Submitted to: Florida Entomologist
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/30/2004
Publication Date: 6/1/2004
Citation: Kanga, L.H., Jones, W.A., Humber, R.A., Boyd, Jr., D.W. 2004. Fungal pathogens of the glassy-winged sharpshooter, Homalodisca coagulata (Say) (Homoptera: Cicadellidae). Florida Entomologist. 87:225-228. Interpretive Summary: The glassy-winged sharpshooter,an efficient vector of Pierce's disease in grapes, is native to the southeastern United States, but is now established in California. Chemical control with pyrethroids and neonicotinoids looks promising against immatures and adults, but it is associated with residue contamination and interferes with biological control strategies. Currently, biological control strategies focus on releases of several egg parasites. Nothing is known about insect pathogens that may attack the sharpshooter. We examined specimens of several populations of the glassy-winged sharpshooter from an epizootic found in 2002 in Poplarville, Mississippi. We found that the main pathogen of the disease is Pseudogibellula formicarum (Mains) Samson & Evans. We found that the fungus caused 93% mortality 21 days after spraying treatments. We also found that another fungal pathogen, Metarhizium anisopliae, infected 75% of it on sharpshooters by the end of 21 days. Overall, P. formicarum and another fungal pathogen, Metarhyzium anisopliae could be useful components in an integrated pest management strategy for the glassy-winged sharpshooter.
Technical Abstract: Fungal diseases on glassy-winged sharpshooter, Homalodisca coagulata (Say) were investigated in the fall of 2002 in Mississippi. Trichothecium roseum and Beauveria bassiana were identified from the cadavers of the sharpshooter bearing conidiophores, but these fungii appeared to be either secondary pathogens or saprobes rather than primary pathogens of the sharpshooter. Pseudogibellula formicarum seems to be the main cause of epizootic of diseases. In the laboratory bioassays, 93% of the sharpshooters were infected with the fungus (at the concentration of 2 x 10 9) spores ml -1), 21 days after the treatments were initiated. However, additional studies are needed to provide a better understanding of host-pathogen interactions, and identify the factors that enhance or limit disease increase in sharpshooter populations under natural conditions. In addition, the sharpshooter was also found to be a suitable host for Metarhizium anisopliae and the fungus (2 x 10 8 spores ml-1) caused 75% infection at the end of the 21-day experimental period. Overall, P. formicarum and M. anisopliae could provide new avenues for the biological control of the glassy-winged sharpshooter and complement current control strategies.