Rearing of Prays citri on callus derived from lemon stigma and style culture

A new method for rearing the citrus flower moth (Prays citri Mill.) (Lepido ptera, Yponomeutidae) on lemon [Citrus limon (L.) Burm.] callus is reported . In the present research callus (an undifferentiated mass of plant cells t hat can be grown under sterile conditions on an artificial medium in vitro) was induced from lemon stigma and style explants cultured on Murashige and Skoog (MS) medium supplemented with 500 mg l(-1) malt extract, 13.3 mu M 6 -benzylaminopurine, and 146 mM sucrose. Also somatic embryogenesis and plan t regeneration were obtained from the cultures of styles and stigmas of lem on. Adults were obtained from larvae on infested flowers collected in the f ield. Different oviposition substrates were used: white oval pearls (WOP), black oval pearls (BOP), rooted shoots (RS) of lemon obtained in vitro, and artificial flowers containing lemon callus (AF). Larvae were reared on lem on callus. Adults oviposited on RS, on WOP, and on AF. BOP were rejected as oviposition substrates. The flower moth reared on callus oviposited fertil e eggs. In our tests P. citri completed three generations on callus or on c allus plus shoots. In the latter case the larvae preferred callus and fed o n shoots only after callus was completely eaten. The life cycle on callus a t 23 +/- 1 degrees C lasted about 21 days. There were significant differenc es between oviposition substrates for what concerns the number of eggs laid . It was observed that females generally preferred WOP (about 25 eggs/femal e) to AF (about 20 eggs/female) or RS (about 12 eggs/female) as oviposition substrate. Nevertheless the percentage of eggs that developed into adults was higher when AF sealed with stretched Parafilm were used (about 70% of e ggs developed into adults). The method of rearing P. citri with AF was labo ur-saving and the feeding substrate (callus) had less tendency to become mo uldy or decompose than when WOP and RS were used. Since such a diet is avai lable for the insect all year round and callus can be produced in unlimited quantity, it could be possible to obtain a mass production of this moth.