A hybrid incompatibility factor in Tribolium castaneum

Hybrid incompatibility and infertility were observed between strains of Tribolium castaneum from India (T-1) and Canada (C). The severity of the syndrome depended on cross direction and temperature. When reared at 32 degrees C, adult hybrids with T-1 fathers produced a high frequency of somatic abnormalities, reduced fertility, and shortened life span. Hybrids with T-1 mothers were normal. At 25 degrees C, abnormalities were more severe and occurred in both reciprocal crosses: hybrids with T-1 fathers died as larvae or pupae, whereas hybrids with T-1 mothers showed a syndrome similar to that produced by T-1 fathers at 32 degrees C. Among a set of strains representing diverse, world-wide geographic origins, eight produced inviable hybrids and nine produced normal hybrids when females were crossed to T-1 males. One of the latter also produced normal hybrids when males were crossed to C females. The syndrome was associated with a dominant factor, H (Hybrid incompatibility factor), which mapped to the ninth linkage group