A number of females of Locusta migratoria have shown tychoparthenogene
tic reproduction (a kind of accidental thelytoky) characterized by: (i
) a female-biased primary sex ratio; (ii) the production of embryos wi
th abnormal ploidy levels, mainly haplodiploid mosaics; (iii) a longer
time for embryo development; and (iv) the capability of producing fem
ale offspring that reproduced in the absence of males. Perfect diploid
ization is not essential for parthenogenetic embryos to reach the adul
t stage but a great majority of embryo cells must be diploid to comple
te properly embryogenesis and hatch. In addition, diploidy is apparent
ly necessary to the ovary of parthenogenetic females so that eggs laid
without mating can hatch. Cytological analyses of embryos at differen
t developmental ages have shown that parthenogenetic embryos begin hap
loid and gradually become diploid, thus passing through a haplodiploid
mosaic stage. The most likely mechanism for ploidy restoration is the
restitution of the sister products of cleavage mitoses, although our
results show that cell fusion could be another mechanism, the relative
importance of which remains to be tested in future work. Although par
thenogenetic females showed a fecundity comparable to that of sexual f
emales, their reproductive output was significantly lower because of a
decrease in the number of embryos per pod and a consequent decrease i
n the rate of embryo production.