Inhibition of the Conversion of Aldrin to Dieldrin in Soils with Methylenedioxyphenyl Synergists

Methylenedioxyphenyl synergists (sesamex, piperonyl cyelonene, piperonyl butoxide, sulfoxide and n-propyl isome) added to aldrin-treated loam soils blocked the conversion of aldrin to dieldrin and increased the persistence of the residues by factors of 1.5 to 1.8 within 4 months of soil incubation at 37±1° C. With no synergists, 21% of the applied insecticide was recovered in the form of aldrin and 25% in the form of dieldrin. Soil samples treated also with synergists at 250 times the concentration of aldrin, still contained 60 to 65% of the applied aldrin and only 7 to 23% in the form of dieldrin. Sesamex inhibited the conversion of aldrin to dieldrin more than any of the other methylenedioxyphenyl compounds. The addition of corn oil to aldrin-treated soil increased the conversion of aldrin to dieldrin. Sesamol, which is a breakdown product of sesamex, and a known antioxidant, caused no significant inhibition of dieldrin formation. Sesamex also reduced populations of microorganisms when added to pure cultures, soil suspension, or soils. Thornton’s culture medium, treated with aldrin and inoculated with a suspension of a silt loam, contained 10 to 30% of thc recovered residues as dieldrin. No dieldrin was formed when sesamex and aldrin were added to the media inoculated with microorganisms. Moreover, the persistence of aldrin increased 4- or 10-fold after 2 or 4 weeks of incubation at 37° C.