Parasitic nematodes, Tetradonema sp. (Mermithoidea: Tetradonematidae) were obwserved in the fire ant. Solenopsis invicta Buren, for the first time. Five colonies in a sample of 14 colonies from one site in Mato Grosso were infected. The infection rate among adult workers was 12..5% in one colony and less than 5% in each of the remaining colonies. Adult reproductive males and females, eggs, and juvenile nematodes were observed in the haemocoel of male and worker ants. The infected worker ants often can be recognized by their slightly enlarged gasters, the dorsal scierites of which vable changes in behavior: infected adult males contained normal sperm. An attempt to transmit the nematode to colonies of S. invicta in the United States was unsuccessful.Título em português: Observações sobre um nematóide parasito (Tetradonematidae) da formiga lava-pé, Solenopsis (Formicidae), em Mato Grosso

JOUVENAZ, D. P.

LOFGREN, C. S.

NAVES, M. A.

WOJCIK, D. P.

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OBSERVATIONS ON A PAAASITIC NEMATODE (TETRADONEMATIDAE) OF FIRE ANTS,SQLENQPS/S (FORMICIDAE), FROM MATO GROSSO 1 DONALD P. JOUVENAZ, DAN I E L P. WOJCIK 2 , MARCIO A. NAVES 3 and CLIFFORD S. LOFGREN 2 ABSTRACT - Parasitic nematodes, Tetradonema sp. (Mermithoidea: Tetradonematidae) were ob-served in the fixe ant, Solenopsis invicta Buren,for the first time. Five colonies in a sample of 14 colo-nies from one site in Mato Grosso were infected. The infection rate among adult workers was 12.5% in one colony and less than 5% in eacli of thc remaining colonies. Adult reproductive males and females, eggs, and juvenile nematodes were observed in the haemocoel of male and worker ants. The infected worker ants oftcn can be recognized by their slightly enlarged gasters, the dorsal sclerites of which may have a scalloped appearance. There are no other morphological signs of infection and no obser-vable changes in behavior. lnfected adult males contained normal sperm. An attempt to transmit the nematode to colonies of S. invicta in lhe United States was unsuccessful. Index terms: Solenopsis invicta, Tetradonema, gaster, scicritcs, morphology, infection OBSERVAÇÕES SOBRE UM NEMATÕIDE PARASITO (TETRADONEMATI DAE) DA FORMIGA LAVA-PÉ, SOLENOPSIS (FORMICIDAE), EM MATO GROSSO RESUMO - Foi observado pela primeira vez um nematôide da familia Tetradonematidae parasitando Soteno pais invicta Ouren. Cinco colônias de um total de quatorze coletadas em Mato Grosso estavam infectadas. A taxa de infecção de adultos foi de 12,5% em uma colônia e as outras colônias restantes apresentaram menos de 5%. As formigas infectadas podem ser reconhecidas por apresentarem os gáste-rei ligeiramente maiores e os escleritos dorsais elevados. Não existem outros sinais morfolôgicos de infecção e nem modificações no comportamento que indiquem a infecção. Os machos adultos infecta-dos tinham esperma normal. A tentativa de transmissão do nematóide para colônias de S. invicta nos Estados Unidos da América foi negativa. Termos para indexação: Solenopsis invicta, Terradonema, infecção, gáster, escleritos, morfologia INTRODUCTION Two species of fire ants, Solenopsis richteri Forel and Solenopsis invicta Buren, were intro-duced jato the United States from South America. 1918 and 1940, respectively (liuren 1972). These infest over 10 8  ha in nine south-eastern states, and are slowly spreading. If they are trans-ported by man across the barrier of the and southwestern United States to more humjd or ir-rigated areas, their range could greatly increase. S. invicta, known in the United States as the "red iinported fire ant", occupies at !east 95% of Acceptcd for publication on June 9,1987. 2  Entomologist, M.Sc., Ph.D., lnsects Affecting Man and Animal Reseaxch Laboratory, U.S. Dcpartment of Agriculture, Agricultural Research Service, Gainesvilie, Flórida 32604, USA. Entomologist, M.Sc., Ph.D., EMBRAPA/UnB. Dep. Biol. Veg. Lab. de Controle Biológico, Caixa Pos-tal 153.081,CEP 70910 Brasília, DF, Brazil. the currentiy infested area. Except for one small enciave, S. richteri, the "black imported fire ant," has been dispiaced by the more recently intro-duced species. The native range of S. invicta is west-central Prazii (Rondonia, Mato Grosso, Mato Grosso do Sul) south along the Paraguay River into northcrn Argentina. S. richterí is native to Uruguay and parts 0f Argentina and southern Brazil (Buren et ai. 1974). The imported fire ants are medically and agricul-turaily important pests in the United States (Lof-gren & Adams 1982). Because of their ability to dominate the ant fauna in disturbed areas and be-cause of concerns about the use of pesticides to control them, there has been intense interest in the United States in the possibility of controlling them bioiogicaiiy. In the United States they are essentiaily free 0f natural enemies (Jouvenaz et ai. 1977); in Brazil, they are beset by both diseases and arthropod enemies (.Jouvenaz 1983). Therefo-re, the insects Affecting Man and Animais Re- Pesq. agropec. bras., Brasilia, 23(5):525-528,maio 1988. 526 	 D.P. JOUVENAZ et ai. search Laboratory, Agricultural Research Service (ARS), U.S. Department of Agriculture (USDA), concluded a cooperative agreement with the Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) in September 1983, to survey for natural enemies of fire ants, and also to explore means of identifying the natural enemies of leaf--cutting ants. The goal of this research isto disco-ver and evaluate specific parasites and diseases of fire ants. Natural enemies potentiaily usefui for fire ant control will be considered for introduction into the United States. The nematode reported here is the first to be found in fite ants in South America. The only other nematode reported from fire ants is an uni-dentified (but different) species that was found recentiy in a few alcohol-preserved specimens of Solenopsis geminata ( F.), a species native to Flori-da (Mitcheli & Jouvenaz 1985). MATERIAL AND METHOOS The procedures for screening large numbers of ants for pathogens have been described by Jouvenaz etal. (1977). Samples of soU are laken frorn nests into lhe labo-ralory in small buckels, lhe sides of which have been dusled with tale lo prevenI lhe anIs from escaping. The soil is moislened if necessary, and allowed tu stand undis-lurbed overnighl lo aliow the anIs lo establish tunneis and gather lhe brood. lhe ants are forced lo lhe surface by slowly dripping water into lhe soil until II is comple-tely submerged. The anIs (including immatures rescued by lhe adult workers) floal in masses and are lransferred easily lo new containers. A sample of ca. 1,000 lo 2,000 mixed adults and immalures froin each colony is then triturated in distilled waler in a giass tissue grinder, and the crude exlract is examined by phase-conlrasl micros-copy for fungai mycelia or spores, prolozoan spores, vi-rus polyhcdra, nematode eggs or larvae, and unusual num-bers of bacteria. Non-occluded viruses cannot, of course, be delected by this procedure. When extracts containing suspectcd palhogens are found, individual anIs from lhe colony are examined lo determine whelher disease is indeed presenl. Nematode eggs, juvenules, and aduits dissecled from the gasters of adult worker ants were preserved in 3% for-malin conlaining 2% glycerine (vfv). Measuremenls were made from calibraled phase-conlrasl photomicrographs. The inlracolonial infeclion rales were delermined by phase-microscopic examinalion of individual squashes of 200 workers randomly selecled. In lhe mosl heavily infecled colony, 200 worker pupae and 200 adull males, and ali 65 adult alale females in the coilection, were also examined, as were lhree aduil and fourteen pupae of lhe Pesq. agropec. bras., Brasilia, 23(5):525-528, maio 1988. parasitic wasp, O,&zsema sp. (liymenoptera: Euchari-tidae). Aduil worker ants from each colony were pre-served in 70% elhanol for positive idenlificalion and for examinalion for morphologicai aberrations. An attempl was made lo infecl Iwo small colonies of S. invicta from Florida wilh lhe nematode. Workers from lhe most heavily infecled coiony were hand-carried (under Brazilian and USDA permits) lo lhe Insecls Mfecting Man and Animais Research Laboratory, ARS, USDA, Gainesville, Florida, USA. Th6re lhey were maintained on autoclaved soil in Iwo large petri disbes for lhree weeks, lhen removed from lhe soll and replaeed wilh Iwo small colonies of S. invicta, After two monlhs, the S. invicta coionies from Florida were examined for infection. Living and preserved workers were also sub-mitled to Dr. W.R. Nickie,Bellsville Agricultural Research Center, ARS, USDA, Beitsville, Maryland. RESULTS A nematode, Tetradoneina sp. (Mermithoidea: Tetradonematidae), infected five of fourteen colo-nies of S. invicta collected 5 February 1985, from a 250 - m section of roadside at icm 616, BR 070, between Cuiabá and Cáceres, MT (disturbed cerra-do). In the most heavily infected colony, 12.5%. of the adult workers and 2% of the adult males were infected. None of the 65 adult females col-lected from this colony were infected, nor was infection detected in worker pupae (early infec-tion may be difficuit to detect). The specimens of parasitic wasps, Orasema sp., from this colony were not infected. In the other four colonies, the infection rates were no more than 5% in adult workers. The coliection site for the infected colonies was a roadside having a slope ca. 15 0 - 200. No pattern of distribution of infected coionies was apparent, as non-infected colonies were located between infected colonies. Two infected colonies were located upsiope (34 m and 53 m) and two downslope (108 m and 119 m) from the coiony with the highest infection site. Ali 0f the colonies, including the infected ones, were large and con-tained abundant brood Eggs, juveniles, and egg-iaying adult nematodes were found in S. invicta workers. The eggs andju-veniles (Fig. 1) are readily observed in aqueous extracts or squashes of ants (phase-contrast mi-croscopy). By placing a living ant in water under OBSERVATIONS ON A PARASITIC NEMATODE 	 527 FIG. 1. Two nematode eggs and a juvenhie from the fire ant, S. invicta. X 650. a covcr siip, the active nematode juveniles rnay also be sccri under iow magnification (200 X) phase.contrasc nicroscopy in che haemoiyrnph throughouc thc body of the host, including thc mandibles, aritennae, and tarsi. The eggs and aduits are confined to the gaster. The aduit nematodes are usualiy dcstroyed in cxtracts and squashes, and are best observcd hy dissecting thc gasters of large workers (Fig. 2 and 3). Thc adult nematodcs measure 1.2 moi co 1.4 mm iii icngt ii and ca. 0,17 mm in diameter. From 17 to 35 werc dissected frorn thc gasters of iarge workcrs. Thesc ratlier thick-bodied riernatodes contained eggs chroughout thcir hodics. The juvenhles rneasu-re ca. 0.15 rum iii icngth, che cggs slight!y less than 0.04 mm in dianieter. At least 1,000 cggs and juveniles (tocai) were prescnt in largc workers. W.R. Nickje, U.S.D.A., ARS, Beitsville, MD, FIG. 2. Adult female nematodes in a partially dissected gaster of a worker tire ant, S. invicta. X 32. 1111 1111 FIG, 3. Adult female nematodes dissected from the qas-ter of a worker tire ant, S. invicta. Divisioris are in mm. X 15. obscrved a mia!i aduli male nensatode iii a worker ant. Living ants para sitized by these nematodes may often be rccognized by thcir s!ightly eniarged gas-ters, thc dorsal scierites ot which have a scailoped appearance. There are no other morpho!ogical signs of infection, nor are tlierc any observable changes iii bebavior. Ali four of the infected males containcd sperm. An attempt to transrnit the infection to two colonies of S. iui'icta froni Flori-da was not successfui. Thc nernatode was coliected in Fehruary 1985.   In May, W.A. Bariks, D.F. Williams, and A.C.C. Pereira scrcened eight colonies from the roadsidcs adjaccnt co both ends of the coilection site but djd not find the infection. In June 1984, D.P. Wojcik had coiiccted this sarne site without find-ing ncniatodes. DISCUSSION Wcre exarnined over 1,200 colonies of fire ants from a 150 krn radius 0f Cuiabá, and south through Rondonopólis, Coxim, and Campo Gran-de. Several pachogens have been observed com-monly (Jouvenaz 1983). The presence of nemato-des in íive colonies (in a coHecciun of 14 colonies) f'rom one site on one occasion indicates that this parasite may bc unevenly distributed, or cyclic, or both. Thc fai!ure co transmit the jnfection iii the laboratory may possibie be due to f'actors that restrict the natural distribution of the nema-tode. The propagation and transmissiori, !ife cyc!e. Pesq. agropec. bras., Brasília, 23(5):525-528, maio 1988. 528 	 D.P. JOUVENAZ etal. host range and pathology, and classification of this BUREN, W.F.; ALLEN, Gi.; WHITCOMB, W.H.; LEN- potential biological control agent will be the sub- 	 NARTZ, F.E.; WILLIAMS, R.N. Zoogeography of ject of future research. 	 lhe imported fire ants. J.N.Y. Entomol. Soe., 82: 113-24, 1974. ACKNOWI-EDGMENTS The authors wish to express their gratitude to Dr. William R. Nickle, USDA, ARS, Beltsville, Maryland, USA, for classifying the nematode to genus, and to José Leocádio Gondim de Lima and Jorge Senatore Vargas Rodrigues, U.E.P., Cá-Geres, Mato Grosso State, Brazil, for excellent technical assistance. REFERENCES BUREN, W.F. Revisionary studies on the taxonomy of lhe imported tire ants. J. Os. Entomol. Soc., 7:1-26, 1972. JOUVENAZ, D.P. Natural enemies of fixe ants. Fia. EntomoL, 66:111-21, 1983. JOUVENAZ, D.P; ALLEN, G.E.; BANKS, tA.; W0J-C1K, D.P. A survey for pathogens of tire ants, Solenopsis spp, in the southeastern United States. Fia. EntomoL, 60:275-9, 1977. LOFGREN, C.S. & ADAMS, C.T. Economie aspects of the irnported tire ant in lhe United States. lii: BREED, MD.; M1CHENER, C.D.; EVANS, fiE., ei The biology of social insects. Boulder, Westview, 1982. 419p. MITCIIELL, G.B. & JOUVENAZ, D.P. Parasitie nemato-de observed in the tropical fixe ant. Solenopsis ge-ininata (F.) (Hymenoptera: Formicidae). Fia. Entomol., 68:492-3, 1985. Pesq. agropec. liras., Brasilia, 23(5):525-528, maio 1988. 

Observations on a parasitic nematode (Tetradonematidae) of fire ants, solenopsis (Formicidae), from Mato Grosso.

Parasitic nematodes, Tetradonema sp. (Mermithoidea: Tetradonematidae) were obwserved in the fire ant. Solenopsis invicta Buren, for the first time. Five colonies in a sample of 14 colonies from one site in Mato Grosso were infected. The infection rate among adult workers was 12..5% in one colony and less than 5% in each of the remaining colonies. Adult reproductive males and females, eggs, and juvenile nematodes were observed in the haemocoel of male and worker ants. The infected worker ants often can be recognized by their slightly enlarged gasters, the dorsal scierites of which vable changes in behavior: infected adult males contained normal sperm. An attempt to transmit the nematode to colonies of S. invicta in the United States was unsuccessful.Made available in DSpace on 2019-10-23T18:09:03Z (GMT). No. of bitstreams: 1
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Observations on a parasitic nematode (Tetradonematidae) of fire ants, solenopsis (Formicidae), from Mato Grosso.

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