 One possible reason for this scarcity is the presence of a bacterium in the genus "Wolbachia", which is endosymbiotic in the females' gametes.A female infected with "Wolbachia" produces only diploid eggs, when in the cells of the ovaries presumably cause the fusion of the pronuclei, which leads to entirely female progeny.When the females were treated with antibiotics, they were then able to produce normal male and female eggs.