Factors Influencing the Biological Activity of Technical Chlordane and Some Related Components in Soil1

Abstract

A study was conducted to determine the factors moderating the insecticidal activity of technical chlordane in soil. Direct-contact toxicity tests indicated that chlordane, while effective as a contact insecticide, was less toxic than aldrin or diazinon to 24- to 48-hr-old crickets, Gryllus pennsuylvanicus (Burmeister), and adult picture-winged flies, Chaetopsis debilis (Loew). Both chlordane and aldrin were ineffective against 3rd-stage larvae of the dark sided cutworm, Euxoa messoria (Harris). Soil type was the major factor influencing the biological activity of chlordane, and in moist soils toxicity was negatively correlated with organic content. Soil moisture was a factor of secondary importance. Bioactivity was positively correlated with temperature, but in moist mineral soil it was a factor of secondary importance. However, in dry mineral soil temperature had a marked influence on toxicity. Studies on activity of some of the components and/or metabolites of technical chlordane indicated that, as contact poisons against crickets and flies, the order of toxicity was heptachlor>gamma-chlordane = alpha chlordane = technical chlordane>nonachlor>chlordene> 1-hydroxychlordene> hexachlorocyclopentadiene. In moist mineral soil the order was heptachlor>chlordane = gamma-chlordane> > alpha-chlordane>nonachlor>chlordene> 1-hydroxychlordene. Soil type and moisture influenced the activity of the insecticidally active components. Studies on the persistence of biological activity indicated that in Plainfield sand, nonachlor, alpha-, and gamma-chlordane were as persistent as dieldrin, while heptachlor, technical chlordane, and chlordene were similar in persistence to aldrin.