Evaluation of several insecticides for residual insecticidal activity against adult Thrips tabaci Lindeman and inhibition of Iris yellow spot virus (IYSV) transmission.

Abstract

Lisianthus (Eustoma grandiflorum) necrotic ring spot disease caused by Iris yellow spot virus (IYSV) is one of the most devastating lisianthus diseases. We tested several insecticides under both experimental and field condition to determine the length of the their residual activity in killing the thrips vector (Thrips tabaci) and their ability to inhibit IYSV transmission. The survival rate of T. tabaci was significantly low, and their ability to transmit IYSV was greatly inhibited after treatment with either acephate or spinosad under the experimental conditions. The insecticidal activity of acephate remained for at least 28 days, the longest duration of all examined insecticides. The number of thrips on lisianthus plants treated with acephate remained low until 17 days after treatment (DAT), while thrips density had increased by 10 DAT when thiamethoxam. These results indicated that acephate most effective controls the lisianthus necrotic ring spot disease.