Antagonistic effects of dietary guava (Psidium guajava) leaves extract on growth, hemato-biochemical, and immunity response of cypermethrin-intoxicated Nile tilapia, Oreochromis niloticus, fingerlings

Abstract

Cypermethrin (CYP) is a synthetic pyrethroid insecticide which is used for insects control in agricultural activities near the aquatic ecosystem. It could reach the aquatic environment leading to severe degradation in the fish welfare. Guava leaves extract (GLE) was used as a natural feed supplement for fish because of its stimulating effects on their growth and welfare status. The present research was aimed at investigating the protective effects of dietary GLE on growth, hemato-biochemical, and immunity response of CYP-intoxicated Nile tilapia, Oreochromis niloticus (L.). The half lethal dose of CYP for Nile tilapia fingerlings was determined and it was found to be 5.88 μg/L and a sublethal concentration of 0.294 μg/L of CYP was used in the present study. Fish were classified in five replicates into four groups; the first group was the control group (T1), the second group was fed a diet enriched with GLE (T2), the third group was exposed to 0.294 μg CYP/L (T3), and the fourth group was exposed to 0.294 μg CYP/L and co-supplemented with GLE (T4). After 6 weeks, growth, hemato-biochemical, and immunological variables were determined. Compared to the control group, the toxicity of CYP (T3) caused significant reductions in counts of white blood cells and red blood cells, concentrations of hemoglobin, hematocrit levels, and activity of acetyl cholinesterase accompanied with significant reductions in glucose and cortisol levels. In addition, CYP exposure (T3) exhibited significant immune suppression with marked decreases in total serum protein, albumin, globulin, lysozyme activity, respiratory burst activity, and total immunoglobulin than the control group (T1). On the other hand, the dietary GLE (T2) increased substantially fish growth, hemato-biochemical, and immune variables. The feeding fish on a GLE-enriched diet minimized the negative impacts of CYP toxicity and normalized the above-mentioned variables to be similar to the control group. The present study has revealed that dietary GLE has antagonistic functions against the toxicity of CYP in Nile tilapia.