with 10⁶ spores/ml of Cordyceps javanica from PFR-97 20% WDG and NoFly WP, Beauveria bassiana from Velifer ES and Botanigard MAXX ES, or water only (control) and allowed to air dry. One female citrus red mite was carefully placed on each disk per well. Mites were monitored daily until death. Dead mites were removed, placed into a separate moisture Petri dish chamber, and transferred to a growth chamber (25⁰C, 14-hour photophase) until mycosis occurred. All EPF-based products were more efficacious in killing the mites compared to controls. Median survival time for 50% (ST₅₀) of mites exposed to Velifer, PFR-97, and NoFly was ~4 days. BotaniGard MAXX, containing the strain B. bassiana, induced 90% mycosis with a ST₅₀ of ~2 days. Mycosis in mites exposed to EPF-based products was ≥-60%; no mycosis occurred in the control. BotaniGard MAXX provided the highest mortality and percentage mycosis of all EPF-based products tested.