The histopathological effects of deltamethrin on freshwater mussels (Unio delicatus)

Abstract

Synthetic pyrethroids are among the most widely used pesticides in agricultural practices due to their high biological activity and environmental persistence. However, these compounds pose toxic risks to non-target organisms, especially those inhabiting freshwater ecosystems, thereby threatening biodiversity. Deltamethrin, a member of the synthetic pyrethroid group, acts through contact and ingestion and exhibits significantly higher toxicity toward aquatic invertebrates compared to mammals. This study examined the histopathological effects of sublethal concentrations of deltamethrin on the freshwater mussel Unio delicatus. Individuals of U. delicatus were exposed to deltamethrin dissolved in DMSO at 1/10 (876 µg/L) and 1/100 (87.6 µg/L) of the LC₅₀ for 48 hours and 7 days. At the end of the exposure periods, tissues were dissected and evaluated histologically. In the high-dose group, marked pathological alterations were observed, including hyperplasia and hemocytic infiltration in the gill lamellae, and tubular degeneration in the digestive gland. No significant histopathological changes were detected in other tissues such as the mantle, foot, gonad, nephridium, and adductor muscle. These findings reveal that deltamethrin can cause tissue-level damage in U. delicatus even at low concentrations. Moreover, the study supports the potential use of freshwater mussels as sentinel organisms in toxicological research and in the monitoring of pesticide pollution in aquatic environments.

Keywords

• Deltamethrin
• synthetic pyrethroid
• freshwater mussel
• Unio delicatus
• histopathology
• histopathology

Deltamethrinin tatlı su midyeleri (Unio delicatus) üzerine histopatolojik etkileri

Abstract

Sentetik piretroitler, yüksek biyolojik aktiviteye sahip olmaları ve çevrede uzun süre kalabilmeleri nedeniyle günümüzde tarım alanında yaygın olarak kullanılan pestisitler arasında yer almaktadır. Ancak bu bileşikler, özellikle tatlı su ekosistemlerinde yaşayan hedef dışı organizmalar üzerinde toksik etkilere yol açarak biyolojik çeşitliliği tehdit etmektedir. Sentetik piretroit grubu içerisinde yer alan deltamethrin, kontakt ve mide zehiri etkisi gösteren; memelilere kıyasla omurgasız sucul organizmalara karşı daha yüksek toksisiteye sahip bir insektisittir. Bu çalışmada, deltamethrinin subletal dozlarının tatlı su midyesi Unio delicatus üzerindeki histopatolojik etkileri incelenmiştir. U. delicatus bireyleri, DMSO içinde çözülmüş deltamethrine 1/10 (876 µg/L) ve 1/100 (87.6 µg/L) oranlarındaki subletal konsantrasyonlarda, 48 saat ve 7 gün süreyle maruz bırakılmıştır. Deney sonunda midye dokuları disekte edilerek histolojik incelemeye tabi tutulmuştur. Özellikle yüksek doz grubunda, solungaç dokusunda lamellerde hiperplazi ve hemositik infiltrasyon; sindirim bezi dokularında ise tübül yapısında dejenerasyon gibi belirgin patolojik değişiklikler gözlemlenmiştir. Diğer dokular (manto, ayak, gonad, nefridiyum ve addüktor kas) üzerinde anlamlı histopatolojik bozulmalar tespit edilmemiştir. Elde edilen bulgular, deltamethrinin düşük konsantrasyonlarda dahi U. delicatus bireylerinde doku düzeyinde hasar oluşturabileceğini ortaya koymaktadır. Ayrıca tatlı su midyelerinin bu tür toksikolojik çalışmalarda biyolojik izleme organizması olarak kullanılabileceği ve sucul ortamlardaki pestisit kirliliğinin değerlendirilmesinde etkili bir erken uyarı sistemi sağlaya bileceği sonucuna varılmıştır.

Keywords

• Deltamethrin
• sentetik piretroit
• tatlı su midyesi
• Unio delicatus
• histopatoloji

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