Citrus fruit flies of Sichuan Province (China)

The fruit fly pests on Sichuan citrus include Tetradacus citri and T. tsuneonis (Diptera: Trypetidae), regarded as distinct species in China. Special attention has been paid to the former, which is a quarantine pest in China. It is distributed in 18 counties of Sichuan Province and has caused serious losses in citrus orchards. Its hosts are all the citrus fruits, especially orange and pomelo. T. tsuneonis is distributed in only two counties and attacks only tangerine, but it is a potential hazard to all citrus crops in the province. Both species have only one generation per year. The pupae overwinter in soil. Emergence of T. citri begins at the end of April. Before oviposition the adults need supplementary nutrients. Twenty days after emergence, copulation begins and 15 days later the adult begins ovipositing (peak period mid‐June to early July). The peak period for hatching is in early September. After three instars, the larva becomes mature in mid‐October. The peak period of pupation is from the end of October to mid‐November. Emergence of T. tsuneonis is about 15 days later than T. citri. The larvae bore the flesh of citrus fruits, causing great loss to citrus growers every year. Surveys are regularly conducted to check the distribution of the pests in Sichuan Province. Quarantine regulations enacted in 1982 and 1984 regulate the movements of articles that could spread the pests, with specified safeguards. Before female oviposition, spraying with trichlorfon in sugar solution gives satisfactory results in controlling citrus flies in orchards.