摘要
Chlorfluazuron is an insect growth regulator for controlling the major insect pests in crops. This paper describes the effects of sublethal doses （LD10：1.00 ng/larva; LD3o： 3.75 ng/larva） of chlorfluazuron on spermatogenesis in the adults of the common cutworm, Spodoptera litura （F.）. Chlorfluazuron was applied topically to the newly-ecdysed fifth-instars ofS. litura under laboratory conditions. The secondary spermatocytes, spermatids, elongated spermatocytes with mature sperm and eupyrene sperm bundles were present in testis of newly emerged, 1 and 2 day-old adults, but gradually decreased in their numbers in the controls. However, the spermatogonia were not present in newly emerged, 1 and 2 day-old adults. Moreover, primary spermatocytes were present （174 ± 4.0） in newly emerged adults, but not found in 1 and 2 day-old adults. In the testes of newly emerged LD10-treated adults, the numbers of eupyrene and apyrene sperm bundles were significantly reduced compared with controls, and even significantly reduced in LD30-treated adults compared with LDlo, however, their ratios were not affected. Moreover, the pattern of spermatogenesis was the same in LD10- and LD30-treated male adults compared with controls. Furthermore, numbers of developing spermatocytes were significantly reduced in the LD10 compared with controls, and even significantly reduced in LD30-treated male adults compared with LD10. In newly emerged adults, the width and length of elongated spermatocytes with mature sperm were significantly reduced in LDlo- and more significantly reduced in LD30-treated compared with controls of S. litura. In vas deferens of untreated pre- and newly emerged adult male, both eupyrene and apyrene sperm bundles were found, however, in treated pre-adult male, only apyrene sperm bundles and in treated newly emerged adult male, fe, w eupyrene and numerous apyrene sperm bundles were found. It is concluded that spermatogenesis was significantly affected by chlorfluazuron.
