Tuesday, May 29, 2012

Sustainable Fire Ant Management

The red fire ant or Kerengga or Semut Merah (Solenopsis invicta) are found in tropical area such as Malaysia, Central South America such as Brazil able to use as biological control for selected pests. Though traditionally this S. invicta has become quite a pest but not all fire ant species have achieved pest status. The black fire ant (Solenopsis richteri) that studied with the red fire ant by MARDI and Department of Agriculture . It was found that S. invicta has out-competed its black cousins and also crossed with them, creating hybrids between the two species. This article I would like to share information about the red fire ants or in Malays called 'Kerengga' as an Intergrated Pests Management Concept fo sustainable pest managements especially in Tropical Fruit farms. This article in "Anim Agriculture Technology" I post about sustainable fire ants management in agriculture practice.

The red fire ant or kerengga prospers in open sunny areas such as cropland, pastures and urban lawns. It is an insect of disturbed, low-diversity habitats. In its native Malaysia and many South East Asia, the ant evolved in frequently disturbed floodplain areas. Undisturbed areas, such as swamplands and dense forestsor orchards have very low densities of fire ant nests. There are lots of kerengga at my backyards and their nests on jackfruit, rambutans and ciku trees. The ants have an aversion to deep shade. Their mounds, which they build in almost any type of soil, can reach 18 inches high and be 2 feet wide, with tunnels extending 5 to 6 feet underground. The mounds are often located in rotting logs and around stumps and trees. Ant colonies can also be found in or under buildings. Two types of mounds exist: single-queen colonies where there are typically 30 to 100 colonies per acre, and multiple-queen colonies where the density of mounds per acre may average between 200 and 700, with each mature colony having 200,000 ants. Ants from the single-queen mounds form territories around the mound, which they protect from other fire ants. The multi-queen colonies are not territorial.

Fire ants spread in two ways, according to the type of colony. From the single-queen colonies, winged virgin queens emerge, fly high above the colony, and mate with winged males between spring and early fall. The queens land to establish new colonies alone. Such airborne spread should lead to a patchy distribution of new fire ant colonies interspersed with colonies of native ant species. Multiple-queen colonies spread when a new queen leaves the parent mound with a group of workers to form a new colony nearby. This strategy has been more successful where native ant populations have prevented colonization by single-queen colony virgin females trying to start a colony alone. In a Texas study, imported fire ant spread was observed as a continuous moving carpet of fire ants spreading slowly across the landscape. Once an area had been invaded, there were seven imported fire ant mounds for every native fire ant mound formerly present. After invasion, all native ant species declined, and overall arthropod diversity was reduced by more than 40%.

Least-toxic PesticidesA wide variety of insecticides are labeled for fire ants. Since many field studies have been done in the states with fire ant populations, it is advisable for readers to contact their local Extension agents and other sources for those studies before investing in fire ant treatments. Money and time can be saved with appropriate local information evaluating efficacy of available materials for fire ant control. Information on the least toxic and most environmentally appropriate options is presented below.

Baits containing a toxicant (frequently dissolved in soybean oil) are considered effective methods of controlling fire ants. Corn cob grits are typically used to absorb the toxicant and oil. The baited grits are then applied by hand with a broadcast seeder to a large area around individual mounds. Stringent requirements for these baits dictate that they have delayed toxicity, are effective over a 10-fold dose range, degrade quickly, and are otherwise environmentally acceptable. Baits can poison non-target ants if care is not taken to put the bait around fire ant mounds only. Baits are applied during spring and fall when fire ants are actively feeding, and not during the hottest part of summer. Avoid applying just after a rain or when the ground is wet with dew, as water decomposes the bait.

Avermectin, also known as abamectin is a bait product derived from a soil fungus that inhibits nerve transmission. As a mound treatment, it kills worker ants and colonies quickly, but as a broadcast treatment it acts more like an insect growth regulator, preventing the production of viable eggs. Being an insect growth regulator, it causes sterility of the queen, and eventual death of the entire colony. Fire ant populations were reduced by 87% within six weeks of treatment. Abamectin is quickly degraded in the environment and binds strongly to soil.

Boric acid baitsBoric acid has been used to kill a wide variety of insects in various situations for many years. It can be mixed with sugar or syrup to make a household ant bait as well. In a laboratory study, four dilutions of boric acid (.25%, .50%, .75% and 1%) were mixed with sugar water and offered as a bait to treat fire ant mounds. All dilutions achieved 95 to 100% control within 8 weeks.

Physical Controls

Boiling water
Boiling water is an effective treatment for individual mounds. If it does not kill the queen, it will not eliminate the colony. Boiling water kills grass and sterilizes soil and may best be considered as a last resort. To use hot water as a mound treatment for fire ants, start with a sunny but cool day when ants are near the surface. Be careful to avoid scalding yourself! Pour about three gallons of boiling water slowly over the mound. Try to collapse as much of the mound as possible while pouring. Portable boilers that generate hot water and steam are available. The Original Ant Eater is one such boiler, available from M&B Enterprises. The boiler comes with a dome-shaped delivery device that is placed over the mound and through which the steam passes. The ants, their larvae, and their stored food are all scalded within seconds. A hot-water pressure washer can also be used to apply steam and hot water to ant hills.

Other "Earthfire" is a species specific mound injection tool used to kill whole RIFA mounds in seconds. It is a hand-held tool complete with a propane cylinder, trigger assembly, and probe that is inserted in the mound. Once the probe is in the mound, the trigger is pulled, releasing a propane-charged insecticide into the mound. The tool is a patented low-pressure, sub-surface, vapor-delivery device. It works by creating a venturi, causing the vapor to fill the entire fire ant mound from the bottom up. The ants suffocate from the vapor throughout the tunnel network. The EPA approved and registered pesticide used is a 1% formulation of Resmethrin, a pyrethrin derivative.

Efforts are underway to introduce natural enemies of the red imported fire ant to lessen its competitiveness against native ants. Releases of fire-ant-decapitating phorid flies have been made in several southern states. Mass rearing and additional releases of these flies are underway now. Experimental releases of a disease-causing protozoan have been made in ten southern states. A number of least-toxic fire ant control materials are discussed.

This article I hope able to introduce kerengga as biological control to many tropical fruit pests. In cocoa plantation the artificial black fire ants nest made from the cocoa and coconut leaves and tied at the strategic location of cocoa trunk. This practice able to prove the reduction of fruit damage due to the attack of Helopeltis spp in the farm. The ants eats the larvae of cocoa pod borer and incrase cocoa beans quality. As I visited Malaysian Cocoa Board Agriculture Station in Pahang last year, the reasearcher able to convince many local farmers the sustainable fire ants management to use this technology.

M Anem

Senior Agronomist,
Taman Bukit Saujana,
(Early Sunday Morning)

No comments:

Post a Comment