Spilococcus pacificus ( Borchsenius, 1949 )

Ji, Jungyoun & Suh, Soo-Jung, 2024, Diagnosis of Spilococcus pacificus (Borchsenius, 1949) and an updated list of scale insects (Hemiptera: Coccomorpha) on pears (Pyrus L.: Rosaceae) in South Korea, Insecta Mundi 2024 (44), pp. 1-5 : 2-4

Spilococcus pacificus ( Borchsenius, 1949)

( Fig. 1–6 )

Borchsenius (1949) described Pseudococcus pacificus based on specimens found on apples in Primor’ye Kray, Russia. Borchsenius and Kozarzhevskaya (1966) described Paracoccus betulae found on Betula dahurica Pallas from Primor’ye Kray, Okeanskoy, Russia. Danzig (1980) synonymized P. betulae with P. pacificus and transferred it to Spilococcus pacificus (Borchsenius) . Tang (1992) transferred P. pacificus to Atrococcus pacificus (Borchsenius) which was subsequently transferred back to Spilococcus pacificus (Borchsenius) by Ben-Dov (1994). Paik (1978) misidentified the species as Crisicoccus seruratus ( Kanda 1933) , a species which Tanaka and Kamitani (2022)

Family Species Family Species

Monophlebidae Drosicha corpulenta (Kuwana) Coccidae Nipponpulvinaria horii (Kuwana)

Pseudococcidae Dysmicoccus wistariae (Green) Parthenolecanium corni (Bouché)

Planococcus citri (Risso) Parthenolecanium glandi (Kuwana)

Planococcus kraunhiae (Kuwana) Parthenolecanium persicae (Fabricius)

Pseudococcus comstocki (Kuwana) Diaspididae Comstockaspis perniciosa (Comstock)

* Spilococcus pacificus (Borchsenius) Lepidosaphes conchiformis (Gmelin)

Coccidae Ceroplastes ceriferus (Fabricius) Lopholeucaspis japonica (Cockerell)

Ceroplastes japonicus Green Parlatoria theae Cockerell determined to be a senior synonym of Crisicoccus matsumotoi ( Shiraiwa 1935) . Kwon and Han (2003), Kwon et al. (2003) and Suh (2020) misidentified S. pacificus as Crisicoccus matsumotoi ( Shiraiwa 1935) .

Field diagnosis. Body of adult female about 2.5 mm long, soft and wingless, elongated oval, reddish orange in color, covered with white mealy wax; with short wax filaments on each abdominal side of body. During slidemounting, body contents turn green-black in KOH.

Characteristics of slide-mounted adult female. Body elongate oval, about 2.0 mm long and 1.5 mm wide. Anal lobes well developed; dorsal surface of each lobe with a slightly sclerotized area; ventral surface with well-developed anal lobe bar and long apical seta. Antenna with 8 segments. Legs well developed; hind coxa with translucent pores; claw without a denticle. Circulus usually quadrate. Cerarii numbering 7–8 pairs, all present on abdominal segments; usually each with 2 conical setae. Dorsum with a few oral rim tubular ducts present on submarginal to medial areas of head, thoracic and abdominal segments.

Distribution. China, Russia, South Korea ( García Morales et al. 2023).

Hosts. Betula dahurica ( Betulaceae ), Styphnolobium japonicum (L.) Schott ( Fabaceae ), Broussonetia kazinoki Siebold , Morus sp. ( Moraceae ), Fraxinus sp. ( Oleaceae ), Malus mandshurica (Maxim.) Kom. , M. pumila Mil. , Prunus sp. , Pyrus pyrifolia , P. ussuriensis Maxim. ( Rosaceae ), Acer palmatum Thunb. ( Sapindaceae ) ( García Morales et al. 2023).

Material examined. South Korea. GG: Pyeongtaek , 1 female, on Pyrus pyrifolia , 2-x-2008 (S.J. Lee) ; Anseong , 4 females, same host plant, 30-x-2023 (J. Ji). GB: Gumi, 1 female, on P. pyrifolia , 8-ix-2009 (Y.H. Lee) ; same data, except for 29-x-2007 ; Gunwi , 2 females, P. ussuriensis , 13-ix-2012 (S.J. Suh). JN: Naju, 1 female, on P. pyrifolia , 21-ix-2006 (S.J. Lee) ; same data, except for 13-viii-2007 ; Naju , 26 females, P. pyrifolia , 28-viii-2007 ; Naju , 7 females, same host plant, 28-viii-2007 ; Naju , 3 females, same host plant, 5-x-2007 ; Naju , 1 female, same host plant, 23-x-2007 ; Sinan , 2 females, same host plant, 26-x-2007 ; Naju , 2 females, P. pyrifolia , 30-x-2007 ; same data, except for 2-xi-2007 ; same data, except for 3-xi-2007 ; Naju , 1 female, same host plant, 19-v-2008 ; Naju , 7 females, same host plant, 23-xi-2023 (N.Y. Lee) .

Remarks. This mealybug is fairly common in pear orchards in South Korea. Spilococcus pacificus , compared to the other mealybugs found on pears in South Korea, is most similar to Pseudococcus comstocki , but can be differentiated from that species by having 7–8 pairs of cerarii and about 90 multilocular disc pores on abdomen, provide here the unique character states of S. pacificus . It may also be confused with Planococcus citri and Planococcus kraunhiae but differs from those species by having oral rim tubular ducts.

Figures

Figures 1–6. Spilococcus pacificus (Borchsenius) on pear trees. 1–2) Habitus. 3) Adult female. 4) Head (black arrows: oral rim tubular ducts). 5) Hind leg (black arrow: translucent pores). 6) Anal lobe cerarius (black arrow: anal bar).