Broscus cephalotes

Broscus cephalotes
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Coleoptera
Family:	Carabidae
Genus:	Broscus
Species:	B. cephalotes
Binomial name
	Broscus cephalotes; (Linnaeus, 1758)

Last updated March 18, 2023

Broscus cephalotes is a species of nocturnal, coastal ground beetle found throughout most of Europe. Its range spans from western Europe into western Siberia.^[1] The species was introduced recently (circa 1975) in the eastern areas of Canada and has spread farther south and west into the United States.^[2] As a member of the family Carabidae, Broscus cephalotes is generally considered beneficial to humans due to its predatory habits. Their varied diet often includes crop pests and other small organisms.^[2]

Description

Broscus cephalotes has a dull black coloration, without any metallic hue, and it can be quite large: between 16 and 23 mm.^[1] The morphology of the beetle is similar to other beetles in its family. B. cephalotes is flightless and flatter than many other species of Carabidae, which helps it hide in close spaces (e.g. crevices under stones or under bark).^[3] Body shape and presence or absence of the ability of flight can provide clues to diet of beetles, but does not provide conclusive evidence.^[3] Although mouth-parts are a better indicator of the type of food consumed by the beetle, the best method of determining the diet of a beetle is gut dissection.^[3] The asymmetric mandibles of B. cephalotes are blunt and twice as long as they are wide.^[4] The mandibles are curved to a rounded point at the end, with the left mandible is slightly longer and wider than the right mandible.^[3] These mandibles are multi-purpose tools. The beetle uses them to create and maintain the tunnels in which they spend most of their lives.^[4] The opened mandibles can act as shovels or pull dirt and debris from the walls of their tunnels and deposit it outside the burrow.^[4] Additionally, the mandibles can act as shovels in the loose sand of the beetles’ coastal habitat.^[4] Another critical use of the mandibles is in feeding, as discussed below.

Feeding

Broscus cephalotes are primarily carnivorous beetles; however they will consume a wide variety of food. They are generalists, and the adults do not discriminate much in what they consume.^[5] A recent study showed that B. cephalotes in laboratory conditions will attack everything that runs across the opening of its burrow, though they preferred to attack and eat woodlice and ants.^[6] Some of what has been found in various beetles’ digestive tract include: plant material and various types of insects: ants, wolf spiders, Aphididae, caterpillars, Diptera, Acarina, Bibionidae, Coleoptera, adult Lepidoptera, and Heteroptera.^[5] However, there has been no evidence of cannibalism in this species of beetle.^[5] The diet of the larvae of this family has not been as widely studied because the larvae spend their time in tunnels and are difficult to identify even when not hidden in the soil. Carabidae larvae are usually more carnivorous than adults and have a more restricted diet.^[7] The limited diet may be due to their subterranean habitat and their small size. Additionally, the larvae of Carabidae beetle tend to be fluid feeders, regardless of their status as adults.^[7]

Broscus cephalotes has two main methods to detect prey: tactile cues and olfactory cues. The olfactory cues, however, do not seem to be very specific, as the responses to the cue do not correspond strongly to preference of prey.^[7] The beetle, once in possession of its prey, holds the organism with its forelegs and tears off pieces of the organism to consume. The mandibles are used to tear open the cuticular structures of its meal and expose the soft tissue areas within the organism.^[5] Fluid is produced in the mouth during feeding that causes the discoloration of flesh and begins the digestive process.^[5] This fluid is composed of a variety of enzymes that begin the digestive process before the prey has entered the beetle’s digestive tract. Many samples of B. cephalotes were found to have sand in their digestive tract in addition to prey.^[5] Sand in the digestive tract may help the beetle grind up the tougher parts of the prey, although it has not yet been determined if the sand is ingested for this purpose.^[5]

Habitat and habits

Broscus cephalotes can be found all across temperate western and central Europe, extending into western Siberia.^[1] Specimens are usually found in the coastal regions, but can also be found more rarely inland. It generally can be found in the vegetated dunes on the coast, but prefers the more sparsely vegetated areas.^[1]

The first appearance of B. cephalotes in North America was recorded in Nova Scotia in 1978.^[8] It seemed as though the species was well established in the area at the time, but still a relatively new arrival. The species is still confined to the eastern seaboard in North America and is less common than in Europe.

Broscus cephalotes are mostly nocturnal, although they have been seen scurrying from one hiding place to another during the day.^[4] They hide during the day burrowed under logs and stones in loose, dry sand.^[8] They have been known to rest in groups, but no evidence points to that being the norm or anything but a matter of convenience. Their nocturnal lifestyle may be helpful in the acquisition of prey. As the beetles are active during the night, they can more easily capture prey that is diurnal.^[7] Nocturnal habits also reduce the number of predators active while the beetle is active.^[7]

Most adults do not live through the winter, but the larvae develop during the winter months and emerge as adults in the spring and summer.^[8]

Fighting in the species has been observed under artificial daylight, but the purpose of the fighting has not been determined. Fighting could be over resources like food, burrows, or mates.^[6]

Reproduction and life cycle

Broscus cephalotes breed in the early autumn, when the temperature is still warm and the air still dry.^[2] The eggs are deposited deep into the sandy soil during late summer and early autumn.^[9] The site of oviposition is determined and prepared by the female beetle.^[10] After the eggs are laid there is no parental care.^[10] The eggs hatch and the larvae develop in the tunnels during the winter and early spring.^[9] The larvae spend all their time below the surface, and consequently, are not well studied. The adult beetles emerge from the burrows in the late spring and early summer.^[9] All individuals generally emerge by early July.^[11] The period of reproduction generally spans from the end of July to mid-September, with the first larvae developing at the end of August.^[11] This can lead to some individuals developing on a one-year schedule and others developing on a two-year schedule.^[11] However, most die after their first year of life, and only reproduce once. Some specimens have been kept alive in laboratories for much longer than one year.^[10]

In many beetles in this family, higher temperatures correlate to long reproductive periods and more eggs laid.^[2] Lower temperatures correlate to a shortened reproductive period and fewer eggs produced, despite the presence of an abundance of food.^[2] However, laboratory settings may give a skewed view of the reality of these beetles. There have not been comprehensive field studies on effect of temperature on reproductive success in carabid beetles of any type.

Predators

Birds are major predators of B. cephalotes, which use invertebrates to provide a protein-rich diet for their chicks.^[2] Some species of corvid and raptor birds eat carabid beetles as adults as well.^[2] Farmland birds depend heavily on carabids for food.^[2] Small mammals, amphibians and reptiles may also prey on B. cephalotes.^[2] Mammals, such as hedgehogs, shrews and mice inhabiting areas far from crops often consume these beetles. The beetles constitute a significant (20%) portion of these mammals’ diet in June.^[2] This is primarily due to the beetles’ life cycle, as they are most numerous in June.^[2]

Humans and Broscus cephalotes

In Britain, there has been a large reduction in the area covered by heath lands over the past 150 years. This reduction has been largely due to human activity; expanding industrial and residential areas have reduced the available and habitable heath land.^[12] While the heath lands are not known for diversity in flora, the invertebrate fauna in the region rely on the heath lands for survival.^[12] The remaining habitats in Britain are cut through and connected by roadways. There has been concern in the past that roadways disrupt the habitats of B. cephalotes and that the roads interfere with breeding. However, recent studies show that the sandy roadsides can link habitats and create refuges for the beetles. This leads to greater survival and reproduction in the ground beetle population.^[12]

It is in farmers’ interests for these beetles to continue surviving and reproducing successfully.^[2]B. cephalotes have been recognized as useful to farmers since the early nineteenth century.^[2] Many of their prey fall under the category of crop pests, such as aphids, slugs and dipteran eggs.^[2] However, farmers have only recently begun to consider these beetles in their crop rotations.^[2] Renewed interest in the role of beetles in crop rotations can partially be explained by the decreased value of crops and pressure from environmental groups use more environmentally friendly farming practices.^[2] Most of the more recently adopted farming practices (e.g. selective insecticides and augmenting non-crop habitat) will affect the population of ground beetles, but not immediately.^[2] Pest management effects will not be noticeable until more extensive measures are implemented.^[2]

Related Research Articles

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Tiger beetles are a family of beetles, Cicindelidae, known for their aggressive predatory habits and running speed. The fastest known species of tiger beetle, Rivacindela hudsoni, can run at a speed of 9 km/h, or about 125 body lengths per second. As of 2005, about 2,600 species and subspecies were known, with the richest diversity in the Oriental (Indo-Malayan) region, followed by the Neotropics. While historically treated as a subfamily of ground beetles (Carabidae) under the name Cicindelinae, several studies since 2020 indicated that they should be treated as a family, the Cicindelidae, which are a sister group to Carabidae within the Adephaga.

Hydrophilidae, also known colloquially as water scavenger beetles, is a family of beetles. Aquatic hydrophilids are notable for their long maxillary palps, which are longer than their antennae. Several of the former subfamilies of Hydrophilidae have recently been removed and elevated to family rank; Epimetopidae, Georissidae, Helophoridae, Hydrochidae, and Spercheidae. While the majority of hydrophilids are aquatic, around a third of described species are terrestrial, mostly belonging to the subfamily Sphaeridiinae.

Histeridae is a family of beetles commonly known as clown beetles or hister beetles. This very diverse group of beetles contains 3,900 species found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their geniculate (elbowed) antennae with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species are used in the control of livestock pests that infest dung and to control houseflies. Because they are predacious and will even eat other hister beetles, they must be isolated when collected.

Insect mandibles are a pair of appendages near the insect's mouth, and the most anterior of the three pairs of oral appendages. Their function is typically to grasp, crush, or cut the insect's food, or to defend against predators or rivals. Insect mandibles, which appear to be evolutionarily derived from legs, move in the horizontal plane unlike those of vertebrates, which appear to be derived from gill arches and move vertically.

Carabus auratus, the golden ground beetle, is a species of ground beetle in the genus Carabus. This species is native to central and western Europe and has been introduced into North America.

Neocicindela tuberculata is a species of tiger beetle in the family Cicindelidae, endemic to New Zealand. Its common names include common tiger beetle, moeone, and papapa, and in its laval stage penny doctor, butcher boy, kapuku, kui, kurikuri, moeone, and muremure. Neocicindela tuberculata was the first carabid beetle described from New Zealand. The species can run as fast as 5 miles per hour and are considered to be the fastest running beetles. Adult species prefer clay banks in summer and are good predators when in comes to insects.

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Mecodema antarcticum is a carnivorous carabid beetle that burrows in sand above the high tide mark on New Zealand sandy beaches. First described by Francis de Laporte de Castelnau in 1867 as Brullea antarctica, it has since been reassigned to Mecodema.

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Epomis nigricans is a species of ground beetle native to the Palearctic. It is known from China, Japan, North Korea, and South Korea.

<i>Habroscelimorpha dorsalis dorsalis</i> Subspecies of beetle

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References

1 2 3 4 "Broscus cephalotes". Ground Beetles of Ireland. National Museums Northern Ireland . Retrieved March 22, 2011.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Holland, John M. 2002. “Carabid Beetles: Their Ecology, Survival and Use in Agroecosystems.” The Agroecology of Carabid Beetles
1 2 3 4 Ingerson-mahar, Joseph. 2002 “Relating Diet and Morphology in Adult Carabid Beetles.” The Agroecology of Carabid Beetles.
1 2 3 4 5 Forsythe, Trevor G. 1982. “Feeding Mechanisms of Certain Ground Beetles” (Coleoptera: Carabidae). The Coleopterists Bulletin.: 36.1: 26-73 The Coleopterists Society.
1 2 3 4 5 6 7 Hengeveld, R. 1980. “Polyphagy, Oligophagy, and Food Specialization in Ground Beetles” Netherlands Journal of Zoology 30(4): 564-584.
1 2 Mossakowski D. 2003. “Feeding and fighting behavior in Broscus cephalotes” (L.). Baltic J. Coleopterol. 3 (2):
1 2 3 4 5 Toft, Soren and Trine Bilde. 2002. “Carabid Diets and Food Value.” The Agroecology of Carabid Beetles.
1 2 3 Larivière, M.-C. and A. Larochelle 1989. First Records of Broscus cephalotes (Linnaeus) (Coleoptera: Carabidae: Broscini) for North America The Coleopterists Bulletin. 43.1:69-73. The Coleopterists Society.
1 2 3 Lindroth, Carl. 1985. The Carabidae (Coleoptera) of Fennoscandia and Denmark, Part 1
1 2 3 Lovei, G. L., and K. D. Sunderland. 1996. “Ecology and Behavior of Ground Beetles (Coleoptera: Carabidae).” Annual Review of Entomology 41.1: 231-56.
1 2 3 Matalin, Andrey. 2008. “Evolution of biennial life cycles in ground beetles.” 'Proceedings of the XIII European Carabidologists Meeting, Blagoevgrad, August 20–24, 2007', pp. 259-284.
1 2 3 Telfer, Mark G. and Brian C. Eversham. 1996. “Ecology and conservation of heathland Carabidae in eastern England” Ann. Zool. Fennici 33: 133-138.

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[refone-1] 1 2 3 4 "Broscus cephalotes". Ground Beetles of Ireland. National Museums Northern Ireland . Retrieved March 22, 2011.

[reftwo-2] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Holland, John M. 2002. “Carabid Beetles: Their Ecology, Survival and Use in Agroecosystems.” The Agroecology of Carabid Beetles

[refthree-3] 1 2 3 4 Ingerson-mahar, Joseph. 2002 “Relating Diet and Morphology in Adult Carabid Beetles.” The Agroecology of Carabid Beetles.

[reffour-4] 1 2 3 4 5 Forsythe, Trevor G. 1982. “Feeding Mechanisms of Certain Ground Beetles” (Coleoptera: Carabidae). The Coleopterists Bulletin.: 36.1: 26-73 The Coleopterists Society.

[reffive-5] 1 2 3 4 5 6 7 Hengeveld, R. 1980. “Polyphagy, Oligophagy, and Food Specialization in Ground Beetles” Netherlands Journal of Zoology 30(4): 564-584.

[refsix-6] 1 2 Mossakowski D. 2003. “Feeding and fighting behavior in Broscus cephalotes” (L.). Baltic J. Coleopterol. 3 (2):

[refseven-7] 1 2 3 4 5 Toft, Soren and Trine Bilde. 2002. “Carabid Diets and Food Value.” The Agroecology of Carabid Beetles.

[refeight-8] 1 2 3 Larivière, M.-C. and A. Larochelle 1989. First Records of Broscus cephalotes (Linnaeus) (Coleoptera: Carabidae: Broscini) for North America The Coleopterists Bulletin. 43.1:69-73. The Coleopterists Society.

[refnine-9] 1 2 3 Lindroth, Carl. 1985. The Carabidae (Coleoptera) of Fennoscandia and Denmark, Part 1

[reften-10] 1 2 3 Lovei, G. L., and K. D. Sunderland. 1996. “Ecology and Behavior of Ground Beetles (Coleoptera: Carabidae).” Annual Review of Entomology 41.1: 231-56.

[refeleven-11] 1 2 3 Matalin, Andrey. 2008. “Evolution of biennial life cycles in ground beetles.” 'Proceedings of the XIII European Carabidologists Meeting, Blagoevgrad, August 20–24, 2007', pp. 259-284.

[reftwelve-12] 1 2 3 Telfer, Mark G. and Brian C. Eversham. 1996. “Ecology and conservation of heathland Carabidae in eastern England” Ann. Zool. Fennici 33: 133-138.

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