Cobblestone Tiger Beetle
Scientific Name: Cicindela marginipennis
Taxonomy Group: Arthropods
Range: New Brunswick
Last COSEWIC Assessment: November 2008
Last COSEWIC Designation: Endangered
SARA Status: Schedule 1, Endangered
Image of Cobblestone Tiger Beetle
The Cobblestone Tiger Beetle is 11 to 14 mm in length. Like all tiger beetles, this species has very long legs and is brightly coloured. However, it can be distinguished by its bright red-orange abdomen that is clearly visible during flight and by its continuous cream-coloured border on the elytra, the two hardened wings that cover the flying wings. Adults have large jaws, called mandibles, that are used to capture prey. Adults will readily take flight when approached. The Canadian population is the only known population of this species that possesses green and cobalt-blue individuals. The immature stages of this species have not been described. However, all tiger beetle larvae are similar in appearance. Like the adults, the larvae are predators. They use a sit-and-wait strategy, hiding in a vertical tunnel in the soil. The tops of the thorax and head form a flattened disk that plugs the tunnel, concealing the larva and the tunnel entrance from prey walking on the soil surface. The larva then lifts its disk and ambushes its prey, capturing them with its powerful sickle-shaped mandibles. The dorsal surface of the larva is equipped with two pairs of large hooks that hook into the wall of the tunnel if the prey attempts to drag the larva from its burrow.
Distribution and Population
The Cobblestone Tiger Beetle occurs in several small disjunct populations associated with major river systems, from Mississippi and Alabama northeastward in the United States to Ohio, Indiana, Pennsylvania, New York and New Hampshire. In Canada, where the species was first discovered in 2003, it occurs only in New Brunswick, at nine locations in two isolated areas along the Saint John River and Grand Lake. Population sizes at most of the known sites in Canada are small, with less than 200 individuals. The total Canadian population has been estimated at about 5000 adult individuals. Due to the recent discovery of this species, definite information for evaluating population trends is not available. However, there is some evidence for a population decline at one of the sites on Grand Lake. Close to 75% of potential island habitats for this species were lost with the construction of the Mactaquac Dam on the Saint John River in 1967. Based on the survey effort for new locations, it is believed that the Cobblestone Tiger Beetle is highly unlikely to be found outside New Brunswick in Canada or to occur or in many more locations in New Brunswick, if any.
As its name indicates, the Cobblestone Tiger Beetle occurs almost exclusively among cobblestones and coarse gravel with small patches of sand. In New Brunswick, it occurs only on treed islands of the Saint John River with high, infrequently flooded cobblestone beaches and in similar habitats on the shores of Grand Lake. The habitat where Cobblestone Tiger Beetles live is created in part by the effects of flooding during the spring freshet and the volume and speed of water created by the structure of the islands or beaches themselves. All occupied sites have high cobblestone beaches with sparse vegetation that are probably flooded only during the spring freshet and only rarely after very heavy summer rains. It appears that this feature may be critical for the long-term survival of this species.
Like other beetle species, the Cobblestone Tiger Beetle undergoes complete metamorphosis with four distinct stages of egg, larva, pupa and adult. No studies have been published on the life history of the Cobblestone Tiger Beetle, but its larvae presumably pass through three larval stages or instars, as do the larvae of all tiger beetles. The third-instar larva builds a chamber in the soil and then forms a pupa from which the adult later emerges. Most tiger beetle species have a two-year life cycle, although adults are present each year at any given locality. Tiger beetles are predators on small insects and spiders, in both the larval and adult stages. Unlike the larvae, which are sit-and-wait predators, adults are active predators that run down and capture their prey. Adults are active only during summer. The Cobblestone Tiger Beetle overwinters as larvae. In New Brunswick, adults are present from late June to late August. Other species of tiger beetles begin reproductive activity shortly after emergence and deposit eggs singly up to 1 cm below the surface of the soil. Once the egg hatches, larvae construct a vertical tunnel at the site selected by the female for oviposition. The larvae apparently live within the same burrow throughout the three instars, enlarging it as necessary.
Declines in habitat have occurred at one region, where the pressures on the habitat of the Cobblestone Tiger Beetle from development and recreation appear to be continuing. Because the larvae live in burrows among the cobblestones, beach traffic from all-terrain vehicles (ATVs) may cause significant larval mortality as well as substantial changes by compaction of soil and damage of the plant community by the tires. Habitat on islands in the Saint John River is not accessible to ATV traffic, but habitats on Grand Lake are accessible. One population at a site at Grand Lake may have declined owing to habitat degradation by ATVs in 2007. Pollutants such as farm waste products and silt washing in from recently ploughed fields after heavy rain may alter the plant community, making the habitats unsuitable for a ground-based insect by increasing plant cover and reducing shoreline prey. Since all known sites for the Cobblestone Tiger Beetle along the Saint John River are near agricultural areas, their contamination by pollutants could be a significant threat to the species. In Canada, this species occurs in small populations at only a few locations in a very specialized and fragile habitat, making this species extremely vulnerable to habitat loss or alternation. The apparent low propensity of the Cobblestone Tiger Beetle to disperse to other sites will compound the effects of habitat loss and degradation. This results in a high probability of extirpation of this insect from any given site. It is this limited distribution and the small, isolated populations that are the most important factors affecting the status of this species and its long-term persistence in Canada. The small population size and popularity of tiger beetles for insect collectors make this species susceptible to over-collecting. Reductions in distribution caused by habitat loss or loss of a population due to other factors could have a significant impact on the entire population by reducing genetic variability of the overall Canadian population and negatively influencing the ability of the species to adapt to future environmental changes, such as global climate change.
Federal ProtectionThe Cobblestone Tiger Beetle is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
The Cobblestone Tiger Beetle is not protected by any provincial legislation in New Brunswick.
Provincial and Territorial Protection
Status of Recovery Planning
Recovery Strategies :
Name Recovery Strategy for the Cobblestone Tiger Beetle (Cicindela marginipennis) in Canada
Status Final posting on SAR registry
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
8 record(s) found.
- COSEWIC Status Reports (1 record(s) found.)
- COSEWIC Assessments (1 record(s) found.)
- Response Statements (1 record(s) found.)
- Recovery Strategies (1 record(s) found.)
- Orders (2 record(s) found.)
- COSEWIC Annual Reports (1 record(s) found.)
- Consultation Documents (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2009 (2009)2009 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
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