Laboratory Evaluation of Candidate Materials as Potential Soil Insecticides1

Abstract

Thirty-four materials were evaluated for their initial activity in soil. Five tests were conducted on each material: direct contact toxicity to the test insects, activity in moist mineral soil, fumigant activity in soil, activity in relation to soil moisture, and activity in relation to soil type. First-instar nymphs of a common field cricket, Acheta (= Gryllus) pennsylvanicus (Burmeister), and adult picture-winged flies, Chaetopsis debills (Loew), were used as the test insects. Aldrin was used as a standard for comparison. Although more than 1/2 of the materials were as or more effective than aldrin as contact poisons, only a limited number were as effective in soil. Sixteen of the materials were volatile. In mineral soil, moisture was a major factor influencing insecticide activity. Although some materials were equitaxic in moist and dry mineral soil, others were less active by a factor of as much as 100. Soil type was also of major importance. Several organophosphorus and carbamate insecticides gave consistently good results under all conditions. Several materials, including some of the most commonly used soil insecticides, showed good activity in moist mineral soil, but were strongly inactivated in both dry mineral soil and moist muck soil. Some materials showed complementary action in soil and the possibility of using mixtures of insecticides to obtain more consistent control is discussed.