Peter H. Adler

Insect Biodiversity: Science and Society

Preface. Acknowledgements. 1. Introduction Peter H. Adler and Robert G. Foottit . 2. The Importance of Insects G.G.E. Scudder . Part I. Insect Biodiversity: Regional Examples . 3. Insect Biodiversity in the Nearctic Region Andrew B. T. Smith and Hugh V. Danks. 4. Amazonian Rainforests and Their Richness of Coleoptera, a Dominant Life Form in the Critical Zone of the Neotropics Terry L. Erwin and Christy J. Geraci. 5. Insect Biodiversity in the Afrotropical Region C.H. Scholtz and M.W. Mansell . 6. Biodiversity of Australasian Insects Peter S. Cranston . 7. Insect Biodiversity in the Palearctic Region Alexander S. Konstantinov, Boris A. Korotyaev and Mark G. Volkovitsh. Part II. Insect Biodiversity: Taxon Examples. 8. Biodiversity of Aquatic Insects John C. Morse. 9. Biodiversity of Diptera G.W. Courtney, T. Pape, J.H. Skevington and B.J. Sinclair . 10. Biodiversity of Heteroptera Thomas J. Henry. 11. Biodiversity of Coleoptera P. Bouchard, V.V. Grebennikov, A.B.T. Smith and H. Douglas. 12. Biodiversity of Hymenoptera John T. Huber . 13. Lepidoptera Biodiversity Michael G. Pogue. Part III. Tools and Approaches . 14. The Science of Insect Taxonomy: Prospects and Needs Quentin D. Wheeler . 15. Insect Species - Concepts and Practice Michael F. Claridge . 16. Molecular Dimensions of Insect Taxonomy Felix Sperling and Amanda Roe . 17. DNA Barcodes and Insect Biodiversity Robin M. Floyd, John J. Wilson, Paul D. N. Hebert . 18. Insect Biodiversity and Informatics Norman F. Johnson . 19. Parasitoid Diversity and Insect Pest Management John Heraty . 20. Taxonomy of Crop Pests: The Aphids Gary L. Miller and Robert G. Foottit . 21. Adventive Insects: A Global Overview Alfred G. Wheeler, Jr. and E. Richard Hoebeke . 22. Biodiversity of Biting Flies: Implications for Humanity Peter H. Adler . 23. Reconciling Ethical and Scientific Issues for Insect Conservation Michael J. Samways . 24. Insect Biodiversity: Assessment and Taxonomy Ke Chung Kim. 25. Insect Biodiversity - Millions and Millions May Berenbaum. Taxonomic Index. Subject Index

Evolution, epidemiology, and population genetics of black flies (Diptera: Simuliidae)

More than 2000 species of black flies feed on vertebrate blood; 1.5% of all species are vectors of pathogens that cause human diseases. Of nine simuliid-borne animal diseases, only two, mansonellosis and onchocerciasis, afflict humans. Onchocerciasis is a debilitating disease infecting an estimated 40 million people in Africa, Latin America, and Yemen, whereas mansonellosis is a mild disease in the Neotropics. Cytogenetic studies of natural populations of more than 500 species of black flies have revealed that the classic morphospecies of taxonomists is typically a complex of two or more reproductively isolated entities, or sibling (cryptic) species. Most vectors of human pathogens are sibling species, each ecologically unique in traits such as breeding habitats, dispersal capabilities, and degree of vector competence. We review the evolution of black flies, the cytogenetics that have revealed about 260 cytologically distinct entities, the molecular studies that continue to expose additional hidden biodiversity, and a case study of the epidemiology of the Simulium damnosum complex, the largest species complex of blood-feeding arthropods on Earth and the premier group of black flies responsible for human onchocerciasis.

Vertebrate host specificity of wild-caught blackflies revealed by mitochondrial DNA in blood

Blood–feeding blackflies (Diptera: Simuliidae) transmit pathogens, harass vertebrate hosts and may cause lethal injuries in attacked victims, but with traditional methods it has proved difficult to identify their hosts. By matching mitochondrial DNA (mtDNA) sequences in blood collected from engorged blackflies with stored sequences in the GenBank database, relationships between 17 blackfly species and 25 species of vertebrate hosts were revealed. Our results demonstrate a predominance of large hosts and marked discrimination between blackflies using either avian or mammalian hosts. Such information is of vital interest in studies of disease transmission, coevolutionary relationships, population ecology and wildlife management.

Development of the Black Soldier Fly (Diptera: Stratiomyidae) in Relation to Temperature

ABSTRACT The black soldier fly, Hermetia illucens L., was reared on a grain-based diet at 27, 30, and 36°C. Survival of 4- to 6-d-old larvae to adults averaged 74–97% at 27 and 30°C but was only 0.1% at 36°C. Flies required a mean of ≈4 d (11%) longer to complete larval and pupal development at 27°C than at 30°C. At 27 and 30°C, females weighed an average of 17–19% more than males but required an average of 0.6–0.8 d (3.0–4.3%) longer to complete larval development. At both temperatures, adult females lived an average of ≈3.5 d less than adult males. The duration of larval development was a significant predictor of adult longevity. Temperature differences of even 3°C produce significant fitness tradeoffs for males and females, influencing life history attributes and having practical applications for forensic entomology.

Black flies in the boreal biome, key organisms in both terrestrial and aquatic environments: A review

Abstract: The boreal biome is rich in running waters suitable for the development of black flies. Here we review the ecological roles of black flies and the options available for their management. Large numbers of these insects play quantitatively important roles in a number of processes, not only in the running-water habitats of the larvae but also in the terrestrial environments of the adults. Black flies suck blood from mammals, including humans, and from birds, with negative effects including occasional death of animals. Black flies also transmit parasites, including filarial worms and haemosporidians. In the last two decades, programs to control black flies by treating the larvae, using Bacillus thuringiensis var. israelensis, have been developed, with predominantly positive results but with limited understanding of the indirect impacts to the aquatic and terrestrial ecosystems. On a more positive side, adult black flies are food for a variety of predators and may favour pollination, as well as helping in nature conservation by deterring people from visiting wilderness areas. Black fly larvae feed on suspended particles, linking this energy source to invertebrate and vertebrate predators (e.g., salmonids). Because larval densities often are high, considerable amounts of sedimenting faecal pellets increase the local retention of organic material, and this provides nutrition for invertebrates and micro-organisms, and potentially fertilizes river margins. Larvae also produce silk, the role of which in the ecosystem is poorly known but potentially important.

Scale, time, space, and predictability : species distributions of preimaginal black flies (Diptera : Simuliidae)

Abstract This study examines species-specific distributions of preimaginal black flies (Diptera: Simuliidae) over two large spatial scales (within and across ecoregions) and two seasons (spring and summer). The study area in the western two-thirds of South Carolina, United States, was divided into three ecoregions (Mountains, Piedmont, Sandhills). The mean correct classification of species distributions among stream sites was 81.3%. Predictability of species distributions varied with spatial scale, location, and time. Species occurrence was not independent of ecoregion; distributions of 12 of the 13 species examined at this scale were predictable on the basis of changes in water column (temperature, percentage dissolved oxygen) and channel characters (velocity, streambed-particle size). However, with the exception of the Mountains during the summer, predicting species distributions within ecoregions was far less successful than predicting distributions across these regions; predictability was particularly poor in the Sandhills. Seasonal effects on predictability were most pronounced in the Mountains. As stream sites became more homogeneous, predictive capability declined. Species-level identifications, aided by cytogenetic techniques, were of paramount importance in recognizing the association between species distributions and stream conditions, emphasizing that considerable ecological information is lost when species are not considered. This study emphasizes the critical role of taxonomic resolution, linked with spatial and temporal scale of observation, in elucidating patterns of species assemblages. It also demonstrates that predictability of species distributions at a fixed scale can vary with geographic location and time.

Cryptic biodiversity and phylogenetic relationships revealed by DNA barcoding of Oriental black flies in the subgenus Gomphostilbia (Diptera: Simuliidae).

Understanding the medical, economic, and ecological importance of black flies relies on correct identification of species. However, traditional taxonomy of black flies is impeded by a high degree of morphological uniformity, especially the presence of cryptic biodiversity, historically recognized by details of chromosomal banding patterns. We assess the utility of DNA barcoding, based on cytochrome c oxidase subunit 1 (COI) sequences, for identifying 13 species of Oriental black flies in the subgenus Gomphostilbia. Samples of larvae fixed in Carnoys solution were used to gather molecular and chromosomal data from the same individual. We found that larvae refrigerated in Carnoys fixative for as long as 11 years can be used for DNA study. Levels of intraspecific genetic divergence, based on the Kimura-2 parameter, range from 0% to 9.28%, with a mean of 2.75%, whereas interspecific genetic divergence ranges from 0.34% to 16.05%. Values of intraspecific and interspecific genetic divergence overlap in seven species owing to incomplete lineage sorting and imperfect taxonomy, implying that DNA barcoding to identify these species will be ambiguous. Despite a low level of success, we found that DNA barcoding is useful in revealing cryptic biodiversity, potentially facilitating traditional taxonomy. Phylogenetic analyses indicate that species groups currently recognized on morphological criteria are not monophyletic, suggesting a need to reevaluate the classification of the subgenus Gomphostilbia.

Hydrophobic–hydrophilic dichotomy of the butterfly proboscis

Mouthparts of fluid-feeding insects have unique material properties with no human-engineered analogue: the feeding devices acquire sticky and viscous liquids while remaining clean. We discovered that the external surface of the butterfly proboscis has a sharp boundary separating a hydrophilic drinking region and a hydrophobic non-drinking region. The structural arrangement of the proboscis provides the basis for the wetting dichotomy. Theoretical and experimental analyses show that fluid uptake is associated with enlargement of hydrophilic cuticular structures, the legulae, which link the two halves of the proboscis together. We also show that an elliptical proboscis produces a higher external meniscus than does a cylindrical proboscis of the same circumference. Fluid uptake is additionally facilitated in sap-feeding butterflies that have a proboscis with enlarged chemosensory structures forming a brush near the tip. This structural modification of the proboscis enables sap feeders to exploit films of liquid more efficiently. Structural changes along the proboscis, including increased legular width and presence of a brush-like tip, occur in a wide range of species, suggesting that a wetting dichotomy is widespread in the Lepidoptera.

Butterfly proboscis: combining a drinking straw with a nanosponge facilitated diversification of feeding habits

The ability of Lepidoptera, or butterflies and moths, to drink liquids from rotting fruit and wet soil, as well as nectar from floral tubes, raises the question of whether the conventional view of the proboscis as a drinking straw can account for the withdrawal of fluids from porous substrates or of films and droplets from floral tubes. We discovered that the proboscis promotes capillary pull of liquids from diverse sources owing to a hierarchical pore structure spanning nano- and microscales. X-ray phase-contrast imaging reveals that Plateau instability causes liquid bridges to form in the food canal, which are transported to the gut by the muscular sucking pump in the head. The dual functionality of the proboscis represents a key innovation for exploiting a vast range of nutritional sources. We suggest that future studies of the adaptive radiation of the Lepidoptera take into account the role played by the structural organization of the proboscis. A transformative two-step model of capillary intake and suctioning can be applied not only to butterflies and moths but also potentially to vast numbers of other insects such as bees and flies.

DNA barcoding of tropical black flies (Diptera: Simuliidae) of Thailand

The ecological and medical importance of black flies drives the need for rapid and reliable identification of these minute, structurally uniform insects. We assessed the efficiency of DNA barcoding for species identification of tropical black flies. A total of 351 cytochrome c oxidase subunit 1 sequences were obtained from 41 species in six subgenera of the genus Simulium in Thailand. Despite high intraspecific genetic divergence (mean = 2.00%, maximum = 9.27%), DNA barcodes provided 96% correct identification. Barcodes also differentiated cytoforms of selected species complexes, albeit with varying levels of success. Perfect differentiation was achieved for two cytoforms of Simulium feuerborni, and 91% correct identification was obtained for the Simulium angulistylum complex. Low success (33%), however, was obtained for the Simulium siamense complex. The differential efficiency of DNA barcodes to discriminate cytoforms was attributed to different levels of genetic structure and demographic histories of the taxa. DNA barcode trees were largely congruent with phylogenies based on previous molecular, chromosomal and morphological analyses, but revealed inconsistencies that will require further evaluation.