Freshwater organisms are often sensitive to pesticides, but their sensitivity varies across different taxa and with pesticide type and action mode, as shown by multiple acute toxicity tests. Such variability hampers predictions about how freshwater ecosystems may be altered by pesticide toxicity, which is especially critical for understudied areas of the world such as the tropics. Furthermore, there is little information about the sensitivity of some organisms that are key components of stream food webs; this is the case of litter-feeding detritivorous invertebrates, which contribute to the fundamental process of litter decomposition. Here, we examined the sensitivity of three common detritivores [Anchytarsus sp. (Coleoptera: Ptilodactylidae), Hyalella sp. (Amphipoda: Hyalellidae) and Lepidostoma sp. (Trichoptera: Lepidostomatidae)] to three pesticides commonly used (the insecticides bifenthrin and chlorpyrifos and the fungicide chlorothalonil) using acute (48 or 96 h) toxicity tests. Our study demonstrates that common-use pesticides provoke the mortality of half their populations at concentrations of 0.04-2.7 μg L-1. We found that all species were sensitive to the three pesticides, with the highest sensitivity found for chlorpyrifos. Additionally, we used the approach of species sensitivity distributions (SSD) to compare our study species with Daphnia magna and other temperate and tropical invertebrates. We found that the study species were among the most sensitive species to chlorpyrifos and chlorothalonil. Our results suggest that tropical detritivores merit special attention in ecological risk assessment of pesticides and highlight the need for accurate ecotoxicological information from ecologically relevant species in the tropics.

Los polímeros plásticos son comunes en varias actividades, pero su contaminación supone un grave peligro para la salud de los animales, las personas y el medio ambiente. Adicionalmente, la acumulación de residuos plásticos en el entorno es una inquietud en aumento. Por ello, el propósito de esta investigación fue evaluar la capacidad de las larvas de Galleria mellonella para biodegradar plásticos de polietileno de baja densidad (LDPE), poliestireno expandido (EPS) y oxo-biodegradable. El diseño del experimento consistió en colocar las larvas en platos Petri que contenían muestras de los distintos polímeros ya cortados y pesados, para calcular el grado de consumo, a temperaturas de 25 °C y 33 °C. Para observar detalladamente la película de los plásticos LDPE y oxo-biodegradables, se aplicó microscopía electrónica de barrido. También espectrometría de infrarrojos para determinar las huellas de los distintos componentes resultantes de la digestión de las larvas y para observar cambios en la estructura química de los polímeros. Se realizaron pruebas químicas: Si/No de glicoles. El grado de consumo de las larvas resultó más eficaz en los ensayos a 25 °C. Por medio de los análisis de microscopía y la técnica de infrarrojos, se confirmó que hay cambios físicos y químicos. La prueba de Si/No glicoles no permitió determinar la presencia de etilenglicol, ya que resultó positiva en todas las muestras, incluyendo los controles. Cada uno de los resultados sirve como base para redireccionar futuras investigaciones y descubrir todas las posibilidades de las larvas de G. mellonella en la biodegradación de polietileno.

Machine learning is increasingly used to predict pollutant removal in adsorption studies, but models are often fitted to small, replicated experimental datasets and evaluated with a single random train/test split. We examined how the validation design affects model selection and surrogate-based optimization for removing phenolic compounds (quantified as tannins) from sugarcane vinasse using citric-acid-modified sugarcane bagasse, based on 315 measurements (105 conditions in triplicate) spanning temperature, contact time, and vinasse dilution. Eight regressors, from linear and quadratic models to kernel methods, tree ensembles, Gaussian processes, and neural networks, were tuned and evaluated by repeated nested cross-validation that kept all replicates of a condition together, and their errors were compared with the replicate (pure-error) standard deviation of 3.56% removal. Under this replicate-aware validation, all non-linear models performed similarly (RMSE 3.89–4.10%, R² 0.83–0.85), whereas the linear model was clearly worse (RMSE 5.06%). A naive random split increased R² by only about 0.01 (mean ΔR² 0.005–0.013), because, with replicate scatter of this size, memorizing replicates gives no advantage over a smooth model. Holding out entire dilution levels, however, separated the models sharply: the quadratic model remained the most accurate (RMSE 4.58%), whereas random forest and gradient boosting failed (R² ≤ 0.13). Permutation and SHAP analyses identified dilution as the dominant variable. Used as the optimization surrogate, the quadratic model placed maximum removal at 10% v/v dilution in a flat near-optimal region spanning about 37–40 °C and 74–130 min (maximum 97.7%); a confirmatory experiment at 40 °C and 100 min, inside this region, gave 97.4 ± 0.4% (n = 5) against 97.5% predicted. For small replicated adsorption datasets, the held-out unit should match the intended use of the model, and predictions away from the sampled levels require models that extrapolate smoothly.

The accumulation of polyethylene (PE) in the environment represents a persistent ecological challenge, and the search for biological agents capable of degrading it without relying on prior abiotic pretreatment remains an active area of research. In this study, three bacterial strains—Pseudomonas aeruginosa, Enterobacter hormaechei, and Acinetobacter pittii—were isolated from the gut of Galleria mellonella larvae dietarily induced with native low-density polyethylene (LDPE), without prior UV, thermal, or chemical treatment. Molecular identification was confirmed by 16S rRNA gene sequencing and maximum-likelihood phylogenetic analysis. Degradative activity was assessed using a multi-method approach: a colorimetric DCPIP assay, gravimetric mass loss at 45 days, FTIR-ATR spectroscopy, SDS-PAGE, and scanning electron microscopy. All three strains showed metabolic activity toward LDPE, with A. pittii producing the greatest mass loss. FTIR analysis revealed the appearance of hydroxyl and C–O-containing functionalities without detectable carbonyl accumulation, a pattern consistent with the hypothesized activation of an oxidative pathway mediated by the alkane hydroxylase (AlkB) system, pending direct molecular/biochemical confirmation. These results expand the still-limited number of reports on native-PE-degrading activity documented individually for E. hormaechei and A. pittii and reinforce the value of the G. mellonella gut microbiome as a reservoir of bacteria with biotechnological potential for plastic waste management.