Malathion and copper sulfate exposure effects on humoral and cellular components of Pacific white shrimp <em>Litopenaeus vannamei</em>

Abstract

Humoral and cellular responses were evaluated in juvenile Litopenaeus vannamei shrimp following 96-hour (h) exposure to malathion; copper sulfate was used separately. Four concentrations lower than median lethal concentration (LC50-96 h) were applied (1, 10, 20, and 50% of LC50-96 h). Clotting time (CT), hemocyanin concentration (HC), glucose (G), phenoloxidase activity (PO), total hemocyte count (THC), and differential hemocyte count (DHC) were recorded at different times (0, 48, and 96 h); CT was higher in shrimp exposed to copper sulfate, evidently the presence of both substances tested caused a reduction in HC concentration at 48 h and increased at 96-h exposure. The average G level of the exposed shrimp was lower than the average G values of control shrimp. Increase in PO activity was determined in shrimp after 48-h exposure to both chemicals. Malathion caused a greater increase in mean THC values than those of shrimp exposed to copper sulfate. A decrease in hyaline hemocytes and increase in semi-granular and granular hemocytes were evident in shrimp exposed to both chemical concentrations. Finally, the variables analyzed were affected at concentrations below LC50-96 h of both chemicals tested. Evidently, malathion and copper sulfate at relatively low concentrations could affect shrimp physiology affecting their disease susceptibility.