Maximum male emergence has been seen to occur around one hour before maximum female emergence. “Those colonies usually have large numbers of the smaller worker ants in and around them,” she said. “This type of phorid fly is different from the Pseudacton tricuspis, which is already being used in several counties as a biological fire ant control,” Keck said. There are over 70 described species within the Pseudacteon genus, which parasitize a variety of ant species. “You can think of it as a zombie breeding zone.”. And mating occurs while the females are looking for suitable hosts. P. tricuspis was also introduced into the United States for this purpose. It also handles cold weather better than tricuspus, so it’s less likely to die out during fall or winter.”.
The females exhibit aggressive and territorial behavior.
Click for a hub of Extension resources related to the current COVID-19 situation. Interestingly, P. tricuspis has a male-biased sex ratio, where the males are smaller than the females. The females fight over the larger host ants to deposit their eggs in as these eggs will have a larger chance of survival. Phorid flies kill fire ants by “dive-bombing” them in order to lay their eggs in the ant’s thorax, Keck explained.  They have the shape of a torpedo and are injected into the thorax of the worker fire ant by the mother. The new fly, Pseudacton curvatis, is imported from South America and has been acquired though the U.S. Department of Agriculture’s Animal and Plant Inspection Service, Keck said.
Over the years, the population of P. tricuspis fly at these sites continued to grow and expanded beyond the area of the release sites, and in the fall of 2000 the sites fused into one large occupied area. However, the exact mechanism of how this sex determination occurs is unknown. Six fire ant mounds, located at the release site, were collected weekly for four weeks and transported to the phorid fly rearing facility at USDA-ARS, Mississippi State, MS for exposure to the flies. Climates range from rain forests to swamps to dry areas. During this process, neither sex is able to keep flying, causing both to drop to the ground.  While other species within the Pseudacteon genus have been found to be generalists and feed on a wide range of resources, in the field the P. tricuspis fly will only feed on its host.
It causes $1.2 billion per year of economic damage to Texas alone and infests about 80 million acres of rangeland, Plowes said. At that point, the fly will release an enzyme that will cause the ant’s head to fall off. The phorid fly uses the injection stinger on its rear end to squirt an egg into the shoulder joint of a fire ant. Since then, its populated area has expanded across the country, including California. , The daily activity of the P. tricuspis fly starts very low in the early morning, increases gradually, then peaks at midday. Email editor[at]dailytexanonline.com, “Zombie” flies control invasive ant species. “We’ve been releasing a different type of phorid fly in New Braunfels to see how effective it will be in the controlling fire ants,” said Molly Keck, Extension entomologist for Bexar County. Once hatched, the fly larvae migrates into the head of the ant, eating the contents. “So they provide more targets’ for this fly. After two weeks, the developing fly is able to manipulate the ant’s motion and becomes a little zombie worker by having the ability to control the ant’s movement from the inside.
Colonies containing parasitized workers were returned weekly to their original mounds. Overall, phorid flies cause slower fire ant colony growth, which leads to stronger native ant communities. After locating one, the male will grab onto the female, and copulation takes less than a second. Larger females will most likely win these fights, leading to females growing larger than males. Scientists are using brain-munching, mind-controlling flies to “zombify” and kill invasive fire ant species. NEW BRAUNFELS There’s a new phorid fly in town, and this one could be even deadlier to fire ants than other species, said a Texas Cooperative Extension entomologist.
That encounter lasts for about 1/60th of a second, Plowes said. The Daily Texan does not guarantee their accuracy. Other phorid species are known to attack the imported red fire ant, various wasps, bumble bees and honey bees. Pseudacteon tricuspis (commonly referred to as a phorid fly or fire ant decapitating fly) is a parasitic phorid fly that decapitates its host, the imported Solenopsis invicta fire ant. In order to control the fire ant, scientists have imported biological agents from South America called phorid flies, which are natural parasites to fire ants.  Since its introduction to the United States, the species can be found across the country, but is concentrated along the south east parts, including Florida, Alabama, Arkansas, and Louisiana..  This is likely occurs because of the females being aggressive and fighting with other females over depositing their own eggs within a host. Plowes said people can’t use mechanical devices or chemicals to kill the red imported fire ant. P. tricuspis will spend a majority of its life cycle within the host ant, even after the host dies. Aside from the United States, P. tricuspis has also been found in South America, Europe, and Asia.
“Very few native ants are left.”. This correlates to a density dependent response to the availability of the fire ant host, which is greater in the fall due to the frequent rainfall. “It’s more robust and prefers the smaller-sized worker ants.  During both the second and third instar the fly maggot relies heavily on ant hemolymph for nutrition. The ants are extremely detrimental to the environment of the United States, costing around a billion dollars every year in damage and impacting native fauna and habitats. , P. tricuspis was the first species of Pseudacteon fly successfully used as a biological control agent for imported red fire ant in the US. The red imported fire ant poses a significant challenge as an invasive species.
 Eight native Pseudacteon species parasitize native fire ants in the United States (Plowes 2009). P. tricuspis is predominantly found within the natural range of where the host Solenopsis invicta fire ant can be found. The fly will avoid attempting to oviposit in the alates of the colony and will instead exclusively attack worker ants. , The pupae are opaque and have a pale color. , When the adult fly is fully grown, emergence from the host fly takes only a few seconds in total and are ready to mate and lay eggs within the next few hours. The ant, now moving like a lifeless zombie driven by the phorid fly, will then leave the nest and finds somewhere that is safe, normally in a dark area around five to 10 yards away from the nest, Plowes said. “We’re concerned about (the ants’) impact on native species and their potential to disrupt food webs,” Plowes said.
 The ovipositor, which is the organ that is used by the female to lay eggs, has a looks different in all species within the Pseudacteon genus and can be used to distinguish the species from one another. And although it’s likely the two can survive in the same area, the curvatis would likely to out-compete the tricuspus in a given area, so it just makes more sense to release them far enough apart.”. “We’re also trying to keep the release of the new fly far enough away from where we have released or plan to release the Pseudacton tricuspus,” she said. It mainly feeds on the ant’s jaw muscles, causing “zombie-like” dangling jaws.
Phorid flies kill fire ants by “dive-bombing” them in order to lay their eggs in the ant’s thorax, Keck explained. After a couple of days, the maggot will start to feast upon the ant’s head tissues. The adult lifespan is only 3 to 5 days.
, CS1 maint: multiple names: authors list (, "fire ant decapitating flies - Pseudacteon spp", "Biology and Behavior of Pseudacteon Decapitating Flies (Diptera: Phoridae) That Parasitize Solenopsis Fire Ants (Hymenoptera: Formicidae)", 10.1603/0013-8746(2001)094[0097:idoptd]2.0.co;2, "Effects of Temperature, Sugar Availability, Gender, Mating, and Size on the Longevity of Phorid FlyPseudacteon tricuspis(Diptera: Phoridae)", https://en.wikipedia.org/w/index.php?title=Pseudacteon_tricuspis&oldid=956815345, Creative Commons Attribution-ShareAlike License, This page was last edited on 15 May 2020, at 13:32. Eventually, the ant’s head falls off. , The fly hatches from the egg in the first instar and will usually shed their serosa within 24 hours, although the process has been recorded to last up to 20 days.  There are over 70 described species within the Pseudacteon genus, which parasitize a variety of ant species. Pupal development takes around 2–6 weeks, dependent on temperature.  Both sexes are also attracted to the odor of the host fire ant. An initial release of about 75,000 of these flies was completed over three days June 14, 20 and 23 in the southeastern part of the city. By day four the second instar typically will have situated itself fully within the ant's head. In the field, the parasites could potentially obtain sugar from nectar or honeydew, but provision of supplemental sugar sources around release sites of the fly may improve the success rate of the fly as a control for the fire ant.
“Hopefully by the end of this talk, I will have convinced all of you that zombies do exist.”. The head will act as a capsule for the fly for another two weeks, after which the fly will exit the ant’s mouth.
Plowes described this phenomenon as a duck trying to lay an egg on the back of a pick-up truck moving down a highway. This species attacks very small ants in the genus Crematogaster - the acrobat ants - developing within the ants' heads. However, P. tricuspis is very specific to its host ant and will not attack other native ant species, making it a good biological control against the fire ant. Plowes described this phenomenon as a duck trying to lay an egg on the back of a pick-up truck moving down a highway.
The phorid fly uses the injection stinger on its rear end to squirt an egg into the shoulder joint of a fire ant.