Density threshold‐based acaricide application for the two‐spotted spider mite Tetranychus urticae on cassava: from laboratory to the field

Abstract

BACKGROUD The red spider mite Tetranychus urticae is known as a worldwide pest in cassava production which can caused serious economic losses. Because no threshold levels are established for T. urticae in cassava cropping, many growers in China are applying excessive chemical applications per cassava cropping period. This is not only expensive, but also results in lower yields because of severe leaf damage and development of resistance. This study aims to develop an immediate threshold level for T. urticae control which could be determined in the laboratory and fit the field application requirements. RESULTS The mite density of 25 mites/leaf was the threshold which caused significant decrease of photosynthetic pigment contents and protective enzyme activities in cassava leaves in the laboratory. Moreover, 25 mites/leaf was also the threshold density which resulted in significantly lower leaf damage and higher yield levels compared with a higher level of mites/leaf where calendar sprays were used. CONCLUSION The mite density threshold that brought about significant physiological and biochemical changes in the laboratory basically coincided with the threshold that resulted in significant yield loss in the field. It is therefore concluded that the optimum threshold acaricide spray for T. urticae on cassava is 25 mites/leaf. © 2019 Society of Chemical Industry

Effect of broflanilide on the phytophagous mite Tetranychus urticae and the predatory mite Typhlodromips swirskii

“…1), which was consistent with previous studies on soybean Glycine max (L.) Merr 38 . or cassava Manihot esculenta Crantz 39 . In general, heavy infestations of TSSM result in the occurrence of some serious symptoms, for example leaf burning and stippling.…”

“…38 or cassava Manihot esculenta Crantz. 39 In general, heavy infestations of TSSM result in the occurrence of some serious symptoms, for example leaf burning and stippling. However, leaf burning and stippling were not observed in this study probably due to the short test periods.…”

A Review of Crop Protection Methods against the Twospotted Spider Mite—Tetranychus urticae Koch (Acari: Tetranychidae)—With Special Reference to Alternative Methods

“…Previous studies have demonstrated that T. urticae populations develop resistance to major acaricides due to their short life cycle (8-12 days at 30-32 • C) and high fertility (90-110 eggs per female) [86]. Therefore, it is necessary to develop new, natural control methods as an alternative to chemical products.…”

Overexpression of leucoanthocyanidin reductase or anthocyanidin reductase elevates tannins content and confers cassava resistance to two-spotted spider mite

“…The two-spotted spider mite (TSSM; Tetranychus urticae; Acari: Tetranychidae), the most polyphagous species of the Tetranychidae family, is a serious threat to several crops worldwide, including cassava. In China, this mite has been shown to cause about 50–70%, sometimes even 100% yield loss ( Chen et al, 2019 ). Although using resistant cassava cultivars is considered an eco-friendly, effective, and economical strategy for controlling cassava insect pests ( Bellotti et al, 2012 ), the predominant management practices to control TSSM are still largely reliant on pesticides.…”