Acaricidal Management of Abamectin Mixtures against All Stages 0f the Two-Spotted Spider Mite, Tetranychus urticae Koch, Infesting Cucumber Plants

Abstract

Tetranychus urticae is a worldwide common pest for many vegetable species in greenhouses and open fields. The study was conducted to evaluate the performance of two acaricide mixtures: Highpoint ® 10% EC (abamectine + hexythiazox) and Ignar ® 20% SC (abamectine + spirodiclofen), as well as a single active ingredient, Envidor ® 24% SC (spirodiclofen), against the two-spotted spider mite in greenhouse and lab experiments. In the greenhouse experiment, both Ignar ® and Highpoint ® outperformed Envidor ® acaricide against the adult and immature stages through the first 3 days in both experimental seasons. After 24 hours, Ignar ® and Highpoint ® achieved the highest efficacy with percent of reduction 95.00 and 94.86 in the 1 st season and 97.84 and 95.76% in the 2 nd season, respectively. Meanwhile, Envidor ® gave lower reduction percentages of 84.93 and 83.88%, respectively. Regarding the immature stage, Ignar ® , Highpoint ® , and Envidor ® achieved reductions of 95.63%, 94.26%, and 83.31% after 24 hours for the first season and 94.09, 95.79, and 80.57% in the second season, respectively. The residual efficacy gradually decreased to reach 62.22 and 59.72% for Ignar ® and 58.31 and 59.31% for Highpoint ® in both seasons. On the other hand, the initial kill for all acaricides against the egg stage was low after 24 hours. However, after 3 days, Ignar ® and Highpoint ® showed a sharp increase in efficacy, with a reduction percent (81.24 and 51.60% in the 1 st season) and (73.83 and 81.86% in the 2 nd season), respectively. Envidor ® showed high efficacy only at the 7 th day, with varying efficacy during the inspection periods. Laboratory bioassay tests revealed that Ignar ® was the most toxic acaricide against T. urticae adults and immatures, with a 100% toxicity index. Highpoint ® had a moderate toxicity index against adult and immature stages, while Envidor ® was less effective. Ignar ® and Highpoint ® were the most toxic compounds against eggs. Abamectin mixtures are the most toxic compounds. Highpoint ® and Ignar ® , were considered to have the best efficacy on all developmental stages of the two-spotted spider mite. Due to the extensive use of abamectin to eliminate mites and numerous sucking insects, it is better to avoid its repeated use alone or in the same mixtures to control mites for more than one or two applications in the season. The data may suggest that the appropriate acaricide for integrated pest management (IPM) for all stages of T. urticae could be Ignar ® and Highpoint ® .