Search for insecticides: chemical constitution and insecticidal activity

P.M. Bhargava & A.B. Sen

Chemistry Department, Lucknow University, India

Published in: Journal of the Science of Food & Agriculture, 1950, 1, 178-182.

Abstract:

The synthesis of a number of compounds containing mostly a chlorobenzene nucleus as the toxic grouping and a -CCl3 (as –CHOH.CC13, -COCCl3, -O.COCCl3 or >CHCCl3) or a -COCH3 group as the chief lipoid-soluble component, has been described by the authors in the earlier papers of this series. 2,3,4,5 This paper incorporates the results of the investigation of the insecticidal action of 35 of those compounds (containing a combination of a lipoid soluble and a toxic grouping), on the rice-moth Corcyra cephalonica (belonging to the family Pyralidae, order Lepidoptera) which is very common in India, employing the technique of direct spraying. The results have been reviewed in the light of the theory of Läuger, Martin and Müller,l correlating insecticidal action and chemical constitution. A few generalizations pertaining to the effect of some individual groups on the toxicity of a molecule have been put forward. It is concluded that, apart from the presence of a toxic and a lipoid-soluble grouping, certain other factors of yet unknown nature also play an important role in conferring high insecticidal activity.

In all, the 36 compounds shown in Table I were tested for their insecticidal action (contact) on Corcyra cephalonica:

The compounds were tested either as emulsions or as suspensions, generally at concentrations of 4%, 2%, 0.5% and 0.25% (see Tables II to VIII). The need for testing most of the compounds at higher concentrations as suspensions arose out of the fact that they did not give good emulsions at concentrations above 1% with the limited number of solvents and emulsifier that could be tried. The suspensions were obtained from an alcoholic solution of the substance by dilution with water, so that the final concentration of alcohol in the suspension was 10%. The emulsions were prepared in benzene using Whitkol JB as the emulsifier, the concentration of benzene being 10% and that of the emulsifier 3% in all the emulsions used.

Insect material.-Full grown, prepupal stage caterpillars (age 20 to 25 days) of Corcyra cephalonica of approximately the same size (0.5 in.), were used for all the toxicity tests carried out.

DOI: 10.1002/jsfa.2740010607

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Search for insecticides: chemical constitution and insecticidal activity. P M BHARGAVA & A B SEN. Journal of the Science of Food & Agriculture, 1950, 1, 178-182.

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