ACTIVITY OF THE THERMOSTABLE ~-EXOTOXIN OF BACILLUS THURlNGIENSIS BERLINER ON TETRANYCHUS URTICAE AND T. CINNABARlNUS I

Contact activity of thuringiensin. the thennostablc p·cxotoxin of Bacillus lhuringiensis, was highly effective at 0.18% Alan day two post-spray against motile forms of Telran}'chus urticac nnd T. cin!lClborinus, and 2 lower log dilution treatments were highly effective by day 6. In tesls with T. urticae. thuringiensin did not demonstrate systematic or translaminar acrh'ily. A high degree of residual activity was demonstrated for 14 days against females of both mite species. Dicorel was similarly effective for 10 days with 11 significant decrease in activity observed on day 12 and 14. Contact and residual activity was vcry high at 0.18% Al against eggs of the lwospotted spider mile. Egg hatch was also significantly reduced by dienochlor and dicoro!.