The effect of ventral nerve cord cutoff between the third thoracic and the first abdominal segments on oviposition in female imagines of the American cockroach, Periplaneta americana

摘要

The ventral nerve cord of female imagines of P. americana was cut off between the third thoracic and the first abdominal segments to examine the function of the central nervous system in controlling oviposition. When the ventral nerve cord was cut off within three days after emergence, the females each produced only 2.3 ootheca in 90 days (12.5 percent of that of the control group). When the ventral nerve cord was cut off on day 30 after emergence, the females almost stopped ovipositing despite thefact that they had normal oviposition on the previous day. Those females each produced only 1.4 ootheca in 60 days after the surgery. All the oothecae produced after the cutoff were malformed without eggs. These results suggest that the information or directive concerning ovulation may be transmitted through the ventral nerve cord in P. americana.