Toxicity of snail attractant pellets containing eugenol with respect to abiotic factors against the vector snail Lymnaea acuminata

Abstract

Every month during the year 2010–2011, the 24 to 96 h LC50 values of molluscicide eugenol, in snail attractant pellets (SAP), were determined against a snail Lymnaea acuminata, with concomitant determination of levels of temperature, pH, dissolved oxygen, carbon dioxide, and electrical conductivity in test water. On the basis of a 24 h toxicity assay, it was noted that LC50 values 2.55, 2.68, and 2.91% in SAP containing starch+eugenol and 2.67, 2.54, and 2.85% in SAP containing proline+eugenol during May, June, and July, respectively, were most effective treatments in killing the snails, while SAP containing starch or proline+eugenol were least effective in January when the 24 h LC50 was 10.73% and 7.14% for starch and proline, respectively. There was a significant positive correlation between LC50 of eugenol containing SAP and levels of dissolved O2 and pH of water in corresponding months. On the contrary, a negative correlation was observed between LC50 and dissolved CO2 and temperature of test water in the same months. A significant positive rank correlation occurred between AChE activities and the corresponding sublethal concentrations of eugenol in SAP. Moreover, there was a maximum inhibition of 58.96% of AChE in snails exposed to 80% of the 24 h LC50 of eugenol+starch in June.