Shigenori Tsuda

A study of the physical strength of fenitrothion microcapsules

Fenitrothion, a widely used organophosphorous insecticide, was microencapsulated with polyurethane via an interfacial polymerization method, and the relationship between the formulation factors, such as mass median diameter (D) and wall thickness (T), and the physical strength of the microcapsules was studied. It was found that the larger the ratio DT, the smaller the pressure per capsule required to break 50% of microcapsules (P50). This result agreed with the theory of the destruction of an empty sphere with a thin wall. Moreover, the result obtained by the physical breaking test coincided with that obtained by the breaking test of microcapsules by cockroaches.

NEW PYRETHROID INSECTICIDES FOR INDOOR APPLICATIONS

Abstract The potencies of two novel pyrethroid stereoisomers, d -prallethrin and d -cyphenothrin, were evaluated for development in indoor applications under several test methods for control of housefly, mosquito and cockroach. d -Prallethrin, a propargyl analog of allethrin, generally showed a twice or more the knockdown and killing activities of d -allethrin against the pest insects, and d -cyphenothrin showed more than twice the killing activity of permethrin against cockroach. Both of them revealed an outstanding flushing-out activity against cockroach. The insecticidal potencies in practical formulations are also described in detail as associated with their physical and chemical properties.