Die Bedeutung der Integumentbildungen der Insekten für die Wirksamkeit von γ‐Hexachlorcyclohexan

Summary The structure of the integument of Phormia regina, Rhyparobia madera and Geotrupes silvaticus was investigated in the places later to be treated with insecticide, using frozen sections approximately 10 μ thick stained with azan. The poison was applied to the insects in the following places: Phormia: wing, ventral abdomen, mesonotum Rhyparobia: intersegmental membrane, antennae, pronotum Geotrupes: dorsal abdomen, pronotum. Significant differences in the effect of ‘Gammexane’ could be seen in the insects used according to the site of application. For each species, there is a grading in time of effect in the order shown above. There are significant differences according to the site of application for the mean values as well as the scatter of affect times. At the same time, it is seen that ‘Gammexane’ is able to penetrate homogenous cuticle. In the concluding discussion, it is assumed, from the results obtained, that certain parts of the body, because of the nature of their integument, impede the penetration of the insecticide to a lesser extent. These include the wings of Phormia and the antennae of Rhyparobia with their numerous sensoria and, in Rhyparobia , parts of the integument which are comparatively thin and therefore more permeable. In general, strongly sclerotized parts of the body provide more protection than membranous parts, as is seen from the tests with Geotrupes. The importance of physical factors is discussed.