Pests of the forest are spreading

Mountain pine beetle infested forest
Mountain pine beetle infested forest in BC, Canada © Simon Fraser University Public Affairs and Media Relations (CC BY 2.0 license)

Much is covered in the news about deforestation by humans, but less is widely known about the damage done to forests by pests and diseases. The Food and Agriculture Organization (FAO) produces an assessment of the world’s forest resources every five years. Their last report highlighted the effect that climate change will have on forests and their pests.

“A changing climate will alter the disturbance dynamics of native forest insect
pests and pathogens, as well as facilitating the establishment and spread of introduced
pest species.”

There have already been incidences of pests spreading due to abnormally high winter temperatures. For example, the mountain pine beetle, Dendroctonus ponderosae, has been expanding its range in North America for the past fifteen years. Where it was once a pest of the southern Rocky Mountains and west of the American Continental Divide, it is now moving north and east where winters are becoming milder.

When trees suffer climate induced stress from increased drought and extreme climatic events such as storms, they become more susceptible to damage from pests. Also, a pest that establishes in a new territory doesn’t always have the natural enemies present to keep its population numbers in check, providing opportunities for severe outbreaks.

The increased connectivity between countries has facilitated the global spread of forest pests.

“The volume, speed and variety of global trade have increased the opportunities for
pests to move internationally.”

Phytosanitary measures at borders are important now more than ever, to ensure that movement of pests within shipments is limited wherever possible.

There is little information on the global distribution of forests pests, particularly in developing countries. This data is necessary to perform pest risk analyses and provide early warning systems for countries. With a changing climate, it is vital that countries work together to monitor and protect against these pests.

Find out more about forests for International Day of Forests:

FAO (2010) Global Forest Resources Assessment 2010. FAO Forestry Paper 163.

Separating the grains from the chaff, and all the pests that move with it

Contributed by Melanie Bateman, CABI Switzerland, and Roger Day, CABI Africa

Larger stem borer, threat to food security (image: infonet-biovision)

While responding to a food crisis in Tanzania in the 1970s, evidence indicates that the larger grain borer (Prostephanus truncatus) was inadvertently introduced into Africa through an infested food aid shipment[1]. Following this introduction and a later introduction in West Africa, the larger grain borer has now spread to almost 20 different countries in Africa, causing significant losses to grains in the field and in storage both for food and for planting. Consequently, this fateful incursion has had a significant impact on food security in the continent. Even now, other alien pest species such as beetles, snails, weeds and pathogens[2] are intercepted in shipments of grains worldwide. Should these pests become established in new areas, farmers will be confronted with problems they may be ill equipped to solve.

 In order to address this pathway for pest spread, the Commission on Phytosanitary Measures added the topic of the international movement of grains to its work programme and member countries were asked to agree on the best way to approach the issue. While several countries noted the broad scope and complexity of the topic, many countries urged for the development of an international standard. Jack-Vesper Suglo of Ghana noted that

the movement of grain is important for food, but it is also a major means of movement of pests. Africa has been the victim of the movement of pests through grain.

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Invasive species by sea: What can be done?


Contributed by Roger Day and Melanie Bateman from Rome

One major cause of pest spread- sea shipment containers- was a key discussion topic on the first evening of the IPPC’s week-long annual meeting, the CPM8. With over 35 million sea shipments each year, regulation is both crucial and extremely complex.

“The complexity of the situation is such that the EU doesn’t hold a common position on the issue,” noted the EU delegate yesterday. One suggestion was to conduct a survey to clarify the nature and extent of the problem, but even that’s complex.  “Surveys can be difficult, and one on sea containers gives me a headache just thinking about it” said the delegate from New Zealand who is the steward for the proposed standard.

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