FOOD CHAIN CRISIS | EMERGENCY PREVENTION SYSTEM | INFORMATION SHEETS

THE BEETLE’S IMPACTThe female beetle carries several fungal species – one of which is Fusarium euwallaceae – with it when it infests new trees. It makes a hole in the newest layer of the tree and inoculates the fungus into the living wood. The fungus grows in the galleries made by the beetle and serves as food for the beetle larvae. The fungus invades the tree’s vascular system causing branch dieback and subsequently the death of the host tree.

In California, surveys conducted in botanical gardens revealed that more than 200 tree species have been infested, damaged and are often killed by these organisms.

In South Africa, the most visible impact of the PSHB

invasion is in urban forests on street, park and garden trees. Both the horticultural and the commercial forest industries are concerned about the impact of this pest.

It is unlikely that PSHB invasions can be stopped. However, integrated pest management strategies, including biological control, are currently in progress to reduce its impact.

FAO’S ACTIONSTo help member countries address and manage the increased threats to forest health from invasive species such as PSHB, FAO facilitates the Forest Invasive Species Networks for Africa, Asia-Pacific, Europe and Central Asia,

The polyphagous shot hole borer (PSHB), Euwallacea whitfordiodendrus, is an ambrosia beetle (Coleoptera: Curculeonidae: Scolytinae) native to Southeast Asia. The beetle is associated with the fungal symbiont Fusarium euwallaceae.

PHSB and its fungal symbiont attack many different forest and fruit tree species.

It has emerged as an important invasive pest, killing avocado and other urban trees in Israel and the United States of America (especially the State of California) in the early 2000s.

The PSHB and its fungus were discovered in South Africa in 2017. It has already been reported on several popular tree species grown in urban areas of South Africa, and is also a pest of pecan nut trees, avocado trees and other fruit trees.

INVASIVE BEETLE THREATENS FOREST AND FRUIT TREES

FOOD CHAIN CRISIS | EMERGENCY PREVENTION SYSTEM | INFORMATION SHEETS

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KEY FACTS

FAO-Forest health

and the Near East. These networks improve the exchange of information, knowledge and expertise on issues relating to invasive species and enhance collaboration in the regions. They specifically focus on intercountry and interregional cooperation that helps to detect, prevent, monitor and control forest invasive species affecting forests.

In 2014, PSHB caused severe damage to Acer buergerianum, an important urban tree species in Kunming, Yunnan province, China. PSHB has two or three generations a year in Kunming and overwinters as an adult or as a larva.

To face the challenge posed by the beetle in this area, FAO facilitated the China-Viet Nam-United States of America Cross-border Cooperative Study on the Polyphagous Shot Hole Borer and Fusarium Dieback, within the framework of the Asia-Pacific Forest Invasive Species Network (APFISN). The main objectives of this initiative were to determine the beetle’s life cycle, to contribute to taxonomic studies on PSHB and its fungal complex, survey potential biological control candidates, and assess the impact of PSHB-FD on tree species and current management options.

This cross-border cooperative field study on PSHB is only one example of international collaboration and cooperation efforts between network members.

In 2016, the APFISN conducted a workshop in Beijing on the identification of invasive bark beetles, including PSHB.

In 2017, the Forest Invasive Species Network for Europe and Central Asia (REUFIS) conducted a workshop focused on the relationship between climate change and invasive species, with a specific training session devoted to bark and ambrosia beetles and their impacts.

FAO through the networks continues to support the countries to minimise the spread of this pest into new areas.

REFERENCESGomez DF, Skelton J, Steininger MS,

Stouthamer R, Rugman-Jones P, Sittichaya W, Rabaglia RJ, Hulcr J. (2018) Species delineation within the Euwallacea fornicatus (Coleoptera: Curculionidae) complex revealed by morphometric and phylogenetic analyses. Insect Systematics and Diversity 2(6):1-11.10.1093/isd/ixy018.

Paap T, de Beer ZW, Migliorini D, Nel W, Wingfield MJ. (2018) The polyphagous shot hole borer (PSHB) and its fungal symbiont Fusarium euwallaceae: a new invasion in South Africa. Australasian Plant Pathology 47(2):231-237. 110.1007/s13313-018-0545-0.

e-mailFood-Chain-Crisis@fao.org

WebsiteSwww.fao.org/food-chain-crisis

http://www.fao.org/forestry/pests/en/Food and Agriculture Organization of the United Nations

THE POLYPHAGOUS SHOT HOLE BORER (PSHB) IS AN AMBROSIA BEETLE THAT

IS NATIVE TO SOUTHEAST ASIA

THE PHSB SPREAD TO ISRAEL AND THE UNITED STATES OF AMERICA

(ESPECIALLY, THE STATE OF CALIFORNIA) IN THE EARLY 2000S. IN 2017, IT WAS DISCOVERED, TOGETHER WITH ITS

FUNGUS, IN SOUTH AFRICA

THE SPREAD OF THE BEETLE AND THE FUNGUS IS OF MAJOR CONCERN TO

FARMERS, FORESTERS, LANDSCAPERS, HOMEOWNERS AND ECOLOGISTS, AS BOTH PESTS ARE AGGRESSIVE

TREE KILLERS

MUCH ABOUT THE PSHB REMAINS UNKNOWN. WHAT IS KNOWN IS THAT

THE BEETLE POPULATION CAN EXPAND ITS RANGE BY APPROXIMATELY

12 MILES A YEAR. THE BEETLE FLIES FROM TREE TO TREE. MOVEMENT

OF PACKING WOOD AND FIREWOOD HELPS THE BEETLE TO SPREAD

THE FOREST INVASIVE SPECIES NETWORK FOR AFRICA ,THE

ASIA-PACIFIC FOREST INVASIVE SPECIES NETWORK, THE FOREST

INVASIVE SPECIES NETWORK FOR EUROPE AND CENTRAL ASIA WORK TO LIMIT THE SPREAD AND THE DAMAGE

POTENTIALLY CAUSED BY THIS PEST

POLYPHAGOUS SHOT HOLE BORER

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