The alfalfa weevil, Hypera postica (Gyll.) (Coleoptera: Curculionidae) is one of the most important pests on alfalfa, Medicago sativa L., a valuable forage crop in Bulgaria. This article presents in vitro evaluation of the insecticidal activity of cyclohexanespiro-5-hydantoin, cyclopentanespiro-5-(2,4-dithiohydantoin), 4-(2-hydroxyethylimino)-cyclopentanespiro-5-(2-thiohydantoin) and 1-aminocyclo-pentanecarboxylic acid on the 3-rd instar larvae of the tested pest. The compounds used were characterized through physicochemical parameters, IR and NMR spectral data. It was found that the cyclohexanespiro-5-hydantoin and the 4-(2-hydroxyethylimino)-cyclopentanespiro-5-(2-thiohydantoin) manifest strong effectiveness towards the tested pest. The mortality percentage of the larvae was calculated with the Abbott’s formula and statistically analyzed by R language for Statistical Computing, drc package for Dose-Response evaluation.
Investigation of Spirohydantoin derivatives toxicity against Hypera Postica (Gyllenhal, 1813) (Coleoptera: Curculionidae)