Contact effect of juvenoid, pyriproxyfen, on internal reproductive organs of German cockroach Belattella germanica (Dictyoptera: Blattellidae)

German cockroach is one of the worldwide pest with high potential of reproduction, and a carrier of many pathogens and allergen factors in human. Thus, control of this insect is very important from the view point of public health. In this research, the contact effects of pyriproxyfen on histological structure of internal reproductive organs of German cockroach were investigated. The last instar nymphal stage were treated with different concentrations (10, 1, 0.1, 0.01 and 0.001 ppm) of pyriproxyfen until the adults were emerged. To investigate the effects of juvenoid on reproduction, each of the treated insects were kept with an untreated opposite sex leading to the formation of the first egg capsule. Then, for histological investigations, the reproductive organs removed. Morphological studies on treated insects and their reproductive organs compared with untreated insects showed that pyriproxyfen in high concentrations caused sterility of the insects due to incomplete development of the these organs in both sexes, and the imagoes were not emerged either. Histological investigation of testis and ovaries in infertile insects indicated degeneration of ovarian follicle cells, defective vitellogenesis, hypertrophy of testis walls, spermatogenesis disorder and a decrease in the number of spermatocyts and spermatozoa.