Laboratory Studies on the Effectiveness of Chipman R-6199 against Some Cotton Pests

Abstract

Chipman R-6199, the monohydrogen oxalate of, O, O-diethyl S-(2-diethylamino)-ethyl phosphorothioate, was tested against insects introduced on potted cotton plants held in the laboratory. It was as effective as endrin against second- and third-instar larvae of the salt-marsh caterpillar (Estigmene acrea (Drury)), cabbage looper (Trichoplusia ni (Hbn.)), and cotton leafworm (Alabama argillacca (Hbn.)). At 5 mg. per plant it was also effective against adults of the boll weevil (Anthonomus grandis Boh.) and pink bollworm (Pectinophora gossypiella (Saund.)), but the residual effect was short-lived. At the same rate it gave 100% kill of the cotton aphid Aphis gossypii Glov.) for 25 days and of the two-spotted spider mite (Tetranychus telarius (L.)) and nymphs of the thrips (Hercothrips phaseoli (Hood)) for at least 48 days. In fresh deposits R-6199 was more toxic than DDT to pink bollworm moths. Results with a 1:3 mixture of R-6199 and DDT indicated slight additive action. Residues on leaf surfaces decreased rapidly in the first 2 days, but those inside the leaves increased gradually. Detached leaves were also found to absorb the chemical. Translocation to new terminal leaves was slow.