Effects of Dimethoate on Tree Frog, Hyla arborea larvae


Sayım F. , Kaya U.

TURKISH JOURNAL OF ZOOLOGY, vol.30, no.3, pp.261-266, 2006 (Refereed Journals of Other Institutions)

  • Publication Type: Article / Article
  • Volume: 30 Issue: 3
  • Publication Date: 2006
  • Title of Journal : TURKISH JOURNAL OF ZOOLOGY
  • Page Numbers: pp.261-266

Abstract

Abstract: Considering the global decline of amphibian populations, the present study aimed to investigate the sensitivity of tree frogs to a common pesticide, dimethoate. Our study reports the effects of dimethoate on 21st- and 25th-stage Hyla arborea larvae under standardized laboratory conditions in an acute toxicity test using the static system. Specimens used for testing were obtained from the eggs of mating pairs collected at a local natural pond. Each experimental group contained 10 healthy larvae exposed to 5 different concentrations of technical grade dimethoate for 96 h. For each concentration, including the controls, 3 replicates were used. The concentrations of dimethoate causing 50% mortality (LC50) after 96 h were estimated using a probit analysis program. Regarding the lethal concentrations, 21st-stage larvae were more sensitive (LC50 = 20.27 ppm) than the 25th-stage larvae (LC50 = 37.37 ppm). Malformations such as edema and tail deformaities were observed in 21st- and 25th-stage larvae, respectively. Retardation of growth was also observed in dimethoate-exposed 21st-stage larvae. Certain signs of toxicity, such as initial hyperactivity symptoms, followed by loss of balance, motionlessness, and finally death, were observed. Key Words: Acute toxicity, organophosphorus pesticides, dimethoate, Amphibia, Hyla arborea, anuran larvae

Özet: Amfibi populasyonlar›nda gözlenen global azalmalar göz önüne al›nd›¤›nda; mevcut çal›flma, a¤aç kurba¤as›n›n yayg›n bir pestisit olan dimethoate’a olan hassasiyetini ortaya koymada katk› sa¤lamaktad›r. Çal›flmam›z; standart laboratuvar koflullar› alt›nda, statik sistem esas al›narak yap›lan akut tosisite denemeleriyle dimethoate’›n 21. ve 25. evre Hyla arborea larvalar› üzerindeki etkilerini ortaya koymaktad›r. Denemede kullan›lan larvalar, do¤al bir lokal göletten toplanan amplexus halindeki çiftlerin yumurtalar›ndan elde edilmifltir. Sa¤l›kl› on larvadan oluflan herbir deneme grubu, 96 saatlik deney süresince, ticari dimethoate’›n befl farkl› konsantrasyonuna maruz b›rak›lm›flt›r. Her bir konsantrasyon ve kontrol grubu için üç tekrar yap›lm›flt›r. Probit analiz program› kullan›larak 96 saatte, %50 ölüme neden olan dimethoate konsantrasyonlar› (LC50) hesaplanm›flt›r. Letal konsantrasyonlara göre; 21. evre larvalar (LC50 = 20.27 ppm) 25. evre larvalardan (LC50 = 37.37 ppm) daha hassast›r. 21. evre larvalarda ödem ve 25. evre larvalarda da kuyruk deformasyonlar› fleklinde morfolojik anomaliler gözlenmifltir. Ayr›ca, 21. evre larvalarda geliflmede gecikme de gözlenmifltir. Dimethoate uygulanan hayvanlar›n davran›fllar›nda; s›ras›yla hiperaktivite semptomlar›, denge kayb›, hareketsizlik ve son olarak da ölüm gibi baz› toksisite belirtileri gözlenmifltir. Anahtar Sözcükler: Akut toksisite, organofosforlu pestisitler, dimethoate, Amphibia, Hyla arborea, anur larvas›