Thiamethoxam and picoxystrobin reduce the survival and overload the hepato-nephrocitic system of the Africanized honeybee

Autor(es)

Domingues, Caio E. C. ^{[1, 2]} ; Abdalla, Fabio Camargo ^{[1, 2]} ; Balsamo, Paulo Jose ^{[1, 2]} ; Pereira, Beatriz V. R. ^{[1, 3]} ; Hausen, Moema de Alencar ^[1] ; Costa, Monica Jones ^[1] ; Silva-Zacarin, Elaine C. M. ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos UFSCar, PPGBMA, Sorocaba, SP - Brazil

^[2] Univ Fed Sao Carlos UFSCar, Dept Biol DBio, Lab Biol Estrutural & Func LABEF, Sorocaba, SP - Brazil

^[3] Univ Fed Sao Carlos UFSCar, Dept Biol DBio, LEBA, Sorocaba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Chemosphere; v. 186, p. 994-1005, NOV 2017.
• Citações Web of Science: 10

Resumo

Apis mellifera perform important pollination roles in agroecosystems. However, there is often intensive use of systemic pesticides in crops, which can be carried to the colony by forage bees through the collection of contaminated pollen and nectar. Inside the colony, pollen loads are stored by bees that add honey and several enzymes to this pollen. Nevertheless, intra-colonial chronic exposure could induce sublethal effects in young bees exposed to a wide range of pesticides present in these pollen loads. This study was aimed to both determine the survival rate and evaluate the sublethal effects on the hepato-nephrocitic system in response to continuous oral exposure to lower concentrations of neonicotinoid thiamethoxam (TXT) and picoxystrobin fungicide (PXT). Exposure to a single chemical and co-exposure to both pesticides were performed in newly emerged honeybee workers. A significant decrease in the bee survival rates was observed following exposure to TXT (0.001 ng a.i./mu L) and PXT (0.018 ng a.i./mu L), as well as following co-exposure to TXT+PXT/2. After five days of continuous exposure, TXT induced sub-lethal effects in the organs involved in the detoxification of xenobiotics, such as the fat body and pericardial cells, and it also induced a significant increase in the hemocyte number. Thus, the hepato-nephrocitic system (HNS) reached the greatest level of activity of pericardial cells as an attempt to eliminate this toxic compound from hemolymph. The HNS was activated at low levels by PXT without an increase in the hemocyte number; however, the mobilization of neutral glycoconjugates from the trophocytes of the fat body was prominent only in this group. TXT and PXT co-exposure induced intermediary morphological effects in trophocytes and pericardial cells, but oenocytes from the fat body presented with atypical cytoplasm granulation only in this group. These data showed that the realistic concentrations of these pesticides are harmful to newly emerged Africanized honeybees, indicating that intra-colonial chronic exposure drastically reduces the longevity of bees exposed to neonicotinoid insecticide (TXT) and the fungicide strobilurin (PXT) as in single and co-exposure. Additionally, the sublethal effects observed in the organs constituting the HNS suggest that the activation of this system, even during exposure to low concentrations of theses pesticides, is an attempt to maintain homeostasis of the bees. These data together are alarming because these pesticides can affect the performance of the entire colony. (C) 2017 Elsevier Ltd. All rights reserved. (AU)

• Processo FAPESP: 14/04697-9 - Efeitos da interação entre o inseticida tiametoxam e o fungicida picoxistrobina em larvas e adultos de Apis mellifera africanizada
• Beneficiário: Caio Eduardo da Costa Domingues
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 11/17840-6 - Ação do cádmio e do Roundup® original em órgãos internos de Bombus morio e Bombus atratus (Hymenoptera: Bombini)
• Beneficiário: Fábio Camargo Abdalla
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 13/09419-4 - Interação entre pesticidas e infecção por Nosema em Apis mellifera africanizada: efeitos biológicos e detecção de biomarcadores celulares
• Beneficiário: Elaine Cristina Mathias da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Regular