Lions, tigers and giraffes are exotic animals one expects to see when visiting the zoo. Visitors to the Jacksonville Zoo and Gardens in Jacksonville, Fla., however may encounter another exotic animal, the Caribbean crazy ant.
The Caribbean crazy ant, Paratrechina pubens (Forel), also known as the brown crazy ant and the hairy crazy ant, is an emerging pest ant in the southeastern U.S., especially in Florida and Texas. Reports describe infestations of enormous numbers of ants foraging in dense trails.
In 2005, an infestation of Caribbean crazy ants was discovered around the administration building at the Jacksonville Zoo. It is believed the ants were introduced to the zoo via potted shrubs brought in for a landscape project. Two years post-introduction, the ants infest more than 140 acres of the zoo. Caribbean crazy ants are a concern to patrons of the zoo who often mistake them for red imported fire ants, another introduced species known for their very painful sting. Although Caribbean crazy ants do not sting, they do infest animal feed and forage, invade buildings becoming a nuisance for occupants, nest in electrical switch boxes causing shorts and service interruptions and have even brought the zoo’s train to a halt due to the density of trailing ants on the tracks.
Little is known about the biology and behavior of these ants and there are no comprehensive control methods. Researchers from the University of Florida (UF) have been invited by the Jacksonville Zoo to investigate the biology, behavior, habitat and diet of the Caribbean crazy ant with the goal of developing an effective Integrated Pest Management (IPM) strategy.
THE PLAN. The first task was to map the distribution of the ants at the zoo and establish a baseline population to determine success of future control efforts. Mapping the location and relative numbers of ants over time will also provide information about patterns of movement and effects of adverse weather events.
In previously conducted macronutrient preference studies, Caribbean crazy ants at the zoo had demonstrated a preference for proteinacous foods. During the mapping studies, UF researchers placed slices of Vienna sausage at 136 preselected waypoints marked by GPS in 12 separate sampling sites at the zoo. After five minutes, the numbers of ants foraging on the bait were counted and recorded. The bait counts were conducted approximately every six weeks from June 2008 through June 2009.
Weather data were also recorded (visit www.pctonline.com to see a table that summarizes the data collected from these counts). From the study start, the highest numbers of ants foraging on baits were found at sampling sites 1, 2, 3, 11 and 12. Although there were fluctuations due to weather, the counts remained consistent through the length of the study. Most of the sampling sites with heavy infestation are on the perimeter of the zoo. These sampling sites are adjacent to wooded natural areas with ideal nesting habitat and because of the distance from the main areas of the zoo and considerable acreage, are unlikely to be treated with insecticides.
IPM for Zoo Accounts
Here’s a checklist to consider when performing IPM treatments:
- Inspection. Locate and map all areas of insect infestation. Note areas where chemical treatments are not an option.
- Identification. Know the target pest and its behavior and habits. This will help in determining the best treatment options.
- Thresholds. Establish acceptable threshold levels with the customer. Identifiy areas of highest priority.
Develop and implement an IPM plan incorporating non-chemical and chemical options. Items to consider:
- Sanitation: trash management in public areas, animal waste handling.
- Food-handling areas: food storage, waste management, general sanitation.
- Structural maintenance: potential insect entry points, proper maintenance of sprinklers and misting systems.
- Establish quarantine area for incoming landscape materials.
- Use lower risk insecticide formulations such as baits and traps.
- Targeted applications of insecticides where appropriate.
a. Monitoring. Regularly monitor program and implement changes as necessary.
b. Reporting. Provide updates to customer.
SAMPLING THE SITES. Sampling site 1 is the pumping station for the zoo’s Stingray Lagoon. Ants were introduced to this area in pallets of salt that were transported from another heavily infested area of the zoo. The salt pallets, pumping equipment and surrounding natural area of heavy vegetation provide ideal harborage for this tramp ant. Sampling site 11 is most likely the epicenter of the original infestation. This area receives and stores landscape materials for new exhibits and seasonal landscaping projects. Throughout the study, the heaviest infestation of ants has been at this site. Even when extremely cold weather reduced the population of ants in other areas of the zoo, ants in sampling site 11 survived by nesting under the black landscaping fabric.
Overall, the relative number of ants at each sampling site remained consistent compared to the other sites. This suggests that the Caribbean crazy ant is not migrating too far from the points of introduction. It is most probable that the spread of the ant throughout the zoo has been expedited by transportation of infested materials. Of course, some areas of the zoo have received some insecticide treatments (including sampling site 6, where weddings and other events are held and the administrative building, which houses the mainframe servers, located near sampling site 10). However, most of the zoo is not treated pending the IPM strategy recommendations that will result from this study.
Recorded data also suggest that weather may have a negative impact on the Caribbean crazy ant population. Fewer ants foraged on baits during periods of cold weather and extremely cold weather can have an effect for several months. Prior to the March 15, 2009, count, the zoo experienced several consecutive nights of temperatures below 0°C. Ant counts since this period have been fewer than at similar temperatures the previous year. Also, fewer ants were found foraging while raining (Feb. 14, 2009, data) and in the few weeks following an extreme weather event. For example, the counts from Sept. 6 and 27, 2008, were fewer than in previous months at similar temperatures. However, these counts occurred after a hurricane and heavy rains that flooded the zoo.
PCT Ant Field Guide Now Available!
Completely revised and updated, the third edition of the PCT Field Guide for the Management of Structure-Infesting Ants by Stoy Hedges is now available.
Unique behavioral characteristics, rapidly changing dietary needs and dozens of structure-infesting species all make ant control difficult. PCT’s handy field guide is designed for technciains to carry in their vehicle to help with on-the-go identification and control tips.
Topics covered include:
- Basic Ant Biology
- Inspection Tips
- Successful Treatment Strategies
- Instant Ant Identification Guide
- Taxonomic Keys
- Full-Color Photo ID Section
- Emerging Ant Species
The guide features 325 information-packed pages and is $9.95 per copy (quantity discounts available).
"To be without this field guide is akin to doing pest management without a flashlight," said Dr. Austin Frishman, AMF Pest Management Services, Boca Raton, Fla.
Visit www.pctonline.com/store or call 800/456-0707 to order.
FINAL THOUGHTS. The Jacksonville Zoo and Botanical Gardens presents unique challenges to an Integrated Pest Management strategy: transient human activity, valuable exotic animals, food and forage storage areas, snack vending and trash areas, animal waste storage areas, sensitive aquatic habitats and seasonal landscaping activities. Add to that the fact that the pest management professional is limited in the number and types of traditional chemical pest control products that can be used and the task becomes especially difficult.
By combining the traditional aspects of an IPM strategy: inspection, identification, threshold, sanitation and monitoring with the information gathered during this population and distribution study and ongoing ant bait and residual insecticide efficacy studies, the researchers at the University of Florida hope that the Caribbean crazy ant is one exotic animal you won’t see at the zoo.
Dawn Calibeo-Hayes is a graduate student at the University of Florida Department of Entomology and Nematology. She also is global marketing manager-insecticides for BASF Corp. David Oi is a research scientist at the United States Department of Agriculture, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology. Faith Oi is an assistant extension specialist at the University of Florida Department of Entomology and Nematology. E-mail Hayes at email@example.com.