The meager information we currently have on cockroach activities in natural habitats suggests that they may be key agents of nutrient recycling in at least some desert, cave, and forest habitats. They comprise the core diet for a variety of invertebrate and vertebrate taxa, and may play some role in pollination ecology, particularly in tropical canopies. Before we can begin to document and quantify their ecosystem services, however, more time, energy, and financial resources must be devoted to two specific areas of cockroach research.
The first and most obvious requirement is for basic information on the diversity, abundance, and biology of free-living species, as cockroaches remain a largely unin-vestigated taxon. In 1960, Roth and Willis indicated that there were 3500 described species and estimated an additional 4000 unnamed species. Currently, most estimates are in the range of 4000 to 5000 living cockroaches, with at least that many yet to be described. Some of the most diverse families, such as Blattellidae, are strongly represented in tropical climes but very poorly studied (Rentz, 1996).Among described species, the observation by Han-itsch (1928) that "the life history of the insect begins in the net and ends in the bottle" still holds true for the vast majority. Core data on cockroach biology are derived nearly exclusively from insects that have been reared in culture and studied in the laboratory. How closely the results of these studies relate to Blattaria in natural habitats is in many cases questionable. Laboratory-reared cockroaches are domesticated animals typically kept in mixed sex, multiage groups within restricted, protected enclosures, and supplied with a steady, monotonous food source, ad lib water, and readily accessible mating partners. Most tropical species cultured in the United States are derived from just a few sources collected decades ago (LMR, pers. obs.), and are therefore apt to be lacking the variation expressed in free-living populations. The group dynamics (Chapter 8), locomotor ability (Akers and Robinson, 1983; Chapter 2), and fecundity (Wright, 1968) of laboratory cockroaches are known to differ from that of wild strains, and crowded rearing conditions and the inability to emigrate can result in artificially elevated levels of density-dependent behaviors such as aggression and cannibalism. Mira and Raubenheimer (2002) compared laboratory-reared P. americana to "feral" animals loose in their laboratory building and found that the free-range cockroaches had higher growth rates, additional nym-phal stadia, greater resistance to starvation, and a higher numbers of endosymbiotic bacteria in the fat body. Field studies and experiments that incorporate a realistic simulation of field conditions are clearly desirable, incorporating as wide a range of taxa and habitat types as possible. A small army of eager young nocturnal scientists, and perhaps octogenarians, who cannot sleep anyway (LMR, pers. obs.), need to consider cockroaches as worthy subjects of observation and experimentation under natural conditions.
A second requisite for progress lies in bankrolling the training of a new generation of cockroach systematists, a need made especially acute with the passing of the second author of this volume (CAN, pers. obs.). Field studies will have little value if the subject of research efforts cannot be identified, or if collected vouchers languish undescribed in museum drawers. One of LMR's final publications sounded the call for "true systematists interested in studying the biology and classification of cockroaches,"but recommended that "he or she marry a wealthy partner" (Roth 2003c).
Even if these two requirements are in some small measure met, progress in evaluating the ecological impact of cockroaches may be hindered unless we recognize the need for some attitudinal shifts in our approach to cockroach studies. First, evaluation of the role of cockroaches in the nutrient cycles of ecosystems demands a micro-bially informed perspective (Chapter 5). Relationships with microorganisms as food, on food, transient through the digestive tract, and resident in and on the body not only form the functional basis of cockroach performance on a plant litter diet, but also direct their impact on de-compositional processes. Second, it might behoove us to keep the phylogenetic and ecological relationships of cockroaches and termites in mind when attempting to assess the role of Blattaria in ecosystems. Sampling and evaluation techniques employed in termite studies (e.g., Bignell and Eggleton, 2000) may also prove useful in studying their cryptic cockroach relatives. Scattered hints in the literature that the two taxa may be ecologically displacing each other in selected habitats would be well worth characterizing and quantifying. Third, and finally, as biologists we have a responsibility to help alter the lenses through which potential students as well as the general public characteristically regard the subjects of this book. A realistic image with which to begin public relations is that of inconspicuous workhorses, acting beneath the radar to move nutrients through the food web, maintain soil fertility, and support a variety of the complex and cascading processes that sustain healthy ecosystems.
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