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THE TOXICITY OF DDT IN ABRASIVE AND NON‐ABRASIVE DUSTS TO THE RICE WEEVIL, CALANDRA ORYZAE L. (COLEOPT., CURCULIONIDAE)*
Author(s) -
HARLOW P. ANNE
Publication year - 1957
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1957.tb00446.x
Subject(s) - rice weevil , toxicity , sitophilus , biology , curculionidae , toxicology , relative humidity , cuticle (hair) , humidity , abrasive , desiccation , agronomy , botany , materials science , chemistry , composite material , physics , genetics , organic chemistry , thermodynamics
The toxicity of DDT in different dust carriers to the rice weevil, Calandra oryzae , was determined under standardized conditions, using deposits large enough to ensure that the insects accumulated an excess of dust. Some evidence was obtained that DDT is transported to the cuticle as a vapour. At high humidity, the toxicity of DDT was not markedly affected by any carrier except charcoal which reduced the toxicity, probably by absorption of DDT vapour. Small differences in toxicity of DDT caused by other carriers could not be accounted for by differences in their average particle size, bulk density, amount adhering to insect, surface area, abrasiveness to insects or effect on behaviour of the insect. At low humidity, abrasive dusts killed the insects by desiccation, thus adding to the toxic effect of DDT. Abrasion of the insect's cuticle did not affect the apparent rate of penetration of DDT at 50% R. H. or at 95% R. H. Starved insects were more susceptible to DDT poisoning, and in some experiments abrasive carriers increased the toxicity of DDT by preventing the insects from feeding.