Interest in the role of insects in transmitting various fungi and in the potential for outbreaks of insects vectoring plant disease organisms has resulted in a large volume of literature on insect-fungi relationships. Mites are mentioned as an important third partner in these associations. This paper summarizes information and provides an update on major aspects of these intricate associations in the context of woody substrate, modern forestry, global climate change and international trade with wood products. This paper discusses the partners separately and comments on their potential pathogenicity, the reason for the associations and how are they maintained, and addresses the complexity of the research around these issues. Beetles as well as fungi range from being secondary, harmless and pure saprotrophs to being aggressive and pathogenic. Globally there are a number of examples where particular insect-fungi combinations have caused significant economic losses, especially when exotic organisms are imported. The vector-fungus relationship is a strategy that makes both groups ecologically effective; together they spread fast, may have high plasticity, invade new territories, evolve and explore new crops on a global scale. There is an increased awareness of invasive species and more vigorous inspections in many countries causing trade disruptions and market loss. Wood packaging, logs and green lumber are generally considered to be a high-risk pathway. Currently the ISPM-15 standard imposes obligatory phytosanitary treatment (heat treatment at 56°C for 30 minutes to the core or fumigation with methyl bromide) of wood packaging in international trade. Other alternative treatments are actively being investigated and will cover a larger array of traded commodities. Chemical pressure impregnation has been shown to be effective in eradicating some pests. If approved internationally as a phytosanitary treatment it would facilitate trade in treated wood products, protect existing markets and open new ones. It will also reduce the potential cost of additional treatment for phytosanitary purposes. Further research is needed in this area to define effective treatment parameters.

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