Abstract: This study explored the effects of three mulberry sclerotium control drugs on silkworm growth and development. The second-instar (2nd) silkworms were fed with carbendazim, procymidone and thiophanate-methyl until the cocoon stage, respectively, taken fresh water as a control. The effects on the silkworm growth and development were measured by the length of larval stage, the body weight of the fifth instar, and the cocoon quality. Also the activity of antioxidant enzymes in the midgut of the fifth instar larvae on the fourth day was measured by CAT and POD activity kits. The larvae fed with thiophanate-methyl could not complete the generational development, which died at the 2nd instar. The silkworms fed with carbendazim and procymidone could normally develop into cocoon stage. However, compared that with the control group, the larval age of silkworms fed with carbendazim had shortened, while the age of silkworms with procymidone had increased. The weight of silkworms fed with carbendazim and procymidone became lighter, which suggested that these two powders had a negative effect on the cocoon performance of silkworms. The activities of CAT and POD enzymes in the midgut of silkworms had increased. Therefore, for the control of mulberry sclerotium, the usage of thiophanate-methyl should be prohibited, while carbendazim and procymidone might be used.

Key words: Sclerotinia sclerotiorum, Bombyx mori, carbendazim, thiophanate-methyl, procymidone