Abnormal development of embryos induced by inbreeding in Delphacodes pellucida Fabricius and Delphacodes dubia Kirschbaum (Araeopidae, Homoptera), vectors of European wheat striate mosaic virus

The embryos of Delphacodes pellucida Fabricius show various types of abnormalities, and the proportion of abnormal eggs depends on the degree of relationship between the parents. Abnormalities were rare in eggs of females mated to males of another family, but they increased with sibling matings. Many eggs from the first generation of inbreeding were abnormal and failed to hatch, and in the second generation some that hatched produced sterile females. Embryos became abnormal at various stages of growth. D. pellucida is a vector of European wheat striate mosaic virus, and the eggs produced by several groups of infective and noninfective females of laboratory colonies were compared, but no consistent effects of virus on embryonic development were noted. Delphacodes dubia Kirschbaum, a newly discovered vector of European wheat striate mosaic virus, showed abnormalities of embryonic development similar to D. pellucida. Inbreeding, whether or not the individuals were infective, caused abnormalities