Thesis (M.S.)--Eastern Illinois University, 2008. / Includes bibliographical references (leaves 20-22).

The distribution of beetles in the Family Silphidae has not been well studied in Virginia.  The primary purpose of this study was to survey silphid beetles in a more systematic manner across different geographic regions of the state, with a special consideration for Nicrophorus species.  The seasonal abundance and diversity of silphid beetles in Montgomery County, Virginia, was also examined.  Baited pitfall traps were used to sample beetle distribution and abundance, and were placed in each of the five geographical regions of Virginia in the summers of 2007 and 2008.  Traps were placed approximately one kilometer apart and were checked daily over a five day period for each of three sampling periods.  A total of 4375 silphid beetles, consisting of 11 species in four genera, were collected in ten counties with beetles in the subfamily Silphinae being predominant.  Within the Nicrophorinae, Nicrophorus tomentosus and N. orbicollis were dominant in 2007; whereas in the summer of 2008, N. tomentosus and N. pustulatus were the most commonly collected.  Contingency analyses indicated that species abundance was associated with sampling period and geographic region.  Nicrophorus americanus was not collected during either summer of surveying and only three N. carolinus were trapped in Suffolk County in the summer of 2008.  For the Montgomery County survey, a total of 3276 beetles were found between the middle of April and the middle of October.  The prevalent species within Nicrophorinae was Nicrophorus tomentosus and within the Silphinae it was Necrophila americana.  Species abundance was associated with sampling period. / Master of Science in Life Sciences

Necrophilous insects, if correctly identified, can provide useful forensic information. Research in this area has focussed on flies and beetles remain comparatively under-studied, partly because some adult carrion beetles are difficult to identify morphologically, as are their juvenile stages, often requiring specialist expertise in both cases. Molecular taxonomy has been proposed as a solution to these problems. DNA “barcodes" are short fragments of mitochondrial cytochrome oxidase I (COI) DNA that are anticipated to delineate species. This approach is becoming increasingly popular, but has been met with varying enthusiasm from taxonomists. This thesis examines their use in identifying forensically significant beetles.The DNA barcodes of 234 specimens of 25 forensically significant southern African beetle species from seven families (Cleridae, Dermestidae, Silphidae, Staphylinidae, Scarabaeidae, Trogidae and Histeridae) were obtained. Thirty-three initial barcode amplification failures were overcome by using primers other than the standard Folmer pair, undermining the barcode concept’s hope of universal primers that would allow even non-specialists to produce barcodes. Another 150 specimens (64%) entirely failed to yield barcodes, including 18 fresh specimens of three species of Trogidae, implying another lack of universality of the barcoding protocol. The majority of the beetles clustered with confamilials on neighbour-joining and maximum likelihood trees, but 1.3% of the barcodes failed to cluster with their respective families, raising questions concerning the associating power of barcodes. The identification tools of the GenBank and BOLD on-line DNA sequence databases identified 21% of the specimens to the species level, 6% of them correctly. There was evidence of a paralogous sequence in the Cleridae that, while supporting identification now that it has been associated with a morphological identification, would hamper attempts at identification by clustering or phylogenetic analysis.Distance and haplotype network analyses of the barcodes of six widespread species showed that they are not geographically structured. Barcodes are thus unlikely to be indicators of the region of origin of a species and will not determine whether a corpse has been relocated after death. To assess whether a different mitochondrial DNA fragment might address (some of) these problems, a 2.2 kb fragment extending from the 5’ end of the COI gene to the 3’ end of the Cytochrome Oxidase II (COII) gene was analysed for nine species. It was found that, for Dermestidae, Scarabaeidae and Histeridae, higher degrees of diversity occurred downstreamof the barcode region, but the region of highest diversity in the Cleridae was in the barcode region. Thus, finding a more reliable fragment along the COI-COII region for each family may make robust and guaranteed DNA-based identification of these beetles more likely. The possibility of a forensic specimen being incorrectly or not identified based on its barcode alone exists in about 40% of cases, even with the new barcodes reported here. Forensic science sets a very high bar in assessing the performance of its techniques, and it is concluded that barcodes currently have unsettling failure rates as court-worthy evidence.

Nicrophorus americanus is a federally endangered species whose range has decreased dramatically since the 1920s. It is a nocturnal species that is only active from May to September when temperatures reach at least 15.5°C for three nights in a row. It once ranged throughout North America, from Maine and the southern parts of Canada, west to South Dakota and south to Texas. The historic Texas population consists of four Texas specimens from the 1880s residing at the Philadelphia Academy of Science Invertebrate Collection. Since then, there were no confirmed specimens in Texas, until 2003 when a single individual was found in Lamar County, Texas. The population discovered in Lamar County has been on a steady decrease from 2005, 223 individuals captured, until 2008 only 8 individuals captured. Since 2008, no individuals have been captured in Texas, despite intense surveys. It is possible that the Texas population is a sink population with the Oklahoma population to its north, acting as the source. Genetic analysis of the Texas and Oklahoma populations would help to answer this question and analysis of the entire population may answer questions to why the species declined leaving only the peripheral populations. The specific habitat variables that caused the population to re-colonize and go extinct in Texas are unclear, but when determined could play a critical role in managing the population. / text

Necrophagous beetles (Coleoptera) are very interesting and diverse ecological group of species with an immense impact on a natural nutrient cycle. Their main food source and breeding ground are carrions of vertebrates, human remains included. This relationship is often used in various ways by forensic entomology, but its potential was not jet fully reached, because our knowledge of biology and ecology of these beetles is very much incomplete. In this thesis I would like to explore geographic distribution, ecological requirements and developmental biology of several Central European necrophagous beetles as an outcome of their ecological and evolution strategies. For that I raised three broad research questions. Which factors are determining the local abundance of carrion beetles (Coleoptera: Silphidae)? How the current geographical distribution of open-landscape carrion beetles looks like in the Czech Republic? How the temperature affects the development of Sciodrepoides watsoni (Spence, 1813)? We found out that soil type can have significant effect on abundance of carrion beetles. They showed preference for chernozem -- Nicrophorus antennatus (Reitter), N. germanicus (Linnaeus), N. interruptus (Stephens), N. sepultor (Charpentier), Silpha obscura obscura (Herbst), T. sinuatus (Fabricius) or for fluvisol as did N. humator (Gleditsch). These findings support our hypothesis that soil type could be an important factor determining the occurrence of necrophagous European carrion beetles. To collect novel data of the current geographical distribution of carrion beetles we used 420 baited pitfall traps at 84 localities, and we collected 71 234 specimens of 15 silphid species. Among them, three endangered carrion beetle species listed on the Czech Red List of Invertebrates, were found. Two are vulnerable thermophilic species of open landscapes, Nicrophorus antennatus (Reitter, 1884) (collected around Louny and Židlochovice) and Nicrophorus germanicus (Linnaeus, 1758) (Louny, Zábřeh and Židlochovice). The third is the near threatened species, Nicrophorus sepultor Charpentier, 1825 (collected around Louny, Kutná Hora, Zábřeh and Židlochovice), which also prefers open landscapes. We studied development of common Holarctic beetle Sciodrepoides watsoni under five constant temperature regimes in laboratory (15, 18, 21, 25 and 28°C). Parameters of thermal summation models and their standard errors were calculated for each developmental stage (egg, three larval instars and pupae). We also find a new character for larval instar determination (head width) and proposed novel approach for future studies of size-based characters in instar determination.

No description available.