Morphology of internal reproductive system associated with diapause process in the cabbage beetle, Colaphellus bowringi

Key Words： Colaphellus bowringi, diapause, diapause termination, inner reproductive system, dissection

Abstract：      The cabbage beetle Colaphellus bowringi Baly, a pest of cruciferous vegetables, aestivates and hibernates as an adult in soil. Adults of this beetle were dissected and their internal reproductive systems described and illustrated. The internal reproductive system of newly diapausing adults is poorly developed and similar to that of newly emerged adults. In diapausing males, accessory glands and the ejaculatory duct are also poorly developed. In non-feeding post-diapause males, the accessory glands are swollen and obviously wider than the vas deferens, and the ejaculatory duct is obviously enlarged, whereas in feeding, post-diapause males the ejaculatory duct is obviously enlarged and light opaque yellowish-orange in color. In diapausing females, the ovarioles are small in size but slightly larger than those of newly diapausing females and some basal oocytes have faint yolk uptake. In non-feeding, post-diapause females, the ovarioles are developed, large and many basal oocytes have visible yolk uptake. In feeding, post-diapause females, the ovarioles are well developed, large and numerous chorionated eggs can be found at the base of each ovariole, lateral oviducts and the common oviduct. These results suggest that although reproductive development can continue in diapausing adults, and that a portion of the metabolites accumulated during the pre-diapause period can be used in post-diapause development, feeding is necessary for post-diapause mating and oviposition.