Location: Imported Fire Ant and Household Insects Research
Project Number: 6036-32000-051-021-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Jan 15, 2022
End Date: Mar 31, 2024
Objective:
To improve the integrated pest management (IPM) of fire ants in the Coachella Valley of California by extending red imported fire ant (RIFA) control by conserving non-target ants. Maintaining populations of non-RIFA ants should provide biotic resistance to RIFA reinfestation in areas cleared of fire ants. Specific aims are to determine which fire ant baits are not foraged upon by non-RIFA ant species found in the Coachella Valley. While it is known that non-oil feeding ants do not forage fire ant baits, it is hypothesized that some oil-feeding ants in the Coachella Valley will not feed on certain fire ant baits, perhaps due to the repellency of the active ingredient. Understanding the ant species specificity of fire ant baits can inform the development of RIFA baiting strategies that will support the long-term suppression of RIFA, by conserving native and other ant species in treated areas.
Approach:
Year 1) Bait acceptance testing will initially be conducted in Florida to screen commercial fire ant baits on oil-feeding ants (often ants in the subfamily Myrmicinae which includes RIFA). It is anticipated that ant species tested in Florida will be indicators of bait specificity applicable to ants in the Coachella Valley. Tests will be conducted on Myrmicine ants maintained in ARS-CMAVE laboratory colonies (e,g, bicolor trailing ant, Pharaoh ant) and on field populations that are found in urban habitats such as turfgrass and ornamental plantings, gardens, and wooded lots. If necessary, pastures and unmanaged fields will be surveyed to locate populations of oil-feeding ant species. Surveys to find non-RIFA ant include a) visual searches for potential nest sites and ant trailing; and b) survey with transects of food lures in favorable habitats.
Species of ants to be tested will generally not be listed on the bait product label, however some listed species may be indicators of bait specificity. Species to be tested in the field will be oil-feeders and are anticipated to be species in the genera Pheidole (bigheaded ants), Pogonomyrmex (harvester ants), and perhaps Solenopsis (thief ants) which have species within the same genera in southern California. Bait acceptance tests will use methods adapted from Williams & Vail (1993) and Williams and Whelan (1992) where baits are exposed to laboratory colonies or field populations of ants for 30 – 60 minutes and the number of ants on the baits are recorded at 5 – 15 min. intervals, depending on how fast an ant species forage. Baits will be tested separately (no-choice test) on different laboratory colonies or at separated sites to avoid confounding effects of acceptable bait being ignored when highly preferred bait is presented in proximity. The number of ants counted at each time interval will be summed per bait and compared by analysis of variance and Ryan-Einot-Gabriel-Welsch test.
Year 2) Baits that demonstrate evidence of not being accepted by non-target ants in Florida will be further tested in the field in the Coachella Valley, CA. With the assistance of the Coachella Valley Mosquito and Vector Control District, sites where fire ant populations were well controlled (ca. < 30% RIFA positive lures) by baits applied at least 2-3 months earlier, will be surveyed for non-RIFA ants that can be used for the bait acceptance testing. These parameters should allow time for non-RIFA ants to be present prior to the resurgence of fire ants at these sites. Otherwise, unmanaged sites with less dominant RIFA populations may be surveyed for non-RIFA, oil-feeding ant populations that can be tested. Bait acceptance tests and analyses will follow the methods used in the field bait acceptance tests conducted in Florida. Three replicated tests are desired for each non-RIFA species and depending on the size of the ant population one or more sites may be utilized per species. Up to four non-RIFA species will be tested.
