Insecticide-induced accumulation of melanomacrophage centers (MMCs) in Nile tilapia (Oreochromis niloticus Linn.)

Issue Date

4-2008

Abstract

This study aimed to evaluate the pattern of melanomacrophage centers (MMCs) formation as influenced by residual levels of chlorpyrifos and carbaryl insecticides on Oreochromis niloticus Linn. as metabolic reaction to the stress of exposure. Male juvenile O. niloticus were exposed for 15 days to varying concentrations of either chlorpyrifos or carbaryl. The test doses corresponded with the different residual concentration levels persistent in the aquatic ecosystems. In the dose-response experiment, the concentrations used for chlorpyrifos ranged from 0.03 ug/L to 1.34 ug/L, while for carbaryl test concentrations ranged from 0.07 mg/L to 0.30 mg/L. In the recovery experiment, the concentrations used were 2.0 ug/L for chlorpyrifos and 0.3 mg/L for carbaryl. Evaluation of recovery was based on the changes in MMC size at different observation periods upon introduction of individuals to toxicant-free water. Among chlorpyrifos-exposed individuals, more pronounced responses with regard to splenic MMC size related to treatment dose levels were detectable (Fvalue = 12.5, P<0.05). Hepatic MMCs exhibited no dose-related change in size. On the other hand, among carbaryl-exposed individuals, MMC formation showed a dose-dependent response with significant differences in mean size values among treatment groups in both liver (Fvalue = 16.8, P<0.05), and spleen (Fvalue = 3.39, P<0.05). In the recovery experiment, splenic MMCs of both carbaryl and chlorpyrifos-exposed individuals exhibited significantly bigger aggregates than the untreated. No discernable pattern was noted on hepatic MMCs, however. Formation of melanin and ceroid/lipofuscin pigments was dose-dependent for both chlorpyrifos and carbaryl but not hemosiderin pigment.

Source or Periodical Title

Philippine Entomologist

ISSN

0048-3753

Volume

22

Issue

1

Page

71-85

Document Type

Article

Frequency

semi-annually

Physical Description

illustrations; graphs

Language

English

En – AGROVOC descriptors

OREOCHROMIS NILOTICUS; CARBARYL; CHLORPYRIFOS; PIGMENTS; PESTICIDES; INSECTICIDES; MACROPHAGES

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