Acute Toxicity and Latent Effects of Several Insecticides on the Egyptian Cotton Leafworm1,2
Effects of several insecticides on the larval stage of Spodoptera lilloralis (Boisduval) were investigated, The 24-hour observation indicated that the LD50 values were 4047, 1079, 410, and 57 /Jog/g, and the slopes were 1.50, 3.11, 3.30, and 3.06 probit/unit log dose for carbaryl, DDT, Sumithion® (O,O-dimethyl O-(4-nitro-m-tolyl) phosphorothioate), and endrin, respectively. The shallow slope of the carbaryl Id-p line indicates the possibility of appearance of resistance. Sumithion caused the highest mortality during the larval stage, the 48-hr observation in this particular case was more indicative for its toxicity. The pupation was about 19, 18, 13, 10, and 3% for the control, endrin, carbaryl, DDT, and Sumithion, respectively. The treatments generally decreased the range of the developmental period of survivors and had no pronounced effect on the average duration.
The LD30values (sublethal doses) were 26.0, 11.0, 4.cl, and 0.56 µg/larva for carbaryl, DDT, Sumithion, and endrin, respectively. Sublethal doses of carbaryl significantly increased preoviposition and the oviposition periods, male and female longevities, and had a detrimental effect on egg hatching. All insecticides, except carbaryl, displayed a marked decrease in the expected number of the progeny of the filial generations. Carbaryl was the only insecticide that exceeded the control in number of normal adult females produced per generation. Under captivity, when males were held alone, their life span significantly decreased.
Document Type: Research Article
Publication date: April 1, 1972
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