Karen M. Vail

A survey of the urban pest ants (Hymenoptera: Formicidae) of peninsular Florida.

A one year survey was conducted with structural pest control employees of Florida to determine the kinds of ants and types of ant problems confronted in both commercial and household pest control. Eight species of ants were identified as key pests in Florida. Of these, the most common were Solenopsis invicta Buren - 14%, Tapinoma melanocephalum (F.) - 14%, Paratrechina longicornis (Latreille) - 14%, Camponotus abdominalis floridanus (Buckley) - 12%, Monomorium pharaonis (L.) - 11%, Camponotus tortuganus Emery - 8%, Pheidole megacephala (F.) - 7% and Paratrechina bourbonica (Forel) - 4%. More than twenty-five other species of ants which were occasional invaders were also collected in the survey. Customer complaints, nest locations, and treatment strategies for pest ants are also described.

Survival of Imported Fire Ant (Hymenoptera: Formicidae) Species Subjected to Freezing and Near-Freezing Temperatures

Abstract Survival at low temperatures is an important parameter determining distribution of imported fire ants in the United States. Supercooling points and survival at low temperatures, and the effects of species, individual size, and Thelohania solenopsae Knell, Allen & Hazard (Microsporida: Thelohaniidae) infection on these parameters, were examined. We tested Solenopsis richteri Forel, S. richteri X invicta hybrid, and Solenopsis invicta Buren. Great variation was observed in the supercooling points, which are not an appropriate measure of cold hardiness for imported fire ants. When exposed to near-freezing temperatures above their supercooling points, fire ants died at different rates depending on the species and T. solenopsae-infection status. Extended exposure to 4°C resulted in both the hybrid and S. invicta infected with T. solenopsae having significantly lower mortality rates than either the S. richteri or the uninfected S. invicta. At 0.5°C, the hybrids had significantly lower mortality than the uninfected S. invicta, but mortalities for S. richteri and T. solenopsae-infected S. invicta were not significantly different from each other or the hybrid. Ant mortality was 100% for all ant types after 7 d at −4°C. The uninfected S. invicta was consistently less cold-tolerant than the other ant types. The hybrid fire ants and the T. solenopsae-infected S. invicta had the lowest mortalities. These results support the hypothesis that extended cold injury causes winter kill of fire ants, and may partially explain the distribution of fire ant species in the United States.

Statewide survey of imported fire ant (Hymenoptera: Formicidae) populations in Tennessee.

Imported fire ants (Solenopsis spp.; Hymenoptera: Formicidae) occupy 54 counties ([approximately]5.4 million ha) in Tennessee. To better understand the fire ant species distribution in Tennessee, the state was divided into 16.1 x 16.1 km grids, and a single colony was sampled for cuticular hydrocarbon and venom alkaloid analyses within each grid. A total of 387 samples was processed from which 9 (2.3%), 167 (43.2%), and 211 (54.5%) were identified as red (Solenopsis invicta Buren), black (Solenopsis richteri Forel), or hybrid (S. invicta x S. richteri) imported fire ants, respectively. The S. invicta was only found near metropolitan Nashville in Davidson and Williamson counties and at one site in Decatur Co. All samples east of Franklin Co. were identified as hybrids. Tennessee counties west of Lincoln were predominantly S. richteri (86.5%) as opposed to hybrid (13.0%) and S. invicta (0.5%). The exception was Hardin Co., which was predominantly hybrid. Counties containing both hybrid and S. richteri (all in the middle and western part of the state) included Bedford, Decatur, Franklin, Giles, Hardeman, Hardin, Haywood, Lawrence, Lincoln, Marshall, Maury, McNairy, Perry, and Wayne. The S. invicta samples collected from one Williamson Co. site were determined to be polygyne and infected with the Solenopsis invicta virus (genotype SINV-1A). This was the first detection of polygyne imported fire ant in Tennessee. The SINV-1A virus was also a new find at the time of detection, but has been previously reported. The survey results are being used to direct current and future biological control efforts against imported fire ants in Tennessee.

Research Reports: Indoor and Outdoor Foraging Locations of Pharaoh Ants (Hymenoptera: Formicidae) and Control Strategies Using Bait Stations

While Pharaoh ants, Monomorium pharaonis (L.), are generally considered indoor pests, we observed these ants foraging at 51.7% of outdoor monitoring sites located on exterior wall surfaces of apartment buildings in contrast to 11.6% of indoor sites. The number of ants per infested monitoring site did not vary significantly with counts averaging from 46 to 118. Commercial bait stations containing a delayed action toxicant placed solely on the exterior walls of buildings, or outdoors, provided a 94% reduction in Pharaoh ant numbers within 1 week in contrast to a 9% reduction in untreated buildings. This was similar to the reductions from buildings treated with bait stations placed both indoors and outdoors. While a total of 3 ants were found indoors in treated apartments, indoor counts from untreated buildings also were low. Initial outdoor ant counts were 2 to 20 times higher than indoor counts, and the significant population reductions were attributed to a reduction in counts from outdoor sites.

Influences on the structure of suburban ant (Hymenoptera: Formicidae) communities and the abundance of Tapinoma sessile.

ABSTRACT Urbanization can alter the organization of ant communities and affect populations of urban pest ants. In this study, we sampled ant communities in urban and suburban yards to understand the habitat factors that shape these communities and influence the abundance of a common pest species, Tapinoma sessile (Say). We used pitfall traps to sample ant communities and a combination of pitfall traps and baiting to collect T. sessile at 24 sites in Knoxville, TN. In total, we collected 46 ant species. Ant species richness ranged from seven to 24 species per yard. Ant species richness tended to be lowest near houses, whereas T. sessile abundance was highest near houses. The best predictors of ant species richness in yards were canopy cover and presence of leaf litter: ant species richness peaked at mid-levels of canopy cover and was negatively correlated with the presence of leaf litter. Tapinoma sessile abundance increased with presence of logs, boards, or landscaping timbers and leaf litter in yards. Our results indicate that ant communities and the abundance of particular pest species in these urban and suburban landscapes are shaped by many of the same factors that structure ant communities in less anthropogenically disturbed environments.

Trapping Social Wasps (Hymenoptera: Vespidae) in Nurseries with Acetic Acid and Isobutanol

Abstract European hornet, Vespa crabro L., damages bark of nursery trees, and most vespid species can be a sting hazard to nursery personnel when nests are disturbed. We tested acetic acid and isobutanol lures in traps for V. crabro spring queens to determine the seasonality of vespid captures and compare the efficacy of patterns of trap placement in Tennessee nurseries. Forty traps in transects from nursery tree blocks into the forest captured 547 vespid queens during 2001 and 2002. These were 78.8% Vespula maculifrons (Buysson), 6.9% Vespula squamosa (Drury), 6.8% V. crabro, 4.8% Dolichovespula maculata (L.), 2.6% Vespula flavopilosa Jacobson, and 0.2% Vespula vidua (Saussure). Total worker and male wasp captures in these traps were 2525 and 28, respectively. Polistes spp. (n = 416) were also trapped. Peak queen trap catch was in April for V. crabro and V. maculifrons and in May for other Vespula. Numbers of worker wasps captured were greater within nursery blocks or at field-forest edges compared with within forest, except D. maculata. Numbers of V. maculifrons, V. squamosa, and D. maculata queens trapped were greater in blocks in some years. The study demonstrated a strong response of V. crabro and several Vespula spp. to the lure, showed spring queen captures of V. crabro and other wasps, and indicated that trapping of the majority of vespid species was most effective at locations outside of the forest. The trapping of queens indicates some potential for reducing colony founding by queen removal in spring.

Bed Bug (Hemiptera: Cimicidae) Detection in Low-Income, High-Rise Apartments Using Four or Fewer Passive Monitors

Abstract Bed bug, Cimex lectularius L., management in low-income, high-rise housing for the elderly and disabled can be difficult. Early detection is key to slowing their spread, and reducing management cost and time needed for control. To determine the minimum number of passive monitors needed to detect low-level bed bug infestations in this environment, we evaluated three monitors placed one, two, or four per apartment in a 3 by 3 experimental design. One sticky monitor, The Bedbug Detection System, and the two pitfall monitors, ClimbUp Insect Interceptors BG and BlackOut BedBug Detectors, were evaluated. Bed bugs were trapped by the ClimbUp Insect Interceptors BG and the BlackOut BedBug Detector in 88% and 79% of apartments, respectively, but only in 39% of the apartments monitored with The Bedbug Detection System. The Bedbug Detection System required significantly longer time to detect bed bugs than either the ClimbUp Insect Interceptor BG or the BlackOut BedBug Detector. With the less effective Bedbug Detection System data removed from analyses, detection rates ranged from 80 to 90%, with no significant differences among one, two, or four monitors per apartment. Results indicate it is especially important to include a bed placement when only placing a few monitors. Future work should compare the combination of cursory visual inspections with various monitor numbers and placements per apartment to determine the most efficient, cost-effective system that will be accepted and implemented in low-income housing.