20.500.12556/DKUM-92397 Ultrastructural changes in the midgut of Brazilian native stingless bee Melipona scutellaris exposed to fungicide pyraclostrobin Melipona scutellaris is a Brazilian stingless bee that is important for pollinating wild flora and agriculture crops. Fungicides have been widely used in agriculture, and floral residues can affect forager bees. The goal of our study was to evaluate the effects of sublethal concentrations of pyraclostrobin on the midgut ultrastructure of M. scutellaris forager workers. The bees were collected from three non-parental colonies and kept under laboratory conditions. The bees were orally exposed continuously for five days to pyraclostrobin in syrup at concentrations of 0.125 ng a.i./µL (FG1) and 0.005 ng a.i./µL (FG2). The control bees (CTL) were fed a no-fungicide sucrose solution, and the acetone solvent control bees (CAC) received a sucrose solution containing acetone. At the end of the exposure, the midguts were sampled, fixed in Karnovsky solution, and routinely processed for transmission electron microscopy. Ultrastructural analysis demonstrated that both the fungicide concentrations altered the midgut, such as cytoplasmic vacuolization (more intense in FG1), the presence of an atypical nuclear morphology, and slightly dilated mitochondrial cristae in the bees from the FG1 and FG2 groups (both more intense in FG1). Additionally, there was an alteration in the ultrastructure of the spherocrystals (FG1), which could be the result of cellular metabolism impairment and the excretion of toxic metabolites in the digestive cells as a response to fungicide exposure. The results indicate that ingested pyraclostrobin induced cytotoxic effects in the midgut of native stingless bees. These cellular ultrastructural responses of the midgut are a prelude to a reduced survival rate, as observed in previous studies. digestive tract Meliponini mitochondria morphology strobilurin sublethal effects prebavni trakt Meliponini mitohondriji morfologija strobilurin subletalni učinki true false true MDPI Angleški jezik Slovenski jezik Znanstveno delo 2025-04-04 13:59:32 2025-04-07 09:43:02 2025-04-08 03:09:59 0000-00-00 00:00:00 2023 0 0 Str. 1-12 št. 12, št. članka 1028 Letn. 11 2023 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2023-11-21 2023-12-14 2023-12-18 638.1 178049795 10.3390/toxics11121028 2305-6304 Domingues_2023_Ultrastructural_Changes_in_the_Midgut.pdf Domingues_2023_Ultrastructural_Changes_in_the_Midgut.pdf 1 1481B1479D259B366828B2A3F5F924C7 f4e6ba977a84c9f6f4ed3d36752b5f2db3378455911952f4beb10d00a6d506b0 d1bf7653-114f-11f0-b51c-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=189993 https://doi.org/10.3390/toxics11121028 0 45c1ecac-114c-11f0-b51c-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=189991 Fakulteta za kmetijstvo in biosistemske vede 0 0 0