Invasive Insect Pests: The Japanese beetle

The Japanese beetle Popillia Japonica Newman (Coleoptera: Scarabaeidae) (Figure 1) has successfully settled in the USA since its introduction from Japan at the beginning of the 20th century and caused considerable damage (EPPO 2016). In addition to bioclimatic suitability, the lack of natural enemies, the spread of grassland and pasture land and a large number of host plants are factors for the high damage potential (Bragard et al. 2018). After a first discovery in Europe on the Azores in the 70s, the Japanese beetle could establish itself in Italy near Milan in 2014 (Pavesi 2014). The beetle has now reached Switzerland and was first detected in June 2017 near the border to Italy in Stabio (EPPO 2017). The Japanese beetle is a quarantine organism in Switzerland and any infestation must be reported and controlled.

The Japanese beetle is about 1 cm long and has a metallic green neck shield and two white tufts of hair on each abdomen. (Shanovich et al. 2019).

Japankäfer
Figure 1. Adult specimens of the Japanese beetle.
© Servizio fitosanitario Ticino (C. Marazzi)

The Japanese beetle can infest over 300 plant species (Fleming 1972). The larvae live mainly from grass roots in damp meadows. In doing so, they damage grasslands. The beetles feed on leaves, fruits and flowers. Affected are forest trees such as maple, beech or oak, but also crops such as apple, stone fruit, vines, corn, soya or blackberries. The development from egg to adult beetle takes one year, in rare cases even two years. The beetle hibernates as the last larval stage (Potter and Held 2002). When soil temperatures rise above 10°C in spring, the larvae migrate upwards and start feeding at the roots. The larvae pupate after 4-6 weeks. The main flying season is between mid-May and mid-August. The perfect soil for laying eggs has a medium to high soil moisture. The knowledge about the life-history was used to simulate the potential geographical distribution of the Japanese beetle under current climatic conditions (Allsopp 1996; Zhang et al. 2002; Zhu et al. 2017; Kistner-Thomas 2019).

The potential distribution and the seasonal occurrence of the Japanese beetle under present and future climatic conditions in Switzerland were estimated bioclimatically using the CLIMEX model (Kriticos et al. 2015). The simulations are based on the model parameters that were tested specifically for the Japanese beetle (Kistner-Thomas 2019) and on the climate scenarios for Switzerland. Until 2019, only in the Canton Ticino between Stabio and Chiasso were Japanese beetles caught in the traps. The simulations for today's climate conditions show that these sites have an optimal bioclimatic suitability (Figure 2). In the future, the potential distribution area could double. By the end of the century, the Swiss Central Plateau should be highly to very highly suitable for the longer-term survival of the Japanese beetle.

Figure 2: Potential distribution of the Japanese beetle under current (1981-2010) and future (2070-2099) climate conditions. The maps show how favourable the climate at a site is for the insect's long-term survival. Results of simulations with model CLIMEX. The map on the right is based on the local climate scenario A2 for Switzerland.

This estimate shows the importance of preventing the spread of the Japanese beetle to northern Switzerland. A detailed analysis showed that cold and moisture stress could decrease in the future. In Switzerland, therefore, no decrease in suitability is visible as in Southern Europe, South America or Africa. (Kistner-Thomas 2019). An extended period of activity can be expected in all areas in the future.

Additional Information

Literature

Allsopp PG (1996) Japanese beetle, Popillia japonica Newman (Coleoptera: Scarabaeidae): Rate of movement and potential distribution of an immigrant species. Coleopt Bull 50 (1):81-95

Bragard C, Dehnen-Schmut K, Di Serio F, Gonthier P, Jacques MA, Miret JAJ, Justesen AF, Magnusson CS, Milonas P, Navas-Cortes JA, Parnell S, Potting R, Reignault PL, Thulke HH, van der Werf W, Civera AV, Yuen J, Zappala L, Czwienczek E, MacLeod A, PLH EPPH (2018) Pest categorisation of Popillia japonica. Efsa Journal 16 (11). doi:10.2903/j.efsa.2018.5438

EPPO (2016) Popillia japonica: procedures for official control. European and Mediterranean Plant Protection Organization Bulletin 46:543-555

EPPO (2017) First report of Popillia japonica in Switzerland. European and Mediterranean Plant Protection Organization (EPPO) Reporting Service No. 09-2017:2017/2160

Fleming WE (1972) Biology of the Japanese beetle. USDA Tech Bull 1449:1-129

Kistner-Thomas EJ (2019) The potential global distribution and voltinism of the Japanese beetle (Coleoptera: Scarabaeidae) under current and future climates. Journal of Insect Science 19 (2). doi:10.1093/jisesa/iez023

Kriticos DJ, Maywald GF, Yonow T, Zurcher EJ, Hermann NI, Sutherst RW (2015) CLIMEX Version 4: Exploring the effects of climate on plants, animals and diseaes. CSIRO, Canberra

Pavesi M (2014) Popillia japonica specie aliena invasive segnalata in Lombardia. L'Informatore Agrario 32:53-55

Potter DA, Held DW (2002) Biology and management of the Japanese beetle. Annu Rev Entomol 47:175-205. doi:10.1146/annurev.ento.47.091201.145153

Shanovich HN, Dean AN, Koch RL, Hodgson EW (2019) Biology and management of Japanese beetle (Coleoptera: Scarabaeidae) in corn and soybean. Journal of Integrated Pest Management 10 (1). doi:10.1093/jipm/pmz009

Zhang QF, Xu Y, Huang XK, Han XM, Xu RM (2002) Prediction of suitable areas for the Japanese beetle in China. Plant Quarterly 16:73-77

Zhu GP, Li HQ, Zhao L (2017) Incorporating anthropogenic variables into ecological niche modeling to predict areas of invasion of Popillia japonica. J Pest Sci 90 (1):151-160. doi:10.1007/s10340-016-0780-5

Last modification 28.01.2021

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