A Unisexual Strain of the Salt-Marsh Caterpillar, Estigmene acrea123

A predominantly female strain of the salt-marsh caterpillar, Estigmene acrea (Drury), has been maintained in the laboratory for 7 generations. Females must mate before they can produce viable eggs, but there has been no evidence of mating-induced parthenogenesis. The unisexual trait is maternally inherited and appears to be caused by a cytoplasmic factor that kills male embryos. When hemolymph from a pupa of the unisexual strain was injected into a female pupa of a bisexual strain, the resulting adult produced only females. The induced unisexual condition was not permanent, since the progeny of the injected female produced moths of both sexes.