Residual and Direct Contact Toxicities of Crude Extracts and Essential Oils from <i>Acorus calamus</i> L. (Acoraceae) Rhizomes against Cassava Red Mites (Acari: Tetranychidae)

Abstract Tetranychus truncatus Ehara (Acari: Tetranychidae) is a serious economic pest of many plants in Thailand and other countries. The use plant extracts an alternative to conventional synthetic pesticides for controlling mite pests. This study was conducted evaluate the residual direct contact toxicities crude essential oils obtained from Acorus calamus L. (Acoraceae) rhizomes against T. eggs adult females under laboratory conditions. Residual toxicity assayed by applying compounds on leaf discs then releasing female mites discs; spraying females. In assays, 10% (v/v) concentration extracted fresh A. caused 73.8% mortality adults, while treatment with dried 91.8% adults. direct-contact reduced egg hatch 96.3% at 5% 100.0% 10%. Oils 28.8% respective median lethal concentrations (LC50s) were 2.18% 5.91%, based cumulative 7 d after treatment. Methylene chloride (individual extraction method) 100% 91.4% concentration, LC50s 1.31% 2.52%. Based upon our results, methylene appear as suitable botanical acaricides further development management truncatus.