Toxicity and effects of the neonicotinoid thiamethoxam on Scaptotrigona bipunctata lepeletier, 1836 (Hymenoptera: Apidae)

Abstract

The neonicotinoid thiamethoxam is widely used in different agricultural crops, and it has a spectrum of action against insects, affecting both pests and pollinators, such as bees. In this study, the effects of exposure to sublethal concentrations of thiamethoxam on stingless bees Scaptotrigona bipunctata were evaluated. Foragers bees were exposed to the insecticide and subjected to genetic biochemical, histochemical, and morphological analyses after 24, 48, and 72 h of ingestion. Analysis of isoenzyme esterases revealed significant alterations in the relative activity of EST-4, a type II cholinesterase. Evaluation of the S. bipunctata brain revealed changes in the state of chromatin condensation according to the exposure time and concentration of neonicotinoid compared with the control. Morphological changes were observed in the midgut of this species at all concentrations and exposure times, which may interfere with various physiological processes of these insects. We can conclude that, although thiamethoxam at the concentrations evaluated did not cause high mortality, it induced concentration-dependent changes in bees by activating enzymes related with the protection for xenobiotic, internal morphology and probably these changes may lead to alterations in the activity of bees.

Nosema ceranae causes cellular immunosuppression and interacts with thiamethoxam to increase mortality in the stingless bee Melipona colimana

“…Regarding the toxic effect of thiamethoxam at sublethal concentrations, the results of this study agree with previous reports showing reduced lifespans of other stingless bee species 42,43 . Thus, this study supports the notion that neonicotinoid insecticides are more detrimental to stingless bees at sublethal concentrations than N. ceranae infections.…”

“…Clearly, honey bees are negatively impacted by N. ceranae and neonicotinoid insecticides alone or in combination, but we know very little about how they affect other bee species, particularly in the tropics. Few studies have shown that stingless bees, social bees lacking stingers, are negatively impacted by neonicotinoid insecticides 42 , 43 and can be vectors of N. ceranae spores 28 , 29 , but we do not know if N. ceranae is capable of infecting and proliferating in them or if they could be adversely affected if exposed to both stressors, something likely to occur in natural and managed ecosystems. This is important, not only because stingless bees play a significant role as pollinators of flowering plants in the tropics, but also because several species of stingless bees have been managed for honey and cerumen production since ancient times, constituting a source of income for indigenous populations in the Americas 44 , 45 .…”

Fábrica De Abelhas: Estudo De Caso Sobre Um Sistema De Criação De Abelhas Nativas Em Jardim Do Seridó-Rn

“…Inúmeros trabalhos verificaram alterações citotóxicas promovidas por pesticidas nas abelhas (JACOB et al, 2015;MOREIRA et al, 2018;MARQUES, LIMA, BERNARDES, 2020). A espécie A. mellifera, é empregada como organismo modelo em pesquisas, principalmente, as direcionadas para detecção de efeitos a compostos tóxicos (JACOB et al, 2015).…”

“…Os efeitos in vitro de tiametoxam em larvas de A. mellifera foram identificados na avaliação morfológica e imunocitoquímica dos cérebros de abelhas expostas, apresentam células reduzidas e morte celular precoce nas células dos lobos ópticos (TAVARES et al, 2015). Testes em laboratório avaliaram também o neonicotinoide tiametoxam em abelhassem-ferrão Scaptotrigona bipunctata, permitiram observar alterações no intestino médio incluindo desprendimento do epitélio da lâmina basal, além de desorganização epitelial e alterações morfológicas significativas nas células digestivas (MOREIRA et al, 2018).…”

“…Estudos recentes em laboratório relataram os efeitos negativos dos pesticidas sobre as abelhas (GREGORC et al, 2018;MOREIRA et al, 2018;DAI et al, 2019;JACOB et al, 2019). Devido a estes dados, existem fortes evidências que associam o uso desses compostos ao declínio populacional desses polinizadores (MAGGI et al, 2016;WOODCOCK et al, 2016).…”