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The ethanolic extract of the leaves of Catalpa speciosa with feeding deterrent activity against the gypsy moth larvae was fractionated by solvent partitioning and column chromatography. Two weakly active compounds were isolated and identified by spectral and chemical methods to be catalposide (1) and a new iridoid, specioside (2).A search for naturally occurring antifeeding substances active against the gypsy moth larvae, Lymantria dispar L., revealed that the ethanolic extract of catalpa leaves, Catalpa speciosa Warder (Bignoniaceae), possessed feeding de-terrent properties (1). Systematic fractionation of the extract showed that the activity was due to synergistic and cooperative interaction of many components, which when separated were inactive or only very weakly active (2). Two such constituents were identified as iridoid glycosides; one was the well-known catalposide (1) (3, 4), the other a new substance named specioside (2).

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BACKGROUND Bifenthrin is usually considered a Type I pyrethroid, because it lacks an α‐CN group present in Type II pyrethroids, but some previous studies suggest a mixed Type I/II mode‐of‐action. Results are presented for bifenthrin in a rat developmental neurotoxicity (DNT) study along with effects on Na currents in human VGSC subtypes. Molecular modeling comparisons were also made for bifenthrin and other pyrethroids. RESULTS In a rat DNT study, bifenthrin produced tremors and clonic convulsions in dams and pups and slightly reduced acoustic startle response amplitude, and increased Tmax, at PND20 in females. Similar blood levels of bifenthrin were measured in dams and pups at each dose level i.e. no concentration in pups. In human VGSC experiments, using the Nav1.8 subtype, bifenthrin's effects on inactivation were slight, as for Type II pyrethroids, but without large prolongation of the tail current (deactivation) seen with Type II. Molecular modeling of bifenthrin indicates that the o ‐Me group may occupy a similar space to the α‐CN group of cypermethrin and fenpropathrin. CONCLUSION In a DNT study and on human Nav1.8 tail currents bifenthrin showed Type I and II effects, similar to some published studies. Overall, bifenthrin acts as a mixed Type I/II pyrethroid. © 2018 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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