INDEX insecticidal activity

Acaricidal and insecticidal activities of the synthesized compounds were determined as follows. In the case of two-spotted spider mite (T. urticae), female adult mites were placed on the excised leaf of kidney bean seedling, and then, the test solution (test confounds were dissolved in acetone at 20 to 200 ppm) was sprayed onto die leaf. Mortality was determined 2 days after the treatment. In the case of western flower thrips (F. occidentalis), first instar larvae were released on released on the excised leaf of kidney bean seedling (15 larvae per a disk), which was then sprayed with the test solutioa Mortality was determined 2 days after the treatment. In die case of silver leaf Miitefly B. argentifolii), adult whiteflies were released on die cabbage leaf and allowed to oviposit for 24 hours. Adults were removed from the leaf and the leaf was stood for 7 days. A leaf disk of 20 millimeters in diameter was excised from the leaf and sprayed with the test solution. Mortality was determined 6 days after the treatment. The acaricidal and insecticidal activities were indicated as activity indexes 3,2 and 1 which represent the mortality of 100%, 99% to 50% and less dian 49%, respectively. 

Frear, D. E. H., Pesticide Handbook, State College, Pa., Commercial Printing, Inc., 1951. A guide and index to trade names, active ingredients, uses, and manufacturers of commercial insecticides, fungicides, herbicides, rodenticides, and pesticide equipment sold in U. S. 

Many pesticides are esters or amides that can be activated or inactivated by hydrolysis. The enzymes that catalyze the hydrolysis of pesticides that are esters or amides are esterases and amidases. These enzymes have the amino acid serine or cysteine in the active site. The catalytic process involves a transient acylation of the OH or SH group in serin or cystein. The organo-phosphorus and carbamate insecticides acylate OH groups irreversibly and thus inhibit a number of hydrolases, although many phosphorylated or carbamoylated esterases are deacylated very quickly, and so serve as hydrolytic enzymes for these compounds. An enzyme called arylesterase splits paraoxon into 4-nitrophenol and diethyl-phosphate. This enzyme has cysteine in the active site and is inhibited by mercury(ll) salts. Arylesterase is present in human plasma and is important to reduce the toxicity of paraoxon that nevertheless is very toxic. A paraoxon-splitting enzyme is also abundant in earthworms and probably contributes to paraoxon s low earthworm toxicity. Malathion has low mammalian toxicity because a carboxyl esterase that can use malathion as a substrate is abundant in the mammalian liver. It is not present in insects, and this is the reason for the favorable selectivity index of this pesticide. 

PbB has long been used as the standard index of dose in estimating dose-effect and dose-response relationships. Some would argue that it is perhaps less valid than certain other measurements which reflect in quantitative fashion the bioavailable fraction of PbB, much as erythrocyte cholinesterase inhibition reflects the toxic impact of exposure to organophosphate insecticides. Indeed, it has been reported that inhibition of erythrocyte membrane Na, K-ATPase activity is better correlated with lead toxicity than erythrocyte lead concentration (Raghavan ei al, 1981). This was attributed to the fact that the subjects had variable concentrations of a low molecular weight lead binding protein which influenced the bioavailable fraction of PbB. It is possible that EP reflects bioavailable lead in a similar fashion. 

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