-Reproduction of most insects depend on nutrients accumulated during the larval stage, but many lepidopteran species will also depend on nutrients obtained at the adult stage. Feeding at the adult stage allows the intake of carbohydrate and amino acid rich solutions, which may have an effect on the species reproduction and population growth. The objectives of the current study were to characterize the effects of sugar consumption by adults of the potato tuber moth, Phthorimaea operculella (Zeller), on its reproduction. To initially test the food intake by adults, a 10% honey solution or water (control), both containing a liquid dye were offered to adult insects 24h after emergence, and the presence of the dye was observed by analysis of their digestive system. The effects of adult feeding on a 10% honey solution on the reproductive performance of P. operculella were evaluated by assessing the oviposition rate, fecundity and fertility. Adult feeding was proved by the presence of the dye within the digestive system of adults of P. operculella. Although the oviposition rate and fertility were not affected by adult feeding, female fecundity was higher in honey-fed females as compared to the water-fed females.KEY WORDS: Color dye, digestive system, ovarian development, reproductive systemThe potato tuber moth, Phthorimaea operculella (Zeller), is considered one of the main causes of potato losses during harvesting and storage. The pest is present all year round and its larvae damage the leaves, twigs and tubers. It is also a pest to several other cultivated Solanaceae species, such as eggplant, pepper, tobacco and tomato (Filgueira 2003a, b). According to Pratissoli et al (2003), the adults oviposit generally up to ten days after mating, and the adult life cycle may be extended to 43 days, with females surviving for longer periods.Although food resources for reproduction of most insects depend on the nutrients accumulated during the larval stage, many lepidopteran species show feeding habits in the adult stage (Chapman 1998). Food intake at the adult stage allows the utilization of carbohydrate and amino acid rich solutions which may be necessary to complete the development of the reproductive system. In the fi eld, fl ower nectar is the main carbohydrate source, although there may be other sources, such as the extrafl oral nectar and hemipteran honeydew (Romeis & Wäckers 2002). No information on how P. operculella ingests carbohydrate-rich sources is available. It is assumed that, as in other species of the same order, sugar ingestion by adults comes mainly from the nectar of fl owers.Several techniques for insect marking are utilized in ecological studies. They play fundamental roles in fi eld assays, such as dispersion analyses, capture and recapture and in nutritional and phenological studies. These techniques include the use of fl uorescent markers or dyes, which allow easier identifi cation, but in addition they must have the lowest possible infl uence over the performed studies (Hagler & Jackson 2001)...