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Social insects are highly diverse in their social structures, aside from the consistent presence of reproductive castes. Among social insects, the Australian paper wasp Ropalidia plebeiana constructs extremely dense colony aggregations consisting of hundreds of colonies within a few square meters; however, little is known about the aggregation structures. We genetically analyzed the colony and population structure of R. plebeiana, and concomitant variations in colony sex ratios. In spring, the foundress (candidate queen) group started their colonies on a single old comb from the previous season, subsequently dividing these old combs via relatedness-based comb-cutting. Female philopatry, a prerequisite condition of Local Resource Competition (LRC), was confirmed. The colony sex ratio of reproductive individuals (male and female offspring for the next generation) became slightly male-biased in larger colonies, as predicted under LRC. However, the number of foundresses was positively associated with the number of reproductive individuals, suggesting that Local Resource Enhancement (LRE) also operates. Although the population structure appears to meet the prerequisites of LRC, the sex ratio appears to be modulated by factors other than LRC. Rather, through LRE, the availability of female helpers at the founding stage is likely to mitigate the sex ratios predicted under LRC., (© 2022. The Author(s).)

Recent studies have reported incipient morphological caste dimorphism in the Van der Vecht organ size of some temperate Polistes paper wasps. Whether species other than the temperate ones show a similar pattern remains elusive. Here, we have studied some Neotropical Polistes species. By comparing females collected through the year, we showed caste related differences in the size of the Van der Vecht organ in P. ferreri (body size corrected Van der Vech organ size of queens = 0.45 ± 0.06, workers = 0.38 ± 0.07 mm2, p = 0.0021), P. versicolor (body size corrected Van der Vech organ size of queens = 0.54 ± 0.11, workers = 0.46 ± 0.09 mm2, p = 0.010), but not P. simillimus (body size corrected Van der Vech organ size of queens = 0.52 ± 0.05, workers = 0.49 ± 0.06 mm2, p = 0.238). Therefore, it seems that queens and workers of some Neotropical Polistes have diverged in their ontogenic trajectory of the Van der Vecht organ size, providing clear evidence for incipient morphological caste dimorphism. As Polistes are distributed mostly in the tropics, we propose that physical caste differences may be widespread in the genus. Also, we highlight that morphological divergence in the queen–worker phenotypes may have started through differential selection of body structures, like the Van der Vecht organ. [ABSTRACT FROM AUTHOR]

Social insects owe their widespread success to their ability to efficiently coordinate behaviour to carry out complex tasks. Several leaf-cutter ant species employ an advanced type of division of labour known as task partitioning, where the task of retrieving leaves is distributed between workers that cut and drop and those that collect the fallen leaves. It is not entirely clear how such highly coordinated behaviour can evolve, as it would seem to require the simultaneous mutations of multiple traits during the same generation. Here, we use an agent-based simulation model to show how task partitioning in leaf-cutter ants can gradually evolve by exploiting stigmergy (indirect coordination through the environment) through gravity (leaves falling from the treetop on the ground forming a cache). Our simple model allows independent variation in two core behavioural dimensions: the tendency to drop leaves and the tendency to pick up dropped leaves. Task partitioning readily evolves even under these minimal assumptions through adaptation to an arboreal environment where traveling up and down the tree is costly. Additionally, we analyse ant movement dynamics to demonstrate how the ants achieve efficient task allocation through task switching and negative feedback control., (© 2022. The Author(s).)

Independent origins of sociality in bees and ants are associated with independent expansions of particular odorant receptor (OR) gene subfamilies. In ants, one clade within the OR gene family, the 9-exon subfamily, has dramatically expanded. These receptors detect cuticular hydrocarbons (CHCs), key social signaling molecules in insects. It is unclear to what extent 9-exon OR subfamily expansion is associated with the independent evolution of sociality across Hymenoptera, warranting studies of taxa with independently derived social behavior. Here, we describe OR gene family evolution in the northern paper wasp, Polistes fuscatus , and compare it to four additional paper wasp species spanning ∼40 million years of evolutionary divergence. We find 200 putatively functional OR genes in P. fuscatus , matching predictions from neuroanatomy, and more than half of these are in the 9-exon subfamily. Most OR gene expansions are tandemly arrayed at orthologous loci in Polistes genomes, and microsynteny analysis shows species-specific gain and loss of 9-exon ORs within tandem arrays. There is evidence of episodic positive diversifying selection shaping ORs in expanded subfamilies. Values of omega (d N/ d S) are higher among 9-exon ORs compared to other OR subfamilies. Within the Polistes OR gene tree, branches in the 9-exon OR clade experience relaxed negative (relaxed purifying) selection relative to other branches in the tree. Patterns of OR evolution within Polistes are consistent with 9-exon OR function in CHC perception by combinatorial coding, with both natural selection and neutral drift contributing to interspecies differences in gene copy number and sequence. [ABSTRACT FROM AUTHOR]

Climate change is one of the major threats to biodiversity, but its impact varies among the species. Bark beetles (Ips spp.), as well as other wood-boring pests of European forests, show escalating numbers in response to the changes driven by climate change and seriously affect the survival of the forests through the massive killing of trees. Many methods were developed to control these wood-boring beetles, however, their implementation can be detrimental for other forest specialists. Ants are widely used for biological pest-control, so in our study, we aimed to test the effect of Formica polyctena on the control of the wood-boring beetles. The results show that the proportion of infested trees is significantly reduced by the increase of the number of F. polyctena nests, with a strong effect on those infested by Ips species. We also show that the boring beetle community is shaped by different biotic and abiotic factors, including the presence of F. polyctena nests. However, the boring beetle infestation was not related to the latitude, altitude and age of the forests. Based on our results, we assert the effectiveness of the red wood ants as biological pest control and the importance of their conservation to keep the health of the forests., (© 2021. The Author(s).)

Fire ants (Solenopsis invicta Buren in J Ga Entomol Soc 7:1-26, 1972), an invasive alien ant species, first spread from South America to the United States in the 1930s, the southern part of the United States by the end of the twentieth century, Oceania, Taiwan, and China in the twenty-first century, and finally to Japan and South Korea in 2017. As these ants have significant negative economic, human health, and environmental impacts, the purpose of this research was to accumulate cytogenetic information regarding fire ants and provide basic data for developing management strategies for their control. Fire ants were collected from invasive populations from Taiwan, Florida (USA), and Buenos Aires (Argentina), and a native population from Puerto Iguazu (Argentina), their point of origination, and analyzed with regard to chromosome number, morphology, and polyploidy, silver-stained nucleolar organizer regions (Ag-NORs), and 18S rDNA and telomere fluorescence in situ hybridization (FISH). The results showed that (1) fire ants from invaded populations differed in chromosome morphology compared to those from native populations; (2) the Florida and Taiwanese fire ant populations evinced greater variability in chromosome numbers and polyploidy variations; (3) the Taiwanese population exhibited significantly increased Ag-NOR signals in interphase cells, with signal number significantly positively correlating with distance from native populations; and (4) substantial diversity of signals was also apparent following 18S rDNA and telomere FISH analyses. Variation in these characteristics were hypothesized to be due to (1) the effect of hybridizations and interbreeding between closely related species or genetically distant populations, and (2) the potential effect of large amounts of insecticides sprayed for pest control., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

2-Ethyl-3,5-dimethylpyrazine is an isomer of 2-ethyl-3,6-dimethylpyrazine, the alarm pheromone component of the red imported fire ant, Solenopsis invicta Buren. The pyrazine was synthesized and its alarm activity was investigated under laboratory conditions. It elicited significant electroantennogram (EAG) activities, and released characteristic alarm behaviors in fire ant workers. The EAG and alarm responses were both dose-dependent. Two doses of the pyrazine, 1 and 100 ng, were further subjected to bait discovery bioassays. Fire ant workers excited by the pyrazine were attracted to food baits, and their numbers increased over time. Ants displayed very similar response patterns to both low and high doses of the pyrazine. The pyrazine impregnated onto filter paper disc attracted significantly more fire ant workers than the hexane control for all observation time intervals at the low dose, and in the first 15 min period at the high dose. The pyrazine loaded onto food bait directly tended to attract more fire ant workers than the hexane control. These results support the potential use of 2-ethyl-3,5-dimethylpyrazine to enhance bait attractiveness for the control of S. invicta in invaded regions. [ABSTRACT FROM AUTHOR]

This paper presents numeric morphology-based evidence on the broadly overlapping distribution of two thief ant species Solenopsis fugax (Latreille, 1798) and S. juliae (Arakelian, 1991) in the East European Pontic-Caspian region. The paper integrates two autonomous data collections and independent analyses performed by different researchers, using different equipment, considering different character combinations, and evaluating partially different samples. Five type series, the neotype series of Solenopsis fugax (Latreille 1798) and the type series of S. flavidula (Nylander, 1849), S. (Diplorhoptrum) fugax var. furtiva Santschi, 1934, S. (Diplorhoptrum) fugax var. pontica Santschi, 1934, S. (Diplorhoptrum) fugax var. scytica Santschi, 1934 were nested in one cluster and we propose the junior synonymy of the latter four taxa names with S. fugax. The other cluster contained only one type specimen of Solenopsis nitida (Dlussky & Radchenko, 1994) measured from AntWeb images. The naming of this cluster was based on both verbal statements and measurements of gynes given in the original description of Solenopsis juliae (Arakelian, 1991), which represents the oldest available name for this cluster. Hence, S. nitida is proposed as junior synonym of S. juliae. Solenopsis cypridis Santschi, 1934 is raised to species rank based on investigation of worker and gyne type specimens. [ABSTRACT FROM AUTHOR]

As an important historical and cultural heritage, rural red tourism sites have high historical, cultural, and social values. Moreover, rural red tourism sites are suitable for development and protection as tourism resources due to their unique landscape, architecture, culture, and art. In this paper, we propose a path generation model based on an ant colony algorithm to recommend the best path for tourists to visit rural red tourism sites. First, this paper investigates the modeling methods of path planning and multiobjective planning and their related solution algorithms to prepare for the establishment and solution of the tour path generation model for rural red tourism sites. By analyzing the problem description, this paper proposes the two model objectives of the shortest tour path and the highest total rating of the tourist attraction, and the model limitation of the total tour usage time, to model the model with a multiobjective planning approach. Then, by modifying the calculation of visibility and pheromone increments of the ant colony algorithm, the modified ant colony algorithm can take into account the two objectives of shortest path and highest total rating when constructing the path. Finally, this paper proposes to update the optimal path by using the number of ratings per unit path length as the update criterion of the optimal path. [ABSTRACT FROM AUTHOR]

Aphids and ants are mutualistic species with a close space-time relationship, which may facilitate the occurrence of horizontal transfer events between these insect groups. Myrmar-like mariner elements were previously isolated from two ant (Myrmica ruginodis and Tapinoma ibericum) and two aphid species (Aphis fabae and Aphis hederae). The aim of this work is to determine the presence of Myrmar-like mariner elements in new ant and aphid species, as well as to analyze the likelihood of horizontal transfer events between these taxa. To accomplish this, the Myrmar-like element has been isolated from five aphid species and six ant species. Among these new analyzed species, full-length Myrmar-like mariner elements with very high sequence similarity have been isolated from the aphids Aphis nerii, Aphis spiraecola, Brachycaudus cardui, and Rhopalosiphum maidis as well as from the ants Lasius grandis and Lasius niger, even though aphids and ants belong to two insect orders (Hemiptera and Hymenoptera) that have evolved independently for at least 300 million-years. Both Lasius species establish frequent mutualistic relationships with multiple aphid species, including A. nerii, A. spiraecola, and B. cardui. The study of the putative protein encoded by them and the phylogenetic analysis suggests that they could be active transposons shared by aphids and ants through horizontal transfer events. Additionally, mariner elements with internal deletion were found in several aphids and one ant species, showing a high degree of sequence similarity among them. The characteristics of these elements with internal deletion suggest a complex origin involving various evolutionary processes, possibly including also horizontal transfer events. Myrmar-like elements have also been isolated from the other ant species, although without similarity with the aphid mariner sequences. Myrmar-like elements are also present in phylogenetically distant insect species, as well as in one crustacean species. The phylogenetic study carried out with all Myrmar-like elements suggests the probable occurrence of horizontal transfer events., 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 B.V. All rights reserved.)

Human interference and incorrect use of pesticides are easy to induce red imported fire ant (RIFA) escape and migrate from a nest, resulting in ineffective control of RIFA. In order to avoid RIFA alert, we designed an amphiphilic PSI-mPEG-Boc-DAH loaded Pyr to make the microparticles with effective controlled release. The investigation showed that the quantity of Pyr released by Pyr@PSI-mPEG-Boc-DAH under acidic environment was only 36.40 ± 1.90% at 48 h, whereas the release rate of original Pyr was 75.23 ± 5.71%. And the RIFA mortality rate of 1 ppm Pyr in Pyr@PSI-mPEG-Boc-DAH microparticles at 48 h was only 7.78%, which was significantly lower than that of the Pyr (47.78%). Futhermore, the death rate increased sharply after 48 h, and reached 95.84% within a week after using Pyr@PSI-mPEG-Boc-DAH microparticles. Moreover, PSI-mPEG-Boc-DAH carriers could be absorbed and even transported to crop of the RIFA for subsequent trophallaxis by using fluorescence tracking. In the field experiment, the reduction rate of Pyr@PSI-mPEG-Boc-DAH treatment was achieved 99.89% after 7 d. Pyr@PSI-mPEG-Boc-DAH didn't cause RIFA to be alarmed within 48 h and could kill nearly all of ants in the nest after 7 d, which showed a very good control effect in the field experiment. This work provided a new idea and guidance for the effective control RIFA and the development of sustainable agriculture., 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 © 2023 Elsevier B.V. All rights reserved.)

Wireless mesh network (WMNs) can replace the physical existence of wired network; nevertheless, to solve the problem of traffic and congestion, they must carefully arrange radio resource assignment. In this paper, we focus on the major issues while transferring the data over the network and optimization of resources. WMN mainly suffers from congestion problem when numbers of channel transfer data at a same time which indirectly leads to overlapping channels and sometime data cannot be mitigated to destination. To overcome this problem and provide optimal solution we proposed hybrid channel assignment technique which offers four phase solution technique, in this technique firstly by mitigating the traffic than assigning the optimal path based on greedy and BFS. The purpose of this congestion control hybrid ant based greedy-BFS-load balancing (CCHAGBL) technique is to diminish the number of used slots, which is directly related to the overall resource assignment. We also provide optimal solution using Ant colony optimization technique with hybrid algorithm to achieve the network efficiency and resource utilization with randomly generated traffic. With the help of hybrid ant based greedy-BFS-load balancing (GBL) channel assignment algorithm throughput and packet delivery ratio is upgraded and delay is reduced to minimum. [ABSTRACT FROM AUTHOR]

Under the "Double Carbon" background, the development of green agricultural machinery is very fast. An important factor that determines the performance of electric farm machinery is the endurance capacity, which is directly related to the running path of farm machinery. The optimized driving path can reduce the operating loss and extend the mileage of agricultural machinery, then multi-node path planning helps to improve the working efficiency of electric tractors. Ant Colony Optimization (ACO) is often used to solve multi-node path planning problems. However, ACO has some problems, such as poor global search ability, few initial pheromones, poor convergence, and weak optimization ability, which is not conducive to obtaining the optimal path. This paper proposes a multi-node path planning algorithm based on Improved Whale Optimized ACO, named IWOA-ACO. The algorithm first introduces reverse learning strategy, nonlinear convergence factor, and adaptive inertia weight factor to improve the global and local convergence ability. Then, an appropriate evaluation function is designed to evaluate the solving process and obtain the best fitting parameters of ACO. Finally, the optimal objective function, fast convergence, and stable operation requirements are achieved through the best fitting parameters to obtain the global path optimization. The simulation results show that in flat environment, the length and energy consumption of IWOA-ACO planned path are the same as those of PSO-ACO, and are 0.61% less than those of WOA-ACO. In addition, in bump environment, the length and energy consumption of IWOA-ACO planned path are 1.91% and 4.32% less than those of PSO-ACO, and are 1.95% and 1.25% less than those of WOA-ACO. Therefore, it is helpful to improve the operating efficiency along with the endurance of electric tractors, which has practical application value. [ABSTRACT FROM AUTHOR]

Simple Summary: Coffee is an essential agricultural product in the worldwide economy. Unfortunately, the coffee berry borer (CBB), the crop's primary pest, significantly impacts the bean's quantity and quality. One strategy for controlling this insect is to use biological control agents, such as ants, some known for naturally living on coffee plantations and consuming CBB throughout all stages of development. Our paper examines a predator–prey interaction between these two insects using a novel mathematical model based on differential equations, where state variables correspond to adult CBBs, immature CBBs, and ants. Coffee is a relevant agricultural product in the global economy, with the amount and quality of the bean being seriously affected by the coffee berry borer Hypothenemus hampei (Ferrari), CBB, its principal pest. One of the ways to deal with this beetle is through biological control agents, like ants (Hymenoptera: Formicidae), some of which are characterized by naturally inhabiting coffee plantations and feeding on CBB in all their life stages. Our paper considers a predator–prey interaction between these two insects through a novel mathematical model based on ordinary differential equations, where the state variables correspond to adult CBBs, immature CBBs, and ants from one species, without specifying whether preying on the CBB is among their feeding habits, in both adult and immature stages. Through this new mathematical model, we could qualitatively predict the different dynamics present in the system as some meaningful parameters were varied, filling the existing gap in the literature and envisioning ways to manage pests. Mathematically, the system's equilibrium points were determined, and its stability was studied through qualitative theory. Bifurcation theory and numerical simulations were applied to illustrate the stability of the results, which were interpreted as conditions of the coexistence of the species, as well as conditions for eradicating the pest, at least theoretically, through biocontrol action in combination with other actions focused on eliminating only adult CBBs. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of multi-robot task scheduling in Antarctic environments. There are various algorithms for multi-robot task scheduling, but there is a risk in robot operation when applied in Antarctic environments. This paper proposes a practical multi-robot scheduling method using ant colony optimization in Antarctic environments. The proposed method was tested in both simulated and real Antarctic environments, and it was analyzed and compared with other existing algorithms. The improved performance of the proposed method was verified by finding more efficiently scheduled multiple paths with lower costs than the other algorithms. [ABSTRACT FROM AUTHOR]

The comprehensive assessment of the long-term impacts of constant exposure to pollutants on wildlife populations remains a relatively unexplored area of ecological risk assessment. Empirical evidence to suggest that multigenerational exposure affects the susceptibility of organisms is scarce, and the underlying mechanisms in the natural environment have yet to be fully understood. In this study, we first examined the arthropod candidate species, Gammarus roeselii that - unlike closely related species - commonly occurs in many contaminated river systems of Central Europe. This makes it a suitable study organism to investigate the development of tolerances and phenotypic adaptations along pollution gradients. In a 96-h acute toxicity assay with the neonicotinoid thiacloprid, we indeed observed a successive increase in tolerance in populations coming from contaminated regions. This was accompanied by a certain phenotypic change, with increased investment into reproduction. To address the question of whether these changes are plastic or emerged from longer lasting evolutionary processes, we conducted a multigeneration experiment in the second part of our study. Here, we used closely-related Hyalella azteca and pre-exposed them for multiple generations to sublethal concentrations of thiacloprid in a semi-static design (one week renewal of media containing 0.1 or 1.0 µg/L thiacloprid). The pre-exposed individuals were then used in acute toxicity assays to see how quickly such adaptive responses can develop. Over only two generations, the tolerance to the neonicotinoid almost doubled, suggesting developmental plasticity as a plausible mechanism for the rapid adaptive response to strong selection factors such as neonicotinoid insecticides. It remains to be discovered whether the plasticity of rapidly developed tolerance is species-specific and explains why closely related species - which may not have comparable adaptive response capabilities - disappear in polluted habitats. Overall, our findings highlight the neglected role of developmental plasticity during short- and long-term exposure of natural populations to pollution. Moreover, our results show that even pollutant levels seven times lower than concentrations found in the study region have a clear impact on the developmental trajectories of non-target species., 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 © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

This paper introduces an agent-based model grounded in the ACO algorithm to investigate the impact of partitioning ant colonies on algorithmic performance. The exploration focuses on understanding the roles of group size and number within a multi-objective optimization context. The model consists of a colony of memory-enhanced ants (ME-ANTS) which, starting from a given position, must collaboratively discover the optimal path to the exit point within a grid network. The colony can be divided into groups of different sizes and its objectives are maximizing the number of ants that exit the grid while minimizing path costs. Three distinct analyses were conducted: an overall analysis assessing colony performance across different-sized groups, a group analysis examining the performance of each partitioned group, and a pheromone distribution analysis discerning correlations between temporal pheromone distribution and ant navigation. From the results, a dynamic correlation emerged between the degree of colony partitioning and solution quality within the ACO algorithm framework. [ABSTRACT FROM AUTHOR]

The purpose of geographic location selection is to make the best use of space. Geographic location selection contains a large amount of spatiotemporal data and constraints, resulting in too many solutions. Therefore, this paper adopts the ant colony algorithm in the meta-heuristic search method combined with the incomplete quadtree to improve the searchability of the space. This paper proposes an improved ant colony algorithm in nonuniform space to solve the P-center facility location problem. The geographic space is divided by the incomplete quadtree, and the ant colony path is constructed on the level of the quadtree division. Ant colonies can leave pheromones on multiple search paths, and optimized quadtree encoding in nonuniform space stores pheromone matrices and distance matrices. The algorithm proposed in this paper improves the pheromone diffusion algorithm and the optimization objective at the same time to update the pheromone in the nonuniform space and obtain the ideal solution. The results show that the algorithm has excellent performance in solving the location problem with good convergence accuracy and calculation time. [ABSTRACT FROM AUTHOR]

Reverse logistics (RL) network can be adequately planned and implemented to gain additional benefits such as maximizing customer satisfaction and a positive image of the business organization, even though most distribution networks are not equipped with reverse channels to deal with the return of merchandise. Therefore, the main objective of this paper is to develop a new mixed-integer nonlinear programming (MINLP) mathematical model with a single-objective, single-product, multi-stage closed-loop supply chain network design (CLSC ND), considering the fixed transportation charge in the distribution network that has been neglected in the recently published papers in the field of CLSC ND. Since such network design challenges belong to the class of NP-hard problems, an algorithm based on ant colony optimization (ACO) is proposed to design a multi-stage RL network with fixed transportation cost and variable cost for the routes. Four network characteristics of different sizes were designed, and 30 instances were randomly generated for each network characteristic to evaluate the effectiveness of the proposed algorithm. The computational analysis of the results shows the high-quality effectiveness of the proposed ACO algorithm compared with the exact results. [ABSTRACT FROM AUTHOR]

Aiming at the problems of complex space, long planning time, and insufficient path security of 3D path planning, an improved ant colony algorithm (TGACO) is proposed, which can be used to solve symmetric and asymmetric path planning problems. Firstly, the 3D array is used to access the environment information, which can record the flight environment and avoid the inefficiency of planning. Secondly, a multi-objective function of distance and angle is established to improve the efficiency and safety of the path. Then, a target-guided heuristic function is proposed, and an anti-deadlock mechanism is introduced to improve the efficiency of the ant colony algorithm. Next, the node pheromone update rules are improved to further improve the efficiency of the algorithm. Finally, experiments prove the effectiveness of the improved algorithm, TGACO, and its efficiency in complex environments has obvious advantages. In the 20 × 20 × 20 environment, compared with the ant colony algorithm (ACO), the improved algorithm (TGACO) in this paper improves the path length, total turning angle, and running time by 17.8%, 78.4%, and 95.3%, respectively. [ABSTRACT FROM AUTHOR]