1964] 
Roth — Reproduction in Cockroaches 
235 
These experiments show that partial or complete starvation 
affected the resumption of oocyte development when the ootheca was 
removed from the uterus at different periods in gestation. In 
partially fed females the effect was greatest (fewer females oviposited 
and developed yolk), the shorter the exposure to food (i.e., when 
the oothecae were removed 5-6, or 10 days after oviposition and 
the females were then starved). In totally starved females the effect 
was about the same, regardless of when the oothecae were removed; 
0-17% oviposit. In both partially and completely starved females, 
mating had a stimulating effect and increased the percentage of 
females that oviposited and had yolk deposited in the oocytes. 
DISCUSSION 
During gestation the female remains unreceptive, apparently because 
mechanical stimuli resulting from the ootheca in the uterus prevents 
the receptivity center from being reactivated. Thus, if the nerve 
cord is transected in a pregnant female, the inhibitory signals from 
the uterus are interrupted, the receptivity center becomes activated 
and after a few days the female mates again in spite of the fact that 
she is carrying an ootheca. The return of receptivity in females whose 
oothecae are removed at different periods in gestation usually, but 
not always can be correlated with onset of corpus allatum activity, 
as indicated by yolk deposition in the oocytes. However, N. cinerea 
mate even if they are allatectomized <6 hr. after emergence or have 
their inactive corpora allata removed during pregnancy; the latter 
females mate after parturition (Roth and Barth, 1964). Roth and 
Barth suggested that some event, possibly the release of neuro- 
secretion, which occurs at about the same time as onset of corpus 
allatum activity, determines whether or not the female will accept 
the courting male. 
Engelmann (1960b) observed that some females of L. maderae 
do not mate (but their oocytes mature) even though they have access 
to males. He concluded from his observations that “. . . the corpus 
allatum hormone must be present in low titer to stimulate the respon- 
siveness of the female. A high titer of the hormone has no effect since, 
fr >m a total of 80 females, none mated that had oocytes exceeding a 
size of 1.46 mm. Apparently as soon as a certain titer is surpassed, 
the female does not accept the male any more.” Since in Engelmann’s 
experiment the females had constant access to males, his conclusion 
that females will not mate when corpus allatum hormone is high 
is not warranted because these nonreceptive females did not mate 
