Bark Beetles
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EUROPEAN JOURNAL OF ENTOMOLOGYENTOMOLOGY ISSN (online): 1802-8829 Eur. J. Entomol. 113: 307–308, 2016 http://www.eje.cz doi: 10.14411/eje.2016.038 BOOK REVIEW VEGA F.E. & HOFSTETTER R.W. (EDS) 2015: BARK BEETLES: also a few variegate species in the genus Aphanarthrum (distrib- BIOLOGY AND ECOLOGY OF NATIVE AND INVASIVE uted mainly in the Macaronesian region) with opalescent greenish SPECIES, 1st ed. Elsevier, Academic Press, Amsterdam, Bos- spots on their elytra (mostly visible only in live specimens). ton, Heidelberg, London, New York, Oxford, Paris, San Diego, Taxonomy of bark beetles is very diffi cult not only due to their San Francisco, Singapore, Sydney, Tokyo, 640 pp. ISBN small body size and uniformity. There is a lack of comprehensive 9780124171565. Price EUR 92.95. worldwide keys to genera and species. As an example, there are rather good keys to species of Ips in North America and the same The title appropriately indicates a group of insects of high re- for Europe. But an inexperienced (e.g., quarantine) entomolo- cent economic and environmental importance, which includes gist with a specimen of unknown origin could identify the same some of the most damaging agents in forests and most frequent specimen/species as two (or more) species using these “local” “unwanted passengers” in world-wide trade. Bark beetles, al- identifi cation keys. In bark beetles, probably more than in any though generally considered secondary pests, can infl ict consid- other group of insects, the availability of reliably identifi ed com- erable damage and cause enormous economic losses. There can parative museum material is very important and, in most cases, be outbreaks of some species when conditions are suitable, dur- comparison is the only way to correctly identify species. But even ing which they rapidly switch from a “quiet” lifestyle to primary museum collections frequently contain misidentifi ed material. attackers of their host plants, mostly forest trees. They can also Proper identifi cation is the essential fi rst step in bark beetle re- kill their host when the original reason for the outbreak (such as search, otherwise our conclusions could lead to serious mistakes. drought) is not necessarily fatal for the forests. The identifi cation of bark beetles is diffi cult even at the generic At the beginning of this book, general information about bark level. In addition, properly determined specimens are scattered in beetles, their relationship with host plants and their role in nature many museums. Last but not least, the preparation is very often is given, and the following chapters continue with discussions of not good enough to allow reliable identifi cation; glued specimens all the aspects of bark beetle life. The book contains 15 chapters, on rectangular card (“European” type) often do not show many of which deal with natural history and ecology, morphology, taxon- the details necessary for generic identifi cation, as most characters omy and phylogeny, evolution and diversity, population dynam- are hidden by paper card or in drops of glue, which is in marked ics, resistance, symbiotic associations, natural enemies, climate contrast to those mounted on triangles (“American” type). All change, management strategies, economics and politics of bark these aspects make the identifi cation of bark beetles very compli- beetles. Each chapter is prepared by a team of leading specialists cated. With the increasing number of young specialists it is likely in the respective topics (33 contributors altogether). Both editors there will be a somewhat brighter future. are outstanding experts in bark beetle ecology. As one of the most serious pests of forests, bark beetles are Bark beetles are species with very “secret” lifestyles. They studied by foresters and applied biologists as well as professional spend nearly their whole life hidden under bark, within wood, in entomologists, which has also contributed to the problems with seeds or other plant tissues. The adults spend only a short time in their systematics and nomenclature. It may well be the group of the open, mostly just for dispersal and searching for suitable host insects with the highest number of species synonyms. The assign- plants, which take just a few hours or a few days at most. Other- ment of the same species to different genera by different authors wise they spend most of their lifetime excavating their breeding are not real synonyms and should not be included in synonymic galleries in which the mating (with some exceptions), oviposi- lists (Table 10.1). Even though the whole group was treated his- tion and brood care take place. Such circumstances logically torically separately, mostly at the family level, recent phylogenet- result in behavioural and morphological adaptations to living in ic results indicate bark beetles should be included as a subfamily tight galleries, for overcoming host defence, attacks of internal of true weevils (Cuculionidae), the Scolytinae. This placement and external natural enemies, etc. All these aspects are precisely has been debated for several decades and although still not uni- explained and discussed in the corresponding chapters, includ- versally accepted, mainly by the practitioners, there is an evident ing the most recent knowledge on these topics. We would know need for this change. This development is described in detail in much more about their lives if we could follow their behaviour the chapter on taxonomy and phylogeny, which refl ects the cur- under bark (excavating the tunnels, ovipositing, tunnel maintain- rent status quo. All notorious non-believers, to which I partly be- ing, sexual behaviour, brood care, etc.). Recent studies using the long (for practical reasons and simply being of the “old school”), most modern techniques and rearing them on artifi cial diets in are recommended to study this chapter in detail, but should bear the laboratory are promising in this respect. For the reasons men- in mind that a new comprehensive classifi cation of bark beetles tioned above, nearly all bark beetles are rather uniform in colour is still needed. All the 247 currently recognized genera need to and shape as they do not have to display for pairing or protect be newly organized based on current knowledge (the 282 genera themselves against “visual” predators. As mentioned in the book, mentioned on page 70 is probably a misprint because the follow- among the usually uniformly yellowish brown to dark brown spe- ing Table 2.8 contains the correct number of genera, as does the cies there are a few colourful metallic green to bronze species in table in the Appendix to chapter 3). The position of platypodids is the genus Camptocerus, whose adults feed on green leaves before even more complicated and is discussed in a separate section. Hy- tunnelling into the bark to breed. Besides these species there are lobius abietis, a species of true weevils mentioned several times Final formatted article © Institute of Entomology, Biology Centre, Czech Academy of Sciences, České Budějovice. An Open Access article distributed under the Creative Commons (CC-BY) license (http://creativecommons.org/licenses/by/4.0/). 307 Knížek, Book Review, Eur. J. Entomol. 113: 307–308, 2016 doi: 10.14411/eje.2016.038 in chapter 13, should be omitted from the book because it is not they receive this information or even the location of their “ears”. a bark beetle. But hopefully, future research together with the most modern As already mentioned, there are several species that can switch equipment will allow us to learn more about these topics, as is from a relatively inconspicuous existence to an aggressive phase, mentioned in several chapters. leading to outbreaks, which result in great environmental damage This is a valuable and unique book with a lot of useful infor- and considerable economic losses. Their population dynamics, mation. Some particular aspects deserve special mention as they ability to overcome host resistance, reaction to climate change may surprise the reader. First, it is the incredible amount of lit- and consequent human management strategies, economics and erature listed in each chapter, which covers both the history and politics are explained in detail in separate chapters. Actually, not the most recent developments, and refl ects the diligence and thor- many of the slightly more than 6000 bark beetle species described oughness of all the authors of the chapters. Roughly, more than cause such problems; there may be just a few dozen (about 1% 5000 papers (overlaps included) are cited. Second, for some read- is the estimate in this book) among which are just a few species ers it could be the existence of a diminutive species of bark beetle, that are really very seriously harmful to forests. Separate chap- Hypothenemus hampei (treated in a separate chapter), which very ters are devoted to the most important species, which explain the seriously damages one of the most popular plants worldwide, situation in broad terms and considerable detail. These chapters coffee, or more precisely coffee seeds. I am pretty sure that the deal mostly with the most serious pest taxa. Some additional im- existence of such species is unknown to most people, including portant genera are added, but they are mostly of Nearctic impor- not only coffee drinkers, but also researchers and entomologists. tance, while similarly important genera from the Palaearctic are It is an excellent example of how important aspects of our lives, not included (e.g., Hylastes, Phloeosinus, Polygraphus, other Ips from well-being to food or medicinal compounds, may depend on and Scolytus species, etc.). For example, Polygraphus proximus such minute organisms. And guess what, even though this pest is recently spread from the Far East westward and is already pres- nearly the smallest species of bark beetle treated in detail in this ent in the European part of Russia where it seriously damages fi r book, the chapter on the tribe Cryphalini contains the longest list stands.