Efficacy of Insecticides Against Strawberry Root Weevil Adults, 1989

Abstract

A laboratory study was conducted to determine the efficacy of foliar applications of several pyrethroid insecticides and Orthene for control of SRW infesting eastern hemlock fields. To ensure complete foliar coverage by the insecticides, hemlock twigs were submersed in insecticide solutions. The proximal end of the twigs were then placed in small vials filled with tap water to inhibit desiccation of the plant tissue. Twigs were placed in cages containing five adult SRW that had been collected from hemlock blocks in Mass. nurseries. In addition to the hemlock, each cage also contained a cotton ball that was kept moist with tap water to supply adequate water to the weevils. The cages were kept in an illuminated incubator maintained at 20-21°C and 16 h daylengths. The effect of the insecticides were evaluated at 2 d intervals from 2-20 DAT. Weevils were considered injured if they behaved atypically as compared to untreated SRW; i.e., if they had diminished coordination when walking or were moribund. The % dead insects and % total injury (injured + dead insects) were used to evaluate insecticide efficacy. A completely randomized design with 3 replicates of each treatment was used. The experiment was conducted twice and the data from the 2 trials were combined.