BHC Isomers Research Articles

Absorption and metabolism of BHC in susceptible and resistant houseflies

AbstractQuantitative and qualitative work on the resistance of houseflies to γ‐BHC is described, in which BHC isomers labelled with 36Cl or 14C were used. α‐, β‐, γ‐ and δ‐BHC are converted to water‐soluble compounds by houseflies, the α‐ and γ‐isomers being more susceptible to the conversion than the β‐ and δ‐compounds. The reaction in the cases of α‐, γ‐ and δ‐BHC is accompanied by production of chloride ions corresponding to the removal of 4 to 6 atoms of chlorine from each molecule of BHC metabolized. It is therefore considered unlikely that the metabolites are trichlorobenzene derivatives. Chromatographic evidence indicates the ultimate production of eleven water‐soluble compounds from both α‐ and γ‐BHC. It is deduced from two‐dimensional chromatograms and from paper electrophoresis that the two isomers produce an identical or very similar series of compounds and that these are acidic. The role of metabolism in defending the insect against poisoning is discussed in terms of concentration X times effects and it is concluded that detoxication by metabolism is essential for the complete recovery of the insect following absorption of insecticide. Measurement of the capacity of a number of susceptible insect species to metabolize BHC isomers shows that the susceptible strain of housefly exhibits exceptional ability to eliminate γ‐BHC as water‐soluble products.

Toxicity and Interaction of Stereo-isomers of Benzene Hexachloride in Cockroaches

Some types of joint action of insecticides described by previous authors are discussed, and experiments described on the joint action on Periplaneta americana (L.) of the γ and δ isomers, and of the γ and α isomers, of benzene hexachloride. The values of the mortalities obtained are given in tables and compared with calculations of those that would be expected according to several models of joint action in which no interaction occurs. From statistical evidence it is concluded that only one of these models, namely, independent action with a strong positive correlation of the susceptibilities to the two poisons, can give an appropriate explanation of the results. These results, however, can also be explained by suggesting that antagonistic effects play a part in the joint action of the BHC isomers investigated.

Studies on Aqueous Suspensions of Insecticides. Part IV. The Behaviour of Mosquitos in contact with Insecticidal Deposits

The behaviour of mosquitos in contact with deposits from aqueous suspensions of insecticides has been studied by allowing them to alight individually and measuring the time to the first flight.Anopheles stephensi females flew from all formulations of DDT on various materials after approximately the same time of 2 to 4 minutes, but subsequent kills were high only when the deposit consisted of small (less than 10 microns) particles readily available for pick-up.Mosquitos were also activated by contact with fresh deposits of BHC wettable powder P.520, but all died very quickly. They were not disturbed, however, by the vapour from BHC deposits, when contact was prevented, until in an advanced stage of intoxication. The time to the first flight from surfaces treated with BHC wettable powder increased as the deposits aged and varied with different materials according to the rate of loss by evaporation and/or sorption.Mosquitos remained in contact with deposits of chlordane, dieldrin, aldrin and toxaphene for more than 30 minutes.Experiments with a number of DDT analogues and BHC isomers indicated that lipoid solubility and molecular structure are two factors governing the rate of penetration of a compound.The reactions of other species tested were similar to those of A. stephensi but kills of Culex p. molestus were significantly different from those of the Anopheline species after contact with deposits from a DDT wettable powder.