South American Biological Control Laboratory

Hurlingham, Argentina

South American Biological Control Laboratory

Hurlingham, Argentina
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De Leon J.H.,U.S. Department of Agriculture | Setamou M.,Texas A&M University-Kingsville | Gastaminza G.A.,Seccion Zoologia Agricola | Buenahora J.,Instituto Nacional Of Investigacion Agropecuaria Inia | And 4 more authors.
Annals of the Entomological Society of America | Year: 2011

A phylogeographic analysis inferred from the partial mitochondrial cytochrome oxidase subunit I gene (433 bp) was performed with 22 populations of Diaphorina citri Kuwayama collected in the Americas and one in the Pacific. Eight populations from four countries in South America, 14 from four countries in North America, and one from Hawaii were analyzed. Twenty-three haplotypes (hp) were identified and they fell into two groups: hp1-8 were identified in South America (group 1) and hp9-23 were identified in North America and Hawaii (group 2). Hp1 and nine were present in the highest frequencies within each population and within their group, 81 and 85% for group 1 and group 2, respectively. A diagnostic nucleotide at position 48 was identified that allowed for the discrimination of the two groups; in addition, no haplotypes were shared between the two groups. An analysis of molecular variance uncovered significant genetic structure (Φ CT = 0.733; P < 0.001) between the two groups of the Americas. Two haplotype networks (ParsimonySplits and Statistical Parsimony) discriminated the two groups and both networks identified hp1 and nine as the predicted ancestral or founding haplotypes within their respective group. The data suggest that two separate introductions or founding events of D. citri occurred in the Americas, one in South America and one in North America. Furthermore, North America and Hawaii appear to share a similar source of invasion. These data may be important to the development of biological control programs against D. citri in the Americas.

Porter S.D.,U.S. Department of Agriculture | Graham L.C.,Auburn University | Johnson S.J.,Louisiana State University | Thead L.G.,U.S. Department of Agriculture | Briano J.A.,South American Biological Control Laboratory
Florida Entomologist | Year: 2011

The large fire ant decapitating fly, Pseudacteon litoralis Borgmeier, from northeastern Argentina was successfully released as a self-sustaining biocontrol agent of imported fire ants in south central Alabama in 2005. Five years later, this fly is firmly established at the original release site and has expanded outward at least 18 km. Nevertheless, populations remain very low considering P. litoralis is one of the most abundant fire ant decapitating flies in large areas of its range in South America. The reasons for low densities and why we were only able to establish this fly at 1 of 9 release sites in 4 states (2003-2006) are unknown, but problems with host-matching, release procedures, weather conditions, and competition with previously released decapitating flies are discussed as possible factors.

Valles S.M.,U.S. Department of Agriculture | Allen C.,U.S. Department of Agriculture | Varone L.,South American Biological Control Laboratory | Briano J.,South American Biological Control Laboratory
Virus Genes | Year: 2010

Solenopsis invicta virus 3 (SINV-3) is a recently described positive-strand RNA virus that infects the red imported fire ant, S. invicta. The genome of an Argentinean isolate of Solenopsis invicta virus 3 (SINV- 3ArgSF) obtained from the Santa Fe region of Argentina was sequenced in entirety. Assembly of nine overlapping fragments yielded a consensus genome sequence 10,386 nucleotides long, excluding the poly(A) tail present on the 3' end (Genbank accession number GU017972). With the exception of the poly(A) tail, the genome length of SINV- 3ArgSF was identical to the North American isolate (SINV- 3USDM). The SINV-3ArgSF genome possessed three major open reading frames (ORFs) (comprised of ≥100 codons) in the sense orientation; SINV-3USDM possessed only two. ORFs 1 and 2 had identical start and stop genome positions for both isolates. Blastp analysis of the translated ORF 1 of SINV-3ArgSF recognized conserved domains for helicase, protease, and RNA-dependent RNA polymerase. These domains and their corresponding positions were identical to those reported for SINV-3 USDM. ORF 2a, unique to the SINV-3ArgSF genome, was also found in frame 2 and had a canonical start codon located at nucleotide position 8,351 and a stop codon ending at position 8,827. Blastp analysis of the translated amino acid sequence of ORF 2a revealed no significant similarity in the Genbank database. The two SINV-3 isolates exhibited 96.2% nucleotide sequence identity across the entire genome. The amino acid sequences of ORFs 1 and 2 exhibited higher identities (99.0 and 98.2%, respectively) than the corresponding nucleotide regions within the genome. These data indicated that the nucleotide differences between the SINV-3 isolates were largely synonymous. This observation was corroborated by codon substitution rate analysis. Thus, the majority of the SINV-3 codon changes were silent in the two polyproteins,indicating purifying selection pressure on the viral genome. © Springer Science+Business Media, LLC 2009.

Oi D.H.,U.S. Department of Agriculture | Valles S.M.,U.S. Department of Agriculture | Briano J.A.,South American Biological Control Laboratory
Biological Control | Year: 2010

The host specificity of Vairimorpha invictae, a microsporidian pathogen of fire ants in South America, was assessed in the laboratory. Species evaluated included the tropical fire ant, Solenopsis geminata, the southern fire ant, Solenopsis xyloni, and the Argentine ant, Linepithema humile. The two fire ant species are native to North America. The Argentine ant is a widespread, exotic species that co-occurs with the native North American fire ants as well as with the red imported fire ant, Solenopsis invicta, and the black imported fire ant, Solenopsis richteri, in the US. Inoculations of V. invictae-infected S. invicta brood to laboratory colonies did not result in any infections of S. geminata, S. xyloni, or L. humile, while 60% of the S. invicta colonies developed infections. V. invictae was not detected in smaller groups of S. geminata and S. xyloni larvae that were tended by V. invictae-infected adult, S. invicta workers, but was detected in 40% of the S. invicta larval groups tended by infected workers. This was the first report of V. invictae transmission to larvae by infected adult worker ants. Exposure to V. invictae by contact with infected brood and workers partially emulated possible field interactions between infected and uninfected ant species. These results are congruent with previous field surveys which indicate that the host range of V. invictae is limited to fire ants of the Solenopsis saevissima species group.

Allen C.,U.S. Department of Agriculture | Briano J.A.,South American Biological Control Laboratory | Varone L.,South American Biological Control Laboratory | Oi D.H.,U.S. Department of Agriculture | Valles S.M.,U.S. Department of Agriculture
Journal of Invertebrate Pathology | Year: 2010

The RNA-dependent RNA polymerase (RdRp) region of Solenopsis invicta virus 1 (SINV-1) was sequenced from 47 infected colonies of S. invicta, S. richteri, S. geminata, and S. invicta/richteri hybrids collected from across the USA, northern Argentina, and northern Taiwan in an attempt to infer demographic information about the recent S. invicta introduction into Taiwan by phylogenetic analysis. Nucleotide sequences were calculated to exhibit an overall identity of >90% between geographically-separated samples. A total of 171 nucleotide variable sites (representing 22.4% of the region amplified) were mapped across the SINV-1 RdRp alignment and no insertions or deletions were detected. Phylogenetic analysis at the nucleotide level revealed clustering of Argentinean sequences, distinct from the USA sequences. Moreover, the SINV-1 RdRp sequences derived from recently introduced populations of S. invicta from northern Taiwan resided within the multiple USA groupings implicating the USA as the source for the recent introduction of S. invicta into Taiwan. Examination of the amino acid alignment for the RdRp revealed sequence identity >98% with only nine amino acid changes observed. Seven of these changes occurred in less than 4.3% of samples, while 2 (at positions 1266 and 1285) were featured prominently. Changes at positions 1266 and 1285 accounted for 36.2% and 34.0% of the samples, respectively. Two distinct groups were observed based on the amino acid residue at position 1266, Threonine or Serine. In cases where this amino acid was a Threonine, 90% of these sequences possessed a corresponding Valine at position 1285; only 10% of the Threonine1266-containing sequences possessed an Isoleucine at the 1285 position. Among the Serine1266 group, 76% possessed an Isoleucine at position 1285, while only 24% possessed a Valine. Thus, it appears that the Threonine1266/Valine1285 and Serine1266/Isoleucine1285 combinations are predominant phenotypes. © 2010.

Oleiro M.,South American Biological Control Laboratory | Kay F.M.,South American Biological Control Laboratory | Wheeler G.S.,U.S. Department of Agriculture
Environmental Entomology | Year: 2011

During surveys for natural enemies that could be used as classical biological control agents of Schinus terebinthifolius Raddi (Brazilian pepper), the caterpillar, Tecmessa elegans Schaus (Lepidoptera: Notodontidae), was recorded feeding on the leaves of the shrub in South America. The biology and larval and adult host range of this species were examined to determine the insect's suitability for biological control of this invasive weed in North America and Hawaii. Biological observations indicate that the larvae have five instars. When disturbed, the late instar larvae emit formic acid from a prothoracic gland that may protect larvae from generalist predators. Larval host range tests conducted both in South and North America indicated that this species feeds and completes development primarily on members of the Anacardiaceae within the tribe Rhoeae. Oviposition tests indicated that when given a choice in large cages the adults will select the target weed over Pistacia spp. However, considering the many valued plant species in its host range, especially several North American natives, this species will not be considered further for biological control of S. terebinthifolius in North America. © 2011 Entomological Society of America.

Porter S.D.,U.S. Department of Agriculture | Calcaterra L.A.,South American Biological Control Laboratory
Biological Control | Year: 2013

Self-sustaining classical biological control agents offer hope for permanent wide-area control of imported Solenopsis fire ants in the United States because escape from abundant natural enemies left behind in Argentina is a likely reason for unusually high fire ant densities in the United States. The fire ant decapitating fly Pseudacteon obtusus Borgmeier (Diptera: Phoridae) was released as a biocontrol agent of the red imported fire ant (Solenopsis invicta Buren) in Gainesville, FL because it is a common parasitoid of this ant in Argentina and because it has a higher propensity of attacking fire ants along foraging trails than the two Pseudacteon species previously released. Field surveys of a rapidly expanding P. obtusus population (8-12. km/yr) proved that this fly was capable of thriving and successfully competing with the much more abundant Pseudacteon curvatus Borgmeier. However, Pseudacteon tricuspis Borgmeier, the first decapitating fly released, was effectively excluded from most sample sites when faced with competition from both P. curvatus and the similar-sized P. obtusus. Despite clear evidence for competitive exclusion, P. tricuspis abundance at sample sites was positively correlated with the abundance of its two competitors-probably because of moderate to strong covariability in the suitability of sample sites for all three congeners. The addition of P. curvatus, the second parasitoid released, increased total parasitism pressure on fire ant populations by about 10-fold. The addition of P. obtusus, the third species, did not measurably improve total guild parasitism rates on imported fire ants in North Central Florida (as assessed by roadside trap counts), but the performance of this species will likely vary with habitat, region, and climate. © 2012.

Jia X.,Fudan University | Jia X.,Zhejiang University | Pan X.-Y.,Fudan University | Sosa A.,South American Biological Control Laboratory | And 2 more authors.
Plant Species Biology | Year: 2010

Knowledge about the life-history traits of native conspecifics of exotic invasive plants can be of fundamental importance in exploring their origin of invasiveness and disentangling distinct invasion mechanisms. We conducted a common garden experiment to examine genetically based differentiation in growth and biomass allocation among three native Alternanthera philoxeroides varieties (Alternanthera philoxeroides var. obtusifolia, Alternanthera philoxeroides var. acutifolia and Alternanthera philoxeroides var. lancifolia) from Argentina. Results showed that the high-latitude var. obtusifolia had lower values of relative growth rate and plant size. In contrast, the low-latitude var. acutifolia showed distinctly higher growth vigor. The mid-latitude var. lancifolia generally showed intermediate growth vigor. Regarding allocation, var. obtusifolia allocated a distinctly higher proportion of biomass to storage roots and leaves, whereas var. acutifolia and var. lancifolia allocated more biomass to stems. This pattern of variation might be the outcome of evolutionary differentiation in response to their geographic distributions and local habitats. The acutifolia and lancifolia varieties may have higher potential invasiveness than var. obtusifolia. © 2010 The Authors. Journal compilation © 2010 The Society for the Study of Species Biology.

Calcaterra L.A.,South American Biological Control Laboratory | Cuezzo F.,CONICET | Cabrera S.M.,South American Biological Control Laboratory | Briano J.A.,South American Biological Control Laboratory
Annals of the Entomological Society of America | Year: 2010

The Iber Nature Reserve in northeastern Argentina protects one of the largest freshwater wetlands and reservoirs of species in South America. However, key invertebrate groups such as the ants (Hymenoptera: Formicidae) remain almost unknown. The main objective of this work was to study the ground ant diversity in four main habitats of Iber: grasslands, savannas, forests, and floating islands. Pitfall traps were used to characterize ground foraging ant assemblages, compare ant diversity among environments, and establish habitat associations. We also used bait traps, manual collections, and Winkler and Berlese extractors on the ground, vegetation, and litter strata to increase the species inventory. In total, 94 species in 30 genera were captured, representing the highest number of species reported from a survey of a protected area of Argentina. The richest genus was Pheidole Westwood with 23 species including three species reported for the first time in Argentina. The most common species was Solenopsis invicta Buren. Overall, the savanna was the richest and most diverse habitat with the highest number of exclusive species and functional groups. The grassland showed the highest number of rare species, but only half of the expected species were captured. The forest showed the lowest ant richness, diversity, and equitability, but one half of the species were exclusive to forest habitat. Generalized myrmicines were predominant and dominant in all habitats. Our findings indicate that habitat specialization could be an important factor determining the organization of ant assemblages in Iber. The protection of each of these unique and threatened natural habitats of Argentina is needed to ensure the long-term preservation of their exclusive ant species. © 2010 Entomological Society of America.

Cabrera N.,Museo de La Plata | Walsh G.C.,South American Biological Control Laboratory
Zootaxa | Year: 2010

The new species Diabrotica collicola Cabrera & Cabrera Walsh is described and illustrated based on specimens collected from Balcozna, Catamarca Province (Argentina). A full description is provided and includes adding morphological characters of the mouthparts, hind wing venation, binding patch, metendosternite, and details of male and female genitalia previously overlooked for the genus. Diabrotica collicola is recognized by the following characters: general color parrot green with yellowish vittae, genal space less than 1/4 maximum length of the eye, antennomeres 2 and 3 subequal in males, 3 longer in females, both antennomeres together more than length 1/2 of 4 in both sexes, prothoracic and mesothoracic tarsi of males with ventral adhesive patch, internal sac of the median lobe with four sclerites. Differences with similar species D. mutabilis Baly, D. fulvofasciata Jacoby, D. mapiriensis gussi Krysan & Smith and D. porracea Harold are discussed. A key to D. collicola and similar species is provided. © 2010 Magnolia Press.

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