Determinação da concentração letal média (CL50) do inseticida imidacloprido para larvas de abelhas Scaptotrigona postica Latreille, 1807 e seus efeitos sobre o desenvolvimento.
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Data
2022-11-18
Autores
Oliveira, Daniela Rafael Simões de
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Universidade Estadual Paulista (Unesp)
Resumo
A importância das abelhas se dá pelo fato de serem grandes responsáveis pela polinização mundial. Entretanto, diversos fatores como o uso exacerbado de agrotóxicos está causando danos a espécies de abelhas, levando suas populações a um constante declínio. Dentre os agrotóxicos mais utilizados no Brasil, encontram-se os neonicotinóides, como o imidacloprido. Apesar de existirem estudos realizados com A. mellifera que avaliam os danos que agrotóxicos causam à polinizadores, fazem-se estudos que tenham como modelo abelhas de espécies nativas, de modo a avaliar o dano causado às espécies brasileiras. Além disso, o estágio larval é uma importante fase a ser analisada, visto que permite a avaliação de possíveis efeitos subletais desde o início do desenvolvimento. Análises enzimáticas de órgãos como cérebros e intestinos, permitem observar esses efeitos do imidacloprido ao nível celular, detectando possíveis alterações nas enzimas Acetilcolinesterase, Carboxilesterase e Fosfatase Alcalina. No presente estudo foi determinada a CL50 do imidacloprido para larvas de S. postica no valor de 75, 6 ng i.a./L. Os resultados obtidos mostraram um aumento na atividade enzimática da AChE nas larvas de S. postica expostas à CL50 e à Dose de Campo (DC), aumento na atividade da enzima CaE no grupo exposto à CL50 e não houve alteração na atividade da PAL nos grupos expostos ao imidacloprido em relação ao grupo controle. As análises morfométricas demonstram que a média da distância intertegular das recém emergidas expostas à concentrações de 75 ng i.a./L são significativamente menores do que as medidas encontradas no grupo controle. Enquanto a média da largura da cabeça das abelhas expostas às concentrações de 50 e 75 ng i.a./L foi significativamente menor do que a do grupo controle. Os dados obtidos serão úteis ao preenchimento de lacunas de conhecimento sobre os efeitos de agrotóxicos em abelhas sem ferrão, contribuindo, de forma significativa, para as questões de avaliação ambiental e regulamentação do uso de agrotóxicos.
The importance of bees lies in the fact that they are majorly responsible for global pollination. However, many factors as the excessive use of pesticides is causing damage to bee species, leading their populations to a constant decay. The neonicotinoids, such as imidacloprid, are among the most utilized pesticides in Brazil. Even though there are studies performed in A. mellifera that evaluate the damage that pesticides cause to pollinators, it is necessary to utilize native bee species as study models in order to evaluate the damage caused to Brazilian species.Furthermore, the larval stage is important to be analyzed, since it allows the evaluation of possible sublethal effects since the beginning of the larval development. Enzymatic analysis of organs such as brains and intestines, allow to observate these imidacloprid effects at a cellular level, detecting possible alterations in the Acetylcholinesterase, Carboxylesterase and Alkaline Phosphatase enzymes. At the present study, the LC50 of imidacloprid for S. postica larvae was determined at the value of 75, 6 ng i.a./L. The obtained results showed an increase in enzymatic activity of AChE in the S. postica larvae exposed to the LC50 and the field dose, increase in the CaE activity for the group exposed to the LC50 and there was no alteration in the PAL activity in the groups exposed to imidacloprid, regarding the control group. The morphometric analysis show that de average intertegular distance of the newly emerged bees exposed to the concentration of 75 ng i.a./L are significantly smaller than the control group. While the average head width of bees exposed to concentrations of 50 e 75 ng i.a./L was significantly smaller than the control group.The obtained data will be useful for filling knowledge gaps about the effects of pesticides on stingless bees, contributing significantly with environmental evaluation issues and regulation of pesticides.
The importance of bees lies in the fact that they are majorly responsible for global pollination. However, many factors as the excessive use of pesticides is causing damage to bee species, leading their populations to a constant decay. The neonicotinoids, such as imidacloprid, are among the most utilized pesticides in Brazil. Even though there are studies performed in A. mellifera that evaluate the damage that pesticides cause to pollinators, it is necessary to utilize native bee species as study models in order to evaluate the damage caused to Brazilian species.Furthermore, the larval stage is important to be analyzed, since it allows the evaluation of possible sublethal effects since the beginning of the larval development. Enzymatic analysis of organs such as brains and intestines, allow to observate these imidacloprid effects at a cellular level, detecting possible alterations in the Acetylcholinesterase, Carboxylesterase and Alkaline Phosphatase enzymes. At the present study, the LC50 of imidacloprid for S. postica larvae was determined at the value of 75, 6 ng i.a./L. The obtained results showed an increase in enzymatic activity of AChE in the S. postica larvae exposed to the LC50 and the field dose, increase in the CaE activity for the group exposed to the LC50 and there was no alteration in the PAL activity in the groups exposed to imidacloprid, regarding the control group. The morphometric analysis show that de average intertegular distance of the newly emerged bees exposed to the concentration of 75 ng i.a./L are significantly smaller than the control group. While the average head width of bees exposed to concentrations of 50 e 75 ng i.a./L was significantly smaller than the control group.The obtained data will be useful for filling knowledge gaps about the effects of pesticides on stingless bees, contributing significantly with environmental evaluation issues and regulation of pesticides.
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Produtos químicos agrícolas, Abelhas, Toxicidade, Pesticide, Stingless bees, Toxicity, Larval development