Papilio xuthus is one of the swallowtail butterfly species commonly encountered in South Korea. The majority of swallowtail butterflies in the genus Papilio in South Korea use rutaceous plants as hosts, and most of these butterflies are oligophagous (Honda and Hayashi, 1995). The development of artificial diets and culturing techniques for rearing large numbers of lepidopterous insects has proliferated over the last 15 years and has produced a large body of literature, establishing diets for more than 250 species (King and Hartley, 1992, Singh, 1977). The cabbageworm butterfly (Pieris rapae) (Webb and Shelton 1988) and the painted lady butterfly (Vanessa cardui) have been successfully reared on artificial diets. Artificial insect diets are an essential component in many insect rearing systems that produce insects for research purposes. Complex agar-gelled diets are generally made in large batches and used shortly after preparation because the degradation of perishable diet ingredients such as vitamins and fatty acids can adversely affect insect quality (Brewer, 1984). Extrusion is a processing technology used to produce foodstuffs such as cereals, snack foods, and pet food. Food ingredients can undergo physical and chemical changes if variables such as temperature, moisture, and retention time are controlled in the extruder. The extrusion processing of ingredients can affect their carbohydrate composition, namely, the starch and fiber fractions. The cooking of foods at high temperatures for a few seconds generally has favorable effects in terms of maintaining the properties of food components and active ingredients, while markedly reducing or completely eliminating microorganisms that are present in the starting material. Therefore, the final extruded artificial diet, with its low moisture content, is considered a shelf-stable product. The most common processing steps in the extruder-cooker are gelatinizing, dissolving, denaturing, roasting, mixing, shaping, and expanding (Wiedman and Strobel, 1987). Ready-to-eat extruded snack products are very attractive because of their convenience, textural attributes, shelf stability, and enhanced flavor. Additionally, the nutritional appeal of a highprotein, high-nutritional, low-calorie diet is a value-added attribute of extruded diets originating from plant materials. The manipulation of processing conditions in extrusion results in the gelatinization of starch. Thus, the extruded pellets are more water-stable than other dietary products (Stickney, 1979). This study was conducted to determine the physical quality of the diet pellets produced by feed processing technology and the physiological response of Papilio xuthus larvae to such pellets in terms of their growth and survival. As mentioned above, the use of plant materials is expensive and labor intensive, and their partial or complete replacement would be beneficial to the insect industry. This study examines the use of a broad variety of artificial diets for P. xuthus.

A colony of Papilio xuthus was founded from females collected at the National Academy of Agriculture Science (NAAS). The host plant was collected from the NAAS and maintained in containers and small outdoor plots. Adults were allowed to lay eggs on the leaves of the living host plant, and newly hatched first instars were removed and placed on rearing diets. Neonates were reared on trifoliate orange leaves (Citrus trifoliata) in an environmentally controlled room (25±1°C, 40 ± 10% RH and LD 16:8 h).