Batocera rubus detected in a bonsai plant in France
The NPPO of France recently informed the EPPO Secretariat of the finding of Batocera rubus (Coleoptera: Cerambycidae) in Nanterre (Hauts-de-Seine, Ile-de-France region) on a single bonsai plant (Ficus microcarpa). One adult beetle (5 cm long) emerged from the bonsai and was captured by the owner of the plant. This bonsai had been bought in a French shop but had originally been imported from the Netherlands most probably from an Asian country (investigations are under way to identify the exact origin of the plant). This bonsai plant was examined and subsequently destroyed, but no other insect specimens were found. A short PRA will be carried out by the French NPPO to evaluate the potential risks that B. rubus may present. Interestingly, the NPPO of the Netherlands had detected a similar species, B. rufomaculata (mango tree stem borer) in a glasshouse nursery in February 2005. One larva of B. rufomaculata was found in a stem of a Ficus bonsai originating from China. These incidents highlight once again the risk of introducing tree borers (even large species) with imports of bonsai plants.
B. rubus is widespread in Asia, and according to the CABI Crop Protection Compendium (CPC) it occurs in the following countries:
Asia: Bangladesh, Brunei Darussalam, Cambodia, China (Fujian, Guangdong, Hainan, Hong Kong, Sichuan, Taiwan Xizhang), India (Assam, Karnataka, Kerala, Madhya Pradesh, Maharashtra, Meghalaya, Tamil Nadu, West Bengal), Indonesia (Java, Kalimantan, Nusa Tenggara, Sumatra), Laos, Malaysia (Peninsular, Sabah, Sarawak), Myanmar, Pakistan, Philippines, Singapore, Sri Lanka, Thailand, Vietnam.
B. rubus is a polyphagous insect which attacks many tree species but its main hosts are mango (Mangifera indica), fig (Ficus carica), rubber (Hevea brasiliensis) jack fruit (Artocarpus heterophyllus) and bread fruit trees (Artocarpus altilis and other species). According to Hill (1975), B. rubus and its larger relative B. rufomaculata are frequently encountered in fruit trees and various woody ornamentals in Asia, but B. rubus is seldom a serious pest (whereas B. rufomaculata can be a more damaging pest, in particular on fig and mango trees). Larvae of B. rubus (fully grown larvae can reach 60-80 mm long) bore into the trunk and main branches. On damaged branches, the foliage may die and fruit set may be impaired. Mortality is not commonly seen but it has been reported from Sri Lanka on infested breadfruit trees. Adult beetles emerge through of holes of approximately 20 mm diameter. They are greyish-brown longhorn beetles (30-60 mm long) with conspicuous spots (usually white) on the elytra. Adults feed on green stems and leaves. The number of generations probably varies according to the climatic conditions (from 1 to 3 or more generations per year).
Many pictures of the adults can be viewed on the Internet, for example: www.zin.ru/Animalia/Coleoptera/eng/ziarko2.htm www.singaporeinsects.com/lamiinae/Batocera%20Rubus.jpg
Sources
NPPO of France (2011-05).
NPPO of the Netherlands (2005-10). Short PRA. Batocera rufomaculata, mango tree stem borer. http://www.vwa.nl/onderwerpen/english/dossier/pest-risk-analysis/evaluation-of-pest-risks
Hill D (1975) Agricultural insect pests of the tropics and their control. 2nd edition. Cambridge University Press (GB), p 448.
CABI Crop Protection Compendium (2011) Batocera rubus. www.cabi.org/cpc