Ant Suppression Research Articles

Intraguild Predation of Beneficial Arthropods by Red Imported Fire Ants in Cotton

The red imported fire ant, Solenopsis invicta (Buren), is an invasive species in the southern United States and is expanding its range westward to California and eastward up the Atlantic Coast. This voracious predator can reach extremely high densities and have widespread effects once it invades an ecosystem. We conducted a 2-yr sampling study and a series of greenhouse and field experiments to document the impact of red imported fire ants on beneficial insects in cotton. We found that the densities of 12 of 13 natural enemies sampled on cotton plants in 1999, and 8 out of 8 sampled in 2000, were negatively correlated with the densities of foraging fire ant workers. Red imported fire ants reduced the survival of lady beetles (Coccinella septempunctata L., and Hippodamia convergens Guerin-Meneville) (Coleoptera: Coccinellidae) by 50% and green lacewing larvae (Chrysoperla carnea Stephens) (Neuroptera: Chrysopidae) by 38% in greenhouse experiments. Fire ants did not, however, reduce the survival of spiders (Oxyopidae, Thomisidae, and Clubionidae). We used a commercially available fire ant bait to suppress fire ant populations in cotton fields during the 2000 growing season and compared the densities of beneficial arthropods in treated versus control fields. Densities of lady beetles, spiders, and big-eyed bugs (Heteroptera: Geocoridae) were significantly higher in fields with suppressed fire ant populations than in fields with relatively large fire ant populations. The effect of fire ants on minute pirate bugs (Heteroptera: Anthocoridae) was inconsistent, and populations of damsel bugs (Heteroptera: Nabidae) and hooded beetles (Coleoptera: Anthicidae) were not affected by fire ant suppression. The results of this study suggest that red imported fire ants are major intraguild predators of important beneficial arthropods in cotton.

Ant predation of larval Diatraea saccharalis Fab. (Lep., Crambidae) in new sugarcane in Brazil

Abstract: Ant predation of natural field populations of larval sugarcane borers, Diatraea saccharalis, was evaluated by using insecticidal check techniques, and through survivorship studies of artificial high‐density infestations, in plantations in Brazil. Areas of ant suppression had higher levels of D. saccharalis than unsuppressed areas, although both types of areas normally had extremely low D. saccharalis populations. Artifical infestations of D. saccharalis yielded significantly lower larval survivorship in unsuppressed areas than in suppressed areas. Fire ants (Solenopsis spp.) were always the most abundant ant. This study has demonstrated that ants are important pest predators in Brazilian sugarcane fields.

Northern Bobwhite Chick Mortality Caused by Red Imported Fire Ants

Northern bobwhite (Colinus virginianus) populations have declined throughout their range during the last 30 years. Change in land management is thought to be a primary cause of this decline, but the invasion of northern bobwhite habitats by the red imported fire ant (Solenopsis invicta) also may be involved. We compared hatching success and subsequent survival of wild northern bobwhite chicks on the Coastal Prairie of Texas in 1997 and 1998 between broods that hatched under natural conditions or following fire ant suppression treatments. In 1997, the fire ant suppression treatment resulted in a 70% reduction in the number of red imported fire ants on baits placed in treated nests on the day after hatch. Using 2 fire ant suppression treatments in 1998 reduced the number of red imported fire ants on baits by >99%. No year or treatment × year interaction effects were detected for hatching success or survival, and no treatment effect was detected for hatching success (P > 0.10). However, the proportion of chicks surviving to 21 days was higher (P = 0.010) for treated nests (n = 18) than control nests (n = 25; proportions of broods surviving: 53.5 8.6% [x SE] vs. 24.7 ± 6.6%; chick survival: 60.1 ± 7.6% vs. 22.0 ± 6.2%). The probability of chick survival decreased (P < 0.001) as our index of red imported fire ant activity in the nest increased. These results indicate northern bobwhite chicks can suffer high levels of mortality due to red imported fire ants, which could explain declines in some northern bobwhite populations following infestations by red imported fire ants. Current methods for controlling red imported fire ants are expensive and may last <3 months. Thus, strategies for mitigating the effect of red imported fire ants to northern bobwhite populations in this area should probably focus on reducing other mortality factors or increasing productivity.

Impact of Seed-Protecting Insecticides on Sorghum and Corn Seed Feeding by Red Imported Fire Ants (Hymenoptera: Formicidae)

The red imported fire ant, Solenopsis invicta (Buren), damages corn and sorghum seeds and seedlings, and seed treatments have traditionally been used to prevent damage. Recently, granular chlorpyrifos (Lorsban 15 G) has been registered for fire ant suppression. A series of tests was conducted to demonstrate the effectiveness of seedprotecting insecticides. Results demonstrate that seed protectants do not repel ants but rather offer seed protection by preventing recruitment of additional ants to the treated material. Granular chlorpyrifos applied as a T-band (banded over an open furrow) effectively prevents seed damage and suppresses foraging activity, provided that soil is moist when ants are foraging. Under dry foraging conditions in the laboratory, the seed treatment provided better protection than the T band application of granular chlorpyrifos.

Bermudagrass, Attempts At Fire Ant Suppression, Tifton, 1978

Abstract There have been several reports of red imported fire ant suppression in pastures in south Georgia following fertilization with anhydrous ammonia (G. W. Burton personal communication, E. F. Suber personal communication). There-fore we tested this as a management tool for this controversial pasture insect. A predominently 'Coastal' bermudagrass hay pasture (ca. 4-8 in. high) growing in Tifton sandy loam soil with a considerable amount of bahiagrass and a moderate infestion of red imported fire ants was selected for the test. Treatments were applied with a Sutton System tractor-mounted anhydrous ammonia applicator by “kniving in” to a depth of ca. 8 in. at ca. 125 lb pressure and 5 mi/hr, or ap-plied with a galvanized metal bucket as 1 gal of solution that was poured over a 4 sq ft area with its center being the center of the mound. Ten mounds were used for each treatment. Mounds were checked before and after treatment for presence of an active colony by digging slightly into the mound. Mounds were flagged and a ca. 20 ft radius of the ground surface around each treated mound was inspected for presence of a new mound which indicated movement rather than effective mortality.