Growth, abnormalities, and mortality of tadpoles of American toad exposed to combinations of malathion and nitrate

Abstract

American toad tadpoles (Bufo americanus) were exposed to malathion and nitrate in a fully factorial experiment that crossed four concentrations of malathion ranging between 0 and 1,000 µg malathion/L, and five concentrations of nitrate ranging from 0 to 16 mg NO(3) -N/L to identify single and interactive effects. In this 21-d experiment, we recorded tadpole length, mass, survivorship, and frequencies of diamond-shaped and stiff-tail abnormalities. Malathion increased frequency of diamond-shaped and stiff-tail abnormalities, and negatively affected survivorship, but did not affect tadpole size. Nitrate did not affect survivorship but did have sublethal effects, including effects on tadpole length and the frequency of both abnormalities. The interaction of malathion and nitrate has no effect on survivorship or tadpole size but did affect the frequency of abnormalities, with nitrate reducing malathion's effect. Results of the present study suggest that at the environmentally realistic concentrations used in our experiment, malathion has both lethal and sublethal effects, but nitrate had only sublethal effects on American toad tadpoles. The combination of malathion and nitrate had limited effects at the tested concentrations under laboratory conditions. However, the effect of the combined treatments on the frequency of tadpole developmental abnormalities suggests that such interactions may play a role under field conditions, in which pesticide and nitrate fertilizers are typically applied simultaneously.

Effects of combinations of malathion and cypermethrin on survivability and time of metamorphosis of tadpoles of Indian cricket frog (Fejervarya limnocharis)

“…[13,[26][27][28] In the present study, individual effect of malathion at the tested concentrations revealed that the survivability of tadpoles was similar to that of the control (Figs. 1 and 2), thus this pesticide is less toxic to F. limnocharis even at ten times higher concentration of cypermethrin.…”

“…including atrazine, malathion, methyl parathion, carbaryl, chloropyrifos, cypermethrin, and diazinon) influence the amphibians, either singly or in combination; either directly or indirectly and produce a negative effect on growth and development. [6,[9][10][11][12][13] Response to the pesticide exposure is known to vary among different species. [10] Further, the adult population in agro-ecosystems showed many morphological abnormalities than that of adult amphibians in undisturbed habitats [14,15] indicating the degraded environmental health and severity of chemical contaminations.…”

“…[6] Organophosphate pesticides (e.g., malathion, methyl parathion) are known to cause negative effects on growth, development, metamorphosis and behaviour of the tadpoles. [6,[9][10][11][12][13]19,20] [21] and is widely considered as an ideal insecticide in agriculture. [22] Pyrethroids are highly toxic to non-target species including amphibians and produce negative effects on tadpoles and adult frogs.…”

Malathion acute toxicity in tadpoles of Duttaphrynus melanostictus, morphological and behavioural study

“…Upon the study of photographs it was possible to quote that the abnormalities observed were purely dependent on the concentration of exposed malathion. Some authors have earlier reported that malathion is known to cause negative effects on the survivability of amphibians (Webb and Crain, 2006;Mackey and Boone, 2009;Krishnamurthy and Smith, 2010). This however can be taken as a support for the present study.…”

Morphological and behavioral alterations induced by endocrine disrupters in amphibian tadpoles

“…Malathion was found to induce abnormalities in the head, trunk and tail in tadpoles of Microhyla ornata (Pawar, Ghate and Katdare 1983), bending of tails in Xenopus laevis (Webb 2003), and increased frequency of diamond-shaped stiff-tails in the toad Bufo americanus (Krishnamurthy and Smith 2010). Similarly, exposure of B. melanostictus, Polypedates cruciger and Rana clamitans larvae to OP diazinon leads to tail curving and bending (Harris et al 1998;Ratnasooriya 2008a, 2008b).…”