OCTOBER 2 0 0 9 N P M A L I B R A R Y U P D A T E Insert this update into the NPMA Pest Management Library, which can be Updatepurchased from the Resource Center. Phone: 703-352-NPMA (6762); Fax: 703-352-3031 Biocontrol Agents Used as Pest Management Tools Biological control is a type of pest manage- Utah, and thus protected a fledgling population ment approach where one organism is used and their crops. to manage or control another. The biological In more recent times, with the evolving control (or biocontrol) agent is often called a new environmental and greener approaches to natural enemy or a beneficial organism. We pest management, the biological control organ- see natural examples of this in our everyday isms we tend to be most interested in are the environment when we see a native lady beetle ones that might attack pests within an urban feeding upon aphids, scale, whiteflies, mites, environment, such as various cockroaches, ants or mealy bugs on a rose for instance. The lady or flies. But, we have even heard of instances beetles get their fill of food while feasting where larger pests, like rodents or toads, have upon a gardener’s worst nightmare — aphids been controlled naturally by bringing in snakes that will destroy the rose plant by sucking its to pursue them. plant juices, destroying both foliage and flower In urban pest management scenarios, we blooms. have seen toads, lizards, bacteria, protozoa, Almost all animals have natural enemies. beetles, mites, flies and wasps all employed to The pests we encounter are no exception. get rid of cockroaches in an account. Parasitoid However, biological control is not always wasps have probably had the most success in considered when we think of controlling a pest controlling cockroaches. Parasitoid wasps are infestation. However, natural controls do play tiny insects, harmless to humans; they lay an important role in managing pest popula- their eggs in the cockroach’s egg case (or tions. Natural pest enemies include things like ootheca). The eggs hatch into immature wasps, nematodes, spiders, toads and frogs, centipedes, birds, lizards, geckos, beetles, man- tids, ants and small mammals. Many kinds of organisms will attack We see natural examples others. In agriculture, especially in traditional of biocontrol in our every- cultures, such an approach has long been used day environment when to protect crops and manage pests. Birds will we witness ladybeetles eat grasshoppers and crickets that can destroy eating the aphids from a wheat crop for instance; there are famous our prized roses. stories about the seagulls that ate the Mormon crickets in what would become modern day N P M A L I B R A R Y U P D A T E wasps that feed on the cockroach eggs. Wasps isn’t attracted to native ant species. “We’re hop- can reduce cockroach numbers dramatically and ing the new parasite will reduce the foraging of keep them at low levels, but they cannot com- fire ants, and thereby allow our native ants to pletely eliminate the problem. Parasitoid wasps regain some footing,” says Ludwig. The release have been used successfully in nonresidential of- was part of the Texas Imported Fire Ant Research fice buildings and warehouses, but not in residen- and Management Project. (More information on tial buildings where there is much less tolerance the project and fire ant research can be found at: of cockroaches and other insects. In fact, para- http://web.biosci.utexas.edu/fireant/index.html or sitoid wasps have largely been used in zoo and http://fireants.tamu.edu/.) horticultural park and greenhouse type settings or in a city sewer system in one case; areas where Use of scuttle flies on termites introducing another insect as a control measure Malaysian scientists have recently discovered would be received more positively than in a home a new scuttle fly species that could act as a bio- setting. (These programs are often not popular logical agent in controlling termite infestations. with some customers because they may find the Named Misotermes mindeni, the new species introduction of a biological control agent to be as was found to be a parasite on mound-building distasteful as the one to be controlled.) Another termites by doctoral student Kok-Boon Neoh and concern can often be that traditional pesticide Professor Chow-Yang Lee of the University of Sci- use would have to be minimized or eliminated, ence Malaysia. The species was identified while because a beneficial organism is often even more Neoh was studying termite mounds on the Uni- susceptible to the products used than the one to versity’s Minden campus. The discovery was de- be controlled or managed. tailed in a recent issue of the Journal Sociobiolo- Some biocontrol agents highlighted recently gy. (For more information on this research, go to: in the news include the following scenarios: http://www.upi.com/Science_News/2009/08/20/ Malaysian-scientist-finds-new-fly-species/UPI- Zombie fire ants — the use 42111250774662/.) of phorid flies as a pest management tool A recent report of research out of the Univer- sity of Texas discusses zombie fire ants, created by the introduction of a parasitic phorid fly. Dr. Scott Ludwig released fire ants infected with a new type of phorid fly, a tiny parasite that preys only on red imported fire ants. The infected ants soon exhibit some very bizarre behavior. “First they become zombies, their movements under the control of the parasite. Then their heads fall off and the parasite emerges,” said Ludwig, AgriLife Extension integrated pest management special- ist. The “zombified,” fire ant is made to wander about 55 yards away from the mound to die. When infected with a parasitic phorid fly, fire “The parasite does this so it can complete de- ants exhibit some odd behavior. First they velopment without being detected and attacked become zombies, their movements under the by the fire ant colony,” he says. “By making control of the parasite. Then their heads fall their hosts wander away, the parasite is insur- off and the parasite emerges.Then the “zom- ing its survival.” The phorid fly species in Texas bified,” fire ant is made to wander away from only attacks red imported fire ants. They inject its mound to die. their eggs into their bodies. In response, fire ants withdraw to their underground nests and reduce their foraging range; once established, it is hoped that earlier releases of phorid flies will spread beyond the original release sites. The parasite N P M A L I B R A R Y U P D A T E Use of fungus on carpenter ants Use of parasitoid wasps to A fungus, Ophiocordyceps unilateralis, turns control cockroach oothecae carpenter ants into the walking dead and gets Parasitoid wasps are an important natural them to die in a spot that’s perfect for the fungus enemy of cockroaches. The wasps are parasitoids to grow and reproduce. Scientists have no clue of the cockroach egg case (the ootheca) and how the fungus takes control of the brains of can have a significantly negative impact on ants. But a new study in the September issue of outdoor cockroach populations. Most species of the American Naturalist reveals an incredible set parasitoid wasps are associated with peridomestic of strategies that result. cockroaches like the American and Smokybrown, The carpenter ants nest high in the canopy which live in outdoor harborages such as palm of a forest in Thailand, and they trek to the trees, tree holes, and woodpiles. These wasps forest floor to forage. The fungus prefers to end are very tiny (only 0.03-0.19 inches long!) and up on the undersides of leaves sprouting from do not sting humans. The parasitoids live with the northwest side of plants that grow on the the cockroaches in the harborage parasitizing forest floor, the new study shows. That’s where their egg cases. When the adult male and temperature, humidity and sunlight are ideal for female wasps emerge they mate immediately. Parasitoid wasps the fungus to grow and reproduce and infect The female then begins to sting other oothecae, are an important more ants. Once infected by the fungus, an ant laying her eggs inside of them. The wasp natural enemy is compelled to climb down from the canopy offspring eat the cockroach embryos inside the of cockroaches to the low leaves, where it clamps down with ootheca before they can hatch out. This natural and can have its mandibles just before it dies. “The fungus system results in 60-70 percent of all cockroach a significant, accurately manipulates the infected ants into egg cases being parasitized without any human negative impact dying where the parasite prefers to be, by interference! on outdoor making the ants travel a long way during the last Oothecal wasp parasitoids have been tested cockroach hours of their lives,” said study leader David P. for potential indoor use. Domestic populations populations. Hughes of Harvard. After the ant dies, the fungus of brown-banded cockroaches were successfully continues to grow inside it. By dissecting victims, controlled in a California animal rearing facility by Hughes and colleagues found that the parasite these wasps. Parasitoid wasps mass-reared and converts the ant’s innards into sugars that help used for client accounts present some interesting the fungus to grow. But it leaves the muscles challenges. Only a few individuals or special controlling the mandibles intact to make sure the accounts would actually welcome a population ant keeps its death grip on the leaf. The fungus of 200,000 wasps being released in their home also preserves the ant’s outer shell, growing or businesses even if they promised to eliminate into cracks and crevices to reinforce weak spots, a severe cockroach infestation.