Acaricidal and quantitative structure activity relationship of monoterpenes against the two-spotted spider mite, Tetranychus urticae

Abstract

The acaricidal activity of 12 monoterpenes against the two-spotted spider mite, Tetranychus urticae Koch, was examined using fumigation and direct contact application methods. Cuminaldehyde and (-)-linalool showed the highest fumigant toxicity with LC(50) = 0.31 and 0.56 mg/l, respectively. The other monoterpenes exhibited a strong fumigant toxicity, the LC(50) values ranging from 1.28 to 8.09 mg/l, except camphene, which was the least effective (LC(50) = 61.45 mg/l). Based on contact activity, the results were rather different: menthol displayed the highest acaricidal activity (LC(50) = 128.53 mg/l) followed by thymol (172.0 mg/l), geraniol (219.69 mg/l) and (-)-limonene (255.44 mg/l); 1-8-cineole, cuminaldehyde and (-)-linalool showed moderate toxicity. At 125 mg/l, (-)-Limonene and (-)-carvone caused the highest egg mortality among the tested compounds (70.6 and 66.9% mortality, respectively). In addition, the effect of molecular descriptors was also analyzed using the quantitative structure activity relationship (QSAR) procedure. The QSAR model showed excellent agreement between the estimated and experimentally measured toxicity parameter (LC(50)) for the tested monoterpenes and the fumigant activity increased significantly with the vapor pressure. Comparing the results of the fumigant and contact toxicity assays of monoterpenes against T. urticae with the results of acetylcholinesterase (AChE) inhibitory effect revealed that some of the tested compounds showed a strong acaricidal activity and a potent AChE inhibitory activity, such as cuminaldehyde, (-)-linalool, (-)-limonene and menthol. However, other compounds such as (-)-carvone revealed a strong fumigant activity but a weak AChE inhibitory activity.

Cuminaldehyde: A Potential Drug Candidate

“…Cuminaldehyde was also found to selectively inhibit the acetylcholinesterase in insects and pests feeding on and damaging plants and therefore it could be safely used as an excellent natural bio-fumigant [30][31][32].…”

Estudio preliminar del efecto acaricida de seis extractos metanólicos sobre la arañita bimaculada, Tetranychus urticae Koch

“…Sus plantas hospederas (alrededor de 800 especies) comprenden hortalizas, frutales, maíz, algodón y una amplia gama de ornamentales (Migeon y Dorkeld, 2013). El daño provocado por este ácaro consiste en la remoción del contenido celular, quedando la célula prácticamente vacía, con escaso contenido de material intracelular, dando un aspecto de hoja con puntuaciones cloróticas y bronceada, reduciendo el área de actividad fotosintética, causando la abscisión de las hojas y por último la muerte de la planta (Badawy et al, 2010).…”

Effects of <i>Wolbachia</i> on rDNA-ITS2 variation and evolution in natural populations of <i>Tetranychus urticae</i> Koch

“…The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is an important agricultural pest that can feed on about 1200 host plant species, among which more than 150 are economically important (Badawy et al 2010). It mainly damages vegetables, fruit trees, cotton, soybean, maize and ornamental crops worldwide (Miao et al 2006;Badawy et al 2010).…”

“…It mainly damages vegetables, fruit trees, cotton, soybean, maize and ornamental crops worldwide (Miao et al 2006;Badawy et al 2010). Its high reproductive potential and short life cycle allow it to quickly develop resistance to many acaricides (Nicastro et al 2010).…”

“…Its high reproductive potential and short life cycle allow it to quickly develop resistance to many acaricides (Nicastro et al 2010). It is estimated that T. urticae has developed resistance to more than 80 acaricides in 60 countries (Badawy et al 2010).It is the most damaging mite species on agricultural crops and fruit trees (Miao et al 2006).…”