1 1 Introduction Peter H. Adler1 and Robert G. Foottit2 1 Department of Plant and Environmental Sciences, Clemson University, Clemson, South Carolina, USA 2 Canadian National Collection of Insects, Arachnids and Nematodes, Agriculture and Agri‐Food Canada, Ottawa, Ontario, Canada Every so often, a technical term born in the biodiversity might conjure a forest, a box of ­biological community enters the popular vocab­ ­beetles, or perhaps the entire fabric of life. ulary, usually because of its timeliness, political Among scientists, the word has been defined, implications, media hype, and euphonious ability explicitly and implicitly, ad nauseum, producing to capture the essence of an issue. “Biotechnology,” a range of variants (e.g., Gaston 1996). In its “human genome,” and “stem cells” are terms as original context, the term biodiversity encom­ common in public discourse as they are in scien­ passed multiple levels of life (Wilson 1988), and tific circles. “Biodiversity” is another example. we embrace that perspective. It is “the variety of Introduced in its portmanteau form in the mid‐ all forms of life, from genes to species, through 1980s by Warren G. Rosen (Wilson 1988), the to the broad scale of ecosystems” (Faith 2007). term has grown steadily in popularity. In May Biodiversity, then, is big biology, describing a 2008, the keyword biodiversity generated 17 mil­ holistic view of life. The fundamental units of lion hits on Google. Eight years later, the same biodiversity – species – serve as focal points for search produced nearly 53 million hits. studying the full panoply of life, allowing work­ Not all scientific terms are value‐neutral ers to zoom in and out along a scale from mol­ (Loike 2014). The word biodiversity, however, ecule to ecosystem. The species‐centered view has remained largely unencumbered by the eth­ also provides a vital focus for conserving life ical or political burden carried by terms such as forms and understanding the causes of declin­ “cloning” and “genetically modified organism.” ing biodiversity. Although the term biodiversity generally evokes Despite disagreements over issues ranging positive sentiment amongCOPYRIGHTED both the scientific from definitionsMATERIAL of biodiversity to phylogenetic community and the public, its meaning is often approaches, biologists can agree on four major subject to individual interpretation. Abraham points: (i) the world supports a great number of Lincoln grappled with a similar concern over insects; (ii) we do not know how many species the word “liberty.” In an 1864 speech, Lincoln of insects occupy our planet; (iii) the value of opined, “The world has never had a good defini­ insects to humanity is enormous; and (iv) too tion of the word liberty, and the American peo­ few specialists exist to inventory the world’s ple, just now, are much in want of one … but in entomofauna and to provide the expertise using the same word we do not all mean the ­necessary for conserving and sustainably using same thing” (Simpson 1998). To the layperson, its resources for societal benefit. Insect Biodiversity: Science and Society, Volume I, Second Edition. Edited by Robert G. Foottit and Peter H. Adler. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd. c01.indd 1 6/24/2017 3:16:43 PM 2 Insect Biodiversity: Science and Society By virtue of the sheer numbers of individuals based partly on a view of species as structurally and species, insects, more than any other mac­ distinct from one another. Morphologically roscopic life form, command the attention of similar, if not indistinguishable, species (i.e., biologists. The number of individual insects on cryptic species) typically are not figured into Earth at any given moment has been calculated estimates of the number of insect species. If at one quintillion (1018) (Williams 1964), an putatively well‐known organisms as large as unimaginably large number on par with the crocodiles, elephants, giraffes, and whales are number of copepods in the ocean (Schubel and composites of multiple cryptic species (Wada Butman 1998) and roughly equivalent to the et al. 2003, Brown et al. 2007, Hekkala et al. number of sand grains along a few kilometers of 2011), a leap of faith is not required to realize beach (Ray 1996). The total number of insect that smaller earthlings also consist of addi­ species also bankrupts the mind. Estimates tional, hidden species. When long‐recognized offered over the past four centuries have nominal species of insects, from black flies to increased steadily from 10,000 species, pro­ butterflies, are probed more deeply, the repeti­ posed by John Ray in 1691 (Berenbaum, this tive result is an increase, often manyfold, in the volume), to as many as 80 million (Erwin 2004). number of species (Hebert et al. 2004, Post The number of described insect species recently et al. 2007). No zoogeographical bias in cryptic broke the 1 million mark – it currently stands at species has been detected, after correcting for 1,060,704 (Table 1.1), about 100 times the 1691 species richness and study intensity (Pfenninger estimate. Based on a figure of 1.50 million to and Schwenk 2007). We suspect that the dis­ 1.74 million described eukaryotic species in the coveries of additional cryptic species will far world (May 1998, Costello et al. 2012), insects outstrip the countering effects of synonymizing represent 61–71% of the total. existing names. The members of the class Insecta are arranged The precise number of species, however, is in 29 orders. Four of these orders – the Coleop­ not what we, as a global society, desperately tera, Diptera, Hymenoptera, and Lepidoptera – need. Rather, we require a comprehensive, fully account for more than 80% of all described spe­ accessible library of all volumes (i.e., species), a cies of living insects. The beetles are far in front, colossal compendium of names, descriptions, leading each of the next largest orders, the distributions, and biological information that Diptera and Lepidoptera, by a factor of more than ultimately can be transformed into a directory 2.4 (Table 1.1). A growing number of world of services. An example of societal use of plant checklists, catalogs, and inventories are available diversity provides a view of the potential treas­ online for various families and orders. Outfitted ures that insects could hold. Of the top 150 pre­ with search functions, they provide another tool scribed drugs in the United States, about 56% for handling the taxonomic juggernaut of new can be linked to discoveries in the natural plant species and nomenclatural changes. We can fore­ world (Groombridge and Jenkins 2002). The see a global registry of species in the near future great numbers of insects hold a vast wealth of that is updated with each new species or syno­ various behaviors, chemistries, forms, and nym, allowing real‐time counts for any taxon functions. Furthermore, individual insects offer (Polaszek et al. 2005). a package deal: each insect represents an eco­ The greatest concentration of insect species system of microbial life, teeming with a vast lies in tropical areas of the globe. One hectare array of species, many of which are host‐, gen­ of Amazonian forest contains more than der‐, and stage‐specific (Tang et al. 2012). Of 100,000 species of arthropods (Erwin 2004), of the 1 trillion estimated species of microorgan­ which roughly 80–85% are insects (May 1998, isms on Earth (Locey and Lennon 2016), the Stork et al. 2015). This value is more than 90% proportion specific to insects is unknown. The of the total described species of insects in the diversity, roles, and potential benefits that lie entire Nearctic region. Yet, this tropical skew is within the insect–microbiota relationship c01.indd 2 6/24/2017 3:16:43 PM 1 Introduction 3 Table 1.1 World totals of described, living species in the 29 orders of the class Insecta, tallied May 2016. Order* Described species References† Microcoryphia 548 Mendes, Vol. II Zygentoma 594 Mendes, Vol. II Ephemeroptera 3,436 Morse, this volume Odonata 5,956 Morse, this volume Plecoptera 3,562 Morse, this volume Embiodea 397 Maehr and Hopkins 2016a Zoraptera 40 Maehr and Hopkins 2016b Orthoptera 26,107 Song, Vol. II Phasmatodea 2,976 Bradler, Vol. II Dermaptera 1,931 Haas, Vol. II Grylloblattodea 33 Eberhard et al., Vol. II Mantophasmatodea 19 Eberhard et al., Vol. II Blattodea 7,637 Cockroaches (5,565) + termites (2,072), Djernaes, Vol. II Mantodea 2,469 Otte et al. 2016 Psocoptera 5,640 Mockford, Vol. II Phthiraptera 5,239 Galloway, Vol. II Thysanoptera 6,102 ThripsWiki 2015 Hemiptera 106,971 Heteroptera (45,254; Henry, this volume) + Auchenorrhyncha (43,024; Bartlett et al., Vol. II) + Sternorrhyncha (18,693; Hardy, Vol II) Raphidioptera 248 Oswald, Vol. II Megaloptera 373 Oswald, Vol. II Neuroptera 5,813 Oswald, Vol. II Coleoptera 386,755 Bouchard et al., this volume Strepsiptera 615 Kathirithamby, Vol. II Hymenoptera 154,067 Huber, this volume Mecoptera 713 Bicha, Vol. II Siphonaptera 2,183 Galloway, Vol. II Diptera 157,971 Courtney et al., this volume Trichoptera 14,548 Morse, this volume Lepidoptera 157,761 Goldstein, this volume Total 1,060,704 * While recognizing the dynamic nature of the higher classification of the hexapods, including the combining of traditional orders (e.g., Misof et al. 2014), we follow the ordinal classification recognized by the authors of the chapters in Volumes I and II of Insect Biodiversity: Science and Society. The three orders of the Entognatha – the Collembola (ca. 8,600 species; Bellinger et al. 1996–2016), Diplura (ca. 800 species; Tree of Life Web Project 1995), and Protura (ca. 750 species; Szeptycki 2007) – are not included here with the Insecta. These three orders would add about 10,150 species, giving a total of roughly 1,071,000 species of Hexapoda in the world.