Susceptibility to mineral and vegetable oils of a new key pest of cotton in northern Argentina, the cotton stainer, Dysdercus chaquensis

ZERBA, M.I.; BUTELER, M.; STADLER, T.

Sidney, Australia

Conferencia; Spray Oils Beyond 2000; 1999

University of Western Sidney

We report the outcomes of a study that assessed the toxicity of 3 vegetable oils and an nC21 mineral oil on the cotton stainer, Dysdercus chaquensis Freiberg [Hemiptera: Pyrrhocoridae], a new key pest of cotton (Gossypium hirsutum L. [Malvales: Malvaceae]) in Argentina. Our purpose was to select suitable biorational products for control of the pest that are compatible with integrated pest management practices. Contact bioassays were carried out with laboratoryreared D. chaquensis. Groups of 5 nymphs were exposed to filter papers impregnated with different concentrations of each oil. After 24 h, the nymphs were settled on clean filter paper in Petri dishes, and mortality was recorded every 24 h for 72 h. Although differences in toxicity were found between the oils, they were not relevant for practical purposes. The petroleum spray oil showed a greater toxicity (LD50 5.62 µL/ cm2, 95% CL 4.00–6.95, slope 4.1) than the vegetable oils: jojoba (Simmondsia chinensis (Link) C. Schneider [(Euphorbiales: Buxaceae]) (LD50 7.85 µL/cm2, 95% CL 6.47– 9.01, slope 4.9); cottonseed (LD50 8.52 µL/cm2, 95% CL 7.54– 9.37, slope 7.5) and soybean (Glycine max (L.) Merr. [Fabales: Fabaceae]) (LD50 8.85 µL/cm2, 95% CL 6.47–10.62, slope 4.7). There were no statistical differences (p < 0.05) in the toxicity of the vegetable oils.