Balogh, Emese and Hócza, Szabolcs and Ujhegyi, Nikolett and Kásler, Andrea and Holly, Dóra and Herczeg, Dávid and Ujszegi, János and Gál, Zoltán and Hoffmann, Orsolya Ivett and Bókony, Veronika and Mikó, Zsanett (2026) Effects of pyrethroid insecticides on sex ratios in agile frogs (Rana dalmatina). AQUATIC TOXICOLOGY, 290. No. 107624. ISSN 0166-445X
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Abstract
Environmental pollutants have the potential to alter sex ratios in wildlife through sex-biased mortality. Furthermore, endocrine disruptors may cause sex reversal during early ontogeny in ectothermic vertebrates, resulting in a phenotypic sex that is not concordant with the genotypic sex encoded by the sex chromosomes. Despite the wide-ranging implications of these sex-ratio biasing effects, they are rarely studied in ecotoxicology, especially in a way that allows for disentangling the two mechanisms. We investigated these effects of two synthetic pyrethroids, deltamethrin and etofenprox, that are commonly used insecticides and have been linked to adverse effects on fish and amphibian biodiversity. We assessed the effects of environmentally relevant concentrations of these two pyrethroids on phenotypic sex ratio, sex-dependent mortality, and sex reversal in agile frogs (Rana dalmatina). Tadpoles from field-collected eggs were reared in mesocosm until metamorphosis by adding 0.03 or 0.3 μg/L of deltamethrin or etofenprox three times to the water. We observed no effect in three of the four treatment groups. However, in the lower-concentration etofenprox treatment, phenotypic sex ratio was male-biased two months post-metamorphosis, and genotypic sexing revealed that this was due to female-biased mortality during metamorphosis and not to sex reversal. Although the estimation certainty of these effects was somewhat limited, they highlight that not all sex-ratio distorting effects are caused by sex reversal. Therefore, ecotoxicological studies aiming to understand the endocrine distruptor effects of environmental contaminants should strive to separate the effects on sex determination and sex-dependent mortality.
| Item Type: | Article |
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| Additional Information: | Funding Agency and Grant Number: Development and Innovation Fund [EKO<spacing diaeresis>P-24-3, EKO<spacing diaeresis>P-24-4]; Hungarian Academy of Sciences (MTA) [BO/00549/24/8]; HUN-REN Hungarian Research Network Funding text: We are thankful to Csenge Kalina, Anna Kraxner and Mark Szederkenyi for their help during the experiment and data archiving. We thank Botond Pertics and Ferenc Samu at the NOVI Department of Zoology for providing us with their RT-PCR machine and other lab facilities. The study was funded by the National Research, Development and Innovation Office of Hungary (NKFIH, grants 135016 to V.B., 134241 to Z.M and 142654 to J.U.) . The authors were supported by the strategic research fund of the University of Veterinary Medicine Budapest (Grant No. SRF-001 to E.B. and V.B.) , the New National Excellence Program (UNKP-21-3, UNKP-22-3 to A.K. and UNKP-23-4 to A.K. and J. U.) and the Egyetemi Kutatasi Osztondij Program of the Ministry for Innovation and Technology from the source of the National Research,Development and Innovation Fund (EKOP-24-3 to E.B., EKOP-24-4 to Z. M., N.U. and J.U.) . H.D. gained support from the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences (MTA, BO/00549/24/8) . This project received funding from the HUN-REN Hungarian Research Network. |
| Uncontrolled Keywords: | Sex determination, Sex reversal, Pyrethroids, Deltamethrin, Etofenprox, Amphibian, Sex-dependent mortality |
| Subjects: | Q Science / természettudomány > QL Zoology / állattan |
| SWORD Depositor: | MTMT SWORD |
| Depositing User: | MTMT SWORD |
| Date Deposited: | 21 Sep 2026 14:39 |
| Last Modified: | 21 Sep 2026 14:39 |
| URI: | https://real.mtak.hu/id/eprint/247098 |
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