Ommochrome synthesis and kynurenic acid excretion in relation to metamorphosis and allatectomy in the stick insect, Carausius morosus Br.

End products of tryptophan metabolism in Carausius morosus are the ommochromes ommin and xanthommatin in the epidermis, and kynurenic acid in the faeces. During larval and adult life ommochromes and mainly kynurenic acid are formed. The concentration of kynurenic acid in the faeces of adult females is 2.5 times lower than in the larvae and in adult males. Allatectomy on the first day after a larval moult induces a much longer instar (10 days) than normal. After the following moult, the allatectomized animals are transformed into adultoids. The allatectomized and normal larvae produce similar amounts of kynurenic acid and ommochrome during the larval instar. Twenty days after last ecdysis, the ommochrome content in adult and adultoids is increased. In the faeces of adultoids, however, the concentration of kynurenic acid is higher than in normal female adults, but lower than in males and larvae.