Habitat segregation in four species of adult tiger beetles (Coleoptera: Cicindelidae)

ABSTRACT.

• 1 Habitat segregation in four species of tiger beetles, Cicindela cancellata Dejean, C.cardoni Fleutians, C.minuta Olivier and C.sumatrensis Herbst in a river bank ecosystem was studied in dry and wet seasons.
• 2 The four species segregated distinctly along the river beds into separate habitats, with occasional overlapping in both the seasons.
• 3 Among the habitat characteristics considered, vegetation, soil moisture and available prey-size were found to be important in species segregation.
• 4 D ²-analysis showed that the habitat preferences of C.cardoni and C.cancellata were closer to that of C.sumatrensis. The habitat of C.minuta was distinctly separated.
• 5 There was a positive correlation between the mandible length of each tiger beetle species and the length of prey captured.
• 6 Variance in mandible length within species was related to prey-length distribution pattern and to variance in habitats.

     

Hearing in tiger beetles (Cicindelidae)

ABSTRACT. Tympanic hearing organs (ears) are reported for several tiger beetle (Cicindelidae) species. The paired ears are positioned bilaterally on the first abdominal tergum and consist of cavities covered by thin tympana. When the beetle is not flying the elytra covers its ears and reduces their sensitivity to sound. However, when the beetle is flying, its exposed ears are capable of detecting ultrasonic pulses. Under a microscope, beetles with their elytra artificially raised contract their abdomens in response to ultrasound. Ultrasonic emissions directed toward flying beetles induce them immediately to fly downward and land, a response which probably aids escape from predators, particularly echolocating bats. Other possible uses for the ears are the avoidance of diurnal insect predators and intraspecific communication.     

Testing whether ecological factors promote cladogenesis in a group of tiger beetles (Coleoptera: Cicindelidae)

We investigate the role of ecological differentiation in cladogenesis of a monophyletic group of North American tiger beetles, the subgenus Ellipsoptera (genus: Cicindela), by reconstructing their species-level phylogeny from mitochondrial DNA sequences. Observed reconstructions of ecological characters on the phylogeny are compared to those expected under simple null models of no association with cladogenesis. We find no evidence that ecological disparity is associated with either species coexistence, speciation or long-term persistence and/or radiation of lineages. Ecomorphological traits have evolved in response to differences in habitat occupied by species, but without detectable relationship with cladogenesis.     

Phylogeny and divergence time of island tiger beetles of the genus Cylindera (Coleoptera: Cicindelidae) in East Asia

To examine the diverse colonization histories in eight tiger beetle species of the genus Cylindera (Coleoptera: Cicindelidae) on the East Asian islands, we conducted phylogenetic analyses and divergence time estimation using mitochondrial cytochome oxidase subunit I (COI) and nuclear 28S rDNA sequences. The island fauna consisted of four subgenera: Apterodela, Cicindina, Ifasina, and Cylindera. Apterodela is a flightless group with large bodies, whereas the others are fliers with small bodies. In Apterodela, the divergence among endemic species in Taiwan, Japan, and the mainland was ancient (2.1–4.7 Mya), as expected from their flightlessness. Their dispersal might have occurred across the extended landmass in East Asia during the Pliocene. In the subgenus Cicindina, Cylindera elisae has spread throughout East Asia, from which an endemic species, Cylindera bonina, was derived on the oceanic Bonin Islands during the early Pleistocene (0.9 Mya). This indicates the significance of Cylindera bonina, which is currently confined to a single island, for conservation. In the subgenus Ifasina, Cylindera kaleea is widely distributed in East Asia, and its sister species Cylindera humerula, endemic to Okinawa Island, diverged 1.0 Mya, whereas Cylindera psilica on Taiwan and the Yaeyama Islands diverged approximately 0.8 Mya. In the subgenus Cylindera, the colonization of Cylindera gracilis in Japan from the mainland occurred during the last glacial period. With the exception of C. bonina, which likely colonized new territories by flight or drifting, other dispersal events might have used land connections that occurred repeatedly during the Pliocene and Pleistocene. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 715–727.     

Use of simple remote sensing tools to expedite surveys for rare tiger beetles (Insecta: Coleoptera: Cicindelidae)

Tiger beetles (Insecta: Coleoptera: Cicindelidae) often occupy small patches of suitable habitat in otherwise unsuitable landscapes. Such patches are easily overlooked, which may lead to underestimates of both the number of occurrences and the overall population size. In this study, simple World Wide Web-based tools (Google Earth and Microsoft Terraserver) were used to search high-resolution satellite imagery for patches of suitable habitat for globally and regionally rare tiger beetles on a 3,278 ha wildlife refuge in Maryland, USA. This tract is largely forested but contains scattered small open areas of sand and clay soils that are potential habitat for tiger beetles of conservation concern. Visual inspection of remotely sensed imagery resulted in the identification of 19 potential habitat patches, 15 of which yielded tiger beetle populations when surveyed on the ground. The number of species of tiger beetles recorded from this tract was increased from 3 to 8 and two new sites were discovered for the state sensitive species Cicindela scutellaris rugifrons Dejean. In addition, a small population of C. splendida Hentz was discovered, a species last reported from Maryland in 1948. The technique described here shows great promise for locating small patches of potential tiger beetle habitat in otherwise unsuitable landscapes.     

Visual control of cursorial prey pursuit by tiger beetles (Cicindelidae)

Target detection poses problems for moving animals, such as tiger beetles, that track targets visually. The pursuer's movements degrade target image contrast and induce reafferent image movement that confounds continuous detection of prey. In nature, beetles pursue prey discontinuously with several iterations of stop-and-go running. The beetle's dynamics were analyzed by filming pursuits of prey or experimenter-controlled dummies. Durations of stops are inversely related to prey visual angular velocity; as the prey image moves between neighboring ommatidial fields, the beetle relocalizes it and renews running. During subsequent runs, translation and rotation depend upon prey visual angular velocity and position, respectively, seen during the previous stop. The beetle runs, then stops, while prey continues moving. After two to three iterations of stop-and-go the beetle catches its prey, suggesting open-loop control of running. Computational model simulations produce good qualitative spatio-temporal fit with actual pursuits. However, when pursuing prey dummies, beetles track continuously and quickly follow changes in target position, suggesting closed-loop control using a position-sensitive servo mechanism. Differences between these types of pursuit control system are discussed with respect to limitations in signal detection, particularly spatio-temporal contrast, that may force beetles to use an open-loop system. Accepted: 7 April 1997     

The function of turret building behaviour in the larval tiger beetle, Cicindela willistoni (Coleoptera: Cicindelidae)

Abstract. 1. Cicindela willistoni LeConte (Coleoptera: Cicindelidae) adults and larvae occur only on saline and alkali flats with little or no vegetation in southwestern U.S.A. Unlike other larval tiger beetle species, C.willistoni constructs a chimney-like extension (turret) 1–4 cm above its burrow.
2. The function of these unique turrets was tested in relation to several biotic and abiotic factors in the Sulphur Springs Valley, Arizona, U.S.A.
3. The turrets did not prevent flooding of the larval burrows.
4. They did not prevent or reduce the frequency of parasitoids (mainly bombyliid flies of the genus Anthrax ).
5. The turrets did not make it possible for the adult and larval beetles to feed on obviously different types or sizes of prey.
6. However, larvae with turrets were raised sufficiently above the substrate surface and boundary layer to allow them to thermoregulate in the lower temperatures at these heights and remain active throughout the day.
7. The shade produced by the turrets attracted significantly more potential prey items than were available to turretless larvae in the same habitat.     

Validation of tiger beetles as distinct family (Coleoptera: Cicindelidae), review and reclassification of tribal relationships

The higher-level taxonomy of tiger beetles is re-evaluated in light of recent publications based on large taxon sets and a large number of genetic loci. These studies have demonstrated that tiger beetles are a distinct family, Cicindelidae Latreille, sister to the Carabidae Latreille (ground beetles) or Trachypachidae Thomson (false ground beetles) + Carabidae. Recent phylogenies have also recovered consistent patterns in higher-level relationships within the tiger beetles that challenge the traditional taxonomic framework, most of which is more than a century old. These phylogenetic results are reviewed along with concordant morphological characters to create an updated higher-level classification. The subfamily Collyrinae Csiki is not supported by any modern data. We recognize six tribes, Manticorini Laporte (new sense), Megacephalini Laporte (new sense), Collyridini Brullé, Ctenostomatini Laporte, Cicindelini Latreille and the reinstated Oxycheilini Chaudoir (with emended spelling).     

Cytogenetic analysis of Australian tiger beetles (Coleoptera: Cicindelidae): chromosome number, sex-determining system and localization of rDNA genes

The chromosomes of four species of Australian tiger beetle are documented. The male meioformulae of three species of Cicindela (tribe Cicindelini) were determined as follow: Cicindela cardinalba Sumlin 1987, n = 10 + X₁ X₂ X₃Y; C. sp. ( saetigera group) and Cicindela gillesensis Hudson 1994, n = 11 + X₁ X₂ X₃Y. The male meioformula of Megacephala whelani Sumlin 1992 (tribe Megacephalini) is n = 12 + XY. Fluorescence in situ hybridization (FISH) was used to localize the 18S-28S ribosomal gene clusters on male mitotic and meiotic chromosomes and nuclei using a polymerase chain reaction-amplified ribosomal probe. Fluorescence in mitosis and meiotic first prophase stages in the three Cicindela species showed that rDNA genes are in two of the four chromosomes that form the sex vesicle. In M. whelani hybridization in mitosis and first metaphase stages indicate that rDNA genes are in three, medium- to small-sized, autosomal pairs. Silver staining of male meiotic nuclei reveals the presence of active nucleolar organizing regions (NORs) in the sex vesicle of the three species of Cicindela . The cytogenetic and evolutionary implications of these findings are discussed.     

Hidden burrow plugs and their function in the tiger beetle, Cosmodela batesi (Coleoptera, Cicindelidae)

Tiger beetle larvae excavate and live in underground burrows, whose openings they sometimes plug with soil. This study documents the burrow plugging behavior of the tiger beetle, Cosmodela batesi (Fleutiaux), in the field. We also tested the function of burrow plugs in the laboratory. In the field, C. batesi more frequently made a plug when it rained. Most larvae made plugs inside their burrows (rather than at the soil surface), and the use of an endoscope was necessary to detect these sub-surface plugs. In the laboratory, flooding was simulated by artificially introducing water into specially-made arenas. Water filled the entire burrow when there was no plug, whereas plugged burrows maintained air chambers inside. When a plug was broken with a wire, burrows filled up with water. The burrowing and plugging behavior described in this study is likely an important adaptation of C. batesi to its habitat.     

Exceptional anoxia resistance in larval tiger beetle, Phaeoxantha klugii (Coleoptera: Cicindelidae)

Abstract. The tiger beetle Phaeoxantha klugii inhabits Central Amazonian floodplains, where it survives the annual inundation period in the third-instar larval stage submerged in the soil at approximately 29 °C for up to 3.5 months. Because flooded soils quickly become anoxic, these larvae should be highly resistant to anoxia. The survival of adult and larval P. klugii was therefore tested during exposure to a pure nitrogen atmosphere in the laboratory at 29 °C. Adult beetles were not resistant (< 6 h). Survival of larvae decreased over time, maximum survival was 15 days, whereas time to 50% mortality was 5.7 days (95% confidence interval 3.8–7.9). Anoxia resistance was additionally tested in third-instar larvae submerged within sediment for 40 days before anoxia exposure in the laboratory. Anoxia resistance was greatly enhanced in these larvae, showing a survival rate of 50% after 26 days of anoxia exposure. It appears that the gradual flooding process and/or the submersion phase induced a physiological alteration, most probably a strong depression in metabolic rate, which requires some days for induction. The degree of anoxia resistance in larval P. klugii is remarkable among terrestrial arthropods worldwide, even more so considering the high ambient temperatures. The species is well-suited to serve as a model organism for studying the physiological mechanisms of anoxia and submersion resistance in terrestrial arthropods inhabiting tropical floodplains.     

Evolutionary dynamics of autosomal-heterosomal rearrangements in a multiple-X chromosome system of tiger beetles (Cicindelidae)

Background  

Genetic systems involving multiple X chromosomes have arisen repeatedly in sexually reproducing animals. Tiger beetles (Cicindelidae) exhibit a phylogenetically ancient multiple-X system typically consisting of 2–4 X chromosomes and a single Y. Because recombination rates are suppressed in sex chromosomes, changes in their numbers and movement of genes between sex chromosomes and autosomes, could have important consequences for gene evolution and rates of speciation induced by these rearrangements. However, it remains unclear how frequent these rearrangements are and which genes are affected.     

Glacial refuges and cryptic speciation in a Southern Palearctic tiger beetle (Coleoptera: Cicindelidae)

Pleistocene glaciations had a determining role for shaping the current distribution and diversity of organisms, especially in the Palearctic region. In this work, we carry out a phylogeographic analysis of Iberian and two Eastern European populations of the tiger beetle Calomera littoralis (Fabricius, 1787) in order to infer the processes that may have affected their evolutionary history. According to our results, the genetic diversity of central Iberian C. littoralis populations is very low. The haplotype networks also suggest that these populations experienced a genetic bottleneck in the past, possibly related to the last glacial maxima, similar to that observed in other cicindelid taxa. These results highlight the remarkable dispersal capacity of this species, being able to move freely from one locality to another, despite the relatively long distances of sub-optimal habitat that separates them. The genetic data of central Iberian populations contrast with those of the Eastern European populations, with higher genetic diversity and no hints of any past bottleneck. This can be explained by the different characteristics of both (Iberian and Pontic) glacial refuges. The high degree of genetic differentiation between the three C. littoralis clades, and the inclusion of C. lunulata between them, suggests that the three analysed populations could be considered as different cryptic species. In that case, C. littoralis may correspond to a species complex that is still undergoing a process of speciation, similar to that observed in Cicindela campestris.     

Structure and function of the mandibles of adult dung beetles (Coleoptera : Scarabaeidae)

The mouthparts of adult dung beetles (Coleoptera : Scarabaeidae) are adapted for manipulation of soft, pasty food—usually the excrement of vertebrates. Nutrients are derived primarily from micro-organisms contained in the food and these must be broken up before ingestion. The mandibles, particularly the molar lobes, are designed to finely grind these particulates; the molae function as a mortar-pestle system, which mills the organic “grist” contained in the food by a combination of squeezing and grinding actions. The ability of the molae to finely grind food particles resides primarily in the structure of the molar surface, which consists of a series of ridges bearing rows of submicroscopic scrapers (“tritors”). The incisor lobes of the mandibles scrape food from the surfaces of the galeae and lacinae, which bring food into the preoral cavity. The structure of the mouthparts of Canthon pilularius (L.), which is described in detail, is basically the same as that of 10 other species examined. Those of Aphodius and Geotrupes are similar in some respects to those of scarabaeines but are obviously less well specialized for microphagy.     

Proventricular trituration in adult carabid beetles (Coleoptera: Carabidae)

Adult carabids that ingest particles of food have a muscular proventriculus lined internally with an intima that bears sclerotized projections. In experiments where six species of carabid were allowed to feed upon Drosophila, the average size of cuticular remains found in post-proventricular regions of the gut was generally significantly smaller than those in the crop. This reduction in size of cuticular particles is likely to be due to proventricular trituration rather than prolonged exposure to digestive secretions. There is no evidence that material is triturated by the proventriculus and returned to the crop, the main seat of digestion in carabids, so proventricular trituration is unlikely to enhance digestion. By crushing large, potentially abrasive, cuticular particles, the proventriculus may serve to protect midgut epithelial tissue.     

Cytogenetic analysis of Ctenostomini by C-banding and rDNA localization and its relevance to the knowledge of the evolution of tiger beetles (Coleoptera: Cicindelidae)

In this work, the first cytogenetic data on Neotropical Collyrinae is provided, by way of their karyotypes, C-banding and ribosomal genes (rDNA) localization using fluorescence in situ hybridization (FISH). The two species analysed, Ctenostoma (Procephalus) ornatum ornatum (male) and Ctenostoma (Euctenostoma) rugosum(female) showed, respectively, a diploid number of 17 and 18 chromosomes. C. ornatum ornatum has a multiple sex chromosome system ( n=7 + X₁X₂Y), and mitotic and meiotic metaphase cells showed rDNA gene labelling in the smallest autosomal pair. In this species, no C-bands were obtained, while C. rugosum seems to exhibit centromeric and/or interstitial C-bands in almost all chromosomes. The observation of a multiple sex chromosome system in Ctenostomini ensured the appearance of this characteristic in the hypothetical ancestral of Collyrinae and Cicindelini. The subfamily Collyrinae is not uniform in what concerns diploid chromosome number and rDNA gene localization, because C. ornatum ornatum possesses a lower chromosome number and autosomal rDNA genes when compared with the other Collyrinae species studied ( Neocollyris spp.). Independent events leading to the reduction in chromosome number might have taken place during the split of the Collyrinae into the tribes Ctenostomini and Collyrini.     

Are we doomed to repeat history? A model of the past using tiger beetles (Coleoptera: Cicindelidae) and conservation biology to anticipate the future

Studies of conservation biology involving tiger beetles have become increasingly common in the last 15 years. Governments and NGOs in several countries have considered tiger beetles in making policy decisions of national conservation efforts and have found tiger beetles useful organisms for arguing broad conservation issues. We trace the evolution of the relationship between tiger beetle studies and conservation biology and propose that this history may in itself provide a model for anticipating developments and improvements in the ability of conservation biology to find effective goals, gather appropriate data, and better communicate generalizations to non-scientific decision makers, the public, and other scientists. According to the General Continuum of Scientific Perspectives on Nature model, earliest biological studies begin with natural history and concentrate on observations in the field and specimen collecting, followed by observing and measuring in the field, manipulations in the field, observations and manipulations in the laboratory, and finally enter theoretical science including systems analysis and mathematical models. Using a balance of historical and analytical approaches, we tested the model using scientific studies of tiger beetles (Coleoptera: Cicindelidae) and the field of conservation biology. Conservation biology and tiger beetle studies follow the historical model, but the results for conservation biology also suggest a more complex model of simultaneous parallel developments. We use these results to anticipate ways to better meet goals in conservation biology, such as actively involving amateurs, avoiding exclusion of the public, and improving language and style in scientific communication. CXLV, Studies of Tiger Beetles     

Phylogenetic analysis of slippage-like sequence variation in the V4 rRNA expansion segment in tiger beetles (Cicindelidae)

Sequence variation in the middle part of the small-subunit rRNA was studied for representatives of the major groups in the family Cicindelidae (Coleoptera). All taxa exhibited a much expanded segment in variable region V4 compared to D. melanogaster. This expanded segment was not found in other groups of beetles, including three taxa in the closely related Carabidae. Secondary structure predictions indicate that the expanded segment folds into a single stem-loop structure in all taxa. Despite its structural conservation, the fragment differs strongly in primary sequence, even between closely related sister taxa. Several features of these sequences are consistent with slippage replication as the mechanism that has generated this sequence variation: the level of internal sequence repetition as measured by the relative simplicity factor (RSF), its variation in length between close relatives, and the strong nucleotide bias compared to the remainder of the gene. With few exceptions, there was also a correlation between sequence length and the level of sequence repetition, frequently interpreted as the result of slippage. Phylogenies inferred from the expansion segment were not consistent with existing hypotheses from other molecular data for the group. This indicates that DNA sequences in this region are not homologous throughout the entire Cicindelidae, but it leaves open the possibility that this expansion segment can be used for phylogeny reconstruction within subgroups. The implications of a phylogenetic approach to the understanding of slippage-like evolution are discussed.