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The Argentine ant - A significant invasive species in agricultural, urban and natural environments

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Abstract

The Argentine ant, Linepithema humile (Mayr), is one of the most important invasive ant species in agricultural, urban and natural environments of Mediterranean climates worldwide. The following review is intended to summarize the important literature regarding the systematics, biology and control of this species. Special emphasis has been given to those abiotic and biotic factors that might be important in preventing the spread and impact of this tramp species.

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... It is a cosmopolitan pest (Suarez et al. 2001) and in the U.S., it is found in agricultural and urban areas in at least 21 states, including the southwestern and southern U.S. and Hawaii, due to human-related dispersals (Newell and Barber 1913, Suarez et al. 2001. When foraging, workers will invade urban structures in large numbers in response to temperature extremes, moisture gradients or resource availability (Klotz et al. 1995, Vega andRust 2001). The Argentine ant is a tramp ant species that adapts easily to disturbed, or urban, environments and prefers habitats that are in close proximity to humans (Vega and Rust 2001). ...
... When foraging, workers will invade urban structures in large numbers in response to temperature extremes, moisture gradients or resource availability (Klotz et al. 1995, Vega andRust 2001). The Argentine ant is a tramp ant species that adapts easily to disturbed, or urban, environments and prefers habitats that are in close proximity to humans (Vega and Rust 2001). ...
... They are successfully established throughout the U.S. largely because they are a tramp ant species and have taken advantage of human activities for dispersal. After becoming established in an area, Argentine ants generally out-compete native ants for food and territorial resources (Knight and Rust 1990, Suarez et al. 2001, Vega and Rust 2001. Factors attributed to their rapid spread and extensive range outside of its native range include multiple queens (polygyny) (Vargo and Fletcher 1989), multiple colonies (polydomy), little-to-no intraspecific aggression (unicoloniality) , and using reproductive budding (sociotomy) to form new colonies (Passera 1994). ...
Thesis
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Human structures may be occupied, at least temporarily, by insects and other arthropods. Some are perennial pests, while others occasionally invade structures. A field study in 2008 – 2009 determined that occasional invader species in natural and artificially-created harborages adjacent to buildings were primarily isopods (Malacostraca: Isopoda) (37%), spiders (Arachnida: Araneae) (28%), earwigs (Insecta: Dermaptera) (13%), and adult crickets (Insecta: Orthoptera) (8%). Pitfall trapping demonstrated seasonal differences in activity of occasional invaders with the number of harborages observed. In laboratory assays, five plant-extracted essential oils (spearmint, peppermint, wintergreen, cinnamon and clove) were repellent to Argentine ant, Linepithema humile (Mayr), workers at concentrations from 0.10 to 10% (v/v) at 0 and 7 days after application. Essential oils are viable alternatives to conventional chemical repellents of the Argentine ant and occasional invader species. INDEX WORDS: integrated pest management, IPM, occasional invader pests, essential oils, urban pest management, Argentine ants, Linepithema humile
... The Argentine ant, Linepithema humile (Mayr 1868), is an example of an ant species that has been introduced, has established and consequently invaded areas where it does not occur naturally, including protected areas Human et al., 1998;Krushelnycky & Reimer, 1998a, b;Vega & Rust, 2001;Carpintero et al., 2003;Wetterer et al., 2009). The Argentine ant is classified as a unicolonial invasive species (Holway & Suarez, 2004;Krushelnycky et al., 2004;Silverman & Brightwell, 2008) and as one of the worst invasive alien ants the world has experienced (Skaife, 1961;Hölldobler & Wilson, 1990). ...
... This in turn could have further cascading effects on other trophic levels (Holway et al., 2002;Rowles & O'Dowd, 2007;Silverman & Brightwell, 2008), such as the case of the coastal horned lizard in California whose numbers are being reduced as the result of the Argentine ant outcompeting their food source, i.e. indigenous ants (Fisher et al., 2002). Some of the economic problems the Argentine ant is responsible for are the destruction of irrigation systems and beehives (Buys, 1990;Vega & Rust, 2001;Matthews & Brand, 2004;Silverman & Brightwell, 2008), as well as culturing phloem-feeding hemipterans in agricultural systems (Way, 1963;Vega & Rust, 2001;Nyamukondiwa, 2008;Mgocheki & Addison, 2009). ...
... This in turn could have further cascading effects on other trophic levels (Holway et al., 2002;Rowles & O'Dowd, 2007;Silverman & Brightwell, 2008), such as the case of the coastal horned lizard in California whose numbers are being reduced as the result of the Argentine ant outcompeting their food source, i.e. indigenous ants (Fisher et al., 2002). Some of the economic problems the Argentine ant is responsible for are the destruction of irrigation systems and beehives (Buys, 1990;Vega & Rust, 2001;Matthews & Brand, 2004;Silverman & Brightwell, 2008), as well as culturing phloem-feeding hemipterans in agricultural systems (Way, 1963;Vega & Rust, 2001;Nyamukondiwa, 2008;Mgocheki & Addison, 2009). ...
... The invasive Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), is a highly destructive pest of natural and managed systems worldwide (Vega and Rust 2001;Silverman and Brightwell 2008). Although primarily recognized as an urban structural pest, large, persistent infestations of L. humile are also sustained in agroecosystems. ...
... Although primarily recognized as an urban structural pest, large, persistent infestations of L. humile are also sustained in agroecosystems. Citrus orchards in southern California provide optimal proliferative conditions for L. humile: a mild Mediterranean climate, year-round moisture from irrigation, and abundant honeydew-producing hemipteran mutualists (Vega and Rust 2001). Individual citrus trees have been recorded to receive several hundreds of thousands of visits from L. humile foragers in a single 24-h period (Markin 1970;Milosavljević et al. 2017;Schall and Hoddle 2017). ...
... Individual citrus trees have been recorded to receive several hundreds of thousands of visits from L. humile foragers in a single 24-h period (Markin 1970;Milosavljević et al. 2017;Schall and Hoddle 2017). Workers may obstruct irrigation piping, invade commercial beehives, disrupt native pollinators, and impede biological control of the sap-feeding pests they tend, resulting in pest outbreaks and concomitant plant damages (Buckley 1987;Vega and Rust 2001;Silverman and Brightwell 2008;Hanna et al. 2015). Previous studies have demonstrated the importance of L. humile control for management of ant-tended pests in citrus (e.g., Asian citrus psyllid, Diaphorina citri Kuwayama) which threaten the profitability of California's $7.1 billion-per-year citrus industry (Tena et al. 2013;Milosavljević et al. 2017;Schall and Hoddle 2017;Babcock 2018). ...
Article
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The Argentine ant, Linepithema humile (Mayr), poses a significant economic threat to citrus production in southern California. Broad-spectrum insecticide sprays provide poor ant control and present a hazard to human and environmental health. Liquid sucrose bait infused with a low concentration of insecticide is an effective alternative treatment but current approaches require considerable economic investment in plastic dispensers and continual maintenance. To produce a baiting product for control of L. humile suitable for large-scale application, a biodegradable, broadcastable alginate hydrogel for delivery of aqueous low-dose thiamethoxam sucrose bait was developed and evaluated in replicated field trials in commercial citrus groves. Ant activity was significantly reduced in hydrogel-treated trees. Peak L. humile suppression was achieved 48 h following the final hydrogel disbursement, with an estimated 91% reduction in activity from baseline estimates and a 17-fold lower activity in treated trees in comparison with untreated trees. Significant residual activity of the hydrogel treatments was recorded, with a nearly 70% reduction from pre-treatment levels persisting at least 3 weeks after the last application. We conclude that alginate hydrogels can provide excellent control of L. humile while deploying 99.99% less insecticide into orchards than commercial barrier spray treatments.
... T he Argentine ant is an invasive pest that has spread throughout California since it was fi rst reported from Ontario, Calif., in 1905. Though popularly recognized as a household pest (Vega and Rust 2001), the Argentine ant (Linepithema humile [Mayr]) also causes severe problems in natural systems by displacing native ants and other insect species, and even some vertebrate and plant populations (Holway et al. 2002). In addition, in agricultural systems the Argentine ant is associated with outbreaks of phloem-feeding insects such as mealybugs, scale and aphids, which the ants protect from natural enemies; in exchange, the ants collect the sugarrich food source (honeydew) excreted by the phloem-feeders (Buckley and Gullan 1991). ...
... Liquid baits exploit the social behavior of ants to distribute toxicant to colony members, including larvae and queens (Silverman and Roulston 2003). Argentine ants also use persistent trail pheromones to recruit colony members to food resources, resulting in fidelity to bait-station locations (Aron et al. 1989;Vega and Rust 2001). Because bait is exchanged among colony members via trophallaxis (i.e., ants feeding other ants), baits have the potential to affect the nest population and provide season-long control (Forschler and Evans 1994;Klotz et al. 2006). ...
Article
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Liquid ant baits are an alternative to broad-spectrum insecticide sprays conventionally used to control Argentine ants. We review the development of liquid ant baits, which capitalize on the ants' sugar-feeding requirements and social structure to deliver small doses of toxicant throughout the colony. The ant bait program described here, developed for commercial vineyards, also has the potential to facilitate the use of biological controls for mealybug and scale pests. The implementation of an Argentine ant bait program will enable grape growers to target other pests more selectively with insecticides, further contributing to their sustainable viticulture practices.
... In this study, we sort to determine whether the mutualistic relationship between the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), and six established species of honeydew producers may hinder or favor the establishment of the invasive Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in urban citrus growing in southern California via competition or mutualism. Linepithema humile is one of the most important invasive ant species in agricultural, urban and natural environments that are characterized by Mediterranean climates, including southern California (Vega & Rust, 2001). In agricultural and urban areas, L. humile maintains trophobiotic relationships with various honeydew-producing hemipterans such as brown soft scale, Coccus hesperidum L. (Coccidae), citrus mealybug, Planococcus citri (Risso) (Pseudococcidae), wooly white fly, Aleurothrixus floccosus (Maskell) (Aleyrodidae), cottony cushion scale, Icerya purchasi (Maskell) (Monophlebidae) and several species of aphids. ...
... The invasive Argentine ant, L. humile, was the only ant species observed in our study and it was present in 90% of the citrus trees sampled in ten urban localities in southern California. As previously documented, L. humile has excluded native ants in these residential areas and monopolized sugar sources in the form of hemipteran-produced honeydew (Vega & Rust, 2001). This aggressive and territorial ant provides excellent protection to honeydew producers infesting citrus (Moreno et al., 1987;Klotz et al., 2004;Shik & Silverman, 2013) and the recently introduced D. citri has not been an exception to the tending behaviors of this ant. ...
Article
Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an invasive citrus pest in southern California, which secretes honeydew and has the potential to spread a lethal bacterial disease, huanglongbing, of citrus. In urban citrus, Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), also an invasive pest, tends honeydew-producing hemipterans. We used field data to determine whether the mutualistic relationship between L. humile and six established species of honeydew producers may hinder or favor the establishment of D. citri and its biological control with Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) in citrus via competition or mutualism for ants, respectively. In the field, L. humile and D. citri are engaged in a mutualistic relationship. Ants harvest solid honeydew secreted by psyllid nymphs and tended more than 55% of observed D. citri colonies. Linepithema humile displayed a preference hierarchy when tending honeydew producers infesting citrus. It responded equally or less intensively to D. citri than to other honeydew-producing species. Consequently, the mutualism between L. humile and D. citri was affected by the presence of other honeydew-producing species, and the percentage of D. citri colonies tended by L. humile. The number of ants per D. citri colony also decreased as the number of other honeydew producers increased. Diaphorina citri density was also affected by the presence of other honeydew producers. Both colony size and the number of D. citri nymphs counted per tree decreased as the number of other honeydew producers increased. Our results indicate that competition between honeydew producers for the mutualist ant L. humile may hinder the establishment of D. citri by possibly facilitating increased biological control.
... Linepithema humile (Fig. 1) is native to parts of subtropical South America with a Mediterranean-like climate, i.e., warm dry summers and cool moist winters, and it has become a major pest in many areas around the world with similar climates (Wild, 2004; Wetterer et al., 2009). Where it invades, L. humile often has negative impacts on many other animals, both vertebrates and invertebrates (e.g., Vega & Rust, 2001; Wetterer et al., 2001; Suarez et al., 2005). In addition, L. humile can be a significant agricultural pest, enhancing populations of sap-feeding Hemiptera, such as mealybugs, scale insects, and aphids (Vega & Rust, 2001). ...
... Where it invades, L. humile often has negative impacts on many other animals, both vertebrates and invertebrates (e.g., Vega & Rust, 2001; Wetterer et al., 2001; Suarez et al., 2005). In addition, L. humile can be a significant agricultural pest, enhancing populations of sap-feeding Hemiptera, such as mealybugs, scale insects, and aphids (Vega & Rust, 2001). The ants protect Hemiptera from predators and parasites while feeding on honeydew that the Hemiptera produce. ...
... Argentine ants (Linepithema humile (Mayr)) are a worldwide invasive exotic pest [1][2][3]. In urban areas that have a Mediterranean type climate they often invade dwellings and are one of the most consistently reported pest species [3][4][5][6][7][8][9]. Although L. humile tends to form high-density monocultures outdoors [10][11][12][13][14], it is not ubiquitous in its infestation patterns. ...
... The amount of solution taken was measured every day, and the vials were never completely emptied over this time period. Based on an estimate that an L. humile worker can take 0.3 mg per visit, the total number of ant visits from the amount of liquid removed in a day were calculated (see [6,17] for details of methods). This method is recommended as accurate and the least time-consuming for monitoring comparative levels of Argentine ant activity [17]. ...
Article
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Infestations of buildings by Argentine ants, Linepithema humile (Mayr), were monitored on the campus of the University of California, Los Angeles. Foraging ant activity peaked during the hotter months of the year. The mean monthly maximum temperature, but not rainfall, positively correlated with indoor infestation frequency. Neither garden size nor the predominant groundcover vegetation correlated with the number of foraging ants at baits within gardens. Although the number of foraging ants outside a building varied over 40-fold, ant density in gardens did not predict the likelihood of infestation within the building. Also, the type of vegetative groundcover employed did not predict infestation frequency. There was, however, a significant negative relationship between the size of the garden outside of a building and the number of infestations. Given the large foraging area of L. humile workers, buildings next to small gardens may be infested simply because they lie within the “normal” foraging area of a colony. The best predictor of which rooms were infested within buildings was the presence of a water source. Thus providing water for ant colonies outside and away from buildings may be one method of integrated pest management to reduce the proclivity of ants to infest structures.
... If soil permeability is high in high rainfall areas, it is possible that colony establishment will be limited (Chen et al. 2002). High rainfall can restrict foraging activity (Holldobler 1990) and lower colony establishment potential (Vega & Rust 2001) in Auckland and Tauranga. Napier was certainly much drier and has a larger seasonal soil moisture deicit than both Auckland and Tauranga. ...
Article
Over the last 10 years the National Invasive Ant Surveillance programme, which was established in 2003 by the Ministry of Agriculture and Forestry (now Ministry for Primary Industries) in New Zealand, has resulted in a number of exotic ant detections at the Napier sea port and surrounding facilities. The surveillance is designed to detect newly established nests of exotic ant species at high risk sites around New Zealand, such as shipping ports. Potential factors contributing to exotic ant detections such as import commodity pathways and local climatic conditions in Napier were analysed. The present analysis indicates ant arrival alone or propagule pressure does not necessarily result in establishment. Abiotic factors, such as temperature and rainfall, are likely to be the main factors contributing to successful ant nest establishment at Napier sea port compared to the Ports of Auckland and Tauranga.
... Native to South America , it has now been introduced into various parts of the world as a result of human commercial activities (Höldobler & Wilson 1990;). Its distribution includes areas with Mediterranean-type climates Vega & Rust 2001). Its rapid expansion in invaded zones has been facilitated by habitat disturbance ), but there is increasing evidence of its ability to occupy non-altered habitats Holway 1998). ...
... The Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), is an invasive species that has successfully spread around the world with damaging ecological and economic consequences (Suarez et al., 2001;Holway et al., 2002;Roura-Pascual et al., 2004). Although mainly recognized as an urban pest (Knight & Rust, 1990), the Argentine ant can also have severe negative impacts on natural (Holway et al., 2002) and agricultural environments (Vega & Rust, 2001). In agricultural systems, Argentine ants are often associated with outbreaks of phloem-feeding hemipteran insects such as aphids, scales, mealybugs, and others . ...
Article
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Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), are a significant pest in various agricultural systems around the world, and are often associated with outbreaks of phloem-feeding hemipteran insects. Previous research has evaluated a number of active ingredients and management approaches for controlling Argentine ant populations in agricultural systems, but various regulatory and economic issues have limited the development of effective management tools. Current chemical controls rely on residual sprays or toxic baits, each one posing unique disadvantages that limit their usefulness and efficacy. This study evaluated the potential of water-storing crystals to effectively deliver liquid baits to Argentine ants. The efficacy of bait crystals containing 0.007% thiamethoxam was first evaluated in laboratory colonies. In addition, field studies were performed in a commercial plum orchard to determine the efficacy of the bait crystals. Protein marking was used within the orchard to examine the distribution of the bait in Argentine ant populations when delivered via water-storing crystals. Results of laboratory tests showed that water-storing crystals containing 0.007% thiamethoxam are highly attractive and effective against Argentine ants and require ca. 3–5 days to kill all castes and life stages. Results of the protein-marking study demonstrated that the percentage of ants carrying protein-labeled sugar water decreases sharply with increasing distance from the bait station. Bait movement was limited to within 17 m of the bait dispenser. Furthermore, bait efficacy tests in the field showed that Argentine ants can be effectively controlled using liquid thiamethoxam baits deployed via water-storing crystals. The bait was highly effective and ant densities throughout the baited plots declined by 94 ± 2% within 14 days. The results of this study demonstrate that (1) thiamethoxam is highly effective for Argentine ant control in fruit orchards when used in low concentrations (0.007%), and (2) water-storing crystals are an effective tool for delivering liquid baits to Argentine ants in agricultural settings.
... Argentine ants (Linepithema humile) have been established in New Zealand since 1990 (Green, 1990), and are a major pest for householders and a recognised threat to biodiversity and horticulture (Harris, 2002;Vega & Rust, 2001;Ward, 2009). They have now spread into many towns and cities throughout the North Island and northern South Island, primarily through accidental human-mediated dispersal of propagules (Ward et al., 2005). ...
... Argentine ants (Linepithema humile) have been established in New Zealand since 1990 (Green, 1990), and are a major pest for householders and a recognised threat to biodiversity and horticulture (Harris, 2002;Vega & Rust, 2001;Ward et al., 2010). They have now spread into many towns and cities throughout the North Island and northern South Island, primarily through accidental human-mediated dispersal of propagules (Ward et al., 2005). ...
... Argentine ants (Linepithema humile) have been established in New Zealand since 1990 (Green, 1990), and are a major pest for householders and a recognised threat to biodiversity and horticulture (Harris, 2002;Vega & Rust, 2001;Ward, 2009). They have now spread into many towns and cities throughout the North Island and northern South Island, primarily through accidental human-mediated dispersal of propagules (Ward et al., 2005). ...
... In Florida, generalist predators such as coccinellids can cause >95% mortality of ACP parasitized by T. radiata (Michaud, 2004) and this can cause parasitism estimates in the field to be underestimated (Michaud, 2004;Qureshi and Stansly, 2009). In California, invasive ants such as Linepithema humile (Mayr) (Hymenoptera: Formicidae) which form mutualisms with honeydew producing Hemiptera such as ACP, provide active defence from predators and parasitoids, and can considerably reduce the efficacy of biological control agents in citrus orchards (Vega and Rust, 2001). Whilst undeniably useful in minimizing immigration into commercial orchards from urban trees (backyard citrus) and abandoned groves, the level of control offered by indigenous and imported natural enemies is not adequate as a stand-alone practice in commercial orchards because of ingress of psyllids from abandoned orchards (Lewis-Rosenblum et al., 2015). ...
Technical Report
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Huanglongbing (HLB), also known as citrus greening disease, is one of the most devastating pathogens of citrus worldwide and is caused by closely-related species of systemic Candidatus bacteria. Vectored by the Asian citrus psyllid (ACP), Diaphorina citri, the heat-tolerant, Asian form of the disease, Candidatus Liberibacter asiaticus (CLas) is the most serious and widespread. In East Africa, the heat-sensitive form of the disease is vectored by the African citrus triozid (ACT) Trioza erytreae and remains the most prevalent disease, particularly in the cooler, mid to high altitude areas. Since 2010 however, CLas which can also be transmitted by T. erytreae, has been spreading in the African continent and significantly, the Asian HLB vector has also been detected in Tanzania and Kenya. There is now a clear and present threat of HLB to the citrus industry in Africa, including the previously sustainable warmer citrus producing regions of East Africa. Modelling of environmental suitability suggests that without preventative measures CLas could establish widely in Africa, with potential hotspots in Central and South-eastern Africa, incurring substantial economic losses. The following evidence note reviews the global literature on the HLB pathogen-vector complex, highlighting potential risks and estimating economic impact for Africa. A synthesis of recommendations for biosecurity preparedness, surveillance and management options is outlined to inform decision makers and growers.
... Foragers can travel long distances to find food or water (Heller et al. 2008; Silverman and Brightwell 2008), and a very efficient recruitment system means that once resources or potential nest sites are found, many other ants can rapidly arrive (Human and Gordon 1996; Holway 1999). Thus, Argentine ants readily invade and colonize buildings and homes, and once within, are highly conspicuous (Vega and Rust 2000; Reierson et al. 2001; S. Gilboa, J.H. Klotz, P. Nonacs, unpublished data). Chemical control of L. humile is often difficult. ...
Article
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The invasive success of the exotic Argentine ant [Linepithema humile (Mayr)] is often closely tied to year‐round availability of water sources. Previous studies suggest that the location of such water sources can strongly influence activity patterns of colonies and may be a key predictor of building infestations. We studied activity patterns of Argentine ants in relation to water and food resources in two open‐air structures (aviaries). In one series of manipulations, ant activity inside the aviaries was significantly reduced with the placement of numerous water sources around the outside. Inside activity increased again when the outside water sources were removed. A second series of manipulations involved the placement of water sources at targeted locations outside of the structures. Ant activity inside the aviaries consistently shifted significantly closer to these targeted sites. The results suggest that providing a reliable water source to Argentine ant colonies exterior to buildings can be a non‐chemical method of integrated pest management for reducing ant infestations. Independent of our manipulations, L. humile activity levels predictably declined with time of day, but these changes were uncorrelated with observed surface temperatures. In fact, activity was often noted at surface temperatures higher than those that cause worker mortality under laboratory conditions. This suggests that L. humile exhibits a consistent temperature‐independent circadian activity pattern of reduced foraging in afternoons relative to mornings.
... Em conseqüência dos aspectos biológicos apresentados, as formigas andarilhas podem deslocar ou até mesmo extinguir alguns táxons dos fragmentos. É o caso de L. humile, que foi encontrada nos três locaisem dois deles com alta freqüência de ocorrência -pois é uma espécie característica de ambientes desestruturados (VEGA & RUST, 2001), além de interferir com a diversidade das áreas que invadem (SCHULTZ & MCGLYNN, 2000). Dessa forma, essas espécies podem causar uma diminuição ainda maior da diversidade dos fragmentos de Mata Atlântica da cidade de São Paulo devido à perda das interações biológicas existentes. ...
Article
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In this paper were investigated the ants' communities that inhabit the Atlantic Rainforest fragments surrounded by an urban ecosystem well developed. The richness, the species frequency of occurrence, as well the similarity between the three areas of the city of São Paulo were investigated: Parque da Previdência (PP), Reserva Florestal "Armando Salles de Oliveira" (CUASO) and Horto Oswaldo Cruz (HOC). Pit-fall tramps were put in places where the public visitation is not allowed, during a whole week in the months of March, June, September and December of 2001. Considering the three fragments were collected 79 ant species belonging to nine subfamilies and 32 genera. The biggest species richness was presented by the Subfamily Myrmicinae and the genera Pheidole and Hypoponera. In PP were registered 62 species, in CUASO 46 and in HOC 43. The biggest similarity was found between PP and CUASO and possibly this similarity may be due to the size of both areas and to a similarity between the sites of nesting and feeding. In general, the ants' fauna is generalist, with the presence of some specialists genera as Discothyrea, Acanthognathus, Gnamptogenys, Oxyepoecus and Pyramica or genera that have feeding habits still unknown (Heteroponera and Myrmelachista). The presence of Pheidole megacephala Fabricius, 1793, Linepithema humile Mayr, 1868, Wasmannia auropunctata Roger, 1863, Paratrechina fulva Mayr, 1862, P. longicornis Latreille, 1802 and Tapinoma melanocephalum Fabricius, 1793, species characteristic of household areas, was also observed.
... In urban environments, Argentine ants often reach extremely high densities and become a major nuisance when entering buildings in search of food, water, and shelter Knight 1990, Klotz et al. 2002). In agricultural systems, Argentine ants are often associated with outbreaks of phloem-feeding homopterans such as aphids, scales, and mealybugs (Vega andRust 2001, Daane et al. 2006), which interfere with biological control of honeydew-producing pests and leads to secondary problems such as sooty mold and transmission of plant viruses (Prins et al. 1990, Buckley andGullan 1991). ...
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Ant management in urban and natural areas often relies on toxic baits. Liquid baits are highly attractive to pest ants because they mimic natural food sources such as honeydew and nectar, the principal dietary components of many ants. However, liquid bait use has been limited owing to the lack of bait dispensers that are effective, inexpensive, and easy to service. The current study evaluated the potential of water-storing crystals (polyacrylamide spheres) to effectively deliver liquid thiamethoxam baits to laboratory colonies of Argentine ants, Linepithema humile Mayr. Results of laboratory trials show that bait crystals saturated in 25% sucrose solution containing 0.007% thiamethoxam are highly attractive to Argentine ants and highly effective against all castes and life stages, including workers, queens, and brood. Fresh bait crystals were highly effective and required approximately 2 d to kill all workers and approximately 6 d to achieve complete mortality in queens and brood. Results of bait aging tests show that the crystals lose approximately 70% of moisture in 8 h and the duration of outdoor exposure has a significant effect on moisture loss and subsequently bait acceptance and bait efficacy. A gradual decrease in mortality was observed for all castes and life stages as bait age increased. In general, fresh baits and those aged for < 8 h retained their efficacy and caused substantial mortality. Baits aged longer than 8 h were substantially less attractive and less effective. Horizontal transfer tests examined the transfer of thiamethoxam from live treated donors to live untreated recipients. The results show that donor ants that obtain thiamethoxam by feeding on bait crystals effectively transfer it to untreated recipient ants. The level of secondary mortality depended on the donor:recipient ratio, with approximately 40% recipient worker mortality with the 1:5 ratio and 15% recipient worker mortality with 1:10 or 1:20 ratios. However, no queens died in any transfer tests, suggesting that multiple feedings from multiple donors may be necessary to produce queen mortality. The results of the transfer tests demonstrate the role of trophallaxis in the distribution of thiamethoxam and confirm that thiamethoxam is effectively transferred in Argentine ant colonies. The distribution of thiamethoxam within Argentine ant colonies was further examined using protein marking coupled with an enzyme-linked immunosorbent assay to detect the marker. The distribution of thiamethoxam was highly efficient, with 79 +/- 13% of workers testing positive at 15 min and 100 +/- 0% of workers testing positive at 6 h. In summary, the results of this study demonstrate that water-storing crystals effectively deliver thiamethoxam to all castes and life stages of Argentine ants and may offer an effective tool for Argentine ant management.
... Like other invasive ant species, the Argentine ant, Linepithema humile (Mayr), is an ecologically disruptive and economically important pest. While an economic pest in agricultural settings, L. humile is a major nuisance pest in urban and suburban environments, where it is often found in large numbers foraging in and around homes and other buildings [1]. Historically, ant control around homes has been conducted by the structural pest control industry using liquid, granular, and gel baits; liquid, residual contact insecticides (sprays); and granular formulations applied to soil, mulch, vegetation, perimeter walls, and potential points of entry of infested structures [2]. ...
Article
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Ants (Hymenoptera: Formicidae), especially the Argentine ant, Linepithema humile (Mayr), can be significant nuisance pests in urban and suburban environments. Conventional interventions have primarily relied on the use of chemical insecticides, namely fipronil and bifenthrin, applied as residual, contact treatments around the outside perimeter of infested structures. Despite tightening regulation limiting the scope of insecticide applications in urban settings, dependence on these products to manage ants continues, resulting in significant water contamination. The U.S. EPA, in response, has further restricted the use patterns of many insecticides used for ant control in professional and over-the-counter markets. The purpose of this review is to summarize the relevant literature associated with controlling nuisance pest ants, with emphasis on L. humile, without the use of liquid broadcast applications of EPA-registered insecticides while focusing on low-impact, alternative (to broadcast applications) pest control methods. Specific subsections include Trail Pheromone; Use of Behavior-Modifying Chemicals; Mass Trapping; Hydrogels, “Virtual” Baiting, and Exceedingly-Low Bait Concentrations; Food Source Reduction; Deterrents; and RNA Interference (RNAi).
... Among the 2,500 known species of ants in Brazil, around 50 species are known as tramp ants due to their ability to survive in urban environments (Bueno & Campos-Farinha 1999). This ability to survive in highly disturbed environments is related to certain characteristics that these ants present, such as unicolonialism, polygyny , sociotomy, small size of workers, and migration and fragmentation of colonies in response to changes in environment (Fowler et al. 1994, Passera 1994, Bueno & Campos-Farinha 1999, Vega 2001). The damage that these ants cause in urban areas comes from their presence in residences, invasion and damage of electronic appliances and structures of buildings, like wood ceilings and door frames. ...
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This study aimed to analyze the species composition and functional groups of the ant community and to assess the efficiency of two sampling methods, pitfall and leaf litter sampling, in an urban park. A total of 1,401 ants were collected, which belonged to six subfamilies and 36 species. The predominant species was Wasmannia auropunctata (present in 45.36% of the samples), while the functional group of opportunistic ants were the most frequent (present in 83.75% of the samples) and abundant (95.29% of the total collected specimens) functional group. The Jaccard Similarity Index showed a low similarity between the two sampling methods, as the difference of the number of individuals for each species between these two methods was not significant in only one case (Linepithema sp. 1, p = 0.4561). The fungusgrowing and cryptic ants were more collected in leaf litter samples (p<0.0001; p = 0.0348 respectively). Although there was no significant difference (p = 0.6397) between the two sampling methods for the total individuals of opportunistic ants, more species of this group were collected in pitfall traps. This difference was not significant because of the high presence of W. auropunctata, an opportunistic ant, in samples of leaf litter. Due to the predominance of tramp ants in the studied area, this article illustrates the importance of green urban areas in ant control strategies, since these sites could be used as a source of new colonization for these ants. Furthermore, the combination of the two sampling methods seems to be complementary for obtaining a more complete picture of the ant community.
... En région Provence-Alpes-Côte d'Azur, elle envahit tout le littoral (Blight et al., 2010b ;Berville, 2009). Cette invasion provoque l'éradication des espèces de fourmis indigènes (Cammell et al., 1996 ;Human et Gordon, 1996 ; Abril et Gomez, 2011) et d'autres insectes (Cole et al., 1992) modifiant ainsi les équilibres écologiques de zones naturelles sensibles, et les services écosystémiques rendus par l'entomofaune locale partout où cela a été étudié Holway et al., 2002a ;Vega et Rust, 2001). De plus, la fourmi d'Argentine exerce une action négative sur la survie et la dynamique des populations de plantes en favorisant la prolifération de ravageurs de type homoptère Aphidiens et Coccidiens (pucerons et cochenilles). ...
... Ants enter into an array of mutualistic interactions in agro-ecosystems, and as a result can be categorized as pests. In this way, the Argentine ant is regarded as a significant pest in many agricultural systems, such as vineyards and citrus groves (Vega and Rust 2001;Daane et al. 2008), because it protects honeydewproducing homopterans from their predators. As a consequence, an effectiveness reduction of this component of biological control is obtained (Bartlett 1961;Moreno et al. 1987). ...
Article
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Invasive species often displace native species and can affect ecological processes in invaded habitats. If invasive species become abundant, changes in prey availability may be particularly harmful to specialist predators. The Argentine ant, Linepithema humile Mayr, is an important invasive species on nearly all continents. Spiders of the genus Zodarion are specialised ant-eating predators native to the Mediterranean yet it is unknown if they can exploit invasive ant species. Here we studied spatial and temporal abundance of this invasive ant and the native spider, Zodarion cesari Pekár, during 4 years in four citrus groves. Circadian activity of both spiders and ants, and capture efficiency and prey specificity of the predator were also evaluated. The abundance of Z. cesari was strongly correlated to L. humile abundance. The predatory activity of spiders varied seasonally with differences on the relative frequency of spiders capturing ants depending on the time of the year. In laboratory, Z. cesari displayed most efficient capture upon the native ant Tapinoma nigerrimum (Nylander) and the invasive ant L. humile in comparison with five other native ant species. These results demonstrate that the native spider Z. cesari is successfully exploiting the invasive ant species L. humile and is likely a locally monophagous predator. We suggest that Z. cesari shifted away from native T. nigerrimum post invasion as both ant species are phylogenetically related and of similar size.
... With 24 h foraging, L. humile also appear to compete with bees for nectar in a number of plants elsewhere (Buys 1987, Markin 1970. In Australia, South Africa and the United States, L. humile have been observed raiding honeybee hives, killing bees and stealing honey and destroying hives (Pasfield 1968, Anderson et al. 1980, Pinto 1997, Vega & Rust 2001. One author suggested that it was impossible to keep bees in some areas due to the presence of L. humile (Taber 1994). ...
Article
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Approximately 30 exotic ant species have been introduced into New Zealand, including the Argentine ant Linepithema humile (Mayr). Many of these ant species are known to affect horticulture worldwide by tending hemipteran insects. These ants may protect these hemiptera from their natural enemies, resulting in higher pest densities and potential economic loss. Our aim in this work was to survey the ant species associated with the various horticultural crops in the North Island. Our focus was on L. humile, but we also collected other ants and associated hemipteran species. Linepithema humile appeared to be an opportunistic species and was found on fifteen of eighteen common horticultural crops that we surveyed, as well as on a variety of other plants. It was observed tending 15 different species of hemipteran insects. Linepithema humile has been previously observed tending some of these hemipteran insects overseas, such as the black scale Saissetia oleae (Olivier). Other observed L. humile-hemipteran-plant associations reported here have not previously been recorded, such as with the spirea aphid Aphis spiraecola Patch on plum trees. Eleven other species of ants were found on horticultural crops. Paratrechina vaga (Forel) was common and also tended hemipteran insects on apple, citrus, and tamarillo. Other common ants were Tetramorium grassii Emery, Monomorium antarcticum (Smith), Pheidole rugosula Forel and Ph. vigilans (Smith). Another adventive ant, Ph. megacephala (Fab.), was only sampled in Auckland despite having been in New Zealand for over 50 years. Many of these invasive ants thus do not appear threatening to horticultural crops, though L. humile appears likely to be a significant economic pest for a variety of crops.
... For Napa California, the control of these insects is particularly important, as the Argentine ant tends and protects a persistent pest in vineyards, the mealybug (Vega and Rust, 2001). As a phloem-feeding insect, the honeydew it exuded by the mealybug as a byproduct of its feeding has the tendency to cover the vine and allow an adequate food source and substrate upon which fungi may thrive, rendering a particular bunch useless for harvest (Kent Daane). ...
Article
With a greater emphasis being placed on organic farming as a means of production, more focus needs to be on chemicals such as boric acid and their potential as organic pesticides. This work aims to find the concentration at which boric acid may act as a repellant to Argentine Ants, ultimately determining how boric acid baits can be used as a means of ant population control, rather than repellants. Two separate studies in Napa used different approaches to analyze ant repellency. The first involved a series of six bait tubes each containing concentrations of boric acid from 0.0 to 1.0% in 25% sucrose solution, placed under their own vines, to ensure activity from individual colonies, and testing the general ant repellency of specific concentrations of boric acid. In the second study, all six individual concentrations were tied together and wrapped around the vine. Each "belt" had one colony that could choose from the six different boric acid concentrations, gauging the ants' preference for one concentration of boric acid. The results of first portion of the study show that generally, an increase in the concentration of boric acid leads to fewer ant visits for the bait stations with high boric acid concentration, which means that ants could ultimately be avoiding toxic baits entirely at concentrations of 0.5 and higher.
... Control of Argentine ants has typically relied on chemicals, more specifically, slowacting baits and perimeter sprays (Vega and Rust 2001). Klotz et al. (2007) found that slow-acting fipronil sprays reduced ant activity by 90% in an 8-wk period; however, using a perimeter spray of fipronil and a perimeter-broadcast of bifenthrin granules achieved the greatest reduction of ant activity around structures. ...
Conference Paper
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The Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), is an invasive, cosmopolitan species that was introduced into the U.S. around 1891 via the port of New Orleans, LA (Foster 1908, Newell and Barber 1913, Suarez et al. 2001). In the U.S., the Argentine ant is a major pest in urban, agricultural and natural environments due to its unicolonial structure which allows the formation of supercolonies with multiple shared nests (Newell and Barber 1913, Suarez et al. 1999, Tsutsui et al. 2000, Vega and Rust 2001, Tsutsui and Suarez 2003). Because these ants were introduced and have lost genetic diversity, they lack intraspecific aggression, allowing populations to increase rapidly (Newell and Barber 1913, Holway et al. 1998, Holway 1999, Human and Gordon 1999, Tsutsui et al. 2001, Suarez et al. 2002), which provides a competitive advantage to L. humile when competing against native ants, other introduced ant species (Kabashima et al. 2007), and other insect and arthropod species (Holway et al. 1998, Holway 1999, Tsutsui and Suarez 2003). Other factors in the success of L. humile include sociotomy, polydomy, polygyny, lack of natural enemies, and human dispersal, mostly through commerce and various other business operations (Holway et al. 1998, Holway and Suarez 1999, Holway and Case 2000, Vega and Rust 2001, Tsutsui and Suarez 2003). Control of Argentine ants has typically relied on chemicals, more specifically, slow-acting baits and perimeter sprays (Vega and Rust 2001). Klotz et al. (2007) found that slow-acting fipronil sprays reduced ant activity by 90% in an 8-wk period; however, using a perimeter spray of fipronil and a perimeter-broadcast of bifenthrin granules achieved the greatest reduction of ant activity around structures. Rust et al. (2003) proposed that the broader the range of concentrations in insecticidal baits, the more effective the control because of delayed toxicity. However, they also noted that finding suitable bait bases and active ingredients that provide delayed toxicity are the most difficult obstacles to overcome when formulating effective Argentine ant baits. Klotz et al. (1995) suggested that the lack of information on Argentine ant biology has contributed to the failure of most traditional chemistries to successfully control Argentine ants. According to Curtis et al. (1990), a large number of plants that yield essential oils are known to be feeding deterrents to insects and other arthropods. Some of these plant-extracted oils have been the starting point for some commercially-produced repellents. The long-term repellent characteristics of essential oils have been challenged by some (Buescher et al. 1982, Rutledge et al. 1983, Nerio et al. 2010), who reported efficacy when freshly applied, but reduced effectiveness as the oils began to age. Thus, the objective of this study was to evaluate the repellent effects of freshly-applied and aged essential oils on Argentine ants, using a choice-based assay similar to that of Ebeling et al. (1966).
... The present work demonstrates that Inesfly IGR FITO © can effectively exclude ants from citrus canopies. Field results obtained in two citrus orchards with different ant complex prove that this micro-encapsulated formulation results effective against both L. grandis, the most abundant ant in Mediterranean citrus (Alvis 2003;Vanaclocha et al. 2005;Cerdá et al. 2009), and the invasive Argentine ant L. humile, the most damaging ant in other citrus areas such as Californian citrus (DeBach 1951;Vega and Rust 2001). ...
Article
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Ants have a positive effect on populations of California red scale, Aonidiella aurantii (Maskell), in citrus. Previous studies have shown that the presence of Argentine ant, Linepithema humile (Mayr), as well as the complex of native Mediterranean ant species, Pheidole pallidula (Nylander) and Lasius grandis Forel, increase the densities of A. aurantii at harvest. Sticky barriers have been successfully used to exclude these ant species from citrus canopies. However, this method is too laborious to be applied on large areas. In this study, the efficacy of an insecticidal paint based on chlorpyrifos and pyriproxyfen in a micro-encapsulated formulation (Inesfly IGR FITO ©) to exclude ants was evaluated. Its efficacy was compared to sticky barriers (Tangle-Trap ® Insect Trap Coating, Tanglefoot). Our field results, showed that a single application of Inesfly IGR FITO © in April excluded L. humile, L. grandis and P. pallidula from citrus canopies along the season. Furthermore, the exclusion of L. grandis and P. pallidula significantly reduced the percentage of downgraded fruit by presence of A. aurantii.
... The urban ant fauna presents considerable medical and economic importance, as many species are pests of domiciliary, industrial, and commercial establishments, including some which can cause relevant structural damage; many ant species are serious pests of crops and natural habitats, and some are important mechanical vectors of pathogenic microorganisms in hospital areas, and can cause severe allergic reactions (Vega & Rust 2001;Campos-Farinha et al. 2002;Klotz et al. 2008). Among urban ants, there are those species baptized 'tramp species' , which feature a set of advantageous characteristics that enabled them to adapt to humanized environments, as described in Passera (1994). ...
Article
Tramp ant species present a set of adaptations to their urban habitats, and there is a paucity of knowledge about how they interact with abiotic factors, like temperature. Temperature is well known to interfere with insect activity. The present study evaluated the temperature tolerance of three important tramp ant species: Monomoriumfloricola (Jerdon), Monomoriumpharaonis (Linnaeus) and Tetramorium bicarinatum (Nylander). Tested temperatures were 0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30, 32, 34, 36, 38, 40, 42, 44, 46,48 and 50°C. Ten repetitions with 20 workers each were done with each temperature and analyzed species. The number of dead workers was recorded every hour over a total of 8 hours. All procedures were done using thermal incubators at relative humidity within 50-95%. Workers of M. pharaonis proved more tolerant to high temperatures (30-50°C) than workers of M. floricola and T. bicarinatum. The higher the temperatures tested, greater was the recorded ant mortality, with temperature 50°C being fatal to all species after lh of exposition. The least tolerant species to temperatures below 20°C was T. bicarinatum. Low temperatures tested were not fatal to any of the tested species.
... Temperatures at night (averaging 25°C) than during the day (averaging 33°C) (Lee, 2002). The LD50 of S. geminata minor workers to exposure to high temperatures for an hour is above 40°C Environments with high rainfall reduce foraging time of Solenopsis geminata and may reduce the probability of establishment (Cole et al., 1992;Vega and Rust, 2001). High rainfall also contributes to low soil temperatures. ...
... In agricultural systems, Argentine ants are associated with outbreaks of phloem-feeding hemipterans [41], from which the invasive species collects honeydew [42]. Because Argentine ants usurp resources from beehives, prey upon bees, and possibly spread viruses [7], both the honey production and pollination industries can suffer from the species' presence [41,43]. ...
Article
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The Argentine ant (Linepithema humile, Mayr) is a highly invasive species. Recently, several RNA viruses have been identified in samples from invasive Argentine ant colonies. Using quantitative PCR, we investigated variation in the levels of these viruses in the main European supercolony over the course of a year. We discovered that virus prevalence and amounts of viral RNA were affected by season and caste: ants had more virus types during warm versus cold months, and queens had more virus types and higher virus prevalence than did workers or males. This seasonal variation was largely due to the appearance of positive-strand RNA viruses in the summer and their subsequent disappearance in the winter. The prevalences of positive-strand RNA viruses were positively correlated with worker foraging activity. We hypothesise that during warmer months, ants are more active and more numerous and, as a result, they have more conspecific and heterospecific interactions that promote virus transmission.
... The Argentine ant, Linepithema humile (Mayr), is a major nuisance pest, and in the United States, it is found mainly in southern California and the Southeast [1]. It commonly manifests as a supercolony, and is able to dominate entire landscapes and become highly invasive in human altered habitats [2]. ...
Article
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The Argentine ant, Linepithema humile, is an invasive nuisance, agricultural, and ecological pest from South America. In the United States, its primary distribution is in California and the Southeast. The structural pest control industry responds to property owner complaints when this ant’s populations become problematic and a persistent nuisance. Actions taken to control Argentine ants in the urban and suburban environment are typically complaint-driven, and often involve the application of insecticide sprays applied to the outdoor environment by professional pest managers. In California, and elsewhere, spray treatments of various residual insecticides by property owners and pest management professionals has resulted in significant runoff and in subsequent surface water contamination. As a result, an immediate need exists to develop alternative methods of ant control targeted at reducing environmental contamination. The purpose of this study was to investigate the potential for the development of an alternative method of toxicant delivery focused on the Argentine ant’s behavior modifying cuticular chemistry. In short, methanol and hexane washes of Argentine ant pupae applied to paper dummies were handled significantly more by worker ants than the paper dummies that did not contain the solvent extracts. Additionally, paper wicks soaked in a methylene chloride wash from Argentine ant cadavers, air dried, and then treated with fipronil, were removed by worker ants and placed on a midden pile at the same rate (≈86% to 99% removal at 1 h) as untreated and fipronil-treated ant cadavers. The paper wicks that did not contain the methylene chloride extract were ignored by the worker ants. After three days, the mortality of the ants exposed to the fipronil-treated wicks or the ant cadavers were dose-related. In conclusion, our study suggests that there is potential for the use of ant semiochemicals for the delivery of acute toxicants.
... It is a common ant in European greenhouses and is sometimes encountered in North-American greenhouses (Wetterer et al. 2009). It protects hemipterans and feeds on the honeydew they produce (Vega & Rust 2001). Nests can be found in various ground cavities and they all contain multiple queens. ...
Article
The monitoring of introduced species is becoming more important as global trade intensifies. Although ants make up a larger proportion of species on the list of the most invasive species in the world compared with other groups, little is known about the occurrence of those introduced in France, especially inside heated buildings. Here we review the literature available for mainland France and Belgium and report the results of a survey conducted with the help of tropical building managers between 2014 and 2016. We report for the first time in France the presence of Technomyrmex vitiensis and Plagiolepis alluaudi in multiple greenhouses. Technomyrmex difficilis was also found in one greenhouse for the first time in Europe. The diversity of introduced ants in greenhouses is very low, and these buildings are most often dominated by one or two species. We compared the most recent data and those collected throughout the twentieth century and showed that ant communities have changed substantially. Greenhouses could be responsible for the introduction of invasive species because they regularly import exotic plants, but we found no evidence that the three species of invasive ants present outdoors in France were introduced from greenhouses, where they rarely occur. We also report that introduced ants are pests in greenhouses because they disperse scale insects and kill biological control agents. The suppression of these ants could ease the maintenance of plants inside greenhouses.
... En los tres casos existen afectaciones económicas tanto por la pérdida de productos agrícolas, gastos en químicos para su control y gastos médicos para la población (Carpintero, 2001). También se han reportado daños a la infraestructura de construcciones humanas (Gómez & Oliveras, 2003;Touyama et al., 2003) así como destrucción de sistemas de riego agrícola (Chang y Ota, 1990) y el robo de colmenas de abeja y depredación de abejas, lo que afecta en la producción de miel en las industrias (Vega & Rust, 2001). ...
Technical Report
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El presente reporte tiene como principal objetivo proporcionar información veraz y actualizada sobre 4 especies de hormigas con potencial invasor en México con la finalidad de prevenir, detectar y reducir el riesgo de introducción, establecimiento y dispersión de dichas especies. Se incluye información detallada que permitirá a las autoridades correspondientes tomar decisiones adecuadas en cada caso. En base al conocimiento generado de distribución de estas hormigas invasoras, se pueden establecer programas de erradicación y control de poblaciones para minimizar o eliminar sus impactos negativos favoreciendo la conservación de los ecosistemas. Este documento también será de utilidad para concientizar a la sociedad sobre la importancia de las especies invasoras.
... Tableau 3. Caractéristiques des six espèces de fourmis invasives les plus répandues et dont la surpopulation engendrent un impact majeur dans les milieux qu'elles ont envahi (modifié d'après Holway et al. 2003 (Haines et al. 1994), L. humile (Vega et Rust 2001), P. ...
... Invasive ants penetrate natural ecosystems where they often reduce native ant diversity and affect other organisms both directly and indirectly. The competitive displacement of native ants by invasive ants is the most dramatic and widely reported effect of ant invasions (Vega & Rust 2001, Wetterer et al. 2001, revised by Holway et al. 2002. Given their potential to disrupt ecosystems, invasive ants are an important conservation concern (Holway et al. 2002) Most of the ants observed interacting with the S. romanzoffiana fruits represent species of genera commonly found foraging on the surface of the forest floor; however, we verified the presence of ant species on the fruits that are of genera considered to be preferentially arboreal, such as Pseudomyrmex, Crematogaster, and Camponotus. ...
Article
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On the forest floor of a fragment of the Atlantic Forest which is considered to be in a stage of recuperation, located in southeastern Brazil, we recorded 54 species of ants interacting with the fruits of Syagrus romanzoffiana (Arecaceae). Myrmicinae was the subfamily which was the richest in species, followed by Ponerinae, Formicinae, Ecitoninae, Dolichoderinae, Pseudomyrmecinae and Cerapachyinae. The fruits of S. romanzoffiana can be classified according to whether or not they are preyed by the squirrel Sciurus ingrami, and the ant fauna that visits the fruits has an average similarity. Regarding diversity, the data suggest that there is no significant difference between ant assemblages at preyed and non-preyed-upon fruit falls. The results also indicate that there is no specific interaction between the ant fauna that visits the fruits of S. romanzoffiana, as it consists largely of species with omnivorous feeding habits.
... However, as ants in treated areas did retain some body fat, it could therefore be speculated that the ants may have still been able to forage to some degree. As our plots were of limited size and the Argentine ant is known to forage over distances of more than 50 m (Vega andRust 2001, Cooper et al. 2008), a possible explanation is that workers from treated plots either found some food inside the treated areas or were able to forage outside of the treated plots and return. It is also possible that the ants kept a number of scale insects in underground tunnels on roots of grapevine plants (Daane et al. 2012). ...
Article
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Ant species like Pheidole megacephala (F.), Solenopsis invicta (Buren), and the Argentine ant, Linepithema humile (Mayr), have repeatedly been reported to be strongly associated with honeydew-producing arthropods like aphids, scale insects, and mealybugs, effectively protecting them from biological control agents like parasitoids. Here we report the results of a successful trial using pheromone dispensers to suppress Argentine ant activity over large sections in a commercial vineyard over a period of two months and preventing ant access into and foraging within the vine canopy. We found Argentine ant activity to be significantly reduced in pheromone-treated plots for the duration of the trial period compared with control plots. Our results showed a significant reduction in the numbers of Argentine ant workers recruited to randomly placed food resources within treated plots compared with untreated plots. Furthermore, spatial distribution of Argentine ants alongside transects in untreated plots remained relatively continuous, while increasing sharply beyond the borders of treated plots. Lastly, we measured the body fat content of workers and found a significant reduction in fat among workers from treated plots compared with untreated plots, suggesting an adverse effects on nest fitness. Additionally, we provide an initial assessment of the feasibility of the presented approach. Our results showed that it is possible to control Argentine ant, preventing them access to and foraging within the vine canopy, thereby reducing Argentine ants’ access to honeydew.
... With the development of human commerce, Argentine ants have been unintentionally introduced to many parts of the world during the last 150 years Wetterer et al. 2009]. Their opportunistic nesting behavior [Vega and Rust 2001] and polygyny [Keller et al. 1989] may enhance the opportunity of human-mediated dispersal of nest fragment, and the probability of inclusion of reproductive queens in it [Suarez et al. 2008]. , though they sometimes penetrate natural environments [e.g., Bond and Slingsby 1984;Cole et al. 1992]. ...
Article
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Social insects have obtained their prosperity by cooperation among individuals. This can be applied particularly to the success of invasive ants, which form unusual social structure called supercolonies, within which individuals can move freely among physically separated nests, and thereby gain high population densities to dominate indigenous ants. Native to South America, the Argentine ant Linepithema humile has been unintentionally introduced into many parts of the world during the last 150 years. Although it is well known that the introduced Argentine ant populations form much larger and fewer supercolonies than the native populations, the relationship among beyond-ocean populations has been poorly understood. Recent studies, however, are uncovering the behavioral, chemical and genetic relationships among introduced Argentine ant populations worldwide. Individuals from the dominant supercolonies around the world have very similar cuticular hydrocarbon profiles (nestmate recognition cue), and do not show aggressive behavior toward each other, when artificially put into contact. The supercolonies constitute the largest cooperative unit ever known. Their genetic closeness suggests a common introduction pathway. Considering historical records, descendants of the most ancient introduced population have spread to many parts of the world, without losing memory of their roots. In this chapter, we introduce the nestmate recognition system and mechanism of supercolony expansion in invasive ants, with the global empire of Argentine ants as an example.
... Native to South America (Tsutsui et al. 2001) it has now been introduced into various parts of the world as a result of human commercial activities (Hölldobler and Wilson 1990;Suarez et al. 2001). Its distribution includes areas with Mediterranean-type climates (Passera 1994;Vega and Rust 2001). Its rapid expansion in invaded zones has been facilitated by habitat disturbance (Suarez et al. 1998), but there is increasing evidence of its ability to occupy non-altered habitats (Cole et al. 1992;Holway 1998). ...
... Tableau 3. Caractéristiques des six espèces de fourmis invasives les plus répandues et dont la surpopulation engendrent un impact majeur dans les milieux qu'elles ont envahi (modifié d'après Holway et al. 2003 (Haines et al. 1994), L. humile (Vega et Rust 2001), P. ...
... It has been linked with population declines in a variety of organisms (Cole et al. 1992;Sanders et al. 2003;Rowles and O'Dowd 2009a) as well as damage to agricultural crops by supporting herbivorous pest species (Ward et al. 2010). Populations quickly reach high abundance, and estimates of 50,000-600,000 ants on a trail have been reported (Vega and Rust 2001). Such high abundances allow them to eliminate even comparatively large species (De Kock 1990). ...
Article
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Toxicity and the utilization of venom are essential features in the ecology of many animal species and have been hypothesized to be important factors contributing to the assembly of communities through competitive interactions. Ants of the genus Monomorium utilize a variety of venom compositions, which have been reported to give them a competitive advantage. Here, we investigate two pairs of Monomorium species, which differ in the structural compositions of their venom and their co-occurrence patterns with the invasive Argentine ant. We looked at the effects of Monomorium venom toxicity, venom utilization, and aggressive physical interactions on Monomorium and Argentine ant survival rates during arena trials. The venom toxicity of the two species co-occurring with the invasive Argentine ants was found to be significantly higher than the toxicity of the two species which do not. There was no correlation between venom toxicity and Mo-nomorium survival; however, three of the four Monomorium species displayed significant variability in their venom usage which was associated with the number of Argentine ant workers encountered during trials. Average Monomorium mortality varied significantly between species, and in Monomorium smithii and Monomori-um antipodum, aggressive interactions with Argentine ants had a significant negative effect on their mortality. Our study demonstrates that different factors and strategies can contribute to the ability of a species to withstand the pressure of a dominant invader at high abundance, and venom chemistry appears to be only one of several strategies utilized.
... An effective liquid bait reduces the need for broadcast sprays, thereby decreasing the amount of insecticide used to control ants (Hooper-Bui & Rust 2001). A slow-acting toxin in a highly attractive bait may potentially be distributed throughout the colony by exploiting the recruitment and food-sharing behavior of ants. ...
Article
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Chemical treatments were evaluated for efficacy against specific ant pests in two perennial field crop systems. A directed spray of Lorsban applied in grape vineyards resulted in significant reductions of Formica perpilosa Wheeler (Hymenoptera: Formicidae) for 9 wk. Significant reductions in the number of foraging Argentine ants, Linepithema humile (Mayr) (Hymenoptera: Formicidae), were obtained in citrus for the 4-mo duration of a test with a liquid bait delivery system containing either 0.0001% fipronil or thiamethoxam in 25% sucrose water.
Article
Laboratory bioassays were performed to test the repellent properties of 5 plantextracted essential oils against the Argentine ant, Linepithema humile (Mayr). Three concentrations (0.10%, 1%, and 10% in n-hexane) of peppermint, spearmint, wintergreen, cinnamon and clove oils, as well as a negative control [n-hexane] and positive control [Cinnamite™] were evaluated in choice tests to evaluate repellency against Argentine ant workers by counting the number of ants entering a preferred harborage that was treated and then aged for 2 h (fresh) or 7 d (one-wk-old). When deposits were fresh, all oils at all concentrations were repellent, with repellency defined as statistically fewer ants in harborages compared with harborages treated with only solvent (hexane). After the deposits were aged for 7 d, 4 of the 5 oils formulated at the 0.10% concentration were no longer repellent, whereas only spearmint had retained its repellent property. At 1% and 10% oil concentrations all 5 oils were repellent, whereas only 1% wintergreen was slightly less repellent.
Article
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This study examines some aspects of the basic biology of the worldwide distributed ant Tapinoma melanocepbalum Fabricius. The number of larval instars and the growth ratio between each instar are given. We used colonies containing only queens and workers, and later removed these queens in order to estimate the production of eggs and the duration of immature development of the worker caste. Measurements of larvae cephalic capsule widths revealed that workers of the ghost-ant have four larval instars from egg-hatching to adult. The mean growth rate for the species is 1.38, in accordance with Dyar's rule. The highest egg production was 5.3±2.2 eggs/day/queen and the analysis of these brood suggested the presence of two kinds of eggs inside the colony. The development of workers from egg to adult lasted 16-52 days with the embryonic development longer than larval, prepupal or pupal stages. Despite the slow egg-laying by queens, our findings also showed that colonies of T. melanocephalum grow faster than colonies of other tramp ants.
Article
The Argentine ant, Linepithema humile, has invaded urban, agricultural, and natural habitats worldwide, causing economic damages and disrupting ecosystem processes. As a contribution to Argentine ant management, the present study aimed to test in situ the efficacy of an imidacloprid gel bait. We tested the gel efficacy in terms of Argentine ant eradication at nest scale, conducting experiments on four nests. We recorded a significant decrease in ant abundance for three of the four study nests and three nests presented no activity 21 days after the first. There were strong assumptions that the decrease in ant abundance and activities was a direct consequence of the use of the gel bait, showing that the use of imidacloprid delayed toxic gel may be effective and an alternative to liquid and solid baits as part of much needed management strategies for this major pest.
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The genus Paratrechina (Motschulsky) is composed of about 147 cosmopolitan ant species and subspecies, of which some were accidentally spread by commerce around the world, infesting houses and hospitals. In Brazil, two species are of remarkable economic importance: Paratrechina fulva (Mayr) and Paratrechina longicornis (Latreille). The present paper aims to report the following aspects on the biology of P. longicornis: number of larval instars, growth rates, duration and viability of the developmental stages and some observations on brood-care behaviour. Artificial colonies were kept under controlled temperature (25±2°C) and relative humidity (60±10%) conditions. To access the number of larval instars, we analyzed 1531 larvae fixed in Dietrich by measuring their maximum head capsule widths. We analysed ten artificial colonies daily to measure the developmental time and viability of immatures. We found P. longicornis presented three larval instars and a mean growth ratio of 1.2988. Egg stage was found to last 16.1 ±0.1 days, with a viability of 24.6%; larval stages were found to last 18.3±0.1 days, with a viability of 33.3% and the pupal stage was found to last 12.3±0.1 days, with a viability of 65.3%.
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Background: Insecticide sprays used for ant control cause environmental contamination. Liquid bait is a safe and effective alternative, but it requires bait stations to dispense the toxicant. We developed a biodegradable hydrogel to deliver liquid bait obviating the need for bait stations. Results: Alginate hydrogel beads with preferred rigidity and maximum hydration in 25% sucrose solution were engineered by optimizing a crosslinking process. The moisture content of the substrate on which the beads were placed and the relative atmospheric humidity significantly influenced water loss dynamics of the hydrated hydrogel beads. Laboratory choice studies indicated that hydrated hydrogel beads had reduced palatability to foraging ants when they lost ≥ 50% water. An enzyme linked immunosorbent assay (ELISA) indicated that the insecticide thiamethoxam added to sucrose solution was absorbed into the hydrogel beads. Hydrogel beads conditioned in sucrose solution with 1 mg L(-1) thiamethoxam provided complete control of all castes of Argentine ant Linepithema humile (Mayr) colony by 14 days post-treatment in the laboratory trial and provided a 79% reduction in ant activity after 8 weeks in the field trial. Conclusion: Alginate hydrogel beads provided an effective delivery system for liquid baits laced with low concentrations of insecticide to control Argentine ants.
Chapter
The Argentine ant originates as the popular name indicates from South America and the river La Plata region. It has become a successful invader in many parts of the world that have a Mediterranean-type climate, but nowhere more so than on the northwestern shore of the Mediterranean itself. A key to its invasive success is its tendency to form supercolonies outside its natural distribution area, which allows a much higher density of individuals than opposing native ant species can muster. The largest known supercolony stretches 6000 km from northwestern Iberia via France to Italy and is thought to consist of several billion workers and tenths of millions of queens. Over this area, it dominates the ant community and has replaced native species, even if not driven them to extinction. Cascading effects on animals and plants, of the sort that has been documented elsewhere, are more or less self-evident, even as few have been reported from this area. The initial explosive population development appears to have leveled off, but there are, as yet, no signs of a collapse. So, well over 100 years after its introduction, the Argentine ant is ruling its European fortress.
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The invasive Argentine ant (Linepithema humile) has become established worldwide in regions with Mediterranean or subtropical climates. The species typically disrupts the balance of natural ecosystems by competitively displacing some native ant species via strong exploitation and interference competition. Here we report that Argentine ants utilize glandular secretions for inter and intra-specific communications during aggressive interactions with a heterospecific competitor, California harvester ant (Pogonomyrmex californicus). Chemical analyses indicated that Argentine ants deploy glandular secretions containing two major volatile iridoids, dolichodial and iridomyrmecin, on the competitor's cuticular surface during aggressive interactions. Bioassays indicated that the glandular secretions function as a defensive allomone, causing high levels of irritation in the heterospecific. Furthermore, the same glandular secretions elicited alarm and attraction of conspecific nestmates, potentially enabling more rapid/coordinated defense by the Argentine ants. Two major volatile constituents of the glandular secretion, dolichodial and iridomyrmecin, were sufficient to elicit these responses in conspecifics (as a mixture or individual compounds). The current study suggests that invasive Argentine ants' superior exploitation and interference competition may rely on the species' effective semiochemical parsimony.
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Introduction of alien organisms is a major risk that follows international trade. Ants are among the most harmful groups of invasive organisms, with five species, including the Argentine ant Linepithema humile, listed among the world's 100 worst invasive species by the IUCN. We review the damage, ecology, and dispersal of invasive ants, with the Argentine ant as a representative. Invasive ants attain high population densities in the introduced range, and cause damage to ecosystems, agriculture, and human well-being by the sheer number. The high density may stem partly from formation of expansive "supercolonies (a supercolony is a large network of cooperative nests). In the Argentine ant, the high consistency of their supercolony identities makes them important units in inferring the dispersal history of this species. We highlight two topics in the dispersal history of the species: 1) formation of an unprecedented intercontinental supercolony by the 150th year of international trade; 2) recent successive introductions to Pan-Pacific region seemingly in accordance with globalization.
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We examined the impact of the non-indigenous Argentine ant, Linepithema humile (Mayr), on the native ants of Santa Cruz Island (SCI), the largest of the California Channel Islands. Linepithema humile, a South American native, was first found on SCI in 1996 and now occupies two areas comprising less than 1% of the island. We surveyed ants using four methods: visual surveys, bait stations, tree surveys, and soil/litter samples. We found a total of 23 ant species, including two species not native to SCI: Cardiocondyla ectopia Snelling and Linepithema humile. Numerous native ants occurred at sites uninfested by L. humile and co-occurred with L. humile at the outer boundaries of L. humile-infested territory, but at sites more than 10m within L. humile-infested territory, all but two of these species disappeared, probably due to exclusion by L. humile. Only two tiny ant species, Solenopsis molesta Say and Monomorium ergatogyna Wheeler, were found to coexist deep within the L. humile-occupied areas.
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We have studied the influence of Argentine ant invasion on the level of pollen grain carriage by ants in Euphorbia characias and E. biumbellata, two deciduous shrubs visited by ants. The observations were made in two contiguous areas, invaded and non-invaded by the Argentine ant Linepithema humile, in a Mediterranean cork-oak forest. In the invaded area L. humile displaced all native ants that climb to the cyathia of the inflorescences, except Plagiolepis pygmaea, a tiny ant species. Eight native ant species were detected in non-invaded areas. Camponotus cruentatus (52.06 ± 5.57 pollen grains carried per ant worker of E. characias and 38.84 ± 6.82 pollen grains of E. biumbellata, mean ± se) and Camponotus piceus (42.80 ± 21.57 pollen grains of E. biumbellata) carried much more pollen than L. humile worker ants (0.37 ± 0.06 pollen grains of E. characias and 0.44 ± 0.21 pollen grains of E. biumbellata). The Argentine ant and the native ants collected nectar, but C. cruentatus, the visiting ant species most abundant in the non-invaded area, touched the anthers or the stigma of the flowers three times more frequently than the Argentine ant. These results suggest the Argentine ant displace the native ants and that the invasion could interfere with natural visitors or potential pollinators in several plants.
Chapter
Invasive alien species (IAS) is a scourge that gnaws away at biodiversity, the environment as a whole, and the socioeconomic fabric of countries. In Morocco, nearly 150 IAS have been inventoried and argued, and it is sincerely believed that this number is well below the actual total number of IAS introduced into the country, which suggests other scientific investigations, both on the ground and in the laboratory, to be able to identify them. These IAS cause damage, sometimes catastrophic. Virtually all environments suffer: ecosystems, landscapes, the agro‐ecosystem, the forest ecosystem, wetlands, and the marine and coastal environment. The country's economy, its social stability, as well as human and animal health are also concerned. In agriculture and aquaculture, vital and strategic (food security, jobs, rural economy), IAS pose a real threat to grain farming, arboriculture, seaweed farming, and so on, and almost all species of food interest are threatened by IAS, accidentally or deliberately introduced to the point where yield, of cereal for example, has dropped by 98% in some areas of the country. The reduction in yield concerns not only cultivated plants but also farmed animals (sheep flocks, goats, birds, bees, etc.) because of their toxicity, their aggressiveness, or their competitiveness. The Moroccan forest, which is strategic for the country's overall ecological balance and for its rural economy, also suffers from IAS, in particular its heritage species such as the Atlas cedar. Wetlands that have experienced fish introductions since the beginning of the last century have been greatly affected by these exotic species to the point that, in the early years of introduction, native forms such as pallary trout have been exterminated. The marine and coastal environment, despite its buffering capacity, is beginning to feel the weight of the threat of IAS introduced mainly for aquaculture reasons. The information concerning this environment remains very fragmentary given the insufficient human and material resources available for exploration of this area, particularly for ballast water and bio‐soiling. The little information that exists, however, shows a negative effect of introduced species on native ones. Silverleaf nightshade (in Morocco, morelle jaune) and the pine processionary are also the origin of respiratory or allergic diseases, and the tiger mosquito could be the origin of many more serious diseases. The fight against IAS remains punctual, often mechanical, without a targeted strategy; and the main monitoring instrument remains the establishment of the National Office for the Health Security of Food Products (ONSSA), whose main task is the control of transit, at each point of entry into the national territory, of plants, seeds, animals, and biological material potentially harmful to the environment or health in the country.
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Workers of the Argentine ant, Iridomyrmex humilis,start to explore a chemically unmarked territory randomly. As the exploratory front advances, other explorers are recruited and a trail extends from it to the nest. Whereas recruitment trails are generally constructed between two points, these exploratory trails have no fixed destination, and strongly resemble the foraging patterns of army ants. A minimal model shows how the exploratory pattern may be generated by the individual workers' simple trail-laying and -following behavior, illustrating how complex collective structures in insect colonies may be based on self-organization.
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Bait acceptance and effect of toxic bait consumption on the foraging activity offield colonies of Argentine ants, Linepithema humile (Mayr), were assessed. Nine individual colonies were randomly assigned to receive one of three treatments: a containerized bait containing 0.5% sulfluramid in a peanut butter matrix, a containerized bait containing 0.9% hydramethylnon in an insect pupae-fish meal matrix, and an untreated control. Ant foraging activity was measured using honey-water monitoring stations placed at 0, 1, and 3 m from the colony nest-site. Both containerized baits reduced ant foraging activity to zero ants per monitor within 6 wks, if the equivalent of one containerized bait station was consumed by the colony.
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Recent research in urban ant control provides some new opportunities for developing alternative pest management strategies. Current control of urban pest ants relies heavily on broadcast spraying of residual insecticides. However, recent findings suggest that a combination of ant repellents, baits, and exclusion techniques may be equally effective and offer a safer alternative. Low-toxicity pesticides and nonchemical methods would significantly reduce the risk of exposure to pesticides, as well as serve as a model for ant control based on an environmentally safe approach.
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Interactions between the invasive Argentine ant, Linepithema humile, and native ant species were studied in a 450-ha biological reserve in northern California. Along the edges of the invasion, the presence of Argentine ants significantly reduced the foraging success of native ant species, and vice versa. Argentine ants were consistently better than native ants at exploiting food sources: Argentine ants found and recruited to bait more consistently and in higher numbers than native ant species, and they foraged for longer periods throughout the day. Native ants and Argentine ants frequently fought when they recruited to the same bait, and native ant species were displaced from bait during 60% of these encounters. In introduction experiments, Argentine ants interfered with the foraging of native ant species, and prevented the establishment of new colonies of native ant species by preying upon winged native ant queens. The Argentine ants' range within the preserve expanded by 12 ha between May 1993 and May 1994, and 13 between September 1993 and September 1994, with a corresponding reduction of the range of native ant species. Although some native ants persist locally at the edges of the invasion of Argentine ants, most eventually disappear from invaded areas. Both interference and exploitation competition appear to be important in the displacement of native ant species from areas invaded by Argentine ants.
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In this paper, we examine the hypothesis that reduced intraspecific aggression underlies the competitive prowess of Argentine ants in their introduced range. Specifically, we test three predictions of this hypothesis by comparing the genetic diversity, behavior, and ecology of Argentine ants in their native range to introduced populations. Differences between native and introduced populations of Argentine ants were consistent with our predictions. Introduced populations of the Argentine ant appear to have experienced a population bottleneck at the time of introduction, as evidenced by much reduced variation in polymorphic microsatellite DNA markers. Intraspecific aggression was rare in introduced populations but was common in native populations. Finally, in contrast to the Argentine ant's ecological dominance throughout its introduced range, it did not appear dominant in the native ant assemblages studied in Argentina. Together these results identify a possible mechanism for the widespread success of the Argentine ant in its introduced range.
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A comparison of several physiological parameters of queens of Iridomyrmex humilis in experimental monogynous and polygynous colonies showed that queens in monogynous colonies became heavier, had more developed ovaries and laid about twice as many eggs. Workers in monogynous colonies were more attracted to queens, which therefore probably received more food. This may partially explain the higher weight and fecundity of queens in monogynous colonies of Iridomyrmex humilis and possibly other ant species. In polygynous colonies, queens differed greatly in their fecundity. These differences did not appear to be the result of a dominance hierarchy. These results are discussed from an evolutionary point of view. Two hypotheses of mutualism and colony level selection are proposed as an alternative to kin selection which is unlikely to be the exclusive selective influence in the evolution of polygyny either in I. humilis or in most other ant species.
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We investigated whether the Argentine ant, Linepithema humile (Mayr), trail pheromone, Z9-16:Ald, could enhance recruitment to and consumption of liquid sucrose solutions. All tests were done as paired comparisons with a 10% sucrose solution as food. In the laboratory, mixing 20 microl of a 10-microg/ml solution of the pheromone with 50 microl of the 10% sucrose solution increased the number of ants feeding by >150%. In a field test, we combined the trail pheromone with a 10% sucrose solution in 50-ml vials. These vials were covered with a plastic membrane that has 1.5-mm-diameter holes punched uniformly across its surface. Ants could drink from the holes after the vials were inverted. For half of the vials, 1 microg of the pheromone was put onto the plastic membrane before the vials were filled with a 10% sucrose solution. The remaining vials had no pheromone on the plastic membrane. After 4 h we measured the consumption in each vial. Bait consumption with the pheromone was enhanced by 29%. In a 2nd series of tests, vials were left outside for 24 h. The consumption rate was 33% higher with the pheromone compared with the controls that didn't have pheromone.
Article
Individual colonies of Argentine ants, Linepithema humile (Mayr), were collected and maintained in plastic containers and randomly selected to receive a potted oleander (Nerium oleander L.) plant with one of eight different soil treatments of fipronil, diazinon, or an untreated control. Foraging and mortality rates were observed in each colony. Reductions in the rates of ants foraging on plants were similar with all treatments; however, the mortality rates of the colonies varied among treatments. For example, 1 wk after exposure to treatments, the foraging rates on plants in all treatments except the control had dropped to zero. Soil-mix treatments of fipronil had killed >90% of worker ants at 1 wk, whereas broadcast treatments of fipronil and diazinon killed <50% of workers. The soil-mix treatments of fipronil killed all queens in 4 wk, whereas broadcast treatments of fipronil took 8 wk to kill all queens. The diazinon broadcast treatment did not kill any queens. Only fipronil soil-mix treatments prevented ants from establishing colonies in the pot. These results suggest that when studying pesticide effectiveness against Agrentine ant in the field, equivalent short-term reductions in foraging rates should not be assumed to indicate equivalent mortality of ant colonies.
Article
The southern fire ant, Solenopsis xyloni (McCook), attacks the ground nesting, endangered California least tern, Sterna antillarum browni (Mearns). Baiting with selected baits suppressed ant populations, reduced S. xyloni attacks, and was positively correlated with increased St. a. browni fledging success. Granular bait containing 0.9 % (wt/wt) hydramethylnon (Max Force) suppressed ant colonies up to 6 mo. Even though the numbers of foraging ants were reduced, some colonies persisted. This suggests selective distribution or differential sensitivity to the active ingredient within ant colonies. Area-wide baiting reduced loss of tern eggs and chicks attributed to S. xyloni 40.4% within 4 yr. Strategic baiting around bird nests reduced predaceous ants but was not as effective as area-wide + strategic baiting. Tern hatch success, chick survival, and percent fledging improved as the number of S. xyloni was reduced.
Article
Despite the innumerable ecological problems and large economic costs associated with biological invasions, the proximate causes of invasion success are often poorly understood. Here, evidence is provided that reduced intraspecific aggression and the concomitant abandonment of territorial behavior unique to introduced populations of the Argentine ant contribute to the elevated population densities directly responsible for its widespread success as an invader. In the laboratory, nonaggressive pairs of colonies experienced lower mortality and greater foraging activity relative to aggressive pairs. These differences translated into higher rates of resource retrieval, greater brood production, and larger worker populations.
Article
A one year survey was conducted with structural pest control employees of Florida to determine the kinds of ants and types of ant problems confronted in both commercial and household pest control. Eight species of ants were identified as key pests in Florida. Of these, the most common were Solenopsis invicta Buren - 14%, Tapinoma melanocephalum (F.) - 14%, Paratrechina longicornis (Latreille) - 14%, Camponotus abdominalis floridanus (Buckley) - 12%, Monomorium pharaonis (L.) - 11%, Camponotus tortuganus Emery - 8%, Pheidole megacephala (F.) - 7% and Paratrechina bourbonica (Forel) - 4%. More than twenty-five other species of ants which were occasional invaders were also collected in the survey. Customer complaints, nest locations, and treatment strategies for pest ants are also described. /// Una encuesta de un año fue llevada a cabo con empleados de control de plagas estructurales de la Florida para determinar los tipos de hormigas y de problemas causados por estas que eran confrontados por el control comercial y doméstico de plagas. Ocho especies de hormigas fueron identificadas como plagas claves en la Florida. De estas, las más comúnes fueron Solenopsis invicta Buren-14%, Tapinoma melanocephalum (F)-14%, Paratrechina longicornis (Latreille)-14%, Camponotus abdominalis floridanus (Buckey)-12%, Monomorium pharaonis (L)-11%, Camponotus tortuganus Emery-8%, Pheidole megacephala (F.)-7%, y Paratrechina bourbonica (Forel)-4%. También más de veinte y cinco especies de hormigas invasoras ocasionales fueron colectadas en la encuesta. Las quejas de los clientes, localizaciones de los nidos y estrategias de tratamiento para las hormigas plagas son también descritas.
Article
Human-caused biological invasions by an alien species are a worldwide phenomenon. They are particularly significant on isolated oceanic islands and represent a serious threat to endemic biota. The Argentine ant (Iridomyrmex humilis) has become established in portions of the high-elevation shrubland of Haleakala National Park, Maui, Hawaii, over the past 25 yr. This ecosystem lacks native ants but possesses many locally endemic and rare anthropod species. Pitfall trapping and under-rock surveys were conducted to determine the effects of I. humilis on the local arthropod fauna. More than 180 taxa were sampled, mostly Arthropoda. Presence of the Argentine ant is associated with reduced populations of many native and non-native anthropod species, including important predator species and major pollinators of native plants. Effects of ant invasion were particularly severe at higher elevations of Haleakala volcano where endemic species normally exist at low densities. Some taxa, primarily alien species, were more abundant in the presence of ants. Invasion of the Argentine ant has locally reduced the abundance of many endemic species in the shrubland ecosystem. Although the spread of this ant species is slow, I. humilis appears to have the potential to invade a much larger area of Haleakala National Park than it now occupies. Active management of Argentine ant populations will be necessary if the endemic fauna is to be preserved.
Article
Iridomyrmex humilis has recently invaded areas of Cape fynbos and displaced the dominant native ants. Iridomyrmex differed from native ants in being slower to discover the seeds (morphologically achenes) of ant-dispersed Mimetes cucullatus (Proteaceae), in moving them shorter distances, and in failing to store them in nests below the soil. Seeds left on the soil surface were eaten by vertebrate and invertebrate predators. Seed depots were established and then the area was burned. Emergence was 35.3% in sites not infested by Iridomyrmex and 0.7% in infested sites. Seedlings in naturally occurring stands of M. cucullatus burnt in the same fire were widely distributed in noninfested sites, but were fewer and were confined within the canopy radius in infested sites. Continued invasion of fynbos by Iridomyrmex may eventually lead to extinction of many rare, endemic Cape Proteaceae by slow and subtle attrition of seed reserves. -from Authors
Article
Two different laboratory bioassays were developed to quantitatively determine the repellent activity of semiochemicals, such as famesol and methyl eugenol, against the Argentine ant. lridomymzex humilis (Mayr).One assay, based on the ability of ants to cross barriers of beeswax containing different concentrations of test chemicals, was not designed to discriminate between olfactory or gustatory modes of detection. The other was based on the ability of an ant to detect airborne chemicals and, therefore, measured only the olfactory response of ants to the chemicals. Both assays permitted construction nof dosage-response curves and determination of a Bl50, the concentration that provided 50% behavioral inhibition.
Article
Lemon trees banded with experimental formulations of farnesol and other natural ant repellents were examined for efficacy of disruption of the foraging of the Argentine ant, Linepithema humile (Mayr), at varying periods of time after application. Excellent disruption of foraging was achieved by the use of a band constructed from a single strand of cotton twine permeated with 40 mg each of farnesol and Stickem per centimeter of twine. An “ant tape,” consisting of twine similarly permeated with farnesol and Stickem and covered with a strip of waxed paper, was under some conditions superior in duration of disruption of ant foraging to the noncovered, treated twine. Efforts to produce an effective barrier from farnesol mixed with Stickem and beeswax and formulated into a paste, which was then applied around tree trunks, have not been successful. The better formulations of farnesol tested have given between 2 and 3 mo of complete ant exclusion from banded trees. Other tested repellent compounds have not been as active or provided as long a duration of effectiveness as farnesol.
Article
Inbreeding may have important consequences for the genetic structure of social insects and thus for sex ratios and the evolution of sociality and multiple queen (polygynous) colonies. The influence of kinship on mating preferences was investigated in a polygynous ant species, Iridomyrmex humilis, which has within-nest mating. When females were presented simultaneously with a brother that had been reared in the same colony until the pupal stage and an unrelated male produced in another colony, females mated preferentially with the unrelated male. The role of environmental colony-derived cues was tested in a second experiment where females were presented with two unrelated males, one of which had been reared in the same colony until the pupal stage (i.e., as in the previous experiment), while the other had been produced in another colony. In this experiment there was no preferential mating with familiar or unfamiliar males, suggesting that colony-derived cues might not be important in mating preferences. Inbreeding was shown to have no strong effect on the reproductive output of queens as measured by the number of worker and sexual pupae produced. The level of fluctuating asymmetry of workers produced by inbreeding queens was not significantly higher than that of non-inbreeding queens. Finally, colonies headed by inbreeding queens did not produce adult diploid males. Based on the current hypotheses of sex-determination the most plausible explanations for the absence of diploid-male-producing colonies are that (i) workers recognized and eliminated these males early in their development, and/or (ii) there are multiple sex-determining loci in this species. It is suggested that even if inbreeding effects on colony productivity are absent or low, incest avoidance mechanisms may have evolved and been maintained if inbreeding queens produce a higher proportion of unviable offspring.
Article
The influence of various social factors on the production of males was investigated in the Argentine ant,Iridomyrmex humilis. In this polygynous species, the workers which are monomorphic are unable to lay reproductive eggs, so all the males are the progeny of the queens. Although male eggs appear to be laid by mated queens throughout the year, in large stock colonies males are reared periodically (every 3 or 4 months); males develop from brood taken from these colonies at any point in the cycle and given queenless or queenright (1 to 5 queens) units. This is in striking contrast to many other species of ants where it is generally assumed that male eggs are laid seasonnally. Comparative experiments suggest that several related factors influence the rearing of males as far as the pupal stage. •Worker/larva ratio: The proportion of male larvae developing in standardized units in which the worker/larva ratio was varied from 0.25 to 25 demonstrated that low ratios inhibit male production. •Queen influence: In standardized units where the worker/larva ratio was high the presence of queens did not inhibit the rearing of males suggesting that there is no queen inhibitory pheromone controlling male experimental production. Data suggest evidence that queens prevent male production by means of appropriation of food. •Diet: Male larvae failed to pupate in experimental societies deprived of protein. Thus, the production of males appears to be controlled by the amount of food available to larvae. This depends on foraging activity, the quantity of brood in relation to the number of workers and the number of queens in the society.