Effect of repeated oral administration of quinalphos to male goat (Capra hircus)

Quinalphos given in daily oral doses of 0.5 mg/kg for 110 days induced severe signs of organophosphorus poisoning in male goats. The inhibition of acetylcholinesterase activity in erythrocyte was highly significant. The activity of liver glutamic; oxaloacetic transaminase, glutamic; pyruvic.transaminase, alkaline phosphatase and protein indicated marked alteration. The haematological changes were however, relatively less significant with the exception of a very low count of red blood cells and white blood cells in the treated animals. Among the vital organs, only liver suggested mild cellular changes due to quinalphos intoxication. There was no significant pathological change in other organs of the treated animals. In animals observed after 15 and 30 days rest, the activity of acetylcholinesterase in red blood cells and haematological picture showed a fairly good recovery. This study suggests that although quinalphos in low concentrations did not produce discernible cellular changes, it induced highly significant enzymatic and haematological changes in the goat.     

Effect of insecticides on the emergence ofTrichogramma Brasiliensis [Hymenoptera: Trichogrammatidae] from parasitized host eggs

The effect of 9 insecticides recommended for the control of cotton bollworms was studied, under laboratory conditions, on the emergence ofTrichogramma brasiliensis Ashmead from the parasitized eggs ofCorcyra cephalonica (Stainton) of different age groups. The insecticide concentrations tested were equivalent to those recommended for field application viz. phenthoate 0.14%, phosalone 0.15%, endosulfan 0.25%, permethrin 0.014%, monocrotophos 0.13%, fenvalerate 0.014%, cypermethrin 0.014%, fenitrothion 0.30% and quinalphos 0.14%, quinalphos and fenitrothion caused complete inhibition of emergence of the parasitoid from parasitized host eggs of all ages (1 to 7 days); but in general, adverse effect of insecticides on the disruption of emergence decreased with the advancement in the age of the parasitized eggs. For 1 day old parasitized host eggs, emergence ofT. brasiliensis adults varied from 33 to 57% for the remaining 7 treatments. For the 7 days old parasitized host eggs, emergence of parasitoids from the treatments with endosulfan, phosalone and phenthoate was similar to that from control. However, 46 to 59% inhibition of emergence was observed for permethrin, monocrotophos and cypermethrin. Fenvalerate treatment also significantly inhibited the emergence but at a comparatively lower level (40%). Out of 9 insecticides tested, phosalone and fenvalerate were considered to be relatively safe toT. brasiliensis.      

Biosurfactant Facilitated Biodegradation of Quinalphos at High Concentrations by Pseudomonas aeruginosa Q10

Previous studies indicate that high concentration of pesticides and their associated toxic effects are high at their point source of application. Use of pesticide-degrading bacteria at point sources could augment degradation and thereby reduce toxic effects associated with pesticide persistence in soil. Quinalphos, an organophosphorus insecticide, though ranked “moderately hazardous” in the WHO's acute hazard ranking, still continues to be used extensively in developing countries. The presence of a chloride radical usually makes this pesticide sparingly soluble in water and hence difficult to degrade. The present study aimed to isolate autochthonous bacterial strains capable of utilizing quinalphos as a carbon source. Primary screening of pesticide-contaminated soil by enrichment culture and degradation analysis by UV-VIS spectrophotometry led to the isolation of 12 different bacterial isolates, of which three efficient isolates of Pseudomonas sp, Serratia sp, and Pseudomonas aeruginosa with degradation rate 86%, 82%, 94%, respectively, were selected. GC-MS studies with P.aeruginosa confirmed the formation of 2-hydroxy quinoxaline and phosphorothioic acid as a result of biodegradation. The present study succeeded in isolating autochthonous bacterial strains capable of utilizing high concentrations of quinalphos as a carbon source in a shorter incubation period. This strain also possessed biosurfactant-production ability, which makes quinalphos available to cells at higher concentrations.