In the search for new juvenile hormone analogues (JHAs), a general approach was chosen based on the substitution of the isoprene unit, that carries the epoxy function in the natural hormone JHIII, by 3,3,3-trichloropropyI, 2,2-dichlorocyclopropylmethyl, 3,3-dichloroallyl, or 3-chloroprop-2-ynyl groups. Accordingly, several terpenoid aromatic JHAs were prepared with, or without, oxygen atoms in the aliphatic chain. Structure-biological activity relationships of the most active compounds toward the yellow mealworm (Tenebrio molitor) and the large cabbage white butterfly (Pieris brassicae) are given. With a view to preparing synthetically accessible analogues, some alkyl phenyl ethers were also made, which were not branched in the aliphatic chain and were related terminally to the most active compounds. They were only moderately active against insects when tested for morphogenetic activity, but exhibited a good field persistence. The occurrence of a moderate acaricidal activity among these analogues prompted the examination of several 1,4-disubstituted-phenyl derivatives. The ovicidal effectiveness of these products against a susceptible strain of the two-spotted spider mite, Tetranychus urticae, was ten or 100 times higher than that of the well known and highly potent JHAs. 423 424 P. Piccardi et al.

A new class of compounds, derived from hydroquinones, has been synthesised and bioassayed for juvenile hormone activity on yellow mealworm (Tenebrio molitor), confused flour beetle (Tribolium confusum), and mediterranean flour moth (Anagasta kuehniella). Structure‐biological activity relationships of the most significant products are tabulated and discussed. Two of the new compounds, 1, 4‐bis(5‐chloropent‐4‐ynyloxy) benzene (I) and 1‐(5‐chloropent‐4‐ynyloxy)‐4‐phenoxybenzene (II), showed outstanding activity in morphogenetic assay with T. molitor, and good field persistence. Product II is of particular interest for the control of various Homopteran species, mosquitoes, stored product pests and fire ants.

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A novel series of O,O‐diethyl O‐(1‐R′‐3‐R″‐1,2,4‐triazol‐5‐yl) phosphorothioates, in in which R″ was an alkyl group and R″ was a radical characterised by the presence of a conjugated multiple bond, generally of a vinyl nature, has been synthesised and tested in the search for new insecticides. Several of the compounds showed a broad spectrum of activity, covering important species of Orthoptera, Hemiptera, Lepidoptera, Coleoptera, Diptera and mites. At the same time they were characterised by a relatively low oral toxicity to rats.