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Kozii IV, Barnsley S, Silva MCBD, Wood SC, Klein CD, de Mattos IM, Zabrodski MW, Silva RDCM, Fabela CIO, Guillemin L, Dvylyuk I, Ferrari MCO, Simko E. Reproductive fitness of honey bee queens exposed to thiamethoxam during development. Vet Pathol 2021; 58:1107-1118. [PMID: 34269115 PMCID: PMC8581721 DOI: 10.1177/03009858211031845] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The productivity and survival of honey bee (Apis mellifera) colonies depend on queen bee health. Colony-level neonicotinoid exposure has negative effects on reproductive fitness of honey bee queens. However, it is unclear if the observed effects are a direct outcome of neonicotinoid toxicity or result from suboptimal care of developing queens by exposed workers. The aim of this study was to evaluate larval survival, reproductive fitness, and histopathology of honey bee queens exposed to incremental doses (0, 5, 50 ng) of the neonicotinoid thiamethoxam (THI) applied directly to individual late larvae (7 days post-oviposition) of queens. The 5 ng dose represents a calculated high environmental level of exposure for honey bee queen larvae. Morphometric evaluation revealed that the total area of mandibular gland epithelium in queens exposed to 5 and 50 ng THI was reduced by 14% (P = .12) and 25% (P = .001), respectively. Decreased mandibular gland size may alter pheromone production, which could in part explain previously observed negative effects of THI on the reproductive fitness of queens. We also found that late larval exposure to THI reduced larval and pupal survival and decreased sperm viability in mated queens. These changes may interfere with queen development and reproductive longevity.
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Affiliation(s)
- Ivanna V Kozii
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sarah Barnsley
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - Sarah C Wood
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Colby D Klein
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | | | | | | | | | - Ihor Dvylyuk
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | | | - Elemir Simko
- University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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