Effects of the organophosphate insecticide azinphos-methyl on the reproduction and cholinesterase activity of Biomphalaria glabrata”

KRISTOFF, G; CACCIATORE, L.C.,; VERRENGIA GUERRERO, N; COCHÓN, A.

CHEMOSPHERE

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2011 vol. 84 p. 585 - 591

0045-6535

Abstract Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The snail Biomphalaria glabrata is a freshwater gastropod widely distributed in various parts of South America, Central America and Africa. The aim of the present work was to investigate whether azinphos-methyl causes alterations in the reproduction of B. glabrata. To this end, gastropod pigmented specimens were exposed to various concentrations of the insecticide (0.021, 0.5, 2.5, and 5 mg/L) for either 2 or 14 days. Along 14 days, several reproduction parameters and cholinesterase (ChE) activity were evaluated. In each group, the number of egg masses, the number of eggs per mass, the number of hatchings, the time to hatching, and the survival of the offspring after one month of treatment was evaluated. The results show that, depending on the concentration and time of exposure, azinphos-methyl induces alterations in the reproduction of B. glabrata. These were represented fundamentally by a lower number of egg masses, and in some cases, by a lower or null number of hatchings. Thus, the gastropods exposed to 2.5 and 5 mg/L of azinphos-methyl for 14 days showed ChE inhibitions higher than 35% along time and completely lost their ability to reproduce. On the other hand, exposure to high acute concentrations or exposure to low concentrations for 14 days resulted in ChE inhibition equal to or lower than 35% between 7 and 14 days of treatment and similar alterations in reproduction. These were represented by a decrease in the number of egg masses. At low pestice levels, the number of egg masses and the number of offspring resulted to be more sensitive biomarkers than ChE inhibition.