Invasive Ants Research Articles

Virome of red imported fire ants by metagenomic analysis in Guangdong, southern China

The red imported fire ant (RIFA) has made China its habitat for approximately 25 years, but few reports have described the species and amount of virus circulating in it. Researchers are currently exploring viruses associated with RIFAs as potential biological control agents against invasive ants. The present meta-transcriptome analysis revealed the virome of red imported fire ants in Guangdong, southern China, which included 17 viruses, including Solenopsis invicta virus 4-GD (SINV-4) and Guangdong Polycipiviridae ant virus 1 (GPAV1) in the Polycipiviridae family; Solenopsis invicta virus 1-GD (SINV-1), and Guangdong Dicistroviridae ant virus 2-3 (GDAV2-3) in the Dicistroviridae family; Guangdong Iflaviridae ant virus 4-9 (GIAV4-9) in the Iflaviridae family; Guangdong Parvoviridae ant virus 10 (GPAV10) in the Parvoviridae family; and Guangdong ant virus 11-15 (GAV11-15). A total of 15 novel viruses and 2 known viruses were identified in this study. These findings reveal the virome of red imported fire ants in Guangdong Province and present a different result from that of a similar study reported in the United States, providing more choices for potential classical biological control agents against red imported fire ants in China.

Stable detection frequency of the threatened Christmas Island Boobook Ninox natalis, 2012–2022

ABSTRACT Both island species and raptors are at particularly high risk of extinction but few island raptor populations have been the subject of long-term monitoring. To determine trends in abundance in the Christmas Island Boobook, surveys were conducted annually from 2012–2017, in 2019 and in 2022. Across the survey period the population appears to have been either stable or to have increased slightly. Almost no part of the island lacked owls during the most recent survey. The detection rate averaged 1.56 (out of four surveys at a site); it was lowest in 2013 (1.22) and highest in 2022 (2.38). Detection was more likely on nights with low wind, at wetter sites and in closed vegetation, rather than in open or very low vegetation. In a separate analysis on the same data, the top-ranked dynamic occupancy-detection model found that occupancy increased with increasing elevation and vegetation height. No effect of a suspected threat, the presence of invasive yellow crazy ants Anoplolepis gracilipes at a site, could be detected. We recommend ongoing monitoring and research, potentially using automated recording devices and the tracking of individual owls to understand and refine the assumptions underpinning the interpretation of survey results.

Dominance of a highly invasive ant is limited to the nesting territory of its supercolony

Abstract Ant invasions represent a serious threat to biodiversity, agriculture and public health. Highly invasive ant species exhibit a very high abundance within its introduced range and cause severe impacts on native ant communities. This scenario tends to be different within the native range, where competitor ants may limit its access to food sources, thus its abundance. Here, we evaluated the competitive ability of a typical clonal and supercolonial native population of Wasmannia auropunctata (Roger) (Hymenoptera: Formicidae) in Argentina. We used a combination of pitfall traps and food baits to study the ant interactions within an assemblage where W. auropunctata coexists with another great invader, Solenopsis invicta (Buren) (Hymenoptera: Formicidae). The studied assemblage presented 56 ant species/morphospecies. Although W. auropunctata was the most abundant numerically, its ability to discover baits was intermediate, and its ability to recruit workers massively and monopolise baits was low. Wasmannia auropunctata was not successful defending baits nor attempting to usurp baits dominated by other species. Moreover, it lost all contests against S. invicta, one of the most ecologically dominant species in this assemblage. Wasmannia auropunctata dominated food sources only when they were located within the nesting territory of its supercolony. Within the native range, clonality and supercoloniality may favour the local numerical abundance of a highly invasive ant but may not be enough to achieve ecological dominance. This study sheds light on the important role of biotic interactions as a key factor that may limit the dispersal of invasive species.

Invasive Ant Detection: Evaluating Honeybee Learning and Discrimination Abilities for Detecting Solenopsis invicta Odor.

Invasive red imported fire ants (Solenopsis invicta) create a serious threat to public safety, agriculture, biodiversity, and the local economy, necessitating early detection and surveillance, which are currently time-consuming and dependent on the inspector's expertise. This study marks an initial investigation into the potential of honeybees (Apis mellifera) to detect and discriminate the odor of S. invicta through the olfactory conditioning of proboscis extension responses. Deceased S. invicta were used as conditioned stimuli to ensure relevance to non-infested areas. The results showed that the bees rapidly learned to respond to deceased ant odors, with response levels significantly increasing at higher odor intensities. Bees exhibited generalization across the odors of 25 minor workers, 21 median workers, 1 major worker, and 1 female alate. When conditioned with deceased ant odors, bees effectively recognized live ants, particularly when trained on a single minor worker. Discrimination abilities varied by species and were higher when S. invicta was paired with Polyrhachis dives and Nylanderia yaeyamensis, and lower with S. geminata, Pheidole rabo, and Pheidole fervens. Notably, discrimination improved significantly with the application of latent inhibition. These findings suggest that trained honeybees have the potential to detect S. invicta. Further refinement of this approach could enhance its effectiveness for detection and surveillance.

Fipronil-infused sodium polyacrylate gels provide effective management of Argentine ants in conservation areas.

Various types of hydrogel compounds have recently been developed for controlling invasive and pest ants in a range of environmental settings including agricultural, urban and natural areas. The current study evaluated the potential of sodium polyacrylate (ACR) hydrogels to effectively deliver liquid baits to Argentine ants. Relative to standard polyacrylamide (PAM) hydrogels, individual ACR hydrogel particles were approximately five-fold heavier; this may affect how ants interact with the bait particles, and further influence bait uptake and efficacy. Additionally, ACR hydrogels had significantly higher water absorption capacity and significantly slower rate of water loss, especially during the first 2 h. The efficacy of ACR hydrogel bait containing 0.005% fipronil and various attractants was evaluated on laboratory colonies. Results demonstrated that ACR hydrogel acceptance is significantly increased by the addition of feeding attractants. In addition, a field trial was performed in a nature reserve invaded by Argentine ants to evaluate the efficacy of ACR hydrogel bait. The field trial demonstrated that ACR hydrogel bait containing 0.005% fipronil with various attractants is highly effective and that ant densities throughout the baited plots declined by >99% within 7 days. The results of this study demonstrate that: (i) fipronil is highly effective for Argentine ant control in natural areas when used in low concentrations (0.005%); (ii) ACR hydrogels are an effective tool for delivering liquid baits to Argentine ants; and (iii) hydrogel baits augmented with various attractants including salt, protein and pheromone are highly attractive to Argentine ants. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Insecticide treatment of invasive ant colonies leads to secondary ant invasions and promotes the spread of invasive ants

Insecticide treatment of invasive ant colonies leads to secondary ant invasions and promotes the spread of invasive ants

Invasion by red imported fire ants depletes soil microarthropod communities in agricultural systems

AbstractBiological invasion is one of the major challenges to changing ecosystems worldwide. Red fire ants are a prime example of invasive soil animals. However, the impacts of their invasion on the native soil animal communities are still poorly understood. Here, we investigated how the biomass and diversity of soil microarthropods (incl., Collembola and Acari) vary between areas affected by red fire ants at different degrees (i.e., OA, occurrence area, 0–20 m from the nest; PCA, prevention and control area, 20–50 m; POA, potential occurrence area, 50–100 m). We also tested whether the potential effects of ant invasion on other animals are associated with changes in soil properties in the invaded areas. Our results showed a decline of 64% in species richness, 74% in density, and 72% in biomass of microarthropods in OA in comparison with POA. This reduction was mainly driven by the decrease of Acari, while no reduction in Collembola biomass was observed. Despite soil properties being significantly different between ant‐impacted areas, structural equation models indicated that the direct association of invasion with microarthropod communities is stronger than the indirect association mediated by soil properties. Therefore, we consider that direct biological interaction is more likely the major mechanism behind the observed changes in microarthropod communities. The effects of red fire ants were different among taxonomic and functional groups, with litter‐dwelling Collembola, Oribatida, and Mesostigmata (Acari) affected more negatively than soil‐dwelling and surface‐dwelling Collembola. Further, red fire ants affected the turnover component of beta‐diversity (i.e., replacement of species) for both Collembola and Acari. However, the impact on the nestedness component, which is related to species local extinction and population decline, was only detected for Acari. Our study shows that red fire ant invasion is associated with the depletion of soil microarthropod community, and especially highlights that Acari are more vulnerable to this invasion compared to Collembola. The divergent response between different taxonomic and functional groups of microarthropods and the consequent shift in microarthropod communities may have important significance to soil ecological functioning in the impacted areas.

The ManhattAnt: identification, distribution, and colony structure of a new pest in New York City, Lasius emarginatus

An unidentified ant species was discovered in the heart of New York City in 2011, which garnered national headlines and created the memorable nickname “ManhattAnt.” New York City is one of the oldest and largest cities in North America and has been the site of introduction for some of North America’s most damaging invasive pests. Nevertheless, there has been little follow up research on the ManhattAnt since its discovery, and it has yet to be formally identified. Here we use genetic and morphological approaches to confirm the identity of the ManhattAnt and characterize its introduced range and colony structure. Results from genetic analyses placed the ManhattAnt within the Lasius emarginatus species complex, and morphological comparisons ruled out closely related species to identify the ManhattAnt as the European ant L. emarginatus with 93–99% certainty depending on the nest sample. Since its initial discovery in the region, the ManhattAnt has become one of the most common ants in New York City and has spread at a rate of 2 km/yr into New Jersey and onto Long Island. Based on the climate it inhabits within its native range, L. emarginatus could expand to cover much of the eastern United states from Massachusetts to Georgia. Although many successful invasive ants display supercoloniality with little aggression between neighboring nests, we found no evidence that L. emarginatus colonies in New York City are supercolonial. Continued monitoring of L. emarginatus is warranted, as it has been increasingly reported as an indoor pest and is known to form mutualisms with honeydew producing pests of street trees.

Catch and release: controlling eastern yellowjacket Vespula maculifrons colonies using horizontal insecticide transfer.

Horizontal insecticide transfer is thought to play an important role in controlling a wide range of urban pests including ants, bed bugs, cockroaches and termites. Trap-treat-release is an effective experimental approach that has been used to successfully manage populations of invasive ants in field applications. Trap-treat-release is based on the principles of horizontal transfer. Individuals are captured, treated with the toxicant and released back into the environment. The treated individuals then return to the colony and transfer the toxicant to other members of the population resulting in secondary mortality. The goal of the current study was to evaluate the efficacy of the trap-treat-release technique for controlling field populations of the eastern yellowjacket, Vespula maculifrons. Laboratory experiments demonstrated that fipronil was highly toxic against V. maculifrons across a wide range of concentrations. Furthermore, fipronil was efficiently transferred from treated donors to untreated recipients and caused significant secondary mortality. A field experiment utilized trap-treat-release and demonstrated that fipronil was effectively transferred when foraging worker wasps are trapped, treated, released and allowed to return to their respective colonies. The trap-treat-release method may be an effective alternative to direct nest treatments and could help alleviate problems such as insecticide runoff, environmental contamination, and non-target effects. This method has the potential to provide effective management of social wasps. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Toxicity-Related Behavior in the Invasive Argentine Ant Linepithema humile Mayr in Response to Fipronil Exposure1

Toxicity-Related Behavior in the Invasive Argentine Ant Linepithema humile Mayr in Response to Fipronil Exposure1

Do Dominant Native Ants Outcompete the Invasive Argentine Ant in Mediterranean Citrus Ecosystems? A Laboratory Test.

The invasive Argentine ant (Linepithema humile) poses a significant threat to ecosystem stability worldwide. In Mediterranean citrus ecosystems, its spread may be limited by interactions with dominant native ant species. We conducted laboratory experiments to investigate the competitive dynamics between Argentine ants and two major native species, Tapinoma nigerrimum and Lasius grandis. At the individual level, both native species exhibited superior competitive performance, attributed to their larger body sizes and potential differences in chemical defences. At the colony level, T. nigerrimum demonstrated efficiency in interference competition, successfully defending food resources from Argentine ants. However, the Argentine ant exhibited higher recruitment capacity, albeit it was density-dependent. Our findings support the hypothesis that dominant native ants can serve as barriers against Argentine ant invasion in citrus ecosystems, highlighting the importance of interspecific competition in shaping community dynamics and invasive species management. This study underscores the potential role of native ant species in mitigating the impacts of invasive ants on ecosystem functioning and biodiversity conservation in agricultural landscapes, offering valuable insights for invasive species management strategies in Mediterranean citrus ecosystems.

Three new strategies for improving biosecurity and invasive species management to build resilience in Pacific Islands

The inaugural Pacific Ecological Security Conference (PESC) was held in October 2022, bringing together over 100 island leaders, policy-makers, natural resource managers and global and regional invasive species experts to prioritise the critical issue of invasive species in the Pacific Islands Region. Participants confirmed that invasive species are a major threat to building and maintaining climate resilience and adaptability of Pacific Island ecosystems, as well as food security, biodiversity, sustainable livelihoods and the protection of cultural resources and way of life. Three region-wide strategic action plans were developed to guide interventions focused on the topics of invasive ants, coconut rhinoceros beetle and the use of biological control as a pest and weed management tool. These plans were the major outcome of the PESC and, when implemented, will result in coordinated activities that take a “whole-of-Pacific” approach to invasive species biosecurity and management. Here, we briefly describe the background, planning and engagement process for the three plans, summarise any country- and territory-level data obtained through the process and detail what is planned to occur over the next few years. In addition to the adoption and implementation of the strategies as a result of this inaugural PESC, we anticipate that the PESC will become the premier regional conference aimed at reducing the entry and impacts of invasive species to improve sustainability of environments and peoples of the Pacific.

Pesticide‐free management of invasive ants impacting ground‐nesting wildlife populations

AbstractNonnative, invasive ants, and especially the red imported fire ant, Solenopsis invicta, are a widespread threat to ground‐nesting wildlife. In this paper I describe a method of controlling fire ants using hot water. The hot water approach was applied to reduce fire ant impacts on sea turtles and ground‐nesting songbirds and to demonstrate its utility in protection of different ground‐nesting species in different habitats. Fire ant controls using hot water provided 90% or greater control, significantly improving survival of both turtle and bird hatchlings, without the use of pesticides. The success of the method and the availability of necessary equipment shows that hot water control of fire ant populations should be considered as a tool for wildlife affected by fire ants and is useful for a wide variety of scenarios where fire ant controls are desirable or necessary. The method does require that 1) wildlife nest locations are known and that 2) nearby fire ant colonies can be found and treated with hot water. The method can be used as a complement to broadcast or bait‐station baiting strategies or as a stand‐alone method for managing fire ants.

Establishment of a Microfluidic Chip Based Rapid Detection Method for <i>Wasmannia auropunctata</i>

Invasive alien ants are one of the most aggressive, competitive, and widespread invasive alien species around the world. <i>Wasmannia auropunctata, </i>native to the neotropical zoogeographic area, has been inadvertently introduced all over the world. The first disclosed record of field establishment of <i>W. auropunctata</i> in Chinese mainland was reported in 2022. In this paper, we aim to establish a rapid detection method targeting the <i>W. auropunctata </i>polymorphic microsatellite locus Waur-275, based on the microfluidic chip technology, to contribute to an active response to the crisis caused by this invasive pest. Eight primer sets were generated using the PrimerExplorer v5 online service, and the fifth primer set selected had the lowest Ct in the volume ratio of 8 (FIP/BIP:F3/B3). Method validity with six <i>W. auropunctata </i>samples confirmed the efficiency of this assay. High specificity was demonstrated by the positive result for <i>W. auropunctata</i> out of 6 related insect samples tested. Sensitivity analysis showed that this microfluidic chip method could achieve the detection limit of 1.00×10<sup>1</sup> copies/μL. A rapid screening method is essential for the whole process of interception and control of <i>W. auropunctata </i>in China. It can also help determine the origin of invasion, clarify the path of introduction to ensure biosecurity, and also uncover other possible undetected establishments in the wild.

Ant community composition in a citrus grove reveals eastern expansion in Florida of the South American big-headed ant (Hymenoptera: Formicidae)

Abstract Florida has become a worldwide hotspot for introduced and invasive ants (Hymenoptera: Formicidae). Furthermore, studies have shown that non-native ants support other invasive insects in Florida, such as the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), which is the vector of Candidatus Liberibacter asiaticus, the causal pathogen of citrus greening, the worst citrus disease in the world. The Asian citrus psyllid establishes beneficial interactions with invasive, introduced, and native ants. In this study, we described the ant diversity in a citrus grove in south Florida as a first step to assess ant-Asian citrus psyllid interactions for future studies. During the summer of 2018, 25 pitfall traps were set in a citrus grove. The red imported fire ant, Solenopsis invicta (Buren), was present in all the traps (100 %), and 19 traps (76 %) had Dorymyrmex bureni (Trager), the pyramid ant, which is native to the southeast United States. Two introduced ants, Cardiocondyla emeryi (Forel) and Brachymyrmex obscurior (Forel), were found in 15 (60 %) and 11 (44 %) traps, respectively. The South American big-headed ant, Pheidole obscurithorax (Naves), was found in 14 traps (56 %). This introduced ant has been found to co-exist with S. invicta, and to our knowledge, this is the first report of the species in this eastern part of peninsular Florida. Finally, Cardiocondyla venustula (Wheeler), an introduced ant from Africa, was found in one of the traps. Although, this ant is found in south Florida, it seems uncommon, and this is its first report in this county. Our study highlights the continued spread of introduced and invasive ants in Florida.

Bioactive peptides: an alternative therapeutic approach for cancer management.

Cancer is still considered a lethal disease worldwide and the patients' quality of life is affected by major side effects of the treatments including post-surgery complications, chemo-, and radiation therapy. Recently, new therapeutic approaches were considered globally for increasing conventional cancer therapy efficacy and decreasing the adverse effects. Bioactive peptides obtained from plant and animal sources have drawn increased attention because of their potential as complementary therapy. This review presents a contemporary examination of bioactive peptides derived from natural origins with demonstrated anticancer, ant invasion, and immunomodulation properties. For example, peptides derived from common beans, chickpeas, wheat germ, and mung beans exhibited antiproliferative and toxic effects on cancer cells, favoring cell cycle arrest and apoptosis. On the other hand, peptides from marine sources showed the potential for inhibiting tumor growth and metastasis. In this review we will discuss these data highlighting the potential befits of these approaches and the need of further investigations to fully characterize their potential in clinics.

Ants evade harmful food by active abandonment

Invasive ants, such as the Argentine ant, pose a severe economic and ecological threat. Despite advancements in baiting techniques, effectively managing established ant populations remains a daunting challenge, often ending in failure. Ant colonies employ behavioural immunity against pathogens, raising the question of whether ants can collectively respond to toxic baits. This study investigates whether ant colonies actively abandon palatable but harmful food sources. We provided two sucrose feeders, each generating a new foraging trail, with one transitioning to offering toxic food. Six hours later, ant activity on that path decreases, while activity on the non-toxic food and the trunk trail remains unaffected, excluding factors like population decline or satiation as reasons for the activity decline. Laboratory experiments confirmed that ants remained alive six hours after ingesting toxic food. Ant presence remains low on the toxic food path for days, gradually decreasing along the nearest section of the trunk trail. This abandonment behaviour minimises the entry of harmful food into the nest, acting as a protective social mechanism. The evasion of toxic bait-treated areas likely contributes considerably to control failures. Understanding the behavioural response to toxic baits is essential for developing effective strategies to combat invasive ant species.

A survey and risk screening of non-native ant species colonising greenhouses in Hungary

Invasive species represent a severe threat for ecosystem health worldwide. With increasing global trade and ongoing climate change, monitoring non-native species and their hotspots of potential spread is becoming increasingly important. Invasive ants are one of the most problematic groups of organisms costing billions of dollars a year globally to control. Therefore, emerging ant invasions require more focused engagement to assess their extent, and effective measures to prevent the spread of non-native invasive species can be time consuming and expensive to implement. In addition to places with high commercial traffic, greenhouses are potential hotspots for non-native species as they can be entry points for invasions. However, the role of greenhouses in ant invasions is still understudied. In this study, an extensive survey of greenhouses in zoos and botanical gardens of Hungary was conducted to search for non-native ant species. The five species found in the surveys and an additional two known from Hungary were then screened for their risk of invasiveness in the country under both current and predicted climate conditions. Three species were found to pose a considerable conservation and economic risk for Hungary, and one is already present in the wild. Increased monitoring of greenhouses and other heated premises for the presence of non-native species and targeted chemical eradication are needed to prevent their spread. The risk screening method employed in this study can be applied to a wide range of terrestrial animal taxa, thereby providing a basis for developing more effective prevention and control strategies against invasive species.

Alien Ants (Hymenoptera, Formicidae) in Sicily and Malta: A Review and Updated Checklist

In the last few years, due to globalization, which increases and speeds up the movement of people and goods around the world, the number of alien animal and plant species that have accidentally arrived in Europe has increased considerably; as a result, the problem of alien species, and especially invasive ones, has taken on greater significance. Since the Mediterranean has always been one of the main trade routes, it is of primary importance to turn our attention to those areas that constitute the main entry routes for new species into Italy and Europe, such as Sicily and the Maltese archipelago. This publication aims to collect all available data about alien invasive ants recorded in Sicily and Malta. Among all animal taxa, one of the groups with great adaptability and that easily follows human routes is the Formicidae, which also includes species with high invasive potential. Currently in Sicily there are 10 alien ant species, two of which, Linepithema humile (Mayr, 1878) and Solenopsis invicta Buren, 1972 (recently recorded), are invasive. Whereas for the Maltese archipelago 12 ant species are alien, two are considered invasives, namely L. humile and Pheidole indica Mayr, 1879. An additional species, Cardiocondyla mauritanica Forel, 1890, is considered cryptogenic in both countries. For a proper management of alien species, it is essential to carefully monitor the alien species already present on the territory and considered invasive but also to pay attention to those species that have already caused serious damage in other countries and are easy to introduce. Finally, it is important to monitor potential entry routes followed by invasive aliens, especially those involving interchanges between Sicily and the Maltese archipelago.

Corpse-associated odours elicit avoidance in invasive ants.

Invasive ants, such as Linepithema humile (the Argentine ant), pose a global threat, necessitating a better understanding of their behaviour in order to improve management strategies. Traditional eradication methods, including baiting, have had limited success, but the causes of control failure are not always clear. This study aims to investigate whether ants form associations between food odours and corpses, and subsequently avoid areas or food sources with food odours associated with corpses. We propose that ants may learn to avoid toxic baits in part because of their association with ant corpses, which could have implications for pest control strategies. Ants were tested on a Y-maze after exposure to scented corpses or dummies. 69% (n = 64) of ants avoided branches bearing the scent of scented corpses. Colonies neglected food with corpse-associated odours, with only 42% (n = 273) of foragers feeding from such sources. However, if corpses were produced by feeding ants scented toxicant, focal ants encountering these corpses did not avoid the corpse-associated scent on a Y-maze (53%, n = 65). In dual-feeder tests, ants did not avoid feeding at food sources scented with odours associated with conspecific corpses. Conspecific corpses act as a negative stimulus for ants in a foraging situation, potentially causing avoidance of toxic baits. This study suggests adding odours to baits and cycling them to disrupt the bait-corpse association may be helpful. Interestingly, although avoidance of baits was observed, feeding preferences were not significantly affected. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.