Journal of Taiwan Agricultural Research

Author:Yun Cheng, Dong-Hong Wu, Zu-Hsien Wang, Yu-Bing Huang,*, Ming-Yao Chiang, Hsiu-Ying Lu, and Chung-Min Yang

Abstract:

    The melon fly, Zeugodacus cucurbitae (Coquilett), does not possess the dorsocentral (DC) bristles. In a selected DC (+)-line, two rows of 4–6 median size macrochaetes appeared in the dorsocentral domain of scutum and it is interesting to explore its morphological identity and genetic origin. In morphology, these DC (+) bristles fit into the dorsocentral domains of Diptera chaetotaxy ground plan and those of model insect species, Drosophila melanogaster and Ceratitis capitata. In genetics, by crossing wild type to DC (+)-line, the majority of F₁ progeny were DC (–) phenotype or wild type. Segregation pattern of DC (+) and DC (–) phenotypes in the F₂ progeny fit a 1 : 3 inheritance pattern, with DC (–) phenotype being dominant. The backcross of F1 to the DC (+)-line produced a 1 : 1 ratio in respect to DC (+) and DC (–) phenotypes, while F₁ backcross to wild type produced most DC (–) progeny, confirming that DC (+) bristle was suppressed by a single dominant gene. The gene was given the symbol DCm for DorsoCentral bristles masked. The DC (+) bristle was stereotype patterned instead of randomly expressed, hence the atavistic origin is preferred.

Key words: Dorsocentral bristles, Melon fly, Atavistic origin

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