Abstract
The silkworm Bombyx mori feeds exclusively on mulberry leaves and is highly sensitive to pesticides in general. Although mulberry plantations are free of agrochemicals, pesticide drift can occur. Chlorantraniliprole, a novel insecticide of the anthranilic diamides class, has been used to control pests in field crops. In this study, we investigated the biological effects of different concentrations of chlorantraniliprole on B. mori silkworm commercial Brazilian hybrids. To evaluate the toxicity of chlorantraniliprole, bioassays were carried out and data on the lethal concentrations, symptomatology, morphology and variables of silk production were collected. Results indicated that B. mori is extremely sensitive to chlorantraniliprole, even in low concentrations. The highest silkworm mortality rates were observed in the two highest chlorantraniliprole concentrations, 0.2 and 0.1 ppm. Although lower chlorantraniliprole concentrations did not cause death of all the silkworm larvae, various symptoms of toxicity were observed: feeding cessation, regurgitation, late development and incomplete ecdysis. Such symptoms reflect the morphological changes we observed in the midgut epithelium, which affected nutrient uptake and metabolism, and even the production of cocoons. Exposed larvae also produced thin-shelled cocoons, which constitutes a serious economic problem because this type of cocoon is not useful for the silk industry. The results provided herein confirm the toxicity of chlorantraniliprole in silkworm larvae. Therefore, we strongly suggest that, competent authorities of the National Health Surveillance Agency, in pesticide management should take measures to reduce or eliminate the use of chlorantraniliprole in areas nearest to silkworm cultivation.
Highlights
The silkworm Bombyx mori L. (Lepidoptera: Bombycidae), an insect originally from China, was domesticated 5000 years ago for silk production [1]
We performed bioassays to verify if the symptoms caused by chlorantraniliprole in silkworm larvae are similar to those observed by producers in silkworm farms
Most of the studies reported insecticides that belong to classes which do not include chlorantraniliprole, which is an anthranilic diamide, the symptoms of intoxication are very similar to those we observed
Summary
The silkworm Bombyx mori L. (Lepidoptera: Bombycidae), an insect originally from China, was domesticated 5000 years ago for silk production [1]. (Lepidoptera: Bombycidae), an insect originally from China, was domesticated 5000 years ago for silk production [1]. Silkworms are no longer found in nature and are totally dependent on man to survive. Bombyx mori most likely evolved from B. mandarina, a wild silkworm species with similar characteristics and reproduction to B. mori [2]. Silkworms are herbivorous and feed exclusively on fresh mulberry leaves during the larval phase [3]. The practice of sericulture includes mulberry cultivation, egg production, larvae creation and maintenance until cocoon production and, silk yard production by the industrial sector. Brazil’s weather is favorable for OPEN ACCESS
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