Cycloheximide Derivatives and Mite Control, with Special Reference to Mites on Citrus1

Abstract

Cycloheximide and its acetate, acetoacetate, oxime, semicarbazone, and thiosemicarbazone derivatives were evaluated in the laboratory to ascertain their toxicity to and effects on the fecundity of the citrus red mite, Panonychus citri (McGregor), on citrus, and the Pacific mite, Tetranychus pacificus McGregor, on bean seedlings. Laboratory sprays of these compounds, in the order listed, produced injury to green lemon fruit at concentrations of 2, 0.5, 100, 40, 5, 10 ppm, respectively, and to bean seedlings at 100, 25, 1000, 100, 100, and 100 ppm, respectively. None of the compounds were highly effective in producing direct mortality to either mite species at concentrations which were nonphytotoxic. At concentrations of 10 ppm or above, spray applications of each compound, except the thiosemicarbazone, materially reduced the fecundity of both mite species. In field evaluation trials, the oxime was the only one of these compounds that showed promise for control of P. citri . Most effective control resulted when applications were made between the cycles of plant growth. When applications were made during the growth cycle, adult female mites moved onto new growth where egg laying returned to normal.