Effects of Exposure to Methyl Parathion on Egg Hatchability and Eggshell Chemical Composition inPodocnemis expansa(Testudines, Podocnemididae)

Abstract

Eggshell evaluation may serve as an indicator of the effect of substances released in the environment, which may change eggshell shape, size, structure, and/or chemical composition. Additionally, exposure may interfere with hatching rates in contaminated eggs. The objective of this study was to better understand how exposure to the insecticide methyl parathion interferes with chemical changes in eggshells of Podocnemis expansa throughout their artificial incubation, as well as with egg hatchability. A total of 343 P. expansa eggs were collected in a natural reproduction area for the species. These eggs were transferred to and artificially incubated in the Wild Animal Teaching and Research Laboratory at Universidade Federal de Uberlândia. On the first day of artificial incubation, 0, 35, 350, and 3500 ppb of methyl parathion were incorporated to the substrate. Eggs were collected every three days for chemical analysis of eggshells. Hatchability was evaluated as the number of hatchlings in each treatment, for the eggs that were not used in the chemical analysis. Student's T-test was used for data on eggshell chemical composition, and the Binomial Test for Two Proportions was used in the hatchability analysis, at a 5% significance level. It was observed that the incorporation of methyl parathion to the substrate on the first day of artificial incubation of P. expansa eggs reduced the levels of total fat in the shells throughout their incubation, besides reducing egg hatchability.

Antibacterial Properties of TMA against Escherichia coli and Effect of Temperature and Storage Duration on TMA Content, Lysozyme Activity and Content in Eggs

“…The chemical defense mechanism mainly comprises antibacterial substances in the egg white and yolk. When the outer protective system of an egg becomes compromised, the internal chemical defense mechanism plays a role [ 7 ]. Among the chemical defense mechanisms, the most important are various antibacterial proteins, especially lysozyme [ 8 ].…”

Iron deposition in the liver and guts of giant South American freshwater turtle Podocnemis expansa (Schweigger 1812) from a commercial breeding farm in Acre, Brazil

“…Mercury was found stored in P.expansa livers and muscles, which can be ingested by riverine people (Schneider et al 2010). Tests in eggs artificially incubated and exposed to pesticides such as fipronil and glyphosate resulted in lowered body mass at hatch, impaired development and bone malformation (Mendonça et al 2022) and methyl parathion led to reduced levels of total fat in the shells and reduced egg hatchability (Valdes et al 2015). Chronic exposition to those pesticides may undergo to metabolic bone disease in mature P. expansa turtles (Araújo et al 2019).…”