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Leaf-cutting ants of the genera Atta and Acromyrmex (Hymenoptera: Formicidae) are the most important pests in forest and agricultural plantations and livestock. Toxic baits are the main method to manage these insects. The objective was to determine whether the behavior of allogrooming, touch, and self-grooming among Atta sexdens rubropilosa Forel, 1908 (Hymenoptera: Formicidae) workers disperse the fungicide quinone inside inhibitor and whether this product is toxic to them. This fungicide was applied, topically, in groups of workers and the social interactions between them and their mortality with and without the fungicide were evaluated. The interactions and the quinone inside inhibitor fungicide contamination increased with the number of leaf-cutting ant workers per group. Excessive touches, with subsequent allogrooming, and self-grooming among the ant workers dispersed the quinone inside the inhibitor fungicide causing 100% mortality and indicating its toxicity to this insect. The hypothesis that social interactions contaminated ant colony mates and the toxicity of the fungicide quinone inside inhibitor to workers of the leaf-cutting ant A. sexdens rubropilosa was proven. [ABSTRACT FROM AUTHOR]

Defoliation by leaf-cutting ants alters the physiological processes of plants, and this defoliation can be inferred from satellite imagery used to identify plant injuries. The aim of this study was to evaluate the spectral pattern of defoliation by leaf-cutting ants in eucalyptus plants on a pixel level using unsupervised machine learning techniques applied to remote sensing by satellites. The study was carried out in a eucalyptus plantation in the municipality of Telêmaco Borba, Paraná state, Brazil. The nests of leaf-cutting ants were located and georeferenced. Multispectral images were obtained from the Sentinel-2 (S-2) and planet scope (PS) satellites. The response variables were the RGB-NIR bands and four vegetation indices (VIs). The data obtained from these bands and vegetation indices was separated in an unsupervised method by the k-medoids clustering algorithm and input into a Random Forest (RF) model. The significance of the models was tested with permutational multivariate analysis of variance (PERMANOVA). The k-medoids algorithm classified the spectral response of the RGB-NIR and VIs bands into two main factors of variation in the tree canopy. The models selected were 1200 trees and 6 variables for the S2 satellite (accuracy = 97.74 ± 0.040%) and 900 trees and 5 variables for the PS (accuracy = 97.42 ± 0.026%). The unsupervised machine learning technique, applied to remote sensing, was effective to map defoliation caused by leaf-cutting ants, and this approach can be used in precision agriculture for pest management purposes. [ABSTRACT FROM AUTHOR]

Leaf-cutting ants (genera Acromyrmex, Amoimyrmex and Atta) are the most important generalist herbivores in the Neotropical Region. The subspecies of Acromyrmex subterraneus are morphologically similar but differing from the other species of this genus. Acromyrmex subterraneus complex may be three non-described leaf-cutting ant species. The taxonomic revision of Acromyrmex subterraneus (Hymenoptera: Formicidae) and of three of its subspecies, A. s. brunneus Forel 1911, A. s. molestans Santschi (1925) and A. s. subterraneus Forel 1893 was made based on its workers and male morphology and genome sequencing with mt-COI and mt-COII. Acromyrmex molestans stat. n., Acromymex brunneus stat. n. and Acromyrmex subterraneus stat. n. are here raised to species. The results of this study contribute to the taxonomic knowledge and reaffirm the complex evolutionary history of leaf-cutting ants. [ABSTRACT FROM AUTHOR]

Simple Summary: The used active ingredient sulfluramid for toxic baits for the control of leaf-cutting ants has been included in Annex B of the Stockholm Convention on Persistent Organic Pollutants. The use of entomopathogenic fungi to control these insects has shown promising results, Trichoderma harzianum showed high pathogenicity against A. sexdens rubropilosa larvae and pupae, leading to a faster mortality and a decrease in survival rates. Beauveria bassiana was responsible for causing faster worker mortality and lower survival rates. An individual contaminated with B. bassiana or T. harzianum in a group decreases its survival rate, supporting the hypothesis that entomopathogenic fungi are efficient in controlling leaf-cutting ants when contaminated workers are allocated to groups of healthy workers. In 2009, sulfluramid, the main ingredient in toxic baits for leaf-cutting ant control, was included in Annex B of the Stockholm Convention on Persistent Organic Pollutants. This resulted in interest in the use of entomopathogenic fungi such as Beauveria bassiana and Trichoderma harzianum for leaf-cutting ant control. The efficiency of these fungi in controlling these insects and the way that ants react individually or in group to the biological risks posed by these fungi is poorly understood. For this reason, we assessed the effects of B. bassiana and T. harzianum on Atta sexdens rubropilosa larvae, pupae and workers. Moreover, we investigated whether the number of contaminated individuals within a group has an influence in controlling the spread of fungi among workers. We found that the fungus T. harzianum showed high pathogenicity against A. sexdens rubropilosa larvae and pupae, leading to faster mortality and a survival rates. On the other hand, the fungus B. bassiana was responsible for causing faster worker mortality and lower survival rates. In addition, we observed that an increase in individuals contaminated with B. bassiana or T. harzianum in the group decreases its survival rate. The results support the hypothesis that entomopathogenic fungi are efficient in controlling leaf-cutting ants when contaminated workers are allocated to groups of healthy workers. [ABSTRACT FROM AUTHOR]