Weeds

Waterhyacinth, Eichhornia crassipes
Alligator weed, Alternanthera philoxeroides
Lippia, Phyla canescens
Parkinsonia, Parkinsonia aculeata
Fanwort, Cabomba caroliniana
Brazilian pepper, Schinus terebinthifolius
Brazilian water weed, Egeria densa
Water primrose, Ludwigia hexapetala
Balloon vine & Pompom weed, Cardiospermum grandiflorum & Campuloclinium macrocephalum
Waterlettuce, Pistia stratiotes

Insects

Imported Fire Ants, Solenopsis invicta & S. richteri
Glassy Winged Sharpshooter, Homalodisca vitripennis
Corn Rootworms, Diabrotica spp.
Cactus moth, Cactoblastis cactorum
Little Fire Ant, Wasmannia auropunctata

    Waterhyacinth

Eichhornia crassipes 

SABCL staff in charge:
M. Cristina Hernández
Alejandro Sosa
Guillermo Cabrera
Intern: Gerardo Elsesser

Cooperators: Phil Tipping and Ted Center, USDA-ARS-Invasive Plants Research Laboratory, Ft. Lauderdale, FL, USA, and Martin Hill, Rhodes University, South Africa
IPRL, Fort Lauderdale, Florida
PPRI, South Africa

Waterhyacinth is considered the world’s worst aquatic weed in tropical and subtropical water bodies (Holm et al., 1977).  It was introduced into the US and many other countries in the late 19th and early 20th centuries (Julien, 2001). It spreads at a dramatic rate, particularly under the combination of eutrophication of water bodies and absence of its natural enemies. In the US it occurs in the southeastern states, California and Hawaii.

Although biocontrol has proved to be the most effective method to provide long-term control, additional agents are needed. Some of the Waterhyacinth natural enemies with potential to be used as biocontrol agents are currently being studied at the SABCL. Tests conducted with the mining fly, Thrypticus truncatus, and the delphacid plant hopper, Megamelus scutellaris, showed high specificity on WH. In 2006, Megamelus scutellaris was shipped to quarantine at IPRL in Ft. Lauderdale for further studies and it was recently approved for field release.

The new candidate Taosa spp. (Hemiptera; Dictyopharidae) is currently under study. This planthopper was found and collected in many exploratory trips in South America by SABCL personnel. The collections probably include three undescribed species, some of which may be WH specialist. In 2007, an important detrimental effect of Taosa sp.1 was confirmed. Taosa sp. 1 is being described as a new species for science. Both Thrypticus truncatus and Taosa sp.1 were shipped to quarantine at IPRL in early 2008.

Annual Report 2007 
       Annual Report 2008

FOR MORE INFORMATION CONTACT CRISTINA HERNANDEZ crisher@speedy.com.ar

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    Alligator weed

Alternanthera philoxeroides 

SABCL staff in charge:
Alejandro Sosa
Intern: Cristian Rodríguez

Cooperator: Mic Julien, CSIRO European Laboratory, Montferrier sur Lez, France
CSIRO Entomology

This project has been conducted by SABCL since October 2001 after an agreement between the ARS and CSIRO (Australia). The CSIRO initiated this collaborative research project in Argentina to search for new biological agents, update the list of natural enemies known and to determine the native range of the weed.

Alligator weed, Alternanthera philoxeroides (Mart.) Griseb (Amaranthaceae) is an herbaceous amphibious weed native to southern South America. In northern and central Argentina it is distributed along the catchments of the Paraná and Uruguay rivers, and in the catchments of the San Borombón and Salado rivers respectively. The plant was introduced into many countries becoming in a serious aquatic and terrestrial weed.

This weed drew the attention of biological control specialists in USA in the 1960´s. Surveys were carried out in its natural range and a list of its natural enemies was built. The flea beetle Agasicles hygrophila Selman and Vogt, the moth Arcola malloi (Pastrana) and the thrips Aminothrips andensonii O´Neill (Spencer and Coulson 1976) were  released in the USA. The flea beetle and the moths were subsequently released in Australia and controlled the weed in warm temperate aquatic habitats (Julien and Griffiths 1999). However, terrestrial growth of the weed and aquatic growth in cooler regions of Australia continue to cause serious concern (Julien and Bourne 1988), so new agents are needed to control the weed in those ecosystems.

New agents have been found: the leaf feeder chrysomelid beetles Systena and Phenrica sp., the gall flies Clinodiplosis alternantherae and Ophiomyia marellii, a stem mining fly (possibly Ophiomyia buscki) and two leaf mining flies Ophiomyia alternantherae and one still unidentified. Also, generalist fungi such as Nymbia alternantherae and probably Sphaceloma sp. Clinodiplosis alternantherae was recently shipped to quarantine in Brisbane, Australia for further research and eventual field release. In 2007, genetic effects of the plant were discovered on the life cycle of Agasicles hygrophila.

Annual Report 2007 
Annual Report 2008

FOR MORE INFORMATION CONTACT ALEJANDRO SOSA alejsosa@speedy.com.ar

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    Lippia

Phyla canescens 

SABCL staff in charge:
Alejandro Sosa
Intern: Cristian Rodríguez

Cooperator: Mic Julien, CSIRO European Laboratory, Montferrier sur Lez, France
CSIRO Entomology

Lippia, Phyla canescens (Kunth) Greene (Verbenaceae), is a fast-growing, mat-forming plant, native to South America and introduced into Australia in late nineteenth century as an ornamental. Its spreading nature and deep rooting system are associated with stream bank and soil erosion, structural damage to roads and high control costs.

An agreement with CSIRO (Australia) was signed to determine (1) the centre of origin, (2) the distribution range and (3) the potential biological control agents (insects and pathogens). Pathogens are being studied with the cooperation of Guadalupe Traversa, PhD student at the Universidad Nacional del Sur, Bahía Blanca, Argentina.

Insects found: four beetles (Chrysomelidae), a leaf mining fly (Agromyzidae?), two thrips (Thysanoptera), two micro moths and two hairy caterpillars, eriophyid mites, unidentified stem gallers, four leafhoppers (Cicadellidae), two Cercopidae and recently (May 2007) a weevil. Longitarsus spp. were found throughout the ranges of both plants, only as adults feeding on leaves. Larvae are possibly root feeders as recorded on other Longitarsus sp. feeding on verbenaceous plants (Simelane 2005) but lab rearing has not yet been successful.

The flea-beetle Kuschelina bergi Harold, was found on litter or the ground amongst prostrate stems. In the lab it has five larval stages and takes about two months to complete its cycle. Pupation occurs in the substrate and takes about two weeks. Further studies including host range tests are planned.

Fungi found:  the secondary invaders Nigrospora, Sordaria, Podospora; the pathogenic Puccinia cf. lantanae, Cercospora cf. lippiae, Colletotrichum spp.; and others with unknown pathobiology Fusarium sp., Bipolaris sp., Alternaria sp., Phoma sp., Phomopsis sp. Cercospora cf. lippiae was the most widespread causing a necrotic leaf spot. There are at least three Colletotrichum spp. involved in leaf spot symptoms; one of them might be a new species. The microcyclic rust Puccinia cf. lantanae should be prioritized for further studies but its host range may include also Phyla reptans.

Annual Report 2007 
       Annual Report 2008

FOR MORE INFORMATION CONTACT ALEJANDRO SOSA alejsosa@speedy.com.ar

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Parkinsonia aculeata

SABCL staff in charge:
Fernando Mc Kay
Alejandro Sosa
Interns: Marcelo Parisi, Cristian Rodríguez

Cooperator: Tim Heard, CSIRO Entomology, Indooroopilly, Australia
CSIRO Entomology

Parkinsonia aculeata (Caesalpinioideae), native to the Americas, has a pan-tropical distribution following introduction as an ornamental, hedging, fodder and shade tree. In Australia, also planted as an ornamental and shade tree, it forms dense, thorny, impenetrable thickets along drainage lines, depressions, ephemeral wetlands and uplands.

Investigations on potential biological control of P. aculeata began in 1983. Two insects from the Sonoran Desert Region, Rhinacloa callicrates Herring (a sap-sucking mirid) and Mimosestes ulkei (Horn) (a seed-feeding bruchid) were released in Queensland and the Northern Territory from 1989 to 1994. A third insect from Argentina, the seed-feeding bruchid Penthobruchus germaini Pic. was released in 1995. Because these agents do not have a significant impact and new potential agents are unlikely to be found in the United States or northern Mexico, efforts will be concentrated in South America.

Previous surveys conducted in Argentina and Paraguay by USDA researchers revealed the existence of two moths, Eueupithecia cisplatensis (Prout) and Euacidalia sp. In October 2008, a cooperative agreement was signed with CSIRO Entomology. The main objective of this project is to search for and study the host specificity of the moths. Collections and preliminary laboratory tests are in progress.

FOR MORE INFORMATION CONTACT FERNANDO MC KAY                             fmckay@speedy.com.ar

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Cabomba caroliniana

SABCL staff in charge:
Guillermo Cabrera
Intern: Magalí Dalto

Cooperator: Mic Julien, CSIRO European Laboratory, Montferrier sur Lez, France, and Shon Schooler, CSIRO Entomology, Indooroopilly, Australia
CSIRO Entomology

Fanwort, Cabomba caroliniana Gray, is a submerged aquatic plant distributed and considered native in the neotropics and North America. However, considering the neoptropical distribution of the genus, it is probably naturalized in North America (Orgaard 1991). It is considered a weed in the U.S., Japan and Australia, and may have problematic status in southeast Asia (Mackey 1996). It was most probably dispersed by aquarists and aquarium suppliers who grew the plant, or disposed of them, in open water courses. 

This weed affects the environment by the magnesium excedents during winter fallback of the plant; by the excess of organic matter and eutrophication of water courses and catchments, by displacement of native plants and their associated fauna. Also, it has an important impact on navigation, fishing,  practice of aquatic sports, and other large scale water uses (Mackey 1996). 

In Argentina, the two varieties, Cabomba caroliniana and C. flavida (Orgaard 1991), are cited for Buenos Aires, Rio Negro, Córdoba, Corrientes, Entre Rios, and Santa Fe (Bonetto & Hurtado 1998, Catálogo de las plantas vasculares de la Argentina 2002). It is not considered a weed in South America. This is the first natural enemy survey on this plant.

Current research efforts are concentrated in the weevil Hydrotimetes natans. Adults feed on foliage, and the larvae mine the stems. The pupa develops in a kind of air tight cocoon attached to the stems. It has been collected at several locations in Corrientes. It is a true swimmer/diver that can live under water for hours on end by holding a permanent air bubble surrounding its abdominal sternites. Field and laboratory host range studies indicated that it is specific to fanwort. The weevil was recently shipped to quarantine in Brisbane, Australia.

Annual Report 2007 
Annual Report 2008

FOR MORE INFORMATION CONTACT GUILLERMO CABRERA                                 gcabrera@speedy.com.ar

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Schinus terebinthifolius 

SABCL staff in charge:
Fernando Mc Kay
Guillermo Cabrera
Intern: Marcelo Parisi

Cooperators: Greg Wheeler and Ted Center, USDA-ARS-Invasive Plants Research Laboratory, Ft. Lauderdale, FL, USA.
IPRL, Fort Lauderdale, Florida

The BP was introduced in the U.S. during the late XIX century as an ornamental. At present, it is considered a high-priority target due to its widespread occurrence in Hawaii, California and Florida. First biocontrol efforts against BP were carried out in Hawaii during the 1950´s.  Three insects were released from South America: Episimus utilis Zimmerman (Lepidoptera: Tortricidae) in 1954, Lithraeus atronotatus Pic (Coleoptera: Bruchidae) in 1960, and Crasimorpha infuscata Hodges (Lepidoptera: Gelechiidae) in 1961; E. utilis and L. atronatus got established but exert only negligible control (Krauss 1962; Yoshioka and Martin 1991; Julien and Griffiths 1998; Hight et al. 2002). Additional surveys were conducted in Brazil during the 1980´s and 1990´s (Bennet and Habeck 1991, Medal et al. 1999). However, no insects have been released in Florida against BP. An accidental introduction from South Africa of a seed-feeding wasp, Megastigmus transvaalensis Hussey (Hymenoptera: Torymidae), was recorded in Florida (Habeck et al. 1989). The wasp is currently causing 30% seed mortality (Wheeler et al. 2001). The leaf feeder sawfly Heteroperreyia hubrichi (Hymenoptera: Pergidae) and the sap sucking thrip Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) were introduced in quarantine to conduct risk assessment studies (Hight et al. 2003). Petitions to release these agents have been submitted to the TAG. Although the release of the sawfly was authorized, the decision has been delayed until the impact of the toxins discovered in the larvae is assessed (Hight et al. 2002, Cuda, pers comm.). Additional host range studies of the thrip were requested by TAG.  

In June 2004, a cooperative agreement was signed with the IPRL, Fort Lauderdale, FL. Field surveys were conducted and important organisms were found: the leaf feeder sawfly, Heteroperreyia hubrichi (Hymenoptera: Pergidae), a seed feeder bruchid, probably Lithraeus (=Bruchus) atronotatus Pic, a leaf blotch miner, the weevil Apocnemidophorus blandus (a batch of insects was collected in March 2004 and taken to the quarantine facility in Gainesville, Fl.), and an unidentified eriphyoid mite. More recently, other organisms were found. The research is now focused on the Gracillariidae blotch leaf miner and the moth Tecmessa elegans (Lepidoptera: Notodontidae). T. elegans showed a wide host range within the Anacardiaceae species. A new species of leaf miner moth, possibly Stigmella sp. (Nepticulidae) and an unidentified Gelechiidae leaf miner were found mining leaves of BP and BP and L. molleoides respectively.

Annual Report 2007 
     Annual Report 2008

FOR MORE INFORMATION CONTACT FERNANDO MC KAY fmckay@speedy.com.ar

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Egeria densa

SABCL staff in charge:
Guillermo Cabrera
Intern: Magalí Dalto

Cooperator: Ray Carruthers and Lars Anderson, USDA-ARS-Exotic & Invasive Weed Research Unit, Albany and Davis, CA, USA.
EIWRU, California

Egeria, commonly called Brazilian waterweed, is a South American genus of rooted, perennial, submerged plants (Hydrocharitaceae). Two species, E. densa Planchon and E. najas Planchon, are amply distributed in southern South America where they are not considered weeds, and therefore they have not been studied extensively. Consequently, little is known about their ecology and natural enemies. Egeria densa has weed status in North America, where it invades fresh water courses, forming dense patches that hinder navigation, fishing and other recreational water uses, and presents a severe ecological threat due to its invasiveness.

Surveys conducted in Argentina revealed that E. najas is more abundant than E. densa, at least in the northern regions. In samples of E. densa from Entre Ríos province, we found larvae of a pyralid (Lepidoptera), probably Paraponyx sp., mining the terminal shoots; several stem mines of Chironomidae and of a shore fly Hydrellia (Diptera: Ephydridae); many midge larvae, caddisflies, gastropods, and aquatic beetles. 

Current research is concentrated in Hydrellia nv. sp., found to attack Egeria throughout its distribution in Argentina. The fly was reared successfully in the laboratory, and tested for damage levels and host specificity. It can achieve heavy defoliation of the plant, both in the laboratory and in the field in its native range. Results indicate Hydrellia nv. sp. is a good candidate for the biocontrol of E. densa. It will be shipped to quarantine at the EIWRU during 2009.

Annual Report 2007 
Annual Report 2008

FOR MORE INFORMATION CONTACT GUILLERMO CABRERA                                 gcabrera@speedy.com.ar   

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    Water primrose

Ludwigia hexapetala 

SABCL staff in charge:
M. Cristina Hernández
Guillermo Cabrera
Intern: Gerardo Elsesser

Cooperator: Ray Carruthers and Brenda Grewell, USDA-ARS-Exotic & Invasive Weed Research Unit, Albany and Davis, CA, USA.
EIWRU, California

The genus Ludwigia includes 82 species, 20 of which occur in Argentina. They are predominantly tropical herbs or shrubs with unclear diagnostic differences. In addition, in Argentina and Brazil natural hybrids have been recorded (Munz 1942; Zardini, et al. 1991). L. hexapetala, commonly called water primrose, is native to southern South America and invasive in California. L. grandiflora is also considered a nuisance in south-eastern U.S.

Genetic and molecular studies, combined with traditional morphology and field explorations, are underway in order to clarify the taxonomic problem and tackle the native fauna with specific knowledge of the group. These studies are partially funded by Dr. Hilda Díaz Soltero, USDA-Invasive Species Coordinator, Washington DC.

 Preliminary surveys on Ludwigia spp. were conducted and the following species were collected and preserved: L. grandiflora subsp. hexapetala, L. peploides peploides, L. p. subsp. montevidensis, L. peploides near glabrescens, L. elegans (Cambess.) Hara, L. bonariensis (Micheli) Hara, L. longifolia (DC) Hara, L. caparrosa (Cambess.) Hara, L. leptocarpa (Nutt.) Hara, L. octovalvis (Jacqs.) Raven, L. peruviana (L.) Hara, L. neograndiflora (Munz) Hara, and L. sericea (Cambess.) Hara.

   Larvae found feeding on L.g. subsp. hexapetala, and on subspecies of L. peploides were sampled and the adults obtained. Although the taxonomic identification is pending, the specimens obtained belong to the following taxa: 1) Coleoptera: Curculionidae: Auleutes sp.; Tyloderma sp.; and three species not identified. Chrysomelidae: Lysathia sp., and one not id. 2) Homoptera: Fulgoridae, two species. 3) Thysanoptera, 4) Lepidoptera: Sphingidae, Pterophoridae, Tortricidae, and Pyralidae, 5) Hymenoptera: Pergidae: Lagideus badoae.  

Annual Report 2007 
     Annual Report 2008

FOR MORE INFORMATION CONTACT CRISTINA HERNANDEZ crisher@speedy.com.ar

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Cardiospermum grandiflorum & Campuloclinium macrocephalum

SABCL staff in charge:
Fernando Mc Kay
Intern: Marcelo Parisi

Cooperators: David Simelane and Andrew McConnachie, Agricultural Research Council, Plant Protection Research Institute, Pretoria and Hilton, South Africa
PPRI, South Africa

As part of a new strategy of targeting weeds at an early stage of invasion, a new agreement for cooperative research has been signed in January 2005 between the Plant Protection Research Institute (PPRI), Pretoria, South Africa and the SABCL. The main objective of this project is to search for and study host specific natural enemies of the emerging weeds (EW) Cardiospermum grandiflorum Sw. (Balloon vine), Campuloclinium macrocephalum (Less.) DC. (Pompom weed), and Pereskia aculeata Mill. (Barbados gooseberry). Studies on P. aculeata have been suspended.

Balloon vine (Cardiospermum grandiflorum) is a perennial slightly woody climber of the Soapberry family (Sapindaceae). Original from Tropical and Sub Tropical America (Panamá to Argentina), this tendril-bearing vine also occurs in Australia and Africa (Ferrucci 1991). Some of the organisms found were: Cissoanthonomus tuberculipennis Hustache (Coleoptera: Curculionidae) developing inside fruits; the “hairstreak moth” Chlorostrymon simaethis sarita (Skinner) (Lepidoptera: Lycaenidae), on both Cardiospermum grandiflorum and C. halicacabum (currently in quarantine facilities in Pretoria, South Africa);  a Pyralidae moth destroying the seeds; Gargaphia sp. (Hemiptera: Tingitidae) (was recently shipped to quarantine); the moth Apocera zographica and the fungus Phyllacora rimulosa

Pompom weed (Campuloclinium macrocephalum) is considered a serious invasive weed in South Africa (Henderson 2001). It has showy pink flower heads at the end of green to purplish aerial stems. The plant has a short woody rootstock that ends in thick tuber-like perennial roots, that enables the plant to survive fires, frost and drought conditions. Some of the organisms found on this weed were: the stem-boring, Zeale (=Adesmus) nigromaculatus (Coleoptera: Cerambycidae); Carmenta n. sp. (Lepidoptera: Sesiidae); Liothrips tractabilis; Gelechiidae and a Pterophoridae moth, the fly Trupanea sp.. Recently, the moths Cochylis campuloclinium and Adaina simplicius and the thrips Liothrips tandililensis were shipped to quarantine for specificity testing

Annual Report 2007 
Annual Report 2008

FOR MORE INFORMATION CONTACT FERNANDO MC KAY fmckay@speedy.com.ar

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    Waterlettuce

Pistia stratiotes 

SABCL staff in charge:
Guillermo Cabrera
M. Cristina Hernández
Interns: Magalí Dalto, Gerardo Elsesser

Cooperators: Phil Tipping and Ted Center, USDA-ARS-Invasive Plants Research Laboratory, Ft. Lauderdale, FL, USA
IPRL, Fort Lauderdale, Florida

Waterlettuce (Pistia stratiotes L.)(Araceae) is a floating aquatic plant that affects the water flow in lakes, ponds, streams, and channels in southeastern US and many other tropical and subtropical areas of the world. Also, it has an important impact on submersed animal and plant communities.

In the 70's, SABCL staff tested several insects as biocontrol agents: the weevils Neohydronomus affinis Hustache, Argentinorhynchus bruchi (Hustache), Pistiacola cretatus (Champion), and the pyralid moth Samea multiplicalis (Guenée). Although N. affinis has been used successfully in, among other countries, Australia and Zimbabwe, long-term suppression of waterlettuce has not been observed in the US. Samea multiplicalis is established in Australia but its impact has not been evaluated.

Starting in 2009, renewed efforts are being implemented at SABCL to survey local populations of waterlettuce for additional natural enemies that are known to occur.

FOR MORE INFORMATION CONTACT GUILLERMO CABRERA gcabrera@speedy.com.ar   

Solenopsis invicta & S. richteri 

SABCL staff in charge:
Juan Briano
Luis Calcaterra
Laura Varone
Intern: Leonardo Ramírez

Cooperators:  Robert Vander Meer, Sanford Porter, David Oi, Steven Valles, Dewayne Shoemaker, USDA-ARS-Center for Medical, Agricultural, and Veterinary Entomology (CMAVE), Gainesville, FL, USA.
CMAVE, Gainesville

The red and black imported fire ants, Solenopsis invicta Buren and S. richteri Forel, respectively, where accidentally introduced into the United States from South America in the early 1900´s. The former infests 320 million acres in 12 southern states from Florida to California, also in Puerto Rico, other Caribean areas and Mexico. In 2001, S. invicta was discovered in Brisbane, Australia and Auckland, New Zealand. More recently, it was detected in Taiwan, mainland China and Hong Kong.

Several organisms are under study for the biological control of the imported fire ants in the United States: the microsporidian pathogens Kneallhazia (=Thelohania) solenopsae (Microsporida: Thelohaniidae) and Vairimorpha invictae (Microsporida: Burenellidae), several species of the parasitoid fly Pseudacteon spp. (Diptera: Phoridae), the parasitic ant Solenopsis daguerrei (Hymenoptera: Formicidae), the micro wasps Orasema simplex and O. xanthopus (Hymenoptera: Eucharitidae), and Allomermis solenopsii (Nematoda: Mermithidae). Kneallhazia solenopsae, P. tricuspis, P. curvatus, P. litoralis, and P. obtusus  were released in the field in the United States and are being evaluated. The microsporidium V. invictae is still in quarantine in Gainesville, together with the flies P. nocens and P. cultellatus, and will be eventually field released in the near future.

Ecological interactions of fire ants with competitors ants and phorid flies are being evaluated in different habitats in Argentina. In addition, genetic studies are being conducted at CMAVE with material collected in South America to characterize the populations structure of the parasitic S. daguerrei to match their local populations with their fire ant hosts. Also genetic studies are being performed to detect the source population of the fire ants present in the United States and other countries.

In mid 2008, equipment, supplies and reagents were transferred from CMAVE to conduct PCR studies and detect fire ant viruses in Argentina. Surveys and assays started after a training conducted by Dr. Steven Valles at SABCL in September 2008.

Annual Report 2007 
     Annual Report 2008
Imported Fire Ant Literature Database 

FOR MORE INFORMATION CONTACT JUAN BRIANO jabriano@speedy.com.ar

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Homalodisca vitripennis

SABCL staff in charge:
Guillermo Logarzo
Intern: Mariel Guala

Cooperators: Jesse de León, USDA-ARS-Beneficial Insects Research Unit, Weslaco, TX and Serguei Trapitsyn, University of California, Riverside, CA, USA
BIRU, Texas

The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis Say (Homoptera: Cicadellidae), is native to southeastern US. Since early 1990’s, it has spread dramatically resulting in a very serious pest problem in the Central Valley and coastal viticulture regions in southern California. GWSS is a vector of the bacterial pathogen, Xylella fastidiosa, the causal agent of the Pierce’s disease of grapes, the phoney peach disease in southern US, the variegated chlorosis of citrus in Brazil, and the oleander leaf scorch in southern California. So far, only the egg parasite, Gonatocerus ashmeadi Girault (Hymenoptera: Mymaridae) was recorded against GWSS. Although parasitism rate ranges 80-100%, sufficient numbers of over-wintering adults remain in the field to re-start problems the following season. More work is needed on GWSS biology, management and biological control, including foreign exploration for biological control agents in California.

In 2000, the SABCL started a survey of egg parasitoids of Tapajosa rubromarginata Signoret (Homoptera: Cicadellidae) and other proconiini sharpshooters related to GWSS in Argentina, Chile and Perú. Eight species of Gonatocerus (Mymaridae), one species of Paracentrobia, 2 species of Oligosita and 2 species of Zagella (Trichogrammatidae) were obtained.

Current research is focused on specificity studies of G. tuberculifemur in the lab and in the field. Studies have been conducted also on functional response and climatic tolerance. Surveys for egg parasitoids are continued. Recent molecular, biological and morphological studies revealed the presence of two cryptic species in the G. tuberculifemur complex. Several species were shipped to Mission TX and more recently to Riverside CA for further testing under quarantine conditions. The release of these parasitoids in California is controversial.

Annual Report 2007 
     Annual Report 2008

FOR MORE INFORMATION CONTACT GUILLERMO LOGARZO glogarzo@speedy.com.ar

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Diabrotica spp. 

SABCL staff in charge:
Guillermo Cabrera
Intern: Magalí Dalto

Cooperators: Don Weber, Mike Athanas, USDA-ARS-Insect Biocontrol Laboratory, Beltsville, MD, USA.
IBL, Beltsville

The genus Diabrotica (corn rootworms and cucumber beetles) includes some of the most important row crop and vegetable pests of the Americas. In South America, the most common and problematic species are Diabrotica speciosa (Germar), that causes important damage in maize, cucurbits, potatoes, soybeans, and tender parts of almost every crop; Diabrotica viridula (F.), a pest of corn; and several species akin to the North American striped cucumber beetle (Acalymma vittatum (F.), Acalymma albidovittata (Baly), Acalymma bivittula (Kirsch), and Acalymma bruchii (Bowditch), which cause significant damage to cucurbits.

The parasitoid Centistes gasseni Shaw has been collected in southern Brazil, eastern Paraguay, and northeast Argentina, in Diabrotica spp. and Celatoria bosqi Blanchard was the first one described in South America, where large natural infestations have been observed. C. bosqi has been collected throughout the South American distribution area of its main host, D. speciosa, in an area that includes temperate and tropical lowlands, and semiarid to humid highlands. Both parasitoids thrive in subtropical to temperate climates similar to many parts of the U.S.A., suggesting they could be released as biocontrol agents only in those areas.

Cucurbitacins (Cucs) are triterpenoids, that are almost exclusive of the Cucurbitaceae. They serve the plant as chemical defense against phytophagy owing to their extreme bitterness and toxicity. However, they have been known for several years to have a strong feeding stimulant effect on Diabroticina. So they can be used combining them with toxicants in relatively small quantities, thus drastically cutting the overall quantity of pesticides incorporated to the crop system. At the SABCL we worked on sources of B Cucs; several potential sources of B Cucs were identified and tested and the most important were: Cayaponia spp., Cucurbita andreana, and Apodanthera sp.

We recently evaluated the effect of cucurbitacin rich extracts at different scales, from single release points to 1-ha applications. This evaluation required the implementation of a mark-release-recapture method, which demanded the evaluation of different marking techniques. The most suitable techniques were the use of fluorescent pigments dusted on the insects or added to the diet.

Annual Report 2007 

FOR MORE INFORMATION CONTACT GUILLERMO CABRERA gcabrera@speedy.com.ar

 

Cactoblastis cactorum 

SABCL staff in charge:
Guillermo Logarzo
Laura Varone
Juan Briano
Interns: Mariel Guala, Mariana Manteca, María Moore

Cooperators: Stephen Hight, USDA-ARS-Insect Behavior and Biocontrol Research Unit, Tallahassee, FL, USA.
IBBRU, Florida

    In late 2007, a project was started on biological control of the cactus moth, Cactoblastis cactorum. The objective is to identify host specific natural enemies in its native range of northern Argentina.  Cactoblastis cactorum is invading the southeastern US and attacking species of prickly pear cactus (Opuntia spp.). 

    Life table studies are being conducted in northern Argentina and comparisons of natural enemies of C. cactorum will be made between different habitats. Potential candidates include host specific egg parasitoids, egg-larval parasitoids, larval parasitoids, larval-pupal tachinids that have planidial larvae, which attack neonates before they enter pads, hymenopteran pupal parasitoids, and various larval pathogens.

   General surveys for arthropods and pathogens are being conducted in areas not used for the life tables. So far, the most frequent agents were the larval parasitoid Apanteles alexanderi (Hymenoptera: Braconidae) and the egg parasitoid Trichogramma pretiosum (Hymenoptera: Trichogrammatidae). In July 2008, a few locations were found infected with Nosema-like pathogens.

    Opuntia spp. attacked by cactus moths will be evaluated in various habitats, such as road sides, natural areas, ornamental plantings, empty lots, and/or abandoned plantations. 

Annual Report 2008

FOR MORE INFORMATION CONTACT GUILLERMO LOGARZO glogarzo@speedy.com.ar

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Wasmannia auropunctata

SABCL staff in charge:
Luis Calcaterra
Juan Briano
Intern: Leonardo Ramírez

Cooperator:  Peter Follett, USDA-ARS-Pacific Basin Agricultural Research Center (PBARC), Hilo, HI, USA.
PBARC, Hilo

   In October 2008, a biological control program of the Little Fire Ant (LFA), Wasmannia auropunctata, was started at SABCL to identify host specific natural enemies for potencial use in Hawaii. The LFA is a widespread pest on wildlife, domestic animals, public health and agriculture. Its introduced range includes Galapagos Islands, West Africa, Melanesia, Polynesia, parts of continental US, and subtropical Atlantic islands. In Hawaii, LFA was discovered in 1999; although more than 40 ant species are established, numerous habitats remain still ant-free.

   The native range of LFA encompass from Argentina to Mexico; in Argentina the distribution is mostly associated to forests. So far, only the eucharitid wasp Orasema minutisima has been identified from Cuba as potential natural enemy. Control agents have not been found in South America. Surveys in Argentina concluded in March 2009 revealed that LFA is more common in the east-north-central part of the country and intensive search for natural enemies has been started.

FOR MORE INFORMATION CONTACT LUIS CALCATERRA trapisonda@tutopia.com

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