Insect-truffle interactions – potential threats to emerging industries?

Effect of slug mycophagy on Tuber aestivum spores

Truffles in the genus Tuber produce subterranean fruiting bodies that are not able to actively discharge their spores in the environment. For this reason, truffles depend on mycophagous animals for reproduction. Fungus consumption (mycophagy) is a behaviour typical of both vertebrates and invertebrates. Mammals, especially rodents, are the most studied group of mycophagists and have been found to consume a great variety of fungi. Among invertebrates, mycophagy is documented in arthropods, but rarely in molluscs. In our study we assessed the effect on the morphology and mycorrhizal colonization of Tuber aestivum spores after passage through the gut of slugs (Deroceras invadens) and, for comparison, of a house mouse (Mus musculus). Light, scanning electron and atomic force microscopy revealed that the digestion, especially by slugs, freed spores from the asci and modified their morphology. These are believed to be the reasons why we observed an improvement in oak mycorrhization with the slug and rodent ingested spores in comparison to a fresh spore inoculation. We also demonstrated by molecular barcoding that slugs' guts sampled on a Tuber melanosporum truffle ground contain spores from this species and Tuber brumale, further suggesting that some invertebrates are efficient Tuber spore dispersers.

Virtual Truffle Hunting—A New Method of Burgundy Truffle (Tuber aestivum Vittad.) Site Typing

The aim of this study was to enable searches for truffles (Tuber spp.), particularly the Burgundy truffle (T. aestivum Vittad.), to be carried out in forests based on a method that has been constantly developed since 2007 by the Forest Research Institute. The method is termed “Virtual Truffle Hunting” and it takes 12 parameters into account: bedrock, soil pH, Ca+ and CaCO3 content in soil, C/N ratio, soil structure, altitude of terrain, type of forest site, forest structure, the Burgundy truffle host trees, and the presence of particular species including orchids and insects. A simple “Virtual Truffle Hunting” software has also been developed, which makes the use of the method easy, fast, and effective. This method is to ascertain the truffle potential for all areas in which digital maps are not available. In 2015, the method was tested in 20 sites, representing forests in 5 Polish macroregions. Hunting for hypogeous fungi was conducted from June to October with the help of trained dogs. Thanks to this method, 14 new truffle sites were found. The knowledge of environmental conditions conducive to the Burgundy truffle growth enabled us to form an effective tool in order to identify new sites of truffle presence.

A risk assessment of Europe's black truffle sector under predicted climate change

The black truffle (Tuber melanosporum) is a highly revered culinary icon species that grows symbiotically with its host trees across several parts of southern Europe. Where harvested under natural or cultivated conditions, truffles can have a significant socioeconomic impact and may even form a key component of cultural identity. Although some aspects of truffle biology and ecology have been elucidated recently, the role of abiotic, environmental and climatic factors in the production and maturation of their fruitbodies is still largely unknown. Based on 36-year-long, continuous records of Mediterranean truffle yield, we demonstrate that decreased summer precipitation together with increased summer temperatures significantly reduce the fungus' subsequent winter harvest. Using state-of-the-art climate model projections, we predict that a significant decline of 78-100% in southern European truffle production is likely to occur between 2071 and 2100. The additional threats of forecasted heatwaves, forest fires, pest and disease outbreaks are discussed along with socioeconomic and ecological consequences of a warmer and dryer future climate. Our results emphasize the need for unravelling the direct and indirect effects of climate change on Europe's truffle sector and underline the importance of conservation initiatives at local to international scales.

Truffle renaissance in Poland - history, present and prospects

The use of truffles in Poland has a long tradition, yet due to some historical aspects, this knowledge was lost. Currently, truffles and truffle orchards are again receiving attention, and thanks to, e.g., historical data, they have solid foundations to be established. Publications relating to truffles between 1661 and 2017 were searched for in international and national databases, such as the database of PhD theses, Google Scholar, and catalogues of the National Library of Poland, the Jagiellonian Digital Library, the University Library of J. Giedroyc in Bialystok and the Lower Silesian Digital Library (DBC). A very meticulous survey of the literature on truffles showed that truffles have been known since at least 1661. In the 18th century, the fungi were considered a non-timber forest product. It is interesting to mention the impact of Polish Count Michał Jan Borch in understanding the nature of truffles. The whitish truffle (Tuber borchii) is named after him. The greatest number of publications regarding truffles can be observed at the first half of the 19th and 20th centuries. The fungi were present not only in cookbooks but also in scientific literature, and aspects of their ecology and medicinal use are considered. The "dark ages" for truffles, mainly for social reasons, occurred after the Second World War. In tough times, when Poland was under Soviet communist control (1945-1989), truffles as a luxurious product have been completely forgotten. However, at the end of the 20th century, truffles started receiving attention in Polish society. Yet, the real awakening began in the first decade of the twenty-first century when the first truffle orchards were established. One of them has already produced the first fruit bodies of summer truffle (Tuber aestivum). Truffles have been present in Polish culture for centuries. Their renaissance indicates the need for fostering sustainable agroforestry-centred initiatives aimed at helping truffle growers in growing the precious fungi and thus meeting market demands.