Reinforce the Silkworms' Nutrition Using Essential Oil of Taxodium distichum' Fruits: A Prospective Way to Improve Silk Production

Abstract

Silkworms, being an important source of silk fiber, require adequate nutrition for optimal growth and cocoon formation. However, conventional methods often fall short in meeting their dietary requirements. The present study aimed to evaluate the potential of Taxodium distichum essential oil as a natural product to enhance vitality and silk production in the 5 th larval instar of Bombyx mori , commonly known as mulberry silkworm. The investigation involved employing biochemical and histological approaches. Among the different concentrations tested, a 1% oil concentration exhibited the most significant effects on larval weight (5.004 g), silk gland weight (1.378 g), fresh cocoon weight (1.772 g), and cocoon shell weight (0.386 g) when compared to non-treated larvae. Furthermore, this concentration also resulted in notable improvements in several silk-related parameters such as cocoon silk ratio (21.89%), length of the silk thread (1272.96 m), weight of filament silk (0.390 g), and size of the silk filament measured at 2.212 denier (dn) when compared to other used concentrations and control groups. The tested oil was identified through GC/MS analysis, which revealed that α-pinene was the major compound, representing 74.36% of the total oil composition. Small amounts of other compounds were also identified, including Cis-Thujopsene (8.39%), Sabinene (4.09%), β-Pinene (3.08%), α-Myrcene (2.19%), and Bornyl acetate (1.34%). Histological investigation of larval brains showed no noticeable abnormal pathological changes in treated larvae compared to the negative control group. Observations revealed that the neural lamella extended continuously around the brain in a regular manner, with a dense layer consisting of neurons and glial cells beneath it. The essential oil from T. distichum induced significant biochemical changes in treated larvae, leading to decreased activity of acetylcholinesterase and increased activity levels of Glutathione S-transferase, Superoxide dismutase, Catalase, and Malondialdehyde when compared to their respective negative control group. In conclusion, treatment with T.distichum essential oil enhanced larval vitality in mulberry silkworms ( Bombyx mori ), preserved their brain structure, and improved silk production by promoting an antioxidant defense system against oxidative