Mortality, longevity, and fecundity of some spider mites attacking cotton as affected by selected chemicals

Abstract

A series of laboratory experiments were conducted to study the effect of a group of different chemicals on mortality, longevity, and fecundity of certain spider mites that attack cotton. The spider mites studied were organophosphate-susceptible strains of Tetranychus atlanticus McGregor, T. desertorum Banks, T. tumidus Banks, T. urticae Koch, and T. telarius (L.) and an organophosphate-resistant strain of T. telarius (L.). Three organophosphate compounds, Azodrin® (3-hydroxy-N-methyl-cis-crotonamide dimethyl phosphate), Bidrin® (3-hydroxy-N, N-dimethyl-cis-crotonamide dimethyl phosphate), and CL-47031, cyclic ethylene (diethoxyphosphinyl) dithioimidocarbonate, and 1 carbamate compound, Temik®, 2-methyl-2-(methylthio)-propionaldehyde-0-(methylearbamoyl) oxime, were evaluated as acaricides following foliar and root applications to cotton seedlings. In addition, the effect of Azodrin and Temik on longevity and fecundity of T. telarius (L.) was studied. Also, 30 chemicals were evaluated as chemosterilants against T. telarius (L.) following foliar application of the candidate chemosterilants to cotton seedlings. Additional studies were conducted with the 6 most promising chemosterilants. Azodrin, Bidrin, CL-47031, and Temik were all effective (based on mortality) acaricides following both root and foliar applications. When both methods of application were considered, Azodrin was the most effective compound tested. Root applications of low concentrations of Azodrin and Temik had no effect on rate of development of T. telarius (L.) but both compounds reduced longevity and fecundity. Of the 30 compounds tested as chemosterilants following foliar application, 2-picoline, 1-oxide; tepa; apholate; cycloheximide; cycloheximide acetate, and cycloheximide oxime were the most effective in reducing egg hatch and/or egg production. Tepa, apholate, and 2-picoline, 1 oxide also produced a high level of sterility in males following foliar application. All of the 6 most effective compounds also produced some sterility of spider mites feeding on cotton seedlings whose roots were suspended in solutions of the chemosterilants. However, the chemosterilants were phytotoxic following root applications of highly effective rates.