Effect of Certain Antibiotics and Other Compounds on the Two-Spotted Spider Mite

Egg laying by the two-spotted spider mite ( Tetranychus telarius (L.)) was strongly inhibited by cycloheximide (3-[2-(3,5-dimethyl-2-oxyeyclohexyl)-2-hydroxyethyl] glutarimide), an antibiotic useful against powdery mildew and some other fungous diseases. This inhibition occurred on peach, pear, apple, and rose leaves. The mites were also suppressed on apple leaves when cycloheximide was combined with Sevin® (1-naphthyl methylcarbamate). This antibiotic is systemic, and mites on potted peach trees were controlled by 25 to 200 p.p.m. for 2 to 6 weeks, the period of protection increasing with the concentration. Another antibiotic, cytovirin, a material extremely hazardous to handle, was about equal to cycloheximide in suppressing egg laying, but several other antibiotics, including derivatives of cycloheximide, showed much less or no activity. Both cycloheximide and cytovirin are phytotoxic at low concentrations. Pear seedlings were much more susceptible than apple and peach plants which were not injured in greenhouse tests by levels effective for the control of mites.