Toxicity of Several Stomach-Poison Insecticides to Four Species of Lepidopterous Larvae

Abstract

Several changes in technique of determining M.L.D.''s by the single leaf method of Hansberry and Richardson are descr. A sticker-spreader mixture for holding the dust particles to the foliage was used in some of the tests. A total of 11 M.L.D.''s was detd., representing 4 stomach-poison insecticides and 4 spp. of lepidopterous larvae. There was a marked difference in the susceptibility of the various spp. of insects to the several poisons employed, and a great difference existed in the toxicity of the several poisons to a given species; e.g., the M.L.D. of Na fluoaluminate was .68 mg./g. for Ascia rapae and .17 mg./g. for Anticarsia gem-matilis, whereas acid Pb arsenate exhibited about the same toxicity to both spp. The M.L.D. of Ca arsenate varied from .11 mg./g. for A. gemmatilis to about 2.00 mg./g. for Hyphantria cunea.