Pyrethrum

Abstract: Pyrethroids1 are among the most potent insecticides known. They are synthetic compounds structurally derived from pyrethrin I, one of the six active components of pyrethrum, which is an extract from the dried flower heads of Chrysanthemum cinerariaefolium. The natural pyrethrins have excellent insecticidal properties and low mammalian toxicity, but are of limited use because of their low photostability and high biodegradability (Wouters and van den Bercken 1978). However, pyrethroids are relatively stable, have a high toxicity to a wide spectrum of insects (Elliott 1976), are relatively nontoxic to mammals (Elliott 1976), and have tremendous agricultural potential (Harris and Turnbull 1978). Moreover, pyrethroids are much less persistent than the organochlorine insecticides, such as DDT and dieldrin, and apparently do not accumulate in the environment.

Abstract: Pyrethrum is the most important natural botanical pesticide. Pyrethrins are effective against virtually all insect pests, yet are of very low toxicity to mammals, and break down quickly on exposure to light and air. This study of the place of pyrethrum in ecology and pest management includes discussion of the new synthetic pyrethroids that have been developed, in addition to continuing work on natural product pyrethrins.

Abstract: The toxic effects of Eucalyptus globulus leaf oil-derived monoterpenoids [1,8-cineole, l-phellandrene, (−)-α-pinene, 2-β-pinene, trans-pinocarveol, γ-terpinene, and 1-α-terpineol] and the known Eucalyptus leaf oil terpenoids (β-eudesmol and geranyl acetate) on eggs and females of the human head louse, Pediculus humanus capitis, were examined using direct contact and fumigation bioassays and compared with the lethal activity of δ-phenothrin and pyrethrum, two commonly used pediculicides. In a filter paper contact bioassay with female P. h. capitis, the pediculicidal activity was more pronounced with Eucalyptus leaf oil than with either δ-phenothrin or pyrethrum on the basis of LT50 values (0.125 vs 0.25 mg/cm2). 1,8-Cineole was 2.2- and 2.3-fold more toxic than either δ-phenothrin or pyrethrum, respectively. The pediculicidal activities of (−)-α-pinene, 2-β-pinene, and (E)-pinocarveol were comparable to those of δ-phenothrin and pyrethrum. l-Phellandrene, γ-terpinene, and 1-α-terpineol were relatively less...