First report of Bradysia difformis (Diptera: Sciaridae) Damage to Phalaenopsis orchid in China

• A new insect pest damaging seedling of Phalaenopsis orchid in southern China was reported.
• The pest was identified as Bradysia difformis Frey based on morphological and mt COI molecular characteristics.
• The pest was found in almost every greenhouse with an average temperature of 28 °C and a relative humidity of 70%.

Phalaenopsis orchid is among the most valuable ornamental flowering plants in the world. Since visible damage substantially decreases its amenity, limited damage is allowed in its production. An unknown insect species (Diptera: Sciaridae) was found to cause serious damage to the seedling of the Phalaenopsis orchid in greenhouses in Guangdong, China. The insect occurred in high populations in almost all greenhouses that grow Phalaenopsis orchid and the number of sciarid adults trapped on a yellow sticky card could reach as many as 303 in 24 h. An effective management strategy on any pest requires an accurate identification. Therefore, it is urgent to identify this pest correctly to mitigate its damage to the industry. Damage to Phalaenopsis orchid and morphological characteristics of the pest was described in this study. Molecular analyses based on the 488-bp portion of the mitochondrial DNA from the cytochrome oxidase I(mt COI) region were conducted to supplement morphological characteristics in identifying this pest. Both morphological characteristics and phylogenetic tree constructed with mt COI genes identified this sciarid as Bradysia difformis Frey, 1948 (= Bradysia paupera Tuomikoski, 1960) (Diptera: Sciaridae). A literature search indicated that B. difformis has been a common pest of greenhouse and forestry nurseries in Europe and South Africa. Our study is the first record of B. difformis damaging Phalaenopsis orchid in China.

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