Crisicoccus pini feeds on Pinaceae and is most frequently recorded on species in the genus Pinus. In China, it has also been recorded on plants in the genera Abies, Keteleeria and Larix (Chen et al., 2005), but in North America and Europe, it has only been reported developing on Pinus. It has been intercepted at a US port-of-entry on Pinus sp. and Taxus sp. (Taxaceae) imported from Japan (Miller et al., 2014), but the significance of the Taxus record is unknown and there is some likelihood of cross-contamination in transit from infested Pinus (EPPO, 2023).

Crisicoccus pini is native to Japan (Boselli & Pellizzari, 2016) and has been introduced to other parts of Asia, as well as to North America (Kosztarab, 1996; Miller et al., 2005; von Ellenrieder, 2025), and Europe. There is a single record from Monaco (Germain & Matile-Ferrero, 2006), and a mistaken record from France which appears to be based on the Monaco record (EFSA PLH Panel, 2021; Foldi & Germain, 2018; Germain & Matile-Ferrero, 2006).

The biology of C. pini has been studied in Qingdao, Shandong province, China (Chen  et al., 2005, 2006). It reproduces sexually and has two generations each year. Each female lays about 50 eggs in an ovisac/felt-like wax covering, which is usually found at the junction between the twig and base of the needles. Females have three nymphal instars, and the males have four. The final two male nymphal instars (called prepupa and pupa) are sessile and do not feed. Adult female numbers peak between the end of May to early June, and at the end of September to early October. In the autumn, most of the nymphs migrate from the needles onto the branches, or the lower part of the trunk, to overwinter in bark crevices. In the following spring, they migrate to the new needles. The lower threshold temperature for development is about 13°C and the effective accumulated temperature is 456.7 degree-days (DD) above this threshold. The optimum temperature for development is 25°C. The percentage of eggs hatching was above 90% at temperatures between 21°C and 27°C and decreased at temperatures between 33°C and 36°C. Population levels in Qingdao decreased sharply during hot summers. Average high temperatures in Qingdao in June, July and August are 25°C, 28°C and 29°C, respectively. Kuwana (1902) reported C. pini to be viviparous (producing living young nymphs instead of eggs); however, subsequent studies recorded eggs (Chen  et al., 2005). The first instars (crawlers) of many species of scale insect remain protected under the body of the adult female for a period after hatching and emerge at the same time. Kuwana may have observed large numbers of first instars under the body of an adult female and misinterpreted this as vivipary. Recent observations from Italy also reported C. pini as laying eggs (Boselli & Pellizzari, 2016).

Symptoms

Crisicoccus pini feeds on growing needles and infested tree canopies can exhibit extensive yellowing, necrosis, needle drop and dieback. Host mortality has been observed in Italy (EPPO, 2019). Black sooty mould grows on honeydew egested by the mealybugs, and this contrasts with the white wax secreted by the insects, making large infestations conspicuous.

Morphology

Adult females are broadly oval, 2–4 mm long and up to 2 mm wide, body light orange or reddish and covered in mealy white wax, with short wax filaments on the margin of the last four to six abdominal segments (Kuwana, 1902; Tanaka & Kamitani, 2022). The legs and antennae are brown. Mature females become enveloped in a white cottony wax coat (Kuwana, 1902). The first nymphal instars are oval, 0.35 mm long (Kuwana, 1902). The second and third female nymphal instars are similar in appearance to the adult female but are smaller. The eggs are pink and oval. Males do not appear to have been described other than the information mentioned above.

Crisicoccus pini can only be accurately identified by examination of slide-mounted adult females under a compound light microscope. Morphological descriptions and illustrations of adult female C. pini are provided by Ferris (1950), McKenzie (1967), Kosztarab (1996), Tu  et al. (1988), Danzig and Gavrilov-Zimin (2010, 2015) and Tanaka and Kamitani (2022). Currently, the genus Crisicoccus comprises 37 species that are mainly found in Asia and the Australasian region (Danzig & Gavrilov-Zimin, 2010, 2015). There is no single comprehensive key for the identification of Crisicoccus, but the species present in the Palearctic can be identified using the keys provided by Danzig and Gavrilov-Zimin (2010, 2015), in Japan by Tanaka and Kamitani (2022), in the Republic of Korea by Kwon  et al. (2003), and Son and Suh (2017), and in North America by Ferris (1950), McKenzie (1967) and Kosztarab (1996).

Detection and inspection methods

All developmental stages of C. pini can be found by visual inspection of plant material using a ×10 hand lens, especially of the growing needles. The mealybugs secrete a mealy white wax that covers the body (Boselli & Pellizzari, 2016) and mature adult females may be enveloped in white felt-like wax, which makes them conspicuous. When the population densities of C. pini are high, groups of adult females with ovisacs may be observed on the main trunk. During the autumn and winter months, nymphs may be observed in bark crevices.

Natural spread of C. pini by the first instars crawling or being carried by wind, other animals or machinery occurs locally and relatively slowly. Faster and long-distance movement is likely to be due to adult females and immature stages being carried with plant material in trade, especially with plants for planting (except seeds, tissue culture and pollen).

Economic impact

Feeding by C. pini causes yellowing and necrosis of pine needles (Boselli & Pellizzari, 2016). The mealybugs excrete copious quantities of sticky honeydew that smothers the plant and serves as a medium for the growth of sooty moulds, limiting photosynthesis and gas exchange of needles (EPPO, 2019). In China, C. pini is reported to be a pest of Abies sp., Keteleeria sp., Larix sp., P. densiflora (Japanese red pine), P. massoniana (Masson's pine), P. tabuliformis (Chinese red pine) and P. thunbergii (Japanese black pine or black pine) (Chen  et al., 2005). It has become a major pest of P. densiflora and P. thunbergii in Qingdao since about 1998, causing chlorosis, premature needle drop, branches drooping, poor or no growth, reduction in the size of the needles and many trees were dying (Chen  et al., 2005, 2006). Tang (1984) recorded C. pini being injurious to P. tabuliformis in Northern China. In Italy, it was first detected in September 2015 causing extensive damage to ornamental pines planted along streets and in private gardens in the region of Emilia-Romagna (Boselli & Pellizzari, 2016; EPPO, 2019). A severe decline of P. pinaster (maritime pine) and P. pinea (stone pine) was reported. In southern California (United States), C. pini is considered a minor pest of ornamental P. radiata (Monterey pine) and P. thunbergii along the coast in southern California (Natalia von Ellenrieder, pers. comm., 2025). Crisicoccus pini is reported to have the potential for causing negative environmental impacts in the Mediterranean region by reducing the health of pine forests (Watson & Mifsud, 2017).

Control

An outbreak of C. pini on pines in Italy was successfully managed by a combination of chemical, biological and cultural measures. The most severely infested trees were removed, infested branches on trees expected to survive were pruned, abamectin was applied through trunk injections (endotherapy) and the predatory coccinellid Cryptolaemus montrouzieri Mulsant was released in the spring and summer. After 3 years, there was a significant reduction in mealybug density (average of 5.72 mealybugs per shoot dropped to 0.09), a consistent presence of C. montrouzieri was observed, and the chemically treated pine trees showed signs of recovery (Boselli  et al., 2018).

Many natural enemies of C. pini have been recorded in China, which could be assessed for biocontrol, including predatory coccinellid beetles (Chilocorus kuwanae Silvestri, Coccinella septempunctata L., Harmonia axyridis Pallas and Propylea sp.), lacewings (larvae), hoverflies (larvae), true bugs and parasitoid wasps (Allotropa sp.) (Chen  et al., 2005).

There is limited information available on host–plant resistance or on methods of cultural control.

Phytosanitary risk

Crisicoccus pini was added in 2023 to the EPPO A2 List of pests recommended for regulation as a quarantine pest (A2 listed pests are locally present in the EPPO region), and EPPO member countries at risk are recommended to regulate it as a quarantine pest. It is a quarantine pest in the United Kingdom (since 2023).
Crisicoccus pini has the potential to establish throughout a considerable part of the EPPO region, wherever suitable hosts occur (EPPO, 2023) and presents a potential risk to Abies, Larix and Pinus grown in commercial plantations, in parks and gardens, and in the wider environment. Keteleeria is also at risk but is uncommon in the EPPO region, usually occurring as specimen trees in botanical gardens and specialist collections. There is also a possibility that the presence of C. pini in a country may create difficulties for the export of planting material.

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