An Evaluation of Certain Compounds as Feeding Deterrents Against the Smaller European Elm Bark Beetle, Scolytus multistriatus1

Abstract

The smaller European elm bark beetle, Scolytus multistriatus , was reared in elm logs in culture chambers fashioned from 55-gallon lever-lock drums. Feeding cages were designed and 42 compounds were tested as feeding deterrents against the beetle. None were as effective in reducing feeding at concentrations of 20,000 p.p.m. as was DDT. Four chemicals (decanoic acid, N,N-diethyl-m-toluamide, 3,4-diethoxybenzaldehyde and dimethyl phthalate) proved to be very effective in combination with DDT. Concentrations of 10,000 p.p.m. of the deterrent together with a similar amount of DDT were in each case equal or superior to 20,000 p.p.m. DDT in effectiveness. The same compounds at 5,000 p.p.m., in combination with DDT at 5,000 p.p.m. each, were also equal to 20.000 p.p.m. DDT in reducing feeding.