title: Characterization of Biocontrol Traits in Heterorhabditis floridensis: A Species with Broad Temperature Tolerance.
abstract: Biological characteristics of two strains of the entomopathogenic nematode, Heterorhabditis floridensis (332 isolated in Florida and K22 isolated in Georgia) were described. The identity of the nematode's symbiotic bacteria was elucidated and found to be Photorhabdus luminescens subsp. luminescens. Beneficial traits pertinent to biocontrol (environmental tolerance and virulence) were characterized. The range of temperature tolerance in the H. floridensis strains was broad and showed a high level of heat tolerance. The H. floridensis strains caused higher mortality or infection in G. mellonella at 30°C and 35°C compared with S. riobrave (355), a strain widely known to be heat tolerant, and the H. floridensis strains were also capable of infecting at 17°C whereas S. riobrave (355) was not. However, at higher temperatures (37°C and 39°C), though H. floridensis readily infected G. mellonella, S. riobrave strains caused higher levels of mortality. Desiccation tolerance in H. floridensis was similar to Heterorhabditis indica (Hom1) and S. riobrave (355) and superior to S. feltiae (SN). H. bacteriophora (Oswego) and S. carpocapsae (All) exhibited higher desiccation tolerance than the H. floridensis strains. The virulence of H. floridensis to four insect pests (Aethina tumida, Conotrachelus nenuphar, Diaprepes abbreviatus, and Tenebrio molitor) was determined relative to seven other nematodes: H. bacteriophora (Oswego), H. indica (Hom1), S. carpocapsae (All), S. feltiae (SN), S. glaseri (4-8 and Vs strains), and S. riobrave (355). Virulence to A. tumida was similar among the H. floridensis strains and other nematodes except S. glaseri (Vs), S. feltiae, and S. riobrave failed to cause higher mortality than the control. Only H. bacteriophora, H. indica, S. feltiae, S. riobrave, and S. glaseri (4-8) caused higher mortality than the control in C. nenuphar. All nematodes were pathogenic to D. abbreviatus though S. glaseri (4-8) and S. riobrave (355) were the most virulent. S. carpocapsae was the most virulent to T. molitor. In summary, the H. floridensis strains possess a wide niche breadth in temperature tolerance and have virulence and desiccation levels that are similar to a number of other entomopathogenic nematodes. The strains may be useful for biocontrol purposes in environments where temperature extremes occur within short durations.
authors.affiliation: USDA-ARS, Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008.
authors.forename: David I
authors.initials: DI
authors.lastname: Shapiro-Ilan
authors.affiliation: Department of Biology and Evolutionary Ecology Laboratories, Brigham Young University, Provo, UT.
authors.forename: Dana
authors.initials: D
authors.lastname: Blackburn
authors.affiliation: Entomology and Nematology Department, University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL.
authors.forename: Larry
authors.initials: L
authors.lastname: Duncan
authors.affiliation: Entomology and Nematology Department, University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL. ; Plant Protection Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
authors.forename: Fahiem E
authors.initials: FE
authors.lastname: El-Borai
authors.affiliation: Entomology and Nematology Department, University of Florida, Gainesville, FL.
authors.forename: Heather
authors.initials: H
authors.lastname: Koppenhöfer
authors.affiliation: INRA, Diversité, Génomes & Interactions Micro-organismes-Insectes, Montpellier, France. ; Université Montpellier 2, Diversité, Génomes & Interactions Micro-organismes-Insectes, Montpellier, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tailliez
authors.affiliation: Department of Biology and Evolutionary Ecology Laboratories, Brigham Young University, Provo, UT.
authors.forename: Byron J
authors.initials: BJ
authors.lastname: Adams
keywords: Heterorhabditis floridensis; beneficial trait; biological control; entomopathogenic nematode