RESUMO
The decline of insect pollinators is a significant concern within the current biodiversity crisis. The paradox between the benefits that these animals represent to humans and the evidence of human activities driving their extinction calls for the urgent protection of bees. To address the role of chemical pollution in this scenario, we assessed the acute toxicity as well as four biomarker responses (cholinesterase [ChE], glutathione S-transferase, catalase, and lipid peroxidation [LPO]) elicited by dietary 24-h exposure to three insecticides (malathion, imidacloprid, and fipronil) on the stingless neotropical bee Tetragonisca angustula and the honeybee Apis mellifera. Malathion was the most toxic substance to both species, with 48-h median lethal doses (LD50s) of 0.25 ng/bee to A. mellifera and 0.02 ng/bee to T. angustula. Fipronil was also highly toxic and presented a similar toxicity to both species, with 48-h LD50s of 0.5 ng/bee (A. mellifera) and 0.4 ng/bee (T. angustula). Imidacloprid had the lowest acute toxicity with a 48-h LD50 of 29 ng/bee for A. mellifera, whereas T. angustula tolerated exposure higher than 35 ng/bee. Apparent biomarker responses were observed in bees of both species that survived exposure to higher concentrations of malathion (ChE inhibition) and fipronil (increased LPO). Our results suggest that specific sensitivity to insecticides varies greatly among compounds and pollinator species, but the use of different representative species can facilitate the prioritization of substances regarding their risk to pollinators. Further research is necessary to better characterize the risk that pesticides represent in neotropical agricultural landscapes. Environ Toxicol Chem 2023;42:1022-1031. © 2023 SETAC.
Assuntos
Abelhas , Inseticidas , Animais , Humanos , Biomarcadores , Costa Rica , Inseticidas/toxicidade , Inseticidas/química , Malation , Neonicotinoides/toxicidadeRESUMO
Se prepararon catalizadores de hierro y cobalto, soportados en aerogeles de carbono (AGC), por los métodos de humedad incipiente, intercambio catiónico y adición de una sal del metal a la mezcla precursora de los aerogeles. La caracterización de los catalizadores se realizó por adsorción de N2 a 77 K, descomposición con temperatura programada (DTP) y difracción de rayos X (DRX). Se encontró que los catalizadores preparados por humedad incipiente e intercambio catiónico tienen una textura microporosa, mientras que los preparados por adición de la sal del metal a la mezcla inicial son mesoporosos. Los resultados de DTP muestran que la química superficial del aerogel está influida por el método de preparación y la naturaleza química del metal, y los análisis de DRX pusieron en evidencia que la matriz carbonosa de los aerogeles tiene un carácter reductor capaz de carburizar o reducir el metal incorporado.
Iron and cobalt catalysts supported on carbon aerogels (CA) were prepared by incipient wetness, cationic interchange and the addition of a metal salt to the precursory mixture of the aerogels. The catalysts were characterized by adsorption of N2 at 77 K, temperature programmed descomposition analysis (TPD), and X-ray diffraction (XRD). The results show that the catalysts prepared by incipient wetness and cationic interchange have a microporous texture, whereas the prepared by addition of a metal salt to the initial mixture are mesoporous. TPD results show that the surface chemistry of the aerogels is influenced by the preparation method and the chemical nature of the metal. XRD analyses reveal that the reducing character of the aerogels carbonaceous matrix is able to carburize and/or to reduce the built-in metal.
Foram preparados catalisadores de ferro e cobalto suportados nos aerogeles de carbono (AGC) pelos métodos de umidade incipiente, intercâmbio catiônico e adição de um sal do metal à mistura precursora dos aerogeles. Os catalisadores foram caracterizados por adsorção do N2 em 77 K, desorção a temperatura programada (DTP), e difração de raios X (DRX). Os resultados mostram que os catalisadores preparados por umidade incipiente e intercâmbio catiônico têm uma textura mi-croporosa, enquanto que os preparados pela adição de um sal de metal à mistura inicial são mesoporosos. Os resultados de DTP mostram que a química de superfície dos aerogeles está influenciada pelo método da impregnação e pela natureza química do metal. As análises de DRX revelam que a matriz carbonosa dos aerogeles tem um caráter reductor capaz de carburar e/ou reduzir o metal incorporado.