RESUMEN
Multiple new ant treatment products containing high volumes of sugar have recently been developed specifically for use in ant management programs. The presence of sugar in these products could potentially attract bees, and any such attractancy would likely be fatal given that these products typically contain general insecticides. To determine the risk of such products to bees I present four studies assessing bee attractancy to multiple matrices that are used to make these products. The trials were conducted across multiple years, seasons, and locations, containing various concentrations of sugar in multiple forms, using various experimental setups with many different bee hives, and multiple observers. Not a single bee was attracted to any matrix, nor were bees observed inspecting any matrix, and no bees fed on any matrix, irrespective of whether the matrices were placed close to hives and directly under bee flight paths, or out in areas where bees were feeding. This is in stark contrast to large numbers of bees that were feeding on flowers within the immediate vicinity of all of the matrices in the first two experiments, or flying over the arrays in experiments 3 and 4 travelling to and from other food sources. I present five suggestions for the discrepancy between the trials presented here and the general perception that bees are attracted to sugar. These matrices appear to be acceptable as a basis to make treatment products for broadscale use within ant management programs. However, it should be recognized that bees, and other non-target species, are indeed capable of feeding on these matrices. Therefore vigilance should still be maintained to identify special circumstances where bees may be killed when constituents are added to these matrices that do attract bees, or usage methods can adversely affect bees.
Asunto(s)
Hormigas , Insecticidas , Abejas , Animales , Azúcares , Conducta Alimentaria , FloresRESUMEN
Risk assessments are fundamental to invasive species management and are underpinned by comprehensive characterization of invasive species impacts. Our understanding of the impacts of invasive species is growing constantly, and several recently developed frameworks offer the opportunity to systematically categorize environmental and socioeconomic impacts of invasive species. Invasive ants are among the most widespread and damaging invaders. Although a handful of species receives most of the policy attention, nearly 200 species have established outside their native range. Here, we provide a global, comprehensive assessment of the impacts of ants and propose a priority list of risk species. We used the Socioeconomic Impact Classification for Alien Taxa (SEICAT), Environmental Impact Classification for Alien Taxa (EICAT) and Generic Impact Scoring System (GISS) to analyze 642 unique sources for 100 named species. Different methodologies provided generally consistent results. The most frequently identified socioeconomic impacts were to human health. Environmental impacts were primarily on animal and plant populations, with the most common mechanisms being predation and competition. Species recognized as harmful nearly 20 years ago featured prominently, including Wasmannia auropunctata (little fire ant, electric ant), Solenopsis invicta (red imported fire ant), Anoplolepis gracilipes (yellow crazy ant), and Pheidole megacephala (African big-headed ant). All these species except W. auropunctata have been implicated in local extinctions of native species. Although our assessments affirmed that the most serious impacts have been driven by a small number of species, our results also highlighted a substantial number of less well publicized species that have had major environmental impacts and may currently be overlooked when prioritizing prevention efforts. Several of these species were ranked as high or higher than some of the previously recognized "usual suspects," most notably Nylanderia fulva (tawny crazy ant). We compared and combined our assessments with trait-based profiles and other lists to propose a consensus set of 31 priority species. Ever-increasing global trade contributes to growing rates of species introductions. The integrated approaches we used can contribute to robust, holistic risk assessments for many taxa entrained in these pathways.
Asunto(s)
Hormigas , Animales , Especies Introducidas , Medición de Riesgo , Factores SocioeconómicosRESUMEN
Domain-specific languages (DSLs) are a popular approach among software engineers who demand for a tailored development interface. A DSL-based approach allows to encapsulate the intricacies of the target platform in transformations that turn DSL models into executable software code. Often, DSLs are even claimed to reduce development complexity to a level that allows them to be successfully applied by domain-experts with limited programming knowledge. Recent research has produced some scientifically backed insights on the benefits and limitations of DSLs. Further empirical studies are required to build a sufficient body of knowledge from which support for different claims related to DSLs can be derived. In this research study, we adopt current DSL evaluation approaches to investigate potential gains in terms of effectiveness and efficiency, through the application of our DSL Athos, a language developed for the domain of traffic and transportation simulation and optimisation. We compare Athos to the alternative of using an application library defined within a general-purpose language (GPL). We specified two sets of structurally identical tasks from the domain of vehicle routing problems and asked study groups with differing levels of programming knowledge to solve the tasks with the two approaches. The results show that inexperienced participants achieved considerable gains in effectiveness and efficiency with the usage of Athos DSL. Though hinting at Athos being the more efficient approach, the results were less distinct for more experienced programmers. The vast majority of participants stated to prefer working with Athos over the usage of the presented GPL's API. Supplementary Information: The online version contains supplementary material available at 10.1007/s10664-022-10210-whttps://doi.org/10.1007/s10664-022-10210-w.
RESUMEN
BACKGROUND: Worker reproduction has an important influence on the social cohesion and efficiency of social insect colonies, but its role in the success of invasive ants has been neglected. We used observations of 233 captive colonies, laboratory experiments, and genetic analyses to investigate the conditions for worker reproduction in the invasive Anoplolepis gracilipes (yellow crazy ant) and its potential cost on interspecific defence. We determined the prevalence of worker production of males and whether it is triggered by queen absence; whether physogastric workers with enlarged abdomens are more likely to be reproductive, how normal workers and physogastric workers compare in their contributions to foraging and defence; and whether worker-produced males and males that could have been queen- or worker-produced differ in their size and heterozygosity. RESULTS: Sixty-six of our 233 captive colonies produced males, and in 25 of these, some males could only have been produced by workers. Colonies with more workers were more likely to produce males, especially for queenless colonies. The average number of days between the first appearance of eggs and adult males in our colonies was 54.1 ± 10.2 (mean ± SD, n = 20). In our laboratory experiment, queen removal triggered an increase in the proportion of physogastric workers. Physogastric workers were more likely to have yolky oocytes (37-54.9%) than normal workers (2-25.6%), which is an indicator of fertile or trophic egg production. Physogastric workers were less aggressive during interspecific aggression tests and foraged less than normal workers. The head width and wing length of worker-produced males were on average 4.0 and 4.3% greater respectively than those of males of undetermined source. Our microsatellite DNA analyses indicate that 5.5% of worker-produced males and 14.3% of males of undetermined source were heterozygous, which suggests the presence of diploid males and/or genetic mosaics in A. gracilipes. CONCLUSIONS: Our experimental work provides crucial information on worker reproduction in A. gracilipes and its potential cost to colony defence. The ability of A. gracilipes workers to produce males in the absence of queens may also contribute to its success as an invasive species if intranidal mating can take place between virgin queens and worker-produced males.
RESUMEN
The relationship between levels of dominance and species richness is highly contentious, especially in ant communities. The dominance-impoverishment rule states that high levels of dominance only occur in species-poor communities, but there appear to be many cases of high levels of dominance in highly diverse communities. The extent to which dominant species limit local richness through competitive exclusion remains unclear, but such exclusion appears more apparent for non-native rather than native dominant species. Here we perform the first global analysis of the relationship between behavioral dominance and species richness. We used data from 1,293 local assemblages of ground-dwelling ants distributed across five continents to document the generality of the dominance-impoverishment rule, and to identify the biotic and abiotic conditions under which it does and does not apply. We found that the behavioral dominance-diversity relationship varies greatly, and depends on whether dominant species are native or non-native, whether dominance is considered as occurrence or relative abundance, and on variation in mean annual temperature. There were declines in diversity with increasing dominance in invaded communities, but diversity increased with increasing dominance in native communities. These patterns occur along the global temperature gradient. However, positive and negative relationships are strongest in the hottest sites. We also found that climate regulates the degree of behavioral dominance, but differently from how it shapes species richness. Our findings imply that, despite strong competitive interactions among ants, competitive exclusion is not a major driver of local richness in native ant communities. Although the dominance-impoverishment rule applies to invaded communities, we propose an alternative dominance-diversification rule for native communities.
Asunto(s)
Hormigas/fisiología , Biodiversidad , Animales , Clima , EcosistemaRESUMEN
What forces structure ecological assemblages? A key limitation to general insights about assemblage structure is the availability of data that are collected at a small spatial grain (local assemblages) and a large spatial extent (global coverage). Here, we present published and unpublished data from 51â,388 ant abundance and occurrence records of more than 2,693 species and 7,953 morphospecies from local assemblages collected at 4,212 locations around the world. Ants were selected because they are diverse and abundant globally, comprise a large fraction of animal biomass in most terrestrial communities, and are key contributors to a range of ecosystem functions. Data were collected between 1949 and 2014, and include, for each geo-referenced sampling site, both the identity of the ants collected and details of sampling design, habitat type, and degree of disturbance. The aim of compiling this data set was to provide comprehensive species abundance data in order to test relationships between assemblage structure and environmental and biogeographic factors. Data were collected using a variety of standardized methods, such as pitfall and Winkler traps, and will be valuable for studies investigating large-scale forces structuring local assemblages. Understanding such relationships is particularly critical under current rates of global change. We encourage authors holding additional data on systematically collected ant assemblages, especially those in dry and cold, and remote areas, to contact us and contribute their data to this growing data set.
Asunto(s)
Hormigas/fisiología , Bases de Datos Factuales , Ecología , Animales , Hormigas/clasificación , EcosistemaRESUMEN
Many studies have focused on the impacts of climate change on biological assemblages, yet little is known about how climate interacts with other major anthropogenic influences on biodiversity, such as habitat disturbance. Using a unique global database of 1128 local ant assemblages, we examined whether climate mediates the effects of habitat disturbance on assemblage structure at a global scale. Species richness and evenness were associated positively with temperature, and negatively with disturbance. However, the interaction among temperature, precipitation and disturbance shaped species richness and evenness. The effect was manifested through a failure of species richness to increase substantially with temperature in transformed habitats at low precipitation. At low precipitation levels, evenness increased with temperature in undisturbed sites, peaked at medium temperatures in disturbed sites and remained low in transformed sites. In warmer climates with lower rainfall, the effects of increasing disturbance on species richness and evenness were akin to decreases in temperature of up to 9°C. Anthropogenic disturbance and ongoing climate change may interact in complicated ways to shape the structure of assemblages, with hot, arid environments likely to be at greatest risk.
Asunto(s)
Hormigas/fisiología , Biodiversidad , Clima , Animales , Cambio Climático , TemperaturaRESUMEN
Ants that resemble Camponotus maculatus (Fabricius, 1782) present an opportunity to test the hypothesis that the origin of the Pacific island fauna was primarily New Guinea, the Philippines, and the Indo-Malay archipelago (collectively known as Malesia). We sequenced two mitochondrial and four nuclear markers from 146 specimens from Pacific islands, Australia, and Malesia. We also added 211 specimens representing a larger worldwide sample and performed a series of phylogenetic analyses and ancestral area reconstructions. Results indicate that the Pacific members of this group comprise several robust clades that have distinctly different biogeographical histories, and they suggest an important role for Australia as a source of Pacific colonizations. Malesian areas were recovered mostly in derived positions, and one lineage appears to be Neotropical. Phylogenetic hypotheses indicate that the orange, pan-Pacific form commonly identified as C. chloroticus Emery 1897 actually consists of two distantly related lineages. Also, the lineage on Hawai'i, which has been called C. variegatus (Smith, 1858), appears to be closely related to C. tortuganus Emery, 1895 in Florida and other lineages in the New World. In Micronesia and Polynesia the C. chloroticus-like species support predictions of the taxon-cycle hypothesis and could be candidates for human-mediated dispersal.
RESUMEN
Supercoloniality is a social structure displayed by many invasive ant species, but there has been surprisingly little research quantifying the extent to which individual species display traits underlying such social organisation. This study quantifies three traits for the yellow crazy ant, Anoplolepis gracilipes Smith (Hymenoptera: Formicidae): little or no aggression between workers from different nests; the exchange of workers among nests; and resource exchange among nests, as well as supercolony structure arising from patterns of distribution and density of detections. Supercolonies displayed a structural continuum from being small ( < 10 ha) and "aggregated" with great continuity among detections through to being large (>10,000 ha) and "diffuse" with little continuity among detections. Smaller supercolonies had greater ant densities than larger supercolonies. In laboratory trials, no aggression was observed between workers from different nests sourced from different supercolonies, and paired nests merged within 24 hours. Workers lacked nest fidelity by rapidly populating artificial nests containing alien queens. The daily worker turnover rate per nest was estimated to be below 20%. Resources were readily moved among nests, with a resource being detected up to 13 m away from a source within 24 hours, and as far as 32 m after four days. The rate and distance of resource movement increased with increasing worker and nest density. This research has demonstrated that A. gracilipes displays supercoloniality equivalent to that of the well-studied Argentine ant Linepithema humile. Quantification of these traits is required for other supercolonial species to improve our understanding of this social strategy, especially for invasive ants to aid in understanding factors that promote invasion success and to improve management.
Asunto(s)
Distribución Animal , Hormigas/fisiología , Comportamiento de Nidificación , Animales , Femenino , Especies Introducidas , Northern Territory , Densidad de Población , Conducta SocialRESUMEN
With regard to the recent discovery of the red imported fire ant in Sicily (Menchetti et al. 2023), Genovesi et al. highlight the delay in communicating the observation and call on the scientific communities, scientific journals, and local authorities to ensure that new invasive alien species records are immediately reported for enhancing action.
Asunto(s)
Hormigas , Animales , Procesos de Grupo , Especies Introducidas , SiciliaRESUMEN
Analysis of environmental DNA (eDNA) enables indirect detection of species without the need to directly observe and sample them. For biosecurity and invasion biology, eDNA-based methods are useful to address biological invasions at all phases, from detecting arrivals to confirming eradication of past invasions. We conducted a systematic review of the literature and found that in biosecurity and invasion biology, eDNA has primarily been used to detect new incursions and monitor spread in marine and freshwater ecosystems, with much slower uptake in terrestrial ecosystems, reflecting a broader trend common to the usage of eDNA tools. In terrestrial ecosystems, eDNA research has mostly focussed on the use of eDNA metabarcoding to characterise biodiversity, rather than targeting biosecurity threats or non-native populations. We discuss how eDNA-based methods are being applied to terrestrial ecosystems for biosecurity and managing non-native populations at each phase of the invasion continuum: transport, introduction, establishment, and spread; across different management options: containment, control, and eradication; and for detecting the impact of non-native organisms. Finally, we address some of the current technical issues and caveats of eDNA-based methods, particularly for terrestrial ecosystems, and how these might be solved. As eDNA-based methods improve, they will play an increasingly important role in the early detection and adaptive management of biological invasions, and the implementation of effective biosecurity controls.
Asunto(s)
ADN Ambiental , Ecosistema , Monitoreo del Ambiente , Especies Introducidas , Monitoreo del Ambiente/métodos , Biodiversidad , Código de Barras del ADN TaxonómicoRESUMEN
The efficacy of Distance Plus Ant Bait, containing the insect growth regulator pyriproxyfen, was tested in the field against two invasive ant species in northern Australia: African big-headed ant (Pheidole megacephala (F.)) and yellow crazy ant (Anoplolepis gracilipes (Fr. Smith)). Results were also gained for a third pest species, Singapore ant (Monomorium destructor (Jerdon)), from one trial focused primarily on P. megacephala. Five studies were conducted throughout northern Australia, each with different protocols, but common to all was the broad-scale dispersal of Distance Plus, coupled with long-term monitoring of ant population levels. Additionally, a laboratory trial was conducted to assess if there was a direct toxic effect by the bait on A. gracilipes workers, and ant community data were collected at some sites in the A. gracilipes trial to assess nontarget impacts and subsequent ecological recovery. All three species were greatly affected by the treatments. The abundance of P. megacephala declined dramatically in all trials, and by the final assessment for each study, very few ants remained, with those remaining being attributable to edge effects from neighboring untreated properties. At both sites that it occurred, M. destructor was initially at least codominant with P. megacephala, but by the final assessment, only three M. destructor individuals were present at one lure at one site, and only a single individual at the other site. Abundance of A. gracilipes fell, on average, to 31% of control levels by 91 d and then slowly recovered, with subsequent treatments only providing slightly greater control. No direct toxic effect on workers was found in the laboratory trial, indicating that population declines of A. gracilipes were typical bait-related declines resulting from reduced worker replacement. Nontarget impacts of the bait could not be distinguished from the negative competitive impacts ofA. gracilipes, but there was a noticeable absence of some key common ant species posttreatment, which was more likely the result of baiting rather than competitive exclusion. The species composition of treated and untreated sites was statistically indistinguishable in multivariate analysis within 2 yr posttreatment, indicating ecological recovery. Our findings indicate that Distance Plus has great potential for invasive ant management.
Asunto(s)
Hormigas , Control de Insectos , Insecticidas , Piridinas , Animales , Hormonas Juveniles , Northern Territory , Especificidad de la Especie , Clima TropicalRESUMEN
OBJECTIVE: Venomous invasive ants are rapidly dispersing throughout oceanic islands. Medics unfamiliar with envenomation or venom-induced anaphylaxis may be unprepared for the range of possible reactions and corresponding treatments. We detail the suboptimal treatment of a patient suffering anaphylaxis from an ant sting on a remote island and describe what treatment should have been provided. METHODS: The patient experienced stings on his feet from an ant later identified as tropical fire ant, Solenopsis geminata. Clinical examination revealed throat swelling without obstruction of the airway or pharynx. RESULTS: The patient was provided the following suboptimal treatment: intravenously-administered antihistamine and saline perfusion. Injected epinephrine should be the standard first line of treatment for anaphylaxis, even when not all symptoms are present. CONCLUSION: A rise in invasive hymenopteran stings on oceanic islands is inevitable, and proactively improving public awareness and medical training could save lives.
Asunto(s)
Anafilaxia , Venenos de Hormiga , Hormigas , Mordeduras y Picaduras de Insectos , Animales , Humanos , Anafilaxia/tratamiento farmacológico , Islas , Venenos de Hormiga/uso terapéutico , Mordeduras y Picaduras de Insectos/prevención & controlRESUMEN
BACKGROUND: Aerial treatments for invasive species management are now common, but we are unaware of any work published in the scientific literature quantifying how the interplay of numerous factors affects flight time and therefore operational costs. Here, we analyse aerial treatment data collected from two ant-eradication programmes, quantifying how the relationships between flight time and area are influenced by numerous aircraft/delivery system/bait/flight speed combinations. RESULTS: For bait dispersal by helicopters, and when swath widths are equivalent, side-mounted Isolair was significantly more efficient than the simultaneous use of two underslung buckets, and use of two buckets was slightly but not significantly more efficient than one bucket. In this scenario, delivery by Isolair was, on average, 39.8% and 31.5% more efficient than the use of one or two buckets, respectively. However, when the swath width used with Isolair was halved to 10 m and flight speed was increased slightly, flight time was significantly greater compared to the other configurations. For bait dispersed by drone, flights conducted using an upgraded Flight Management System (FMS) and greater flight speed but smaller swath width were significantly more efficient than flights using the older FMS and lower flight speed. Over 10 and 50 ha the helicopter was 2.87 and 4.82 times more time efficient than the drone. CONCLUSION: We encourage practitioners to publish data from their aerial treatments, and to try new methods, to accelerate improvements in efficiency and reduce the costs of aerial treatments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Asunto(s)
Especies Introducidas , Dispositivos Aéreos No Tripulados , AeronavesRESUMEN
Because different sampling techniques will provide different abundance values, it is currently difficult to compare results among many studies to form holistic understandings of how abundance influences ant ecology. Using three sampling methods in the same location we found pitfall traps best confirmed yellow crazy ant A. gracilipes presence recording the fewest zero values (9.1%), card counts were the least reliable (67.1%), and tuna lures were intermediate (30.1%). The abundance of A. gracilipes from card counts ranged from 0 to 20, in pitfall traps from 0 to 325, and the full range of tuna lure abundance scores (0-7) were sampled. We then determined the relationships between these three standard ant sampling techniques for Anoplolepis gracilipes abundance. Irrespective of the data transformation method, the strongest relationship was between pitfall traps and tuna lures, and the least strong was between pitfall traps and card counts. We then demonstrate the utility of this knowledge by analysing A. gracilipes abundance reported within published literature to show where the populations in those studies sit on an abundance spectrum. We also comment on insights into the relative utility of the three methods we used to determine A. gracilipes abundance among populations of varying abundance. Pitfall traps was the most reliable method to determine if the species was present at the sample level. Tuna lures were predominantly reliable for quantifying the presence of workers, but were limited by the number of workers that can gather around a spoonful of tuna. Card counts were the quickest method, but were seemingly only useful when A. gracilipes abundance is not low. Finally we discuss how environmental and biological variation needs to be accounted for in future studies to better standardise sampling protocols to help progress ecology as a precision science.
Asunto(s)
Hormigas , Animales , EcologíaRESUMEN
BACKGROUND: Hydrogels are a new bait form, and multiple studies have found minimal potential or actual nontarget impacts associated with their use. However, in 2020, aerial applications of hydrogels containing fipronil unequivocally resulted in honey bee deaths. Here we detail four studies that then were conducted to determine how the bees were exposed to the active constituent and how to modify the aerial treatment protocols to eliminate the risk to bees. RESULTS: The first trial confirmed the existence of fipronil in aerosol form. The second trial quantified that in specific wind conditions the aerosols were falling to the ground at a maximum distance determined by an approximate 30° angle from the ground to the dispersal point, and that free-falling hydrogels either do not produce aerosols or, if so, at volumes too negligible to be collected or quantified. The third trial confirmed that even bee hives upwind and several hundreds of metres away from the area being baited can be contaminated by the aerosols. The fourth trial found no bee hive mortality as a result of either free-falling bait or moving bee hives 500 m beyond the treatment area. CONCLUSION: The aerosol issue is likely to occur with every motorized mechanism dispersing hydrogels. It is possible that the same issue happens with solid dry products if they produce a fine dust when propelled during dispersal. Further research into this issue is warranted. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Asunto(s)
Hormigas , Urticaria , Abejas , Animales , Control de Plagas , Aerosoles , HidrogelesRESUMEN
The use of detector dogs within environmental programs has increased greatly over the past few decades, yet their search methods are not standardized, and variation in dog performance remains not well quantified or understood. There is much science to be done to improve the general utility of detector dogs, especially for invertebrate surveys.We report research for detector dog work conducted as part of yellow crazy ant eradication. One dog was first used to quantify the probability of detection (POD) within a strictly controlled trial. We then investigated the search patterns of two dogs when worked through sites using different transect spacings. Specifically, we quantified their presence within set distances of all locations in each assessment area, as well as the time they took to assess each area. In a GIS, we then calculated the relative percentage of the entire search area within six distance categories, and combined this information with the POD values to obtain a site-level POD.The calculated relationship between distance and POD was extremely strong (R 2 = 0.998), with POD being 86% at 2 m and 28% at 25 m. For site-level assessments conducted by the two dogs, both dogs achieved the highest site-level POD when operated on the lowest transect spacing (15 m), with POD decreasing significantly as transect spacing increased. Both dogs had strong linear relationships between area assessed and time, with the area assessed being greater when the transects had greater spacing. The working style of the two dogs also resulted in significantly different assessment outcomes. In 1 h one dog could assess approximately 9.2 ha with transects spaced 20 m apart, and 6.8 ha with transects spaced 15 m apart, whereas the second dog could only assess approximately 6.9 ha with transects spaced 20 m apart, and 4.9 ha with transects spaced 15 m apart.Our study provides insight into the ability of dogs to detect yellow crazy ants, and sets the basis for further science and protocol development for ant detection. With the lessons learned from this work, we then detail protocols for using detector dogs for ant eradication assessments.
RESUMEN
BACKGROUND: Hydrogels that have absorbed a liquid containing a toxicant are a novel form of bait-delivery for ant control. Here, we study the abilities of Argentine ant (Linepithema humile) workers to imbibe liquid from hydrogels. We quantified feeding behavior with: (i) hydrogels containing different sucrose concentrations (20, 30, 40 and 50% w/w); (ii) hydrogels versus liquid droplets; and (iii) hydrogel age (air exposure time). We also performed a field assay to assess visits by L. humile and other ant species to hydrogels. RESULTS: Ingested volume and feeding time decreased with increasing sucrose concentrations, but the number and duration of pauses were similar. Feeding from hydrogels was slower than from a liquid droplet and ants imbibed less liquid and fed for shorter times from hydrogels. Feeding time increased with hydrogel age, whereas ingested volume decreased and approached zero after 120 min under laboratory conditions. In the field, ants attended the hydrogels during the full 120-min study period. When L. humile workers found a hydrogel, they monopolized it to the exclusion of other ant species. L. humile occupied and dominated hydrogels predominantly in shaded locations. CONCLUSION: Hydrogels with sucrose concentrations no greater than 30% appear best for liquid uptake by L. humile. Hydrogels not in direct sunlight will have greater attendance by L. humile and, therefore, less attendance by non-target ant species. Shady and humid places may prolong the longevity of hydrogels, which would imply higher intakes. © 2021 Society of Chemical Industry.
Asunto(s)
Hormigas , Animales , Conducta Alimentaria , Humanos , Hidrogeles , Laboratorios , SacarosaRESUMEN
We present electronic excitation spectra of individual nanoparticles (NPs) in the gas phase obtained by messenger-mediated single nanoparticle action spectroscopy at cryogenic temperatures (cryo-SNAS). Single â¼100 nm diameter SiO2 NPs, either colorless or dye-loaded, are trapped and coated with multiple layers of N2 in a temperature-controllable modified quadrupole ion-trap at 100 K. The NP's mass is monitored quasi-continuously and nondestructively by light scattering. Absorption of electromagnetic radiation from a tunable (400-800 nm), quasi-continuous, supercontinuum laser leads to heating of the NP and subsequent evaporation of N2 molecules. The average change in NP mass as a function of the irradiation wavelength then yields the cryo-SNAS spectrum without further correction. The obtained spectra are similar to direct absorption spectra of the corresponding NP suspensions but reveal narrower bands due to the lower NP temperature. These experiments demonstrate that cryo-SNAS allows the determination of photoabsorption spectra of single, free NPs independently of scattering processes.
RESUMEN
How invasive species overcome challenges associated with low genetic diversity is unclear. Invasive ant populations with low genetic diversity sometimes produce sterile diploid males, which do not contribute to colony labour or reproductive output. We investigated how inbreeding affects colony founding and potential strategies to overcome its effects in the invasive tropical fire ant, Solenopsis geminata. Our genetic analyses of field samples revealed that 13-100% of males per colony (n = 8 males per 10 colonies) were diploid, and that all newly mated queens (n = 40) were single-mated. Our laboratory experiment in which we assigned newly mated queens to nests consisting of 1, 2, 3, or 5 queens (n = 95 ± 9 replicates) revealed that pleometrosis (queens founding their nest together) and diploid male larvae execution can compensate for diploid male load. The proportion of diploid male producing (DMP) colonies was 22.4%, and DMP colonies produced fewer pupae and adult workers than non-DMP colonies. Pleometrosis significantly increased colony size. Queens executed their diploid male larvae in 43.5% of the DMP colonies, and we hypothesize that cannibalism benefits incipient colonies because queens can redirect nutrients to worker brood. Pleometrosis and cannibalism of diploid male larvae represent strategies through which invasive ants can successfully establish despite high inbreeding.