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Wastewater Treatment Plants (WWTP) are a major repository and entrance path of nanoparticles (NP) in the environment and hence play a major role in the final NP fate and toxicity. Studies on silver nanoparticles (AgNP) transport via the WWTP system and uptake by aquatic organisms have so far been carried out using unrealistically high AgNP concentrations, unlikely to be encountered in the aquatic environment. The use of high AgNP concentrations is necessitated by both the low sensitivity of the detection methods used and the need to distinguish background Ag from spiked AgNP. In this study, isotopically enriched 109 AgNP were synthesized to overcome these shortcomings and characterized by a broad range of methods including transmission electron microscopy, dynamic and electrophoretic light scattering. 109 AgNP and gold NP (AuNP) were spiked to a pilot wastewater treatment plant fed with municipal wastewater for up to 21 days. AuNP were used as chemically less reactive tracer. The uptake of the pristine and transformed NP present in the effluent was assessed using the benthic amphipod Hyalella azteca in fresh- and brackish water exposures at environmentally relevant concentrations of 30 to 500 ng Au/L and 39 to 260 ng Ag/L. The unique isotopic signature of the 109 AgNP allowed to detect the material at environmentally relevant concentrations in the presence of a much higher natural Ag background. The results show that the transformations reduce the NP uptake at environmentally relevant exposure concentrations. For 109 Ag, lower accumulation factors (AF) were obtained after exposure to transformed NP (250-350) compared to the AF values obtained for pristine 109 AgNP (750-840). The reduced AF values observed for H. azteca exposed to effluent from the AuNP-spiked WWTP indicate that biological transformation processes (e.g. eco-corona formation) seem to be involved in addition to chemical transformation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Imported fire ants are significant agricultural pests. Repellents can be used to prevent foraging fire ants from entering sensitive areas, including electrical equipment, nursing homes, and hospitals. Bioassay-guided fractionation of the essential oil extracted from gurjun balsam ( Dipterocarpus turbinatus ) resulted in the identification of (-)-α-copaene ( 1 ) as the repellent constituent with a minimum repellent effective dose (MRED) of 15.6 μg/g against both red imported fire ants ( Solenopsis invicta ) and hybrid imported fire ants ( Solenopsis invicta × Solenopsis richteri ). Stereoselective oxidation of 1 via autoxidation and chemical methods produced (-)-5 R -hydroperoxy-α-copaene ( 2 ), (+)-3 S -hydroperoxycopa-4-ene ( 3 ), (-)-α-copaene oxide ( 4 ), (+)-β-copaen-4α-ol ( 5 ), copaenediol ( 6 ), and copaene ketol ( 7 ). Reduction of 2 and 3 with triphenylphosphine afforded (-)-5 R -hydroxy-α-copaene ( 2a ) and (+)-3 S -hydroxycopa-4-ene ( 3a ), respectively, which led to the structural revision of copa-3-en-2α-ol and copa-2-en-4-ol as 2a and 3 , respectively. The configurational assignment of compound 4 in the literature was also clarified by the detailed analysis of 2D NMR spectroscopic data. Compounds 2 - 7 showed repellency with MREDs ranging from 3.9 to 15.6 μg/g against hybrid and red imported fire ants, indicating that chemical modification can enhance the repellent effect of (-)-α-copaene.

Metallic pollutants can have harmful impacts on ant morphology and physiology. We studied the occurrence of labial gland disease in Camponotus japonicus from two polluted areas (traffic pollution and industrial pollution) and one non-polluted area. We further analyzed the metal levels (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb and Zn) and morphological characteristics (head width, body mass, and other morphological traits) of both diseased and healthy workers. Our results showed that labial gland disease was only present in polluted areas, indicating that pollution stress makes ants more vulnerable to infections. Our research revealed that diseased ants in polluted areas accumulate higher levels of metals in their bodies and have lower dry weight and residual body mass compared to healthy ants in non-polluted environments, negatively impacting their development. We evaluated the importance of these elements and found that Cu has the greatest impact on the health risk of C. japonicus. Our study underscores the significant impact of environmental pollution on ant morphology and physiology and raises concerns about the broader ecological implications., Competing Interests: Declaration of Competing Interest All authors disclosed no relevant relationships., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cadmium (Cd) exhibits widely olfactory toxicity to animals. We previously reported that Cd exposure induces the transcriptional dysregulation of olfactory marker proteins (OMPs) of the red imported fire ant Solenopsis invicta. However, it is still unclear how environmental Cd exposure-induced deregulation of OMPs affects the olfactory signal transduction and olfaction-driven social behavior of S. invicta. Here, we showed that S. invicta displayed dull sensory perception on bait in Cd-contaminated areas and dietary Cd ingestion by S. invicta reduced the bait search efficiency. We hypothesize that deregulation of OMPs by Cd exposure blocks the olfactory signal transduction in fire ants. Our results indicated the odor binding protein 14 (SiOBP14) was consistently inhibited in antennal sensilla of fire ants across Cd exposure at 0.5, 5 and 50 mg/kg. Function analysis in vitro and in vivo demonstrated that SiOBP14 is essential in perception of S. invicta to bait odorants. Cd-exposed fire ants showed weak odorant receptor neurons (ORNs) chemosensory signaling and electroantennogram (EAG) response. Moreover, Cd exposure repeals the preference of S. invicta to the active bait odorants, including 2-methyltetrahydrofuran-3-one, 2-methyl-3-furanthiol and 4,5-dimethylthiazole, and even triggers a behavioral transition from preference to repellence. These results indicate that Cd exposure inhibits the specific OMP expression and disrupts olfactory signal transduction, thereby inducing dull sensory perception of S. invicta to bait odorants. The findings provide new implications for monitoring and control of agricultural insect pests in heavy metal polluted areas., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The current study evaluates the antibacterial activity of Camponotus compressus (Hymenoptera: Formicidae) body crude extracts. The increasing antibiotic resistance of bacteria has prompted the world to turn its attention towards insects in the search for new sources of antibacterial compounds. The body crude extract obtained with different solvents were tested against both Gram positive (Staphylococcus aureus, Bacillus subtilis) and Gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae). Standard disc diffusion method was used to perform the activity. The extracts of C. compressus were investigated for their effectiveness against all resistant pathogenic bacteria. Staphylococcus aureus was found to be the most susceptible, exhibiting a high average growth inhibition, while Bacillus subtilis showed a lower average growth inhibition zone. Our findings regarding the inhibitory effect of C. compressus extracts show the presence of a broad-spectrum antibacterial compound. This will be helpful in the search for novel natural antibiotics against robust pathogenic bacterial strains.

Juvenile hormone is considered to be a master regulator of polyphenism in social insects. In the ant Cardiocondyla obscurior, whether a female egg develops into a queen or a worker is determined maternally and caste-specific differentiation occurs in embryos, so that queens and workers can be distinguished in a non-invasive manner from late embryogenesis onwards. This ant also exhibits two male morphs - winged and wingless males. Here, we used topical treatment with juvenile hormone III and its synthetic analogue methoprene, a method that influences caste determination and differentiation in some ant species, to investigate whether hormone manipulation affects the development and growth of male, queen- and worker-destined embryos and larvae. We found no effect of hormone treatment on female caste ratios or body sizes in any of the treated stages, even though individuals reacted to heightened hormone availability with increased expression of krüppel-homolog 1, a conserved JH first-response gene. In contrast, hormone treatment resulted in the emergence of significantly larger males, although male morph fate was not affected. These results show that in C. obscurior, maternal caste determination leads to irreversible and highly canalized caste-specific development and growth., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Background: Given the chemical diversity within stink bugs scent glands, they can be convenient models for bioprospecting novel pest control products. Preliminary behaviour observations indicated that adult Mictis fuscipes stink bugs secrete liquid droplets when defending against Solenopsis invicta fire ants, killing them within minutes. Hence, this study aimed to analyse the chemical composition of the metathoracic scent gland secretions of M. fuscipes adults, as well as assess their biological activities against fire ants., Results: Bioassaying fire ants against secretions of several local stink bugs confirmed that the defensive secretions of two Mictis species are significantly more lethal, where M. fuscipes was the most lethal. Volatiles chromatography analysis indicated the secretions of female and male M. fuscipes stink bugs contains 20 and 26 components, respectively, chiefly hexanoic acid and hexyl hexanoate. Five compounds were consistently present in the secretion of female adults: hexyl hexanoate, hexanoic acid, hexyl acetate, hexyl butyrate, and eugenol. These yielded a strong electrophysiological antennal (EAD) response from S. invicta workers, female alates and males, where hexyl acetate showed the strongest response. The combination of these five compounds proved strongly repellent to S. invicta. When tested singly, hexanoic acid, hexyl butyrate, hexyl hexanoate, and eugenol were repellent to S. invicta, but hexyl acetate seemed slightly attractive. Additionally, the same mixture of five components exhibited strong contact and fumigant toxicity towards S. invicta workers, eugenol being the strongest., Conclusion: Defensive chemicals of M. fuscipes exhibit robust biological activity against S. invicta and could inspire the development of biopesticides. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Leaf-cutting ants are the most important pests in several cropping systems in the Neotropics. Granulated baits containing active ingredients, considered hazardous by the Stockholm Convention, are the usual method to control these ants. Isocycloseram is a new insecticide molecule with high safety margin for mammals, but without registration for the ants in general. Thus, this study investigated the effectiveness of granulated baits with isocycloseram in leaf-cutting ants control under laboratory and field conditions. Initially, the mortality of Atta sexdens workers, fed with dehydrated citrus pulp paste containing different concentrations of isocycloseram was evaluated in the laboratory for 21 days, for toxicological classification. Subsequently, the loading, devolution, and incorporation of baits with different concentrations of isocycloseram and the mortality of A. sexdens colonies were evaluated in the laboratory. After that, the percentages of loading and devolution of baits, foraging activity, and colony mortality treated with 0.05, 0.1, 0.2, and 0.3% of isocycloseram were evaluated for the species A. sexdens, A. laevigata, and Acromyrmex lundii in field conditions. All concentrations of isocycloseram killed more than 15% of ants in 24 h and more than 90% in 21 days in the laboratory, being classified as a fast-acting and highly effective active ingredient. Baits with 0.001 to 0.03% of isocycloseram were highly loaded and exhibited low rate of devolution. The mortality of A. sexdens colony was higher at concentrations between 0.075 and 0.3%, in the laboratory. Baits containing isocycloseram at concentrations of 0.2 and 0.3% were highly loaded, presented low devolution rates, and were highly efficient in controlling A. sexdens, A. laevigata, and A. lundii in the field, at dosages of 6, 10, and 12 g/m² of nest. This is the first report of the use of isocycloseram against leaf-cutting ants, contributing to the development of efficient and toxicologically safer ant baits., Competing Interests: The authors declare that Syngenta’s support may be considered as a potential competing interest. However, the funder had no role in study design, data collection and analysis, interpretation of results, and preparation of the manuscript., (Copyright: © 2024 Zanetti et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Behavioral plasticity is key to animal survival. Harpegnathos saltator ants can switch between worker and queen-like status (gamergate) depending on the outcome of social conflicts, providing an opportunity to study how distinct behavioral states are achieved in adult brains. Using social and molecular manipulations in live ants and ant neuronal cultures, we show that ecdysone and juvenile hormone drive molecular and functional differences in the brains of workers and gamergates and direct the transcriptional repressor Kr-h1 to different target genes. Depletion of Kr-h1 in the brain caused de-repression of "socially inappropriate" genes: gamergate genes were upregulated in workers, whereas worker genes were upregulated in gamergates. At the phenotypic level, loss of Kr-h1 resulted in the emergence of worker-specific behaviors in gamergates and gamergate-specific traits in workers. We conclude that Kr-h1 is a transcription factor that maintains distinct brain states established in response to socially regulated hormones., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Pesticides and pathogens are known drivers of declines in global entomofauna. However, interactions between pesticides and viruses, which could range from antagonistic, over additive to synergistic, are poorly understood in ants. Here, we show that in ants the impact of single and combined pesticide and virus stressors can vary across castes and at the colony level. A fully-crossed laboratory assay was used to evaluate interactions between a sublethal dose of the neonicotinoid thiamethoxam and Acute bee paralysis virus (ABPV) in black garden ants, Lasius niger. After monitoring colonies over 64 weeks, body mass, neonicotinoid residues and virus titres of workers and queens, as well as worker behavioural activity were measured. ABPV, but not thiamethoxam, reduced activity of workers. Neonicotinoid exposure resulted in reduced body mass of workers, but not of queens. Further, thiamethoxam facilitated ABPV infections in queens, but not in workers. Overall, virus exposure did not compromise detoxification and body mass, but one colony showed high virus titres and worker mortality. Although the data suggest additive effects at the level of individuals and castes, co-exposure with both stressors elicited antagonistic effects on colony size. Our results create demand for long-term holistic risk assessment of individual stressors and their interactions to protect biodiversity., (© 2021. The Author(s).)

Biogenic amines play an important role in the regulation of appetitive responses in insects. Among them, serotonin (5-HT) regulates feeding-related processes in numerous insect species. In carpenter ants, 5-HT administration has been shown to depress feeding behavior, thus opening the possibility of using 5-HT modulation in control strategies against those species considered as pest. Here we studied if administration of a 5-HT antagonist, ketanserin, promotes feeding of a sucrose solution and a toxic bait in carpenter ants Camponotus mus. We found that 3 h after a single oral administration of ketanserin, the mass of sucrose solution consumed by carpenter ants increased significantly. A similar effect was found after a chronic administration that lasted 5 days. Yet, ketanserin did neither affect the intake rates nor the activity of the pharyngeal pump that mediates feeding dynamics. In addition, ketanserin promoted the consumption of a toxic bait based on boric acid. Our results thus show that feeding motivation and consumption of both sucrose solution and a toxic bait can be enhanced via prior administration of ketanserin. We discuss the possible mechanisms underlying these effects and conclude that understanding basic physiological and neural principles that underlie feeding motivation allows establishing more efficient control strategies for pest insects., (© 2021. The Author(s).)

Worker division of labor is a defining trait in social insects. Many species are characterized by having behavioral flexibility where workers perform non-typical tasks for their age depending on the colony's needs. Worker division of labor and behavioral flexibility were examined in the little fire ant Wasmannia auropunctata (Roger, 1863), for which age-related division of labor has been found. Young workers perform nursing duties which include tending of brood and queens, and colony defense, while older workers forage. When nurses were experimentally removed from the colony, foragers were observed carrying out nursing and colony defense duties, yet when foragers were removed nurses did not forage precociously. We also administered juvenile hormone analog, methoprene, to workers. When methoprene was applied, foragers increased their nursing and defense activities while nurses became mainly idle. The behavioral flexibility of foragers of the little fire ant may be evidence of an expansion of worker's repertoires as they age; older workers can perform tasks they have already done in their life while young individuals are not capable of performing tasks ahead of time. This may be an important adaptation associated with the success of this ant as an invasive species., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America.)

Chemical communication is common across all organisms. Insects in particular use predominantly chemical stimuli in assessing their environment and recognizing their social counterparts. One of the chemical stimuli used for recognition in social insects, such as ants, is the suite of long-chain, cuticular hydrocarbons. In addition to providing waterproofing, these surface hydrocarbons serve as a signature mixture, which ants can perceive, and use to distinguish between strangers and colony mates, and to determine caste, sex, and reproductive status of another individual. They can be both environmentally and endogenously acquired. The surface chemistry of adult workers has been studied extensively in ants, yet the pupal stage has rarely been considered. Here we characterized the surface chemistry of pupae of Formica exsecta, and examine differences among sexes, castes (reproductive vs. worker), and types of sample (developing individual vs. cocoon envelope). We found quantitative and qualitative differences among both castes and types of sample, but male and female reproductives did not differ in their surface chemistry. We also found that the pupal surface chemistry was more complex than that of adult workers in this species. These results improve our understanding of the information on which ants base recognition, and highlights the diversity of surface chemistry in social insects across developmental stages.

The efficacy and mode of action of biodegradable chitosan (CS) and carboxymethyl chitosan (CMCS) organic polymer nanoparticles (NPs) on insects were studied. The prepared CS/CMCS-NPs were spherical with a particle size of 142.1 ± 2.0 nm. The swelling test showed that they were pH-sensitive, and the swelling rate was 554 % at pH 4.5. It was found that CS/CMCS-NPs had insecticidal efficacy against red fire ants (S. invicta). The mortality of red fire ants on the 6th day after treatment with 0.2 % and 0.06 % CS/CMCS-NPs suspensions was 98.33 ± 1.67 % and 48.33 ± 3.33 %, respectively. After CS/CMCS-NPs treatment, the food intake, growth, and development of red fire ants were inhibited; the midgut was significantly expanded; and the activity of digestive enzymes in the midgut was decreased. Our findings suggest that CS/CMCS-NPs mainly inhibited the digestion function of the midgut, leading to the death of red fire ants., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The discovery of new insecticides improves integrated pest management (IPM), but is usually a long high-risk process with a low probability of success. For over two decades, insect neuropeptides (NPs) and their G-protein coupled receptors (GPCRs) have been considered as biological targets for insect pest control, because they are involved in almost all physiological processes associated with insect life stages. A key roadblock to success has been the question of how large volume chemical libraries can be efficiently screened for active compounds. New genomic and proteomic tools have advanced and facilitated the development of new approaches to insecticide discovery. In this study, we report a novel GPCR-based screening technology that uses millions of short peptides randomly generated by bacteriophages, and a method using an insect Sf9 cell expression system. The fire ant is a good model system, since bioactive peptides have been identified for a specific GPCR. The novel small peptides could interfere with the target GPCR-ligand functions. Therefore, we refer to this new mechanism as "receptor interference" (RECEPTORi). The GPCR-based bioactive peptide screening method offers multiple advantages. Libraries of phage-displayed peptides (~10 9 peptides) are inexpensive. An insect cell-based screening system rapidly leads to target specific GPCR agonists or antagonists in weeks. Delivery of bioactive peptides to target pests can be flexible, such as topical, ingestion, and plant-incorporated protectants. A variety of GPCR targets are available, thus minimizing the development of potential insecticide resistance. This report provides the first proof-of-concept for the development of novel arthropod pest management strategies using neuropeptides, and GPCRs.

Autumn crocus ( Colchicum autumnale L.) is a medicinal plant as it contains high concentrations of colchicine. In this study, we reported that the ground powder of autumn crocus bulb is highly toxic to invasive Solenopsis invicta Buren, commonly referred to as red imported fire ants (RIFAs). Ants fed with sugar water containing 5000 mg/L of bulb powder showed 54.67% mortality in three days compared to 45.33% mortality when fed with sugar water containing 50 mg/L of colchicine. Additionally, the effects of short-term feeding with sugar water containing 1 mg/L of colchicine and 100 mg/L of autumn crocus bulb powder were evaluated for RIFAs' colony weight, food consumption, and aggressiveness, i.e., aggregation, grasping ability, and walking speed. After 15 days of feeding, the cumulative colony weight loss reached 44.63% and 58.73% due to the sublethal concentrations of colchicine and autumn crocus bulb powder, respectively. The consumption of sugar water and mealworm ( Tenebrio molitor L.) was substantially reduced. The aggregation rates decreased 48.67% and 34.67%, grasping rates were reduced to 38.67% and 16.67%, and walking speed decreased 1.13 cm/s and 0.67 cm/s as a result of the feeding of the two sublethal concentrations of colchicine and autumn crocus bulb powder, respectively. Our results for the first time show that powder derived from autumn crocus bulbs could potentially be a botanical pesticide for controlling RIFAs, and application of such a product could be ecologically benign due to its rapid biodegradation in the environment.

The widespread prophylactic usage of neonicotinoid insecticides has a clear impact on non-target organisms. However, the possible effects of long-term exposure on soil-dwelling organisms are still poorly understood especially for social insects with long-living queens. Here, we show that effects of chronic exposure to the neonicotinoid thiamethoxam on black garden ant colonies, Lasius niger, become visible before the second overwintering. Queens and workers differed in the residue-ratio of thiamethoxam to its metabolite clothianidin, suggesting that queens may have a superior detoxification system. Even though thiamethoxam did not affect queen mortality, neonicotinoid-exposed colonies showed a reduced number of workers and larvae indicating a trade-off between detoxification and fertility. Since colony size is a key for fitness, our data suggest long-term impacts of neonicotinoids on these organisms. This should be accounted for in future environmental and ecological risk assessments of neonicotinoid applications to prevent irreparable damages to ecosystems.

Analogies across disciplines often indicate the existence of universal principles such as optimization, while the underlying proximate mechanisms may differ. It was reported recently that trails of ants refract at the border of substrates, on which walking speeds differ. This phenomenon is analogous to the travel-time-minimizing routes of light refracting at the borders between different media. Here, we further demonstrate that ant tracks converge or diverge across lens-shaped impediments similar to light rays through concave or convex optical lenses. The results suggest that the optical principle of travel time reduction may apply to ants. We propose a simple mathematical model that assumes nonlinear positive feedback in pheromone accumulation. It provides a possible explanation of the observed similarity between ant behavior and optics, and it is the first quantitative theoretical demonstration that pheromone-based proximate mechanisms of trail formation may produce this similarity. However, the future detailed empirical observations of ant behavior on impediment edges during the process of pheromone trail formation are needed in order to evaluate alternative explanations for this similarity.

Contact and fumigation toxicity of four isothiocyanates (ITCs), including allyl isothiocyanate (AITC), 3-butenyl isothiocyanate (3BITC), 3-(methylthio) propyl isothiocyanate (3MPITC) and 2-phenylethyl isothiocyanate (2PEITC), were evaluated against the red imported fire ant worker, Solenopsis invicta Buren. 2PEITC and 3MPITC exhibited strong contact toxicity. The median lethal dose (LD 50 )value of AITC, 2PEITC and 3MPITC were 7.99, 2.36 and 2.09 µg/ant respectively. In addition, AITC and 3MPITC also showed strong fumigation toxicity but not 2PEITC. The median lethal concentration (LC 50 ) values of AITC and 3MPITC were 32.49 and 57.6 µg/L, respectively. In contrast, 3BITC did not exhibit any contact and fumigation toxicity even at 100 μg/μL. Esterase (EST), glutathione S -transferase (GST) and acetylcholinesterase (AChE)-inhibiting activities were assessed for three ITCs in S. invicta workers. All three ITCs inhibited both EST and GST activities but not AChE. The in vitro half maximal inhibitory concentration (IC 50 )values of AITC, 2PEITC and 3MPITC for GST were 3.32, 0.61 and 0.66 µg/µL, respectively. These results suggested that naturally occurring ITCs might be potentially useful for developing fire ants control products.

Corpse-removal behavior of the red imported fire ant (RIFA) and the effects of lethal substances on RIFA signal communication were investigated in this study. The RIFA corpses, obtained through freezing, ether, 0.25 mg/L thiamethoxam, and starvation to death treatments, and naturally dead red fire ants were subjected to gas chromatography-mass spectrometry to identify the cuticular hydrocarbon profiles that had an effect on the corpse-removal behavior. The results showed that lethal toxic substances altered the epidermal compounds of RIFA and affected their corpse-removal behavior. Lethal toxic substances increased the number of worker touches with corpses and identification time of corpses. In addition, the content of piperidine (1,1'-(1,2-ethanediyl)bis-) on the surface of the corpse was different following the various treatments. Contamination with toxic substances resulted in the increased secretion of piperidine and led to increased identification time of corpses, number of touch with corpses, and total time for removal of corpses. Piperidine content was higher under conditions of natural death (4.67 ± 0.55%) and with thiamethoxam (10.43 ± 0.78%), freezing (0.83 ± 0.25%), and ether treatment (12.50 ± 0.70%) than under starvation treatment (0). The higher content of piperidine led to a longer number of touches with corpses and identification time. Piperidine compounds may be an element in warning information, which could affect the occurrence of different corpse-removal behaviors., Competing Interests: Declaration of competing interest A competing financial interest's declaration: The authors declare that they have no conflict of interest. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The study evaluates molybdenum disulfide (MoS 2 ) nanoparticles (NPs) induced oxidative stress during cellular toxicity in an invertebrate in vivo system, the weaver ant. The lethal concentration was checked and LC 50 was obtained as 50 µg/mL. Feeding assay and the photoluminescence activity confirmed the ingestion of MoS 2 NPs by the organism. Behavioral assays showed altered grooming behavior in the MoS 2 NP fed ants. A drastic decrease in the hemocyte count in the MoS 2 NP fed ants revealed the anti-proliferative role of MoS 2 . This was further confirmed by 5-bromo-2'-deoxyuridine (BrdU) labeling assay. MoS 2 NPs induced apoptotic activity was also observed in the hemocytes by acridine orange/ethidium bromide (AO/EB) staining. The level of oxidative stress during cellular toxicity was observed. An increased reactive oxygen species (ROS) level was observed in the MoS 2 NP fed ants when compared to the control group. The increased activity of superoxide dismutase (SOD) and the lipid peroxidation (LPO) product were observed. While, the activities of catalase (CAT) and glutathione-s-transferase (GST) and the glutathione content (GSH) were decreased by MoS 2 NPs. The transcript levels of SODs, CAT and GST were up regulated in the treated group. Our results suggest that MoS 2 NPs induced oxidative stress mediates the cellular toxicity in the foragers of the weaver ant., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Achieving nutritional homeostasis is crucial for the fitness of all living organisms [1]. Using "collective wisdom," ants have been shown to excel at making rapid and appropriate decisions under various contexts [2, 3], including foraging [4-7]. Ants often use pheromone trails to share information about food resources [8-10], a process allowing them to focus their foraging activity on the best food source available [7, 11-14]. However, what constitutes the best food source depends on the nutritional context of the colony in relation to its food environment [15]. In this study, we exposed ant colonies to various nutrient deficiencies and observed their compensatory nutritional responses. Ants were deprived of carbohydrate, sterol, protein, a subset of amino acids, or a single amino acid. We found that ants were rapidly able to match their foraging decisions to their nutritional needs, even if the deficiency concerned a single amino acid. An individual-based model demonstrates that these impressive feats of nutritional compensation can emerge from the iterative process of trail-laying behavior, which relies on a simple individual decision: to eat or not to eat. Our results show that, by adjusting their feeding behavior at the individual level, ants sustain homeostasis at the colony level., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Invasive ants are major agricultural and urban pests and a significant concern in conservation areas. Despite long history of control and eradication efforts, invasive ants continue to spread around the globe driven by a multitude of synergistic factors. Lack of effective management tools is one of the biggest challenges in controlling invasive ants. The goal of the current study was to improve the efficacy and safety of ant management and to develop effective control strategies for sensitive conservation areas. We utilized the Argentine ant (Linepithema humile) as a model system to evaluate a target-specific pesticide delivery system that exploits the interconnected nature of social insect colonies to distribute a toxicant effectively within the colony. The approach, based entirely on horizontal transfer, takes advantage of various levels of social interactions in ant colonies to disseminate a toxicant throughout the colony. Results of laboratory studies coupled with LC/MS/MS analysis demonstrate that fipronil is toxic to Argentine ants in extremely small (nanogram) quantities and is efficiently transferred from a single treated donor to multiple recipients, causing significant secondary mortality. A field study was conducted in native fynbos plots invaded by Argentine ants. The study consisted of collecting naïve workers, treating them with fipronil, and releasing them within invaded plots. Results show that the release of fipronil-treated ants reduced Argentine ant abundance by >90% within 24 h. The horizontal transfer approach offers environmental benefits with regard to pesticide use in ecologically sensitive environments and appears ideally suited for ant management in conservation areas.

Some parasites can manipulate the behavior of their animal hosts to increase transmission. An interesting area of research is understanding how host neurobiology is manipulated by microbes to the point of displaying such aberrant behaviors. Here, we characterize the metabolic profile of the brain of an insect at the moment of the behavioral manipulation by a parasitic microbe. Our model system are ants infected with the parasitic fungus Ophiocordyceps kimflemingiae (=unilateralis), which manipulates ants to climb and bite into plant substrates, before killing the host (i.e. zombie ants). At the moment of the behavioral manipulation by the fungus, the host's brain is not invaded by the fungus which is known to extensively invade muscle tissue. We found that, despite not being invaded by the parasite, the brains of manipulated ants are notably different, showing alterations in neuromodulatory substances, signs of neurodegeneration, changes in energy use, and antioxidant compound that signal stress reactions by the host. Ergothionine, a fungal derived compound with known neuronal cytoprotection functions was found to be highly elevated in zombie ant brains suggesting the fungus, which does not invade the central nervous system, is preserving the brain., (Copyright © 2019. Published by Elsevier Ltd.)

Leaf-cutting ants are considered major pests of agriculture and forestry in the Neotropics. Attractive toxic baits are the prevailing method for managing them. Thus, there is great interest in identifying attractants to incorporate into these baits. Moreover, leaf-cutting ants can avoid toxic baits by associating the attractant with the toxin. We evaluated attractiveness of heptyl butyrate, a volatile compound found in fresh apples and plums. We conducted field experiments with ten colonies of Acromyrmex lobicornis. First, we evaluated the behaviour of ants exposed to heptyl butyrate at 1% by surrounding resources. Then, we compared the attractiveness of heptyl butyrate and orange pulp, the most commonly used attractant. Finally, we evaluated whether heptyl butyrate increases the attractiveness of a carbohydrate resource at varying doses. Heptyl butyrate at 1% attracted 92% more ants than the control and that it was as attractive as orange pulp. Heptyl butyrate paired with sucrose at concentrations of 0.001 and 0.1% was more attractive than sucrose alone, but greater concentrations did not increase sucrose's attractiveness. Therefore, heptyl butyrate could be added to toxic baits to manage A. lobicornis as it is as attractive as the most commonly used attractant and can be applied directly to the pellets.

The risk element accumulation ability of two groups of epigeic species, insects from families Coleoptera and Hymenoptera (namely Formicidae), was determined and related to soil risk element content and bioaccessibility. The study was conducted in the district of Příbram, Czech Republic, which was characterised by extremely high aged pollution in the soils, including risk elements, especially As, Pb, Zn and Cd, due to the former mining and smelting activity. Four sampling sites differing in their pseudo-total risk element contents were selected and composite samples of individuals representing either Coleoptera or Formicidae were sampled at the individual sampling points. The results indicate the ability of Coleoptera and Formicidae organisms to accumulate risk elements, especially at the location with extremely high soil risk element content. In soil containing up to 841 mg As kg -1 , 84.6 mg Cd kg -1 , 4250 mg Pb kg -1 and 8542 mg Zn kg -1 , contents in insect bodies reached 239 mg As kg -1 As, 24.2 mg Cd kg -1 , 70.4 mg Pb kg -1 and 335 mg Zn kg -1 in beetles and up to 20.9 mg As kg -1 , 29.9 mg Cd kg -1 , 111 mg Pb kg -1 and 657 mg Zn kg -1 in ants. Therefore, bioaccumulation factors (BAFs) varied between 0.02 and 0.55. Increasing Cd content in Coleoptera bodies with increasing soil pseudo-total element content was observed only among the investigated elements. However, the results indicate increasing BAF values with decreasing soil element levels, especially for Cd, Pb and Zn, indicating limited uptake of elements by the organisms living in contact with extremely contaminated soil.

The phenotypic diversity of ant workers plays a fundamental role in their biology. In this study, we asked if the body size variation of monomorphic workers of the ant Lasius niger (Formicidae) responds adaptively to metal pollution in a post-mining metal-polluted area. Nest samples of workers were collected along a pollution gradient to calculate the within-colony variance in body size (expressed as maximum head width, HW). The results showed that the body size variation of L. niger was unrelated to the pollution index but demonstrated considerable variation between colonies even within the same study site. We suggest that the differences in morphological diversity between the colonies of L. niger could be shaped by colony personality traits, i.e., by colony-specific foraging and/or the feeding efficiency of nursing workers. The study supports previous findings, showing that morphological traits in Lasius ants are weakly related to environmental metal pollution.

Fipronil (FIP), a phenyl-pryazole pesticide, has been widely used for crop protection due to its broad insecticidal spectrum, especially for urban insect management. FIP also serves as the active ingredient of major baits used for the control of the red imported fire ant (RIFA; Solenopsis invicta). Although a vast majority of laboratory-based research has been performed using worker ants as a model, limited information is available regarding the toxicity of FIP in individuals from different castes and developmental stages. In this study, we investigated the interaction between FIP and this important pest, including FIP toxicity and transformation, RIFA enzyme activity and responses to FIP exposure. The topical and feeding toxicity of FIP in five adult castes, worker larvae and worker pupae were determined and compared. Topical toxicity assays showed that there were significant differences in FIP toxicity among adult workers (LD 50  = 1.17 μg/g), larvae (LD 50  = 1891.00 μg/g) and pupae (LD 50  = 23981.00 μg/g). Although, no obvious differences in topical toxicity were observed among the adult castes, the differences in feeding toxicity were significant. For example, the LC 50 value for the workers was 3.96-fold lower than that for soldiers at 24 h, and the LC 50 value was slightly lower for male alates than for female alates at day 3 and day 4, respectively. The activities of detoxification enzymes in individuals of different castes and developmental stages were investigated with or without FIP treatment. Cytochrome P450 activity was approximately 24-fold higher in larvae than in workers, and adult workers exhibited 4-fold higher FIP-induced cytochrome P450 activity than individuals from other adult castes. In addition, in vitro experiments demonstrated that FIP was transformed into FIP-sulfone, and this process may be primarily mediated by RIFA P450(s)., (Copyright © 2019. Published by Elsevier Ltd.)

The process of urbanization of natural environments has dramatically increased the incidence of pest insects. To control these organisms in urban environments, the last decades have been marked by an increase in the use of synthetic insecticides. However, the intensive and indiscriminate use of synthetic insecticides has provoked a series of environmental problems and human health. In this way, the concern and the searching for environmentally safer alternatives for the control of urban pests is increasing. In the present study we evaluated the lethal and sublethal effects of essential oils (EOs) of six accessions of Varronia curassavica (Jacq.) (Cordiaceae) and their constituents (E)-caryophyllene and α-humulene on the ant Dorymyrmex thoracicus Gallardo, 1916 (Formicidae: Dolichoderinae), a species commonly found in urban environments and which can cause damage to human health. Bioassays of fumigation toxicity and locomotor activity in partially treated arenas were performed. The lethal concentrations to kill 50% of the D. thoracicus population ranged from 0.69 to 2.48 μL/L for EOs and from 3.75 to 1.49 μL/L for the (E)-caryophyllene and α-humulene compounds. The survival of the ants exposed to LC 95 of the treatments was reduced over time, ranging from 4.2 to 35.6 h to kill 50% of the D. thoracicus population. In general, EOs of V. curassavica caused repellency and affected the locomotor activity of the ants. Our results indicate that EOs of V. curassavica are a promising source for the control of the urban ant D. thoracicus.

Fire ant venom contains insecticidal alkaloids named 'solenopsins'. Whilst species-specific differences are reported, little attention has been given to caste-specific venom adaptations. The venom of fire ant queens has remained particularly poorly studied, though studies have shown it to be strikingly similar across different species, in being primarily composed of the alkaloid isosolenopsin A, regardless of the chemical configuration in workers. We predict that this is the evolutionary outcome of stabilising selection, implying that a shared mechanism is responsible for the conserved venom composition among fire ant queens. The present investigation tests whether venom plays a role in nest founding, when queens must succeed in isolation in the field against competitor species. Here, we report that fire ant queen venom and isosolenopsin A are faster to incapacitate alien ants than the venom of fire ant workers. Representative sympatric competitor ant species were selected and exposed on their heads to the venom of workers and queens of the invasive fire ant species Solenopsis invicta and S. geminata. Queen venom was found to incapacitate rival foragers quicker than worker venom. The effects were reproduced using synthetic solenopsins, establishing that solenopsin A analogues are particularly effective contact neurotoxins. Overall, the venom of S. invicta is more lethal than of S. geminata, regardless of the incapacitation speed. We believe these are fundamental aspects of the chemical ecology of the invasive ants which remain overlooked, and emphasise the need for further studies into the venom biology of founding queens., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Coordinated social behaviour is fundamental for ant ecological success. However, even distantly-related organisms, such as plants, have evolved the ability to manipulate ant collective performances to their own advantage. In the parasitic system encompassing Maculinea butterflies, Myrmica ants, and Origanum vulgare plants, the ant-plant interaction elicits the release of a volatile terpenoid compound (carvacrol) which is used by the gravid butterfly to locate the ideal oviposition site. Here we show that this ant-plant association is maintained by the effect of O. vulgare terpenoids on ant behaviour and that food plants might gain protection by Myrmica ants by chemically manipulating workers to forage in their surroundings. The variation in the locomotor ability of three ant species (Formica cinerea, Tetramorium caespitum, and Myrmica scabrinodis) was studied after treatment with the two major O. vulgare terpenoid volatile compounds (i.e., carvacrol and thymol). The brain levels of three biogenic amines (dopamine, tyramine and serotonin) were analysed in ants exposed to the O. vulgare terpenoids by HPLC-ESI-MS/MS. Carvacrol and thymol increased the locomotor activity of all ant species tested, but if blended reduced the movement propensity of Myrmica scabrinodis. Dopamine and tyramine production was positively correlated with the worker locomotor activity. In Myrmica ants, both brain biogenic ammines were negatively correlated with the aggressive behaviour. Blends of O. vulgare volatiles affected the locomotor ability while increased the aggressiveness of Myrmica workers by altering the aminergic regulation in the ant brains. This behavioural manipulation, might enhance partner fidelity and plant protection. Our findings provide new insights supporting a direct role of plant volatiles in driving behavioural changes in social insects through biogenic amine modulation., Competing Interests: The authors have declared that no competing interests exist.

Leaf-cutting ants are important pests of forests and agricultural crops in the Neotropical region. Atta sexdens colonies can be composed of thousands of individuals, which form a highly complex society with a single reproductive queen. Successful control of this species is achieved only if the queen is affected. Few data are available on the lethal or sublethal effects of toxic compounds on leaf-cutting ant queens. Azadirachtin has been claimed as an effective biopesticide for insect control, but its action on leaf-cutting ants has been little explored. This study shows that azadirachtin affects oviposition in A. sexdens queens, impairing egg development by decreasing protein reserves. Azadirachtin inhibits the synthesis of vitellogenin, the major yolk protein precursor. The negative effects of azadirachtin on the reproduction of leaf-cutting ant queens suggest a potential use for the control of these insects., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Much research has focused on the effects of neonicotinoids on honey bees, however, relatively few studies have investigated their effects on ants, a taxonomically-related eusocial insect of high ecological importance. This study quantified how dietary exposures to environmentally-relevant levels of a neonicotinoid insecticide (imidacloprid) affected foraging and nest building of the western harvester ant over 14 days. Using a replicated design, statistically-significant reductions in ant foraging success (50% or greater) occurred at concentrations as low as 50 ppb compared to controls. Both the number of ants entering the maze and the percentage of foraging ants able to locate food were impacted by imidacloprid exposure. Ants exposed to 50 ppb also took three times longer than controls to find food in a test maze. This concentration is among the lowest levels of imidacloprid reported to affect ants and is well within the range of concentrations found in pollen and nectar of imidacloprid-treated plants. Ant foraging success was also impaired at comparable levels as those reported for the honey bee. Although more refinement and research are needed, results from this study suggest that the western harvester ant may be useful for screening the effects of neurotoxic chemicals on their navigation and foraging, two behaviors which are critical to maintaining colony health of ants and the ecological services they provide.

To understand whether flavor enhancers pose potential risks to the environment, it is important to assess its effects on insects. Therefore, the objective of this study was to evaluate the toxicity of flavor enhancers on the survival and behaviors of the red imported fire ant, Solenopsis invicta. In this study, we found that the mortality of S. invicta workers that were fed glutamic acid monosodium salt hydrate, glycine, L-alanine, succinic acid, succinic acid disodium, inosinate 5'-monophosphate disodium salt hydrate, and GMP were significantly higher than the mortality rates of workers fed sucrose. Moreover, glycine and GMP exhibited the strongest toxicities and caused 100% mortality in workers after 84 h. LC 50 values were 0.004 g/ml and 0.02 g/ml for GMP and glycine, respectively. Additionally, at sublethal doses, both GMP and glycine solutions decreased foraging and digging behaviors. Our results suggest that flavor enhancers are toxic to insects and also likely to have a negative impact at sublethal concentrations.

Acromyrmex leafcutter ants form a mutually beneficial symbiosis with the fungus Leucoagaricus gongylophorus and with Pseudonocardia bacteria. Both are vertically transmitted and actively maintained by the ants. The fungus garden is manured with freshly cut leaves and provides the sole food for the ant larvae, while Pseudonocardia cultures are reared on the ant-cuticle and make antifungal metabolites to help protect the cultivar against disease. If left unchecked, specialized parasitic Escovopsis fungi can overrun the fungus garden and lead to colony collapse. We report that Escovopsis upregulates the production of two specialized metabolites when it infects the cultivar. These compounds inhibit Pseudonocardia and one, shearinine D, also reduces worker behavioral defenses and is ultimately lethal when it accumulates in ant tissues. Our results are consistent with an active evolutionary arms race between Pseudonocardia and Escovopsis, which modifies both bacterial and behavioral defenses such that colony collapse is unavoidable once Escovopsis infections escalate.

Background: Habituation to sex pheromones is one of the key mechanisms in mating disruption, an insect control tactic. Male moths often show reduced sexual response after pre-exposure to female sex pheromone. Mating disruption is relatively rare in insect orders other than Lepidoptera., Results: As a positive control we confirmed habituation in a moth (Epiphyas postvittana) using 24 h pre-exposure to sex pheromone to reduce subsequent activation behaviour. We then tested the impact of pre-exposure to sex or trail pheromone on subsequent behavioural response with insects from three other orders. Similar pre-exposure for 24 h to either sex pheromone [Pseudococcus calceolariae (Homoptera) and apple leaf curling midge Dasineura mali (Diptera), or trail pheromone of Argentine ants (Linepithema humile (Hymenoptera)], followed by behavioural assay in clean air provided no evidence of habituation after pre-exposure in these latter cases., Conclusions: The moths alone were affected by pre-exposure to pheromone. For pests without habituation, sustained attraction to a point source may make lure and kill more economical. Improved knowledge of behavioural processes should lead to better success in pest management and mechanisms should be investigated further to inform studies and practical efforts generally enhancing effectiveness of pheromone-based management. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

Background: Historically, inert insecticidal powders such as diatomaceous earth were researched for pest management applications, and it was revealed that these types of powders killed insects by desiccation. However, data on the critical material properties that affect their efficacy are sparse. The present study investigated the insecticidal effect of powdered materials on the pharaoh ant, a notorious domestic pest., Results: The insecticidal activity of 24 porous materials was tested. Eight of these materials performed better than the benchmark, diatomaceous earth. Zeolite Y and carbon black II performed best, inducing 50% mortality within 40 and 55 minutes, respectively. Statistical analysis of seven material properties revealed that macroporous surface area and Brunauer-Emmett-Teller (BET) specific surface area were most predictive of insecticidal activity. For zeolites and ordered mesoporous silica materials, the most important parameters were, respectively, BET and large mesopore surface area. Finally, gas chromatography-mass spectrometry (GC-MS) analysis confirmed the adsorption of epicuticular hydrocarbons onto the zeolite powders., Conclusion: This study shows clear potential for the use of environmentally friendly, inert porous materials as insecticides against the pharaoh ant and identified the key material properties influencing insecticidal activity. The GC-MS data support the hypothesis that the mortality was caused by the removal of the protective epicuticular hydrocarbons. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

Uptake of lead from soil was examined in order to establish a site-specific ecological protective concentration level for the Texas Horned Lizard (Phrynosoma cornutum) at the Former Humble Refinery in San Antonio, Texas. Soils, harvester ants, and rinse water from the ants were analyzed at 11 Texas Harvester Ant (Pogonomyrmex barbatus) mounds. Soil concentrations at the harvester ant mounds ranged from 13 to 7474 mg/kg of lead dry weight. Ant tissue sample concentrations ranged from < 0.82 to 21.17 mg/kg dry weight. Rinse water concentrations were below the reporting limit in the majority of samples. Two uptake models were developed for the ants. A bioaccumulation factor model did not fit the data, as there was a strong decay in the calculated value with rising soil concentrations. A univariate natural log-transformed regression model produced a significant regression (p < .0001) with a high coefficient of determination (0.82), indicating a good fit to the data. Other diagnostic regression statistics indicated that the regression model could be reliably used to predict concentrations of lead in harvester ants from soil concentrations. Estimates of protective levels for P. cornutum were developed using published sub-chronic toxicological findings for the Western Fence Lizard that were allometricly adapted and compared to the Dose oral equation, which estimated lead consumed through ants plus incidental soil ingestion. The no observed adverse effect level toxicological limit for P. cornutum was estimated to be 5500 mg/kg.

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.

In this study, the insecticide potential of eight phthalides derived from furan-2(5H)-one was evaluated against Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) larvae. The potency of the most active phthalides and the susceptibility of six different T. absoluta populations to these compounds were determined. The toxicity of these molecules to two non-target species (Solenopsis saevissima Smith and Tetragonisca angustula Latreille) was also evaluated. Two phthalides (3 and 4) presented insecticide potential against T. absoluta. Phthalide 4 was as toxic as piperine (positive control) and both phthalides exhibited rapid action (LT 50 < 2 hours). The variation in the susceptibility of T. absoluta populations to the phthalides 3 and 4 was low. Neither phthalide presented physiological selectivity for non-target species. Therefore, the phthalides 3 and 4 are promising molecules, or at least, a starting point for a chemical optimization program leading to formulations for the management of the tomato leafminer. The application of such products should be conducted according to the principles of ecological selectivity.

Background: Investigating the impact of pesticides on non-target organisms is essential for sustainable integrated pest management programs. We therefore assessed the toxicity of ten insecticides to the brassica caterpillar Ascia monuste and its ant predator Solenopsis saevissima and examined the effect that the insecticide synergists had on toxicity to the predator. We also assessed the residual period of control and impact of the insecticides during the brassica growing cycle., Results: All insecticides except flubendiamide exhibited mortality above the threshold required by Brazilian legislation (80%). Chlorantraniliprole, cyantraniliprole, indoxacarb and spinosad exhibited lower toxicity to the ant predator than they did to the brassica caterpillar. The results obtained for synergized insecticides suggest that selectivity to the predator was due the involvement of cytochrome P450-dependent monooxygenases. Chlorfenapyr and cyantraniliprole exhibited the highest residual periods of control to the brassica caterpillar, whereas malathion had the greatest impact on the predator., Conclusion: Most of the insecticides efficiently controlled the brassica caterpillar, but not all exhibited selectivity to the predator. Therefore, due to the distinctive responses of organisms with respect to residual periods of control and the impact of the insecticides, spraying frequency must be strongly considered in integrated pest management programs. © 2017 Society of Chemical Industry., (© 2017 Society of Chemical Industry.)

The first synthesis of 2-methyl-6-pentadecyl-Δ 1,6 -piperideine (1), a major alkaloid of the piperideine chemotype in fire ant venoms, and its analogues, 2-methyl-6-tetradecyl-Δ 1,6 -piperideine (2) and 2-methyl-6-hexadecyl-Δ 1,6 -piperideine (3), was achieved by a facile synthetic method starting with glutaric acid (4) and urea (5). Compound 1 showed in vitro antifungal activity against Cryptococcus neoformans and Candida albicans with IC 50 values of 6.6 and 12.4 μg/mL, respectively, and antibacterial activity against vancomycin-resistant Enterococcus faecium with an IC 50 value of 19.4 μg/mL, while compounds 2 and 3 were less active against these pathogens. All three compounds strongly inhibited the parasites Leishmania donovani promastigotes and Trypanosoma brucei with IC 50 values in the range of 5.0-6.7 and 2.7-4.0 μg/mL, respectively.

Sweet orange oil fractions were prepared by molecular distillation of cold-pressed orange oil from sample A (Citrus sinensis (L.) 'Hamlin' from America) and sample B (Citrus sinensis Osbeck 'Newhall' from China) respectively, and their fumigant activities against medium workers of red imported fire ants (Solenopsis invicta Buren) were investigated. The volatile composition of the orange oil fractions was identified and quantified using GC-MS. Fractions from sample A (A1, A2, and A3) contained 23, 37, and 48 chemical constituents, and fractions from sample B (B1, B2, and B3) contained 18, 29, and 26 chemical constituents, respectively. Monoterpenes were the most abundant components, accounting for 73.56% to 94.86% of total orange oil fractions, among which D-limonene (65.28-80.18%), β-pinene (1.71-5.58%), 3-carene (0.41-4.01%), β-phellandrene (0.58-2.10%), and linalool (0.31-2.20%) were major constituents. Fumigant bioassay indicated that all orange oil fractions exerted good fumigant toxicity against workers of fire ants at 3, 5, 10, and 20 mg/centrifuge tubes, and B1 had the strongest insecticidal potential, followed by A1, B2, A2, B3, and A3. The fractions composed of more high volatile molecules (A1 and B1) showed greater fumigant effects than others. Compounds linalool and D-limonene, which were the constituents of the orange oil, exhibited excellent fumigant toxicity against red imported fire ant workers. Linalool killed red imported fire ant workers completely at 5, 10, and 20 mg/tube after 8 h of treatment, and D-limonene induced >86% mortality at 8 h of exposure., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Neonicotinoid seed treatments are under scrutiny because of their variable efficacy against crop pests and for their potential negative impacts on non-target organisms. Ants provide important biocontrol services in agroecosystems and can be indicators of ecosystem health. This study tested for effects of exposure to imidacloprid plus fungicide or fungicide-treated seeds on individual ant survival, locomotion and foraging capabilities and on field ant community structure, pest abundance, ant predation and yield., Results: Cohorts of ants exposed to either type of treated seed had impaired locomotion and a higher incidence of morbidity and mortality but no loss of foraging capacity. In the field, we saw no difference in ant species richness, regardless of seed treatment. Blocks with imidacloprid did have higher species evenness and diversity, probably owing to variable effects of the insecticide on different ant species, particularly Tetramorium caespitum. Ant predation on sentinel eggs, pest abundance and soybean growth and yield were similar in the two treatments., Conclusion: Both seed treatments had lethal and sublethal effects on ant individuals, and the influence of imidacloprid seed coating in the field was manifested in altered ant community composition. Those effects, however, were not strong enough to affect egg predation, pest abundance or soybean yield in field blocks. © 2016 Society of Chemical Industry., (© 2016 Society of Chemical Industry.)

The Dolichoderus thoracicus (Smith) has seriously infested urban, village, and agricultural environments in Taiwan. To develop optimal bait for the effective control of D. thoracicus, we investigated the feeding preferences of this ant at different sugar and amino acid concentrations in a laboratory setting. The number of feeding workers was significantly higher for 20% sucrose compared with that for other sugars at 10% and 20% concentrations. Furthermore, among all tested concentrations of monosodium glutamate (MSG; 1%, 3%, 5%, and 10%), the highest number of ants were attracted by 1% MSG with 20% sucrose. The consumption of each bait solution was also measured, and the results were similar to those for ant number. Regarding toxicants, the toxicity and repellency of 3% boric acid and borax bait were evaluated individually. Both 3% boric acid and borax demonstrated no repellency against D. thoracicus workers. The LT50 of the 3% boric acid bait was 4.87 d, whereas that of 3% borax bait was only 1.56 d. Thus, 3% boric acid showed further delayed action, facilitating workers spreading the toxicant to their nestmates through trophallaxis. In combination with our unique bait station, we propose an optimal bait formulation comprising 20% sucrose, 1% MSG, and 3% boric acid as a promising candidate for controlling D. thoracicus., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: The demand for sustainable agricultural practices and the limited progress toward newer and safer chemicals for use in pest control maintain the impetus for research and identification of new natural molecules. Natural molecules are preferable to synthetic organic molecules because they are biodegradable, have low toxicity, are often selective and can be applied at low concentrations. Microbes are one source of natural insecticides, and microbial insect symbionts have attracted attention as a source of new bioactive molecules because these microbes are exposed to various selection pressures in their association with insects. Analytical techniques must be used to isolate and characterize new compounds, and sensitive analytical tools such as mass spectrometry and high-resolution chromatography are required to identify the least-abundant molecules., Results: We used classical fermentation techniques combined with tandem mass spectrometry to prospect for insecticidal substances produced by the ant symbiont Streptomyces caniferus. Crude extracts from this bacterium showed low biological activity (less than 10% mortality) against the larval stage of the fall armyworm Spodoptera frugiperda. Because of the complexity of the crude extract, we used fractionation-guided bioassays to investigate if the low toxicity was related to the relative abundance of the active molecule, leading to the isolation of porphyrins as active molecules. Porphyrins are a class of photoactive molecules with a broad range of bioactivity, including insecticidal. The active fraction, containing a mixture of porphyrins, induced up to 100% larval mortality (LD 50  = 37.7 μg.cm -2 ). Tandem mass-spectrometry analyses provided structural information for two new porphyrin structures. Data on the availability of porphyrins in 67 other crude extracts of ant ectosymbionts were also obtained with ion-monitoring experiments., Conclusions: Insect-associated bacterial symbionts are a rich source of bioactive compounds. Exploring microbial diversity through mass-spectrometry analyses is a useful approach for isolating and identifying new compounds. Our results showed high insecticidal activity of porphyrin compounds. Applications of different experiments in mass spectrometry allowed the characterization of two new porphyrins.

Determining the success of eradication of an invasive species requires a way to decide when its risk of reoccurrence has become acceptably low. In Japan, the area populated by the Argentine ant, Linepithema humile (Mayr), is expanding, and eradication via chemical treatment is ongoing at various locations. One such program in Tokyo was apparently successful, because the ant population decreased to undetectable levels within a short time. However, construction of a population model for management purposes was difficult because the probability of detecting ants decreases rapidly as the population collapses. To predict the time when the ant was eradicated, we developed a multinomial-mixture model for chemical eradication based on monthly trapping data and the history of pesticide applications. We decided when to declare that eradication had been successful by considering both 'eradication' times, which we associated with eradication probabilities of 95% and 99%, and an optimal stopping time based on a 'minimum expected economic cost' that considered the possibility that surveys were stopped too soon. By applying these criteria, we retroactively declared that Argentine ants had been eradicated 38-42 months after the start of treatments (16-17 months after the last sighting).

Leaf-cutting ants are pests of great economic importance due to the damage they cause to agricultural and forest crops. The use of organosynthetic insecticides is the main form of control of these insects. In order to develop safer technology, the objective of this work was to evaluate the formicidal activity of the essential oils of two Hyptis pectinata genotypes (chemotypes) and their major compounds on the leaf-cutting ants Acromyrmex balzani Emery and Atta sexdens rubropilosa Forel. Bioassays of exposure pathways (contact and fumigation) and binary mixtures of the major compounds were performed. The major compounds identified in the essential oils of H. pectinata were β-caryophyllene, caryophyllene oxide and calamusenone. The essential oils of H. pectinata were toxic to the ants in both exposure pathways. Essential oils were more toxic than their major compounds alone. The chemotype calamusenone was more toxic to A. balzani in both exposure pathways. A. sexdens rubropilosa was more susceptible to the essential oil of the chemotype β-caryophyllene in both exposure pathways. In general, the binary mixtures of the major compounds resulted in additive effect of toxicity. The essential oils of H. pectinata is a raw material of great potential for the development of new insecticides.

There is increasing demand for new products for vegetable pest management. Thus, the aim of this study was to assess the toxicity of pyrethroids with acid moiety modifications to measure the insecticidal activity of these compounds on the lepidopteran vegetable pests Diaphania hyalinata (L.) (Lepidoptera: Pyralidae) and Asciamonuste (Latreille) (Lepidoptera: Pieridae) and evaluate their selectivity for the predatory ant Solenopsis saevissima (F. Smith) (Hymenoptera: Formicidae) and pollinator Tetragonisca angustula (Latreille) (Hymenoptera: Apidae: Meliponinae). Racemic mixtures of five new pyrethroids (30 µg molecule mg -1 insect body weight) resulted in high (100%) and rapid (stable LD 50 after 12 h) mortality in D. hyalinata and A. monuste. In A. monuste, the trans-pyrethroid [12] isomer showed similar toxicity to permethrin. For D. hyalinata, the trans-pyrethroid [9] isomer and cis-pyrethroid [10] isomer were as toxic as permethrin. Due to their low selectivity, these new pyrethroids should be applied on the basis of ecological selectivity principles to minimize impacts on nontarget organisms S. saevissima and T. angustula.

The red imported fire ant, Solenopsis invicta (Buren), left most of its natural enemies behind in South America when it arrived in Mobile, AL, in the 1930s and spread rapidly throughout the southeastern United States, reaching population levels up to 10 times those found in South America. The large population densities and propensity for disturbed habitats led to direct conflict with human activities. Bait control methods were first developed for fire ants in the early 1960s and little has changed in the subsequent decades, despite the drawback that the bait carrier rapidly breaks down when wet. The southeast United States is wet; thus, bait labels have various guidance-restricting applications based on potential wet conditions. Here we compare a hydrophobic fire ant bait to the equivalent standard bait formulation and demonstrate in a paired-mound field experiment under natural wet conditions in Florida (heavy dew on ground), a significant advantage for the hydrophobic bait. An effective hydrophobic ant bait would extend the utility of current bait insecticides to wet conditions and also fill an important gap in our ability to control invasive pest ant species that thrive in wet tropical and subtropical habitats, e.g., Wasmannia auropunctata (Roger), the little fire ant., (Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.)