Investigation of hybrid Freeman maple resistance to Chrysobothris flatheaded borers (Coleoptera: Buprestidae)

Authors: POUDEL, ASMITA - Tennessee State University

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2024
Publication Date: N/A
Citation: N/A
DOI: https://doi.org/10.1093/ee/nvae079

Interpretive Summary: Imported fire ants are a major problem in agriculture and landscapes in the southeastern United States. Multiple pathogens have been identified in red imported fire ants (in native and introduced ranges, but diseases infecting black imported fire ants or hybrid ants are less studied. Pathogens can reduce colony growth and survival, thereby bringing populations back into balance with the environment. The objective of this work was to determine the distribution and seasonality of different diseases of fire ants in Tennessee, where hybrid ants are dominant. Across the state of Tennessee, 74.1% of ant colonies were hybrid, 25.3% black, and 0.6% red. With over 500 colonies tested, prevalence of disease or parasite infection was 4.2% (SINV-1), 1.3% (K. solenopsae), 0.9% (SINV-3), 0.1% (SINV-2), and 0.1% (Pseudacteon). Parasite prevalence in Tennessee hybrid ants was very low compared to red ant populations further south. The low infection rate may limit the impact of diseases on fire ant populations at the northern border of their range.

Technical Abstract: Multiple pathogens have been identified in red imported fire ants (Solenopsis invicta Buren) in native and introduced ranges, but pathogens infecting black (Solenopsis richteri Forel) or S. invicta × S. richteri hybrids are less studied. Pathogens like Kneallhazia solenopsae (Knell, Allen & Hazard) and Solenopsis invicta virus 3 (SINV-3) negatively impact colony growth and survival and offer augmentative biocontrol potential. The objective of this work was to determine the geography and phenology of K. solenopsae, SINV-1, SINV-2, and SINV-3 pathogens within the Tennessee hybrid-dominated populations. During 2015'2016, 62 fire ant-infested counties were gridded (12.1-by-12.1 km), and one colony sampled per grid in warm (July to October) and cool (January to April) periods. Species were determined by cuticular hydrocarbon and venom alkaloid analysis. Samples were evaluated for pathogen and parasite infection and social form by molecular analysis. Ant species frequencies were hybrid (74.1%), black (25.3%), and red (0.6%). Infection rates were low (9.5% and 1.3% in warm and cool periods, respectively). Parasite prevalence was 4.2% (SINV-1), 1.3% (K. solenopsae), 0.9% (SINV-3), 0.1% (SINV-2), and 0.1% (Pseudacteon). Hybrid colony infection rates were higher (82.2%) than black and red (17.8%) colonies. Polygyne colonies were infrequent (n=6) but were more frequently infected (66.7%) than monogyne (11.8%). The most widely distributed pathogen was SINV-1. Higher elevations may negatively influence SINV-1 range expansion. Higher hybridity values (i.e., more red-like) had increased likelihood of virus, but not Kneallhazia infection. Parasite prevalence was low in Tennessee hybrid-dominated monogyne populations, which may limit their impact on fire ant populations.