Non-Spinning Syndrome in Silkworm (Bombyx mori L.) Rearing and Its Possible Causes

Abstract

The silkworm (Bombyx mori L.) is an economically important domesticated insect that has been traditionally raised for silk production for nearly five thousand years. The silkworm undergoes complete metamorphosis, passing through four life stages; egg, larva, pupa, and adult. At the end of its larval stage, the silkworm spins a cocoon made of silk filament, the main product of the silk industry. Non-spinning syndrome, is characterized by larvae appearing healthy and developing normally until they reach the cocoon-spinning stage, but they are unable to spin cocoons and die after living for another one or two weeks. This problem, which has become widespread in cocoon-producing countries in recent years, causes silkworm farmers to lose the larvae they have raised for about a month at the cocoon-spinning stage, resulting in significant economic losses. In many studies, even very low doses of new-generation, broad-spectrum pesticides with insect growth regulator properties, especially juvenile hormone analogs like pyriproxyfen, fenoxycarb and methoprene are reported to cause non-spinning syndrome in silkworms. Silkworms are exposed to pesticides mainly through leaf contamination. This is mostly due to the transfer of pesticides from non-mulberry crops, or from pesticide applications in vector control to mulberry trees and their leaves. This paper provides an overview of examples of non-spinning syndrome in silk-producing countries, the non-spinning behavior of silkworm larvae and the biochemical changes observed during this process, the effects of insect growth regulators on silkworm larvae and cocoon production, and studies conducted on non-spinning syndrome, and offers suggestions.