Justification/objective: Ants perform important functions in natural environments such as soil structuring, nutrient cycling, herbivory, predation, and dispersal of diaspores. However, some ants, like the leaf-cutting ants, are the main eucalyptus pests and are the targets of formicide baits, when ingested, has a lethal effect. These baits are considered non-selective for ants in general. Therefore, we aimed to assess the effects over time of the formicide baits on the ant richness and composition of non-target ground-dwelling ants and on the seed dispersal rate in forest fragments adjacent to eucalyptus plantations. Methods: We applied the formicide baits inside the eucalyptus plantations and on the edge of forest fragments. We evaluated the richness and composition of ground-dwelling ants and the seed dispersal rate into adjacent forest fragments 30 days before and 30, 120, and 180 days after the application of the formicide baits. Results: The application of ant bait in eucalyptus plantations did not affect the ant species richness in adjacent forest fragments, and this variable remained stable over time after treatment. However, the application of ant bait altered seed removal rates both when applied within eucalyptus plantations and in forest fragments, indicating functional impacts on ant-mediated ecological processes. Furthermore, the application of bait in forest fragments resulted in a temporary change in the composition of ant communities compared to fragments where bait application occurred only in eucalyptus, with noticeable changes detected 30 days after application. In these areas, after 120 days of application, the species composition returned to conditions similar to those observed before the bait application. The application of ant bait affected the composition of the ant community, with species exclusivity varying between environments: 38.5 % of the species were found only in the area without bait, 16.9 % at the edge of the forest with bait and 17.7 % in the eucalyptus area with bait. Conclusion: The formicide baits application does not change ant richness by ground-dwelling ants but modify the ground-dwelling ant community composition and seed removal rates in adjacent forests fragments. Additionally, species losses, temporary appearances, and changes in occurrence frequency were observed, indicating both immediate and long-term impacts on community structure, especially in forest fragments and eucalyptus areas with formicide baits application. Therefore, we recommend baits application only inside the eucalyptus plantations and not into forest fragments edges around plantations, as it can affect species composition.

The body size of insects influences the surface area-volume ratio and can affect the thickness of the cuticle and the amount of cuticular lipids, particularly in eusocial species, such as leaf-cutting ants of the genus Atta , which exhibit pronounced worker polymorphism. In this study, we evaluated the relationship between body size, cuticular lipid intensity, and cuticle thickness in workers of Atta laevigata (Smith, 1858) (Hymenoptera: Formicidae) and Atta sexdens (Linnaeus, 1758) (Hymenoptera: Formicidae). Small, medium, and large workers, defined according to the width of the cephalic capsule, were compared regarding relative cuticle thickness and cuticular lipid intensity. Both traits varied among worker size classes. Small workers showed higher cuticular lipid intensity and greater relative cuticle thickness, while medium and large workers exhibited lower values for both traits, indicating that different cuticle components respond similarly to body size, regardless of the species. Although the intensity of cuticular lipids was not differentiated between species, cuticle thickness was consistently greater in A. sexdens than in A. laevigata in all size classes. Overall, our findings suggest that the different components of the cuticle of A. laevigata and A. sexdens are not determined solely by body size, but also reflect the specific function performed by the workers within the colony.

Introduction: Soil degradation and land abandonment caused by intensive agriculture threaten ecosystem functions, yet conservation programs often overlook arthropods such as insects and spiders and their essential roles in food webs. Aims/Methods: We evaluated the effects of urban dehydrated sewage sludge on Sapindus saponaria (Sapindales) by comparing fertilized (T1) and unfertilized (T2) plants in a degraded area of Montes Claros, Minas Gerais, Brazil. We measured leaves per branch, branches per plant, ground cover, and arthropod abundance, diversity and richness over 24 months under both treatments. Results Plants receiving sewage sludge were significantly higher in numbers of leaves per branch, branches per plant and percentage ground cover (all p < 0.05). Arthropod abundance, diversity and species richness, including chewing insects, predators and total arthropod assemblages, were also greater in the fertilized treatment (all p < 0.05). Discussion Urban sewage sludge, a nutrient-rich organic amendment, enhances both plant growth and the structure of arthropod communities, likely by increasing habitat complexity and resource availability during ecosystem recovery. Implications for insect conservation: Application of dehydrated sewage sludge in restoration schemes can boost arthropod biodiversity and support trophic interactions, contributing to more resilient insect populations in degraded tropical habitats.

Foraging in leafcutter ants alternates between periods of inactivity and activity that extend over several days or weeks. Many factors could influence this alternation, with a preponderance of environmental factors, such as temperature, humidity, and rain. Moreover, ant colony size and the management practices used for their control could also modify the cycles of activity/inactivity. We surveyed the foraging activity of the nests of the leaf-cutting ant Atta sexdens (Linnaeus) in Eucalyptus plantations and evaluated the relative importance on foraging activity of temperature, past possible immediate experience in foraging, and use of machinery. Twenty transects with an average of 6 colonies in each were selected. Each nest was checked for foraging activity once in different months of the year and we investigated whether foraging inactivity was influenced by nest size, temperature, number of favourable hours for foraging on the day preceding the evaluation, and the use of agricultural machinery. The management practices of A. sexdens nests in Eucalyptus plantations had no influence on the occurrence of foraging inactivity, contrary to nest size and possible past immediate experience in foraging. The probability of foraging inactivity decreased by about 23% for each 10 m2 increment in the nest size. A nest was also more likely to be active on a certain day if the conditions for foraging activity had been favourable on the preceding day. Leaf-cutting ants are one of the main herbivores in Brazil, often reaching pest status in several crops. Our results indicate that the efficiency of their control in Eucalyptus plantations could be increased by implementing control strategies several times a year and by increasing the number of bait applications in areas with a high density of small nests (less than 20 m2), as these areas are more prone to inactivity and thus may lead to increased control failures.

One of the most stressful factors for insects is increasing temperature because of the risk of potentially fatal dehydration linked to their small size. We used respirometry to study the effect of both temperature and body mass on water loss and metabolic rate in individual workers of the polymorphic ant species Messor barbarus. As expected, we found that large ants exposed to increasing temperatures have a lower rate of water loss than small ants and that their mass-specific metabolic rate increases more slowly. However, counterintuitively, the measure of worker sensitivity to changes in temperature, as assessed by the instantaneous Q10 value (i.e., the rate of change across 10°C temperature intervals), shows that large ants are more sensitive than small ants to changes in temperature in terms of both water loss and metabolic rate. Such differential thermal sensitivity allows to make testable predictions on the temporal distribution of foraging activity among workers of different sizes in polymorphic ant species, as well as how these species may alter their colony demographics in response to rising temperatures.

Tropical rainforests are rapidly disappearing due to human activities, particularly land-use changes, resulting in a heterogeneous mosaic of landscapes that substantially contribute to global terrestrial biodiversity loss. We investigated how changes in land-use affect species richness, composition, and functional guilds of ground-dwelling ants within various land-use systems at a local scale in the Amazonian rainforest. Our focus was to respond to the following: (i) How do local species richness and community composition reflect differences among land-use systems? (ii) Are ground-dwelling ants, especially specialists, negatively impacted by intensified land-use changes? We surveyed 55 sites representing five land-use systems: primary forest, secondary forest, forest corridor, selective logging, and Eucalyptus plantation. We registered 150 ant species, and species richness ranged from 43 to 94. Richness varies according to the land-use systems, likely influenced by differences in habitat structural complexity both vertically and horizontally. Ant species composition and guilds distribution also varied among land-use systems studied. Environments characterized by reduced structural complexity or higher disturbed levels, such as Eucalyptus plantations, tend to support lower resource availability, which may lead to decreased species richness. However, the surrounding matrix appears to play a key role in maintaining regional biodiversity, as evidenced by the absence of differences in ground-dwelling ants diversity across all land-use systems studied.

The functional relationship between ecosystem biodiversity and its functioning enables the categorization of organisms into guilds based on resource utilization, allowing for the assessment of biological diversity in modified environments over temporal scales, such as forest plantations. The present study sought to compare the composition of ant trophic guilds associated with the understory of eucalyptus stands at various stages of succession, aiming to determine whether turnover in species composition occurs within these guilds. We employed the Winkler extractor to collect litter ants in fifteen eucalyptus stands, ranging in age from 1.5 to 10.3 years. Our findings revealed the presence of fifteen ant guilds. The guild of small arboreal ants with massive recruitment exhibited a decline in species richness as the understory matured, while the guild of specialized predatory cryptic myrmicines demonstrated an increase in species richness in older stands. Camponotus crassus Mayr and Wasmannia auropunctata Roger were more prevalent in younger understory stands, whereas Pheidole fallax Mayr was predominantly found in native vegetation. Ants can serve as indicators of environmental conditions in eucalyptus plantations and contribute to environmental certification efforts. Our results demonstrate that eucalyptus plantations with understory vegetation effectively support the conservation of ant species over time, providing habitat for diverse ant guilds that utilize the available resources in this environment and may act as a species source for the surrounding landscape.

Polybia occidentalis (Olivier) (Hymenoptera: Vespidae) is an important predator of soft-bodied arthropods, and its association with plant species can provide information about the preference of this wasp for plant substrate and the mechanisms for this choice. The objective was to report the first occurrence of P. occidentalis nesting on a Lafoensia glyptocarpa (Koehne) (Lythraceae) plant in the Cerrado biome of Brazil. Individuals of the Vespidae were collected and identified using a dichotomous key and by comparison with individuals deposited in the Biological Collection of Social Vespas (CBVS) of the Instituto Federal de Educação, Ciências e Tecnologia do Sul de Minas Gerais (IFSULDEMINAS), Campus Inconfidentes, Minas Gerais state, Brazil. The foliage density and perennially of the plant L. glyotocarpa can reduce temperature and increase humidity within its canopy, and the shade of the branches can contribute to camouflage, which can favor the choice of this plant as a nesting site for P. occidentalis. Due to the climatic conditions of the region, the plant species can be important to conserve this Vespidae species.

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.

Terminalia argentea Mart. (Combretaceae), native to Brazil, is used in habitat restoration programs. Arthropods are bioindicators because their populations reflect changes in the environment. We evaluated the recovery of a degraded area by using ecological indices and analyzing arthropod interactions on T. argentea plants. The richness and diversity of sap-sucking Hemiptera and the abundance of tending ants and Sternorrhyncha predators increased with the number of T. argentea leaves. The correlation of the abundance of tending ants and Sternorrhyncha predators was positive with that of the sap-sucking Hemiptera, and the abundance of Sternorrhyncha predators was negative with that of tending ants and sap-sucking Hemiptera. The positive correlation between the abundance, richness, and diversity of insect groups and numbers of T. argentea leaves is an example of the bottom-up regulation mechanism, with the population dynamics of the lower trophic levels dictating those of higher trophic levels. The contribution of T. argentea, a host plant of many arthropods, to the recovery of ecological relationships between organisms in degraded ecosystems is important.

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 work is properly cited. Sewage sludge is a byproduct of sewage treatment, rich in N and P, which can be used as soil fertilizer in forest plantations and in degraded areas recovery (Mota et al., 2021). Platycyamus regnellii (Benth) (Fabales: Fabaceae) is a tree used in environmental recovery and its hardwood is used in home construction (Ferreira et al., 2015). Tree development and growth are essential to assess the recovery of an environment, because the structure, biomass, and diversity of vegetation are related to ecosystem functions and fauna colonization (Monteiro et al., 2019). The arthropod biodiversity is susceptible to environmental conditions and the presence of some functional groups is an indicator of the success of environmental recovery (Burgio et al., 2015). There is a lack of studies evaluating P. regnellii on recovery of degraded areas and the arthropod fauna feeding and/or living on this plant. The objective was to evaluate, for 24 months, the ecological indices of arthropods on P. regnellii saplings (young trees) in a degraded area using or not dehydrated sewage as a fertilizer. The study was carried out in a degraded area on the campus of the “Universidade Federal de Minas Gerais” in Montes Claros, Minas Gerais, Brazil (latitude 16°51’ S, longitude 44°55’ W, altitude 943 m) from March 2018 to February 2020. The experimental design was completely randomized with two treatments (20 L of dehydrated sewage sludge per plant or without it), with 24 replications and one plant each. Information on climatic conditions, soil, characteristics of the dehydrated sewage sludge, seedling production, spacing between plants in the field, irrigation, and fertilization in this area are available (Gomes, 2018). The leaves per branch were measured monthly by visual observation on 48 P. regnellii saplings. Insect defoliation was evaluated visually by the leaf area losses on a 0–100% scale with 5% increments for removed leaf area (Mota et al., 2021). The sum of data (i.e. 12 leaves/ sapling/survey) from a single sapling was used. Ecological indices (abundance, diversity, and species richness) were calculated per group of arthropods (i.e. coleopterans and spiders) and treatment (fertilization or not with dehydrated sewage sludge). Abundance and species richness were the total number of individuals and species, respectively, per sapling. The diversity was calculated using Hill ́s formula per sapling. The abundance, diversity, and species richness of arthropods, and leaves per branch were submitted to the non-parametric statistical hypothesis Wilcoxon signed-rank test (P< 0.05). Platycyamus regnellii saplings fertilized with dehydrated sewage sludge produced significantly (P< 0.05) more leaves/branch per sapling (7.56 ± 0.29) compared to unfertilized ones (5.58 ± 0.23). The defoliation, abundance and species richness of chewing insects, species richness of natural enemies, and number of Eumolpus sp. (Coleoptera: Chrysomelidae), Araneidae (Araneae), Oxyopes salticus Hentz (Araneae: Oxyopidae), and tending ants (Hymenoptera: Formicidae) were higher on P. regnellii saplings fertilized with dehydrated sewage (Table 1). These results may be due to the greater biomass (leaves) as a result of fertilization, a food resource with high quality for these chewing insects, attracting their natural enemies (predator following prey). Insect herbivore populations may also have a positive association with N and P levels in the soil (Joern et al., 2012). Differences in plant quality reflect the availability of soil nutrients which may affect plant morphology and quality (Chau and Heinz, 2006). This influences the preference of these insects (Sarfraz et al., 2009), attracting a higher number of natural enemies, as on Acacia mangium (Fabaceae) trees fertilized with sewage sludge (Silva et al., 2020). Natural enemies (e.g., spiders) prey insects and thus are important, in natural and agricultural systems (Sunderland and Samu, 2000), reducing pest numbers such as reported for Epiphyas postvittana Walker (Lepidoptera: Tortricidae) on Malus domestica (Borkh.) Borkh. (Rosales: Rosaceae) (Hogg et al., 2017). This fact may explain the low rate of herbivory (≈5%) observed in fertilized P. regnellii saplings. Spiders may reduce herbivory, even when they Can dehydrated sewage sludge, used as fertilizer, affect arthropods on Platycyamus regnellii (Fabaceae)?

Abstract Plant species, monitoring measures, and alternative fertilization with sewage sludge accelerate recovering of degraded areas. The objective of this study was to evaluate the numbers of leaves/branch and branches/plant of Sapindus saponaria L., the ground cover by this plant and the ecological indexes of abundance, diversity, and species richness of insects and spiders, and of their interactions, during 24 months on trees grown in a degraded area with or without dehydrated sewage sludge as fertilizer. The metrics of plant, soil cover, and arthropods were higher on the S. saponaria plants fertilized with dehydrated sewage sludge. The abundance of chewing insects, tending ants, and spiders was greater on larger S. saponaria tree crown. The abundance of these last groups of organisms associated, negatively, with that of Coleoptera, but those of ants reduced that of the predators. The ecological indexes of arthropods on S. saponaria plants shows the suitability of this plant for recovering programs of degraded areas and the use of dehydrated sewage sludge as fertilizer increased these indices and the possibility of using insects and spiders on the crown of this plant as bioindicators.

Termites are social insects with high species diversity in tropical ecosystems. Multivariate analysis with near-infrared spectroscopy (NIRS) and data interpretation can separate social insects belonging to different colonies of the same species. The objective of this study was to propose the use of discriminant analysis by partial least squares (PLS-DA) combined with NIRS to identify the colonial origin of the Syntermes grandis (Rambur, 1842) (Blattodea: Termitidae) in 2 castes. Six ground S. grandis colonies were identified and mapped; 30 workers and 30 soldier termites in each colony were submitted to spectral measurement with NIRS. PLS-DA applied to the termites' spectral absorbance was used to detect a spectral pattern per S. grandis colony by caste. PLS-DA regression with NIRS proved to be an approach with 99.9% accuracy for identifying the colonial origin of S. grandis workers and 98.3% for soldiers. The methodology showed the importance of qualitatively characterizing the colonial phenotypic response of this species. NIRS is a high-precision approach to identifying the colony origin of S. grandis workers and soldiers. The PLS-DA can be used to design ecological field studies to identify colony territorial competition and foraging behavior of subterranean termite species.

Leaf-cutting ants, notorious for causing defoliation in commercial forest plantations, significantly contribute to biomass and productivity losses, impacting forest producers in Brazil. These ants construct complex underground nests, highlighting the need for advanced monitoring tools to extract subsurface information across large areas. Synthetic Aperture Radar (SAR) systems provide a powerful solution for this challenge. This study presents the results of electromagnetic simulations designed to detect leaf-cutting ant nests in industrial forests. The simulations modeled nests with 6 to 100 underground chambers, offering insights into their radar signatures. Following these simulations, a field study was conducted using a drone-borne SAR operating in the P-band. A helical flight pattern was employed to generate high-resolution ground tomography of a commercial eucalyptus forest. A convolutional neural network (CNN) was implemented to detect ant nests and estimate their sizes from tomographic data, delivering remarkable results. The method achieved an ant nest detection accuracy of 100%, a false alarm rate of 0%, and an average error of 21% in size estimation. These outcomes highlight the transformative potential of integrating Synthetic Aperture Radar (SAR) systems with machine learning to enhance monitoring and management practices in commercial forestry.

Soils present high fungal diversity, including entomopathogenic species. These fungi are used in pest control, providing easy production, multiplication, application, and dispersion in the field. The objective of the present study was to evaluate entomopathogenic fungal diversity in soils from eucalyptus and soybean crops and natural forest areas. These fungi were isolated using the "Bait Method" with Tenebrio molitor (Linnaeus, 1758) (Coleoptera: Tenebrionidae) larvae from 10 soil samples per area, collected at 10 cm deep in a zig-zag pattern. The isolated entomopathogenic fungi were cultivated in Petri dishes using PDA medium and their mycelia separated after seven days of incubation in a BOD-type chamber. Species of Aspergillus, Beauveria, Cordyceps, Fusarium, Metarhizium, Penicillium and Purpureocillium were identified. The "Bait Method" with T. molitor larvae is efficient to isolate entomopathogenic fungi with higher diversity from soils of the natural forest than the cultivated area.

The presence of leaf-cutting Acromyrmerx ants in industrial forest plantations is one of the main causes of the loss of biomass and productivity that affect the large pulp producers in Brazil. Thus, the development of monitoring tools that allow the extraction of information below the surface in large areas, such as Synthetic Aperture Radar (SAR) systems, is of crucial importance. This work presents a set of unprecedented electromagnetic simulations for the detection of Acromyrmex ant nests with 1 up to 13 chambers in industrial forests. Ant nests in bare soil and under forest cases were considered for simulations, obtaining promising results that can be used in subsequent tests with real data based on SAR circular and helical survey.

Defoliation by leaf-cutting ants in commercial forest plantations is one of the leading causes of biomass and productivity losses affecting all of Brazilian industrial forest. Thus, the development of monitoring tools that allow extracting the information below the surface in large areas, such as synthetic aperture radar (SAR) systems, is crucial. This work presents a method for ant nest size estimation in industrial forest based on SAR images. A field study is carried out using a drone-borne SAR system to survey a commercial eucalyptus forest by using a helical flight pattern and P band transmitting frequency and finally generating a ground tomography. A convolutional neural network (CNN) is employed for the ant nests size estimation from the tomograms. A mean error of 5 % and 21 % was achieved for a training a validation dataset, respectively.

Tomography using drone-borne synthetic aperture radar (SAR) has proven to be very useful and efficient in surveying the subsurface of areas with gravimetric soil moisture ranging from 0 to 50%. The drone-borne SAR, along with the back-projection processing algorithms, and the proof of concept through the detection of a corner reflector buried 1.7 meters deep in clayey soil, are presented. Anthills with areas ranging from 0.05 m2 to 120 m2 were detected under an industrial eucalyptus forest, with a detection probability of more than 80% in two different regions.