Acute Toxicity ofCalotropis ProceraLatex toClarias gariepinusJuveniles

Abstract

Acute toxicity of the latex of C. procera on Clarias gariepinus juveniles was measured over a period of 96-h as a management tool in killing predatory fish in earthen ponds in Nigeria. The latex concentrations of 0.0 mg/l, 10.0 mg/l, 22.0 mg/l, 45.0 mg/l, 100 mg/l, 220 mg/l and 1000 mg/l were used under laboratory conditions in plastic aquaria. The 96 h Lc 50 was 64.0 mg/l obtained using graphic and probit methods. The regression equation for the probit curve was y = 2.46x + 0.58 (where probit value = Y, X = log concentration per treatment). Behavioral changes observed during exposure of fish to toxicant include hyperactivity, erratic swimming, imbalance coupled with loss of co-ordination, inclination at the water-air interface, increased opercular beats, clustering and crawling and submergence coupled with paralysis (death). De-pigmentation of the skin increased with increase in latex concentration with a complete bleaching from black/dark brown to pure white occurred at 45.0 and 100.0 mg/l. Histological changes included congestion, haemorrhage, multiple foci of spongiosis of white matter, necrosis and cellular infiltration in the brain tissues. Liver exhibited degeneration, fatty change and infiltration, and generalized haemorrhage. Gill showed congestion of capillaries, keratinization, stunting, necrosis and cell infiltration. The heart-tissues were indifferent to treatments. Histological effects increased in intensity with increase in the concentration of C. procera latex.

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“…Loss of aggregation at a locus (bottom of jars) was thus observed during the initial hours in high concentrations (4.55mL /L) or at latter days of exposure in low concentrations (0.94mL /L and 2.07ml/L). Similarly, this restlessness and attempt to jump or swim out of toxic solutions were observed in fish exposed to different kinds of toxic agents by researchers [14]. The median lethal concentration (LC50) value of 1.55mL /L and 0.67mL /L were obtained at 48-hour…”

“…One hundred and twenty leeches (H. quardrata) were harvested from inactive earthen fishponds of Oyo State College of Agriculture and Technology, Igboora, Oyo state, Nigeria. Sweepnetting method for the invertebrates was used [13,14]. The leech recorded an average length (cm) and weight (g) of 4.24 and 0.4, respectively.…”

Toxicity of Lime Fruit Juice to an African Leech (Hemiclepsis Quardrata) and Blood Sucking Potential

“…One hundred and twenty leeches (H. quardrata) were harvested from inactive earthen fishponds of Oyo State College of Agriculture and Technology, Igboora, Oyo state, Nigeria. Sweepnetting method for the invertebrates was used [13,14]. The leech recorded an average length (cm) and weight (g) of 4.24 and 0.4, respectively.…”

The predatory behaviour of nymphs of dragonfly (Africocypha varicolor) on fry of African mud catfish (Clarias gariepinus) and control by skunk weed (Petivera alliacea) root-extract in aquaculture

“…This increase in yield is achievable by the eradication of unwanted aquatic biota like naiads using natural plant-toxicants (botanicals) which are preferred to synthetic chemicals for an effective sanitation of ponds [3,4]. That is botanicals do not persist in the tissue of animals and the environment concern whereas convectional chemicals such as formaldehyde do [4,5]. An example of such plant of appreciable but untapped toxic potential is Petivera alliacea.…”

“…There is the need, therefore, to boost yield of fish by eradicating the nymphs of dragonfly (naiads) that is commonly responsible for a drastic reduction in the seed of African mud cat-fish. This increase in yield is achievable by the eradication of unwanted aquatic biota like naiads using natural plant-toxicants (botanicals) which are preferred to synthetic chemicals for an effective sanitation of ponds [3,4]. That is botanicals do not persist in the tissue of animals and the environment concern whereas convectional chemicals such as formaldehyde do [4,5].…”