The obscure mealybug, Pseudococcus viburni (Signoret, 1875) (Hemiptera: Pseudococcidae) is a polyphagous cosmopolitan pest, damaging vineyards and fruit orchards, including apple, pear, strawberry, plum, grapevine, persimmon, mango, etc. (Mani and Shivaraju, 2016). The species was formerly known as Pseudococcus affinis (Maskell) or Pseudococcus obscurus (Essig), and both were synonymized to P. viburni (Ben-Dov and Matile-Ferrero, 1995). Pseudococcus viburni is placed within the maritimus species complex (Wilkey and McKenzie, 1962), and is considered as a native US pest (Miller et al., 2005).

The species has long been quarantined in Korea and has never been recorded in the wild in Korea. However, one note in Gimpel’s Ph.D. dissertation (1983) unexpectedly added Korea in its distribution, with one sample which is noted collected on persimmon.

We consider the occurrence note of P. viburni in Korea by Gimpel is an error, probably by misidentification. Even Gimpel stated that this species is unusually variable and so difficult to identify morphologically, such as from P. maritimus (Ehrhorn). He also mentioned that the species is possibly mixed with more than one species and no single character can separate the species from others. In fact, a molecular and morphological phylogenetic analysis of Pseudococcidae confirmed that P. viburni and P. maritimus are more closely related to each other than to their congeners (Hardy et al., 2008).

To confirm the absence of P. viburni in Korea, we have searched for the species from the orchards of apple, pear, grape, tomato, and persimmon as well as nurseries and greenhouses in Korea. 533 sites of persimmon orchards, 144 sites of apple and other orchards, and 281 sites of nurseries and greenhouses were surveyed for the last three years (2015- 2017) (Supplementary Table 1). Whenever any mealybugs are found, at least one mealybug sample per each site was either slide-mounted for morphological identification or DNAextracted for molecular barcode identification if further confirmation is needed.

As we suspected, and noted in our survey result presented in Australia (Jeong et al., 2017), not even one specimen of P. viburni was found through the extensive survey. Our conclusion based on the survey on the Pseudococcus pest species in Korea is the following: