RESEARCH Control of the turfgrass , neoniger, in Ohio

New tactics and products can help control a common golf course pest.

David J. Shetlar, Ph.D.

A small ant, Lasius neoniger, has been a nuisance on golf courses in an area extending from New Hampshire across most of the northcentral United States. Recently, this ant has acquired the moniker "turf grass ant," although the name is not officially recognized by the Entomological Society of America.

The problem The ant causes problems in high-mainte- nance turf by building volcano-shaped mounds, 2 to 4 inches in diameter, which are most evident on tees and putting greens. Even though the mounds are flattened by mowers each day, the soil covers the turf well enough to cause dead patches. The sand and soil in these mounds also dull mower blades rapidly. The turf grass ant is common in pastures, Mounds built by the so-called turfgrass ant, Lasius neoniger, are a nuisance on golf courses across the country. This fields and home lawns, but the mounds and mound is under construction. burrows in these areas generally go unno- ticed. Lasius neoniger is closely related to the cornfield ant, which builds much larger with a limited budget, only temporary relief Swier, Ph.D. (University of New mounds in clean crop fields, where it tends has been achieved. This course would have Hampshire)j Patricia Vittum, Ph.D. to protect that attack various field been an excellent site for studying the biology (University of Connecticut) j and Dan Potter, crops. Across North America, other species of of the turf grass ant, but studies had already Ph.D. (University of Kentucky). build similar mounds. As more and been initiated in the mid-1990s by Stanley more golf courses use sand-based tees and life cycle greens, and as standards for greens have risen, Little is known about L. neoniger, although the turf grass ant and its relatives have KEYI points publications include a report on its nest struc- become a more significant problem. In fact, More Info: www.gcsaa.org ture (3) and some preliminary findings by it is a rare golf course that does not have some Werle and Vittum (4). The following com- The so..called turfgrass ant is a nuisance species of ant throwing up small mounds on ments about its life cycle are a blend of per- on golf courses from New England to the some of the greens. northcentral United States. sonal observations, published literature and Spring application of some insecticides discussions with Swier, Vittum and Potter. Origins of this study results in effective control throughout Harry D. Niemczyk, Ph.D., introduced the season. Habitat and diet me to the turf grass ant by showing me his When ant activity is extensive, baits The turf grass ant appears to produce favorite ant study site, a golf course in Clyde, appear to be effective only when they extensive colonies that consist of intercon- Ohio. Built on very sandy soils, this course are applied at high rates. nected subcolonies. It is generally believed was almost entirely pockmarked with ant Future research will test the usefulness 0 that there is one queen per colony. The queen mounds, from tee to green and across most fall insecticide applications in preventing and workers apparently maintain chambers of the roughs. The owners have tried many ants from returning in the spring. at varying depths in the soil in which eggs kinds of sprays to knock out this ant, but and brood (larvae) are reared. During the

GeM 117 February 2003 I RESEARCH

summer, additional chambers near the soil surface are constructed, and each of these chambers may have an opening to the out- side and an associated mound. Therefore, a colony may have one major opening and numerous satellite openings, each with its associated mound of soil. This ant seems to feed on all kinds of food: fats, proteins and sugars (2). Therefore, the ants eat other (fats and proteins) and maintain honeydew-produc- ing insects (sugar producers). A student of Potter has recently confirmed a close associ- ation between the turf grass ant and root- infesting (soil) aphids (1).

Reproduction An interesting paper published by a The turfgrass ant is closely associated with root-infesting (soil) aphids. USDA ant researcher in the 1930s (from Clyde, Ohio) reported that the ant seems to produce one major brood after opening its much larger individuals that generally do not builds a small chamber in the soil, often nests in the spring. The queen steps up egg mature until late July and Aug~st. throwing up a small mound of soil that may production when food begins to flow into the On warm afternoons, often after recent be %- to ~-inch in diameter. The chamber is nest. The brood from this peak egg produc- rains, the new queens and drones swarm by usually only an inch deep. Most queens die tion develop rather slowly through May, June the thousands, and all colonies in an area before making chambers, and the ones that and July. New adult workers (all female) commonly release these winged forms at the successfully dig a burrow appear to die from begin to appear in July, and mound prolifer- same time. During these events, the ants can predation or other causes within a week or ation increases dramatically. These workers become nuisances around lights at night. two. Queens that survive in constructed continue to collect food during the summer New queens are about five times the body chambers lay a small batch of eggs, and the months, apparently storing the reserves in the weight of a worker or winged males. Like larvae that develop are fed regurgitated food nest in anticipation of lean periods. When most ants, the new queens and drones mate that appears to come from fat and wing mus- colonies have matured, a considerable per- while flying, and once the nuptial flight is cle reabsorbed by the queen. centage of the brood develops into a new completed, the female seeks a new place to Within six weeks, the small batch of new batch of winged reproductives (queens and build a chamber. Upon landing on the worker ants (which are often half the size of drones). The reproductive cast consists of ground, the queen chews off her wings and normal workers) break open the brood cham-

118 GeM February 2003 RESEARCH ber, forage for food and help feed another only two to three weeks. spring, for nearly five seasons and the results small brood. By this time, winter has arrived In studies in the 1990s, Niemczyk and I have been fairly consistent. and activity in new as well as established found that several of the pryrethroid insecti- Halofenozide seems to have no measur- colonies ceases. Established colonies and new cides - cyfluthrin (Tempo), bifenthrin able affect on the turf grass ant. Fipronil colonies that survive the winter resume activ- (Talstar), deltamethrin (Deltagard), lambda- (either as sprays or the recently registered ity from late April into early May in Ohio. cyhalothrin (Scimitar) - provide the same bait) tends to knock down the mounds after level of control as chlorpyrifos, especially if two to three weeks, and often the mounds do Ant control they are used when mounds first appear. not reappear for six to 10 months. Suspecting this kind of life cycle, Later in the season, do not expect more than Imidacloprid seems to act very slowly, with Niemczyk has stated that the time to control two weeks of mound suppression. mound-building suppression not occurring this ant is when the mounds first appear in When imidacloprid (Merit), halofeno- until four to six weeks after the initial appli- the spring. At this time, the colonies are at zide (MACH2), fipronil (Chipco Choice), cation. However, once it occurs, mound sup- their weakest point: low on food reserves, and thiamethoxam (Meridian - not regis- pression tends to last for the rest of the with older workers and few new brood. An tered for turf grass usage) were being devel- season, and perhaps into the next season. application of chlorpyrifos (Dursban) within oped, Niemczyk and I began trials to Thiamethoxam has knocked down the ant a week of mound appearance in the spring evaluate how these insecticides might influ- activity in only two to three weeks consis- has often provided four to six weeks of ence mound building by L. neoniger over an tently; ants usually do not return for the rest mound suppression. Applications made later entire season. We have applied these mate- of the season. in the season usually suppress mounds for rials, at first mound formation in the Applications ofimidacloprid and fipronil

Rate Treatmentt (pound ai/acre) 1 WAT 2WAT 16WAT

Talstar 0.2G 0.20 3.84 a (35) 5.8 a (25) 5.1 a (0) 7.4 b (0) 6.4b (0) 4.1 b, Fipronil0.0143G~ 0.0125 6.0 a (0) 8.3 ab (0) 6.0 a (0) 6.4 b (6) 6.6b (0) 2.0 ab Fipronil0.0143G 0.025 7.9 ab (0) 7.1 a (7) 6.0 a (0) 6.4 b (20) 3.8 ab (32) 0.8 a Merit 75WP 0.40 11.8 a (0) 13.75 (0) 12.3 b (0) 10.38 b (97) 5.3 b (5) 2.8 ab' Meridian 0.33G 0.26 5.4 a (7) 5.8a (25) 3.4 a (31) 1.0 a (84) 0.4 a (93) t3a Check 5.8 a 7.6 ab 4.9 a 6.3 b 5.5 b 4.4.b

tTreatments applied May 7, 2000, to plots 10 by 15 feet replicated four times. No post-treatment irrigation. *Data taken May 14, May 21, June 18, July 2, July 30, and Sept. 10 based on the same central 2 square yard area observed each time within each plot. Means followed by the same letter are not significantly different. sRpronil was an experimental insecticide at the time of this tre.atment. The current product with fipronil as the active ingredient is Rrestar.

Data are shown for the efficacyof insecticidesin controllingant mounds of Lasius neoniger (Emery) one to 16 weeks aftertreatmentryvAT) on a golf course fairway at Crockett'sGreen HillsGolf Course, Clyde, Ohio. Data are forthe 2001 season.

Rate Active mounds/4 square yards(% reduction)* Treatmentt (pound ai/acre) 1 WAT 2WAT 3WAT 4WAT 5WAT 6WAT SWAT

Firestar0.00015 B 10.0 8.5 bc (79) 6.5 a (53) 2.5 a (38) 6.8 bcd (63) 8.5 abe (53) (3) 13.8 ab (42) Rrestar 0.00015 B 15.0 11.0 bc 6.5 a 2.5 a 6.5bcd 4.8 be 9.8 ab (73) (53) (38) I,. (64) (74) (48) (59) Firestar0.00015 B 30.0 5.5 c (87) 3.8 a (73) 1.8 a (56) 2.0 cd (89) 1.5 bc (93) (74) 5.3 b (78) Meridian 0.33 G 0.26 11.0 bc (73) 2.5 a (82) 0.3 a (94) 05d (97) 0.3 e (99) (100) 0.0 b (100) Check 41.3 a 13.8 a 4.0 a 18.3 a 18.3 a 23.8 a

tTreatments applied June 24, 2002, to plots 15 by 15 feet, replicated four times. No irrigation after treatment. *Data taken July 1, July 8, July 15, July 22, JUly 29, Aug. 5 and Aug. 19, based onthe same central 4-square-yard. area observed each time within' each plot. Means followed' by the same letter are not significantly different.

Data are shown forthe efficacyof treatments with Firestarbaitand Meridian incontrollingant mounds.of Lasius neoniger (Emery) one to 8 weeks aftertreatment ryvAT)on a golfcourse fairway at Crockett'sGreen HillsGolf Course, Clyde, Ohio. Data are forthe 2002 season.

February 2003 I GeM 119 RESEARCH formulations after the workers have been for- ants involved. In these situations, the baits being considered, including application of imi- aging for severalweeks have resulted in much must be reapplied on a regular basis (possibly dacloprid, thiamethoxam or fipronil when the less suppression later in the season. However, every two weeks, for three applications), or the new queens establish colonies in September. fipronil baits have significantly reduced ant early-spring control tactic will have to be used. The thought behind this method is that the ant mound construction, even in midseason. Where only a few mounds appear on a golf colonies would take in enough material during I believe that their unique modes of action green or tee, application of either bait over a the fall to lower their winter survival, and ant explain how imidacloprid and fipronil work. small area should knock out the ants. colonies eliminated in the fall and winter Imidacloprid has been shown to change nor- should not reappear the following spring. mal behavior, and an early application Severity of the problem may somehow disrupt the rearing of the Currently, my recommendations for ant Acknowledgments brood, which would explain the action control depend on the severity of the problem. We thank Bob Crockett, owner of Crockett's Green Hills Golf Course, Clyde, Ohio, for allowing us to use his golf appearing four to six weeks after application. Fo,r a few occasional mounds, an early appli- course in our studies. Fipronil is a slow-acting poison and is appar- cation of a pyrethroid or chlorpyrifos (which is ently picked up by the workers, taken back to still available for use on golf courses) followed References the colony and fed to other workers, brood with subsequent applications of baits if the 1. Lopez, R., D.W. Held and D.A. Potter. 2000. Management of a mound-building ant, Lasius and even the queen before they know that mounds should return with either hydra- neoniger Emery, on golf putting greens using they have been poisoned. methylnon or fipronil-based products should delayed action baits of fipronil. Crop Science 40: provide satisfactory results. On courses where 511-517. Ant baits large populations of this ant cause problems on 2. Traniello, IF.A. 1983. Social organization and for- aging success of Lasius neoniger (: Because Potter and his students (1) greens, tees and fairways regularly, an early Formicidae): behavioral and ecological aspects of found very good control of L. neonigerwith application of imidacloprid or fipronil should recruitment communication. Oecologica 59:94- hydramethylnon bait (Maxforce), we eliminate ant activity for much of the season. 100. included it in our studies and compared it We have also learned quite a bit about 3. Wang, D., K. McSweeney, B. Lowery and J.M. Norman. 1995. Nest structure of the ant Lasius with the recently registered fipronil ant bait baits. As has been shown, when baits are used neoniger Emery and its implications on soil mod- (Firestar). At label rates of Maxforce, ant to control fire ants, the turf grass ant can be ification. Geoderma66:259-272. mound suppression was minimal, but this rather finicky about the quality of the bait. If 4. Werle, S.F., and P.J. Vittum. 1999. The turfgrass ant a necessary nuisance? Golf Course result was similar to results achieved with the baits are used, be sure to apply them to dry Management 67:49-52. lower rates of Firestar. In fact, high rates of turf when rainfall is not likely to occur and both baits were required to get significant irrigation can be withheld for about two days. reductions in ant-mounding activity. Apparently, rain and irrigation render most of I believe that when very high populations the baits unattractive. of the turfgrass ant are present, the established David J. Shetlar, Ph.D. ([email protected]), is an asso- baiting rates are not sufficient to supply Future research ciate professor of entomology at Ohio State University, enough active ingredient to the biomass of Different control tactics for this ant are Columbus.

SWAT

0.26 (53) 2.2 a (69) 1.9 a (74) 0.07 (0) 10.1 cd (0) 8.0 c (0) 1.5 (68) 5.8 abe(18) 5.6 abe (22) 0.13 (0) 11.0 d (0) 6.6 be (8) 0.20 (0) 3.4 a (31) 9.1 c (0) 0.000225 (11) 9.3 cd (0) 6.9 be (4) 0.00225 (78) 4.0 ab. (44) 3.6 ab (50) 7.1 d 7.2 be

120 GeM February 2003