Pterostichus melanarius

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Pterostichus melanarius, the Rain Beetle, [1] is a type of carabid (ground beetle) of the genus Coleoptera. It is native to Europe but is increasingly found in North America after being introduced to the region in the 1920s. It is a predatory beetle that eats invertebrate pests, which makes it a valuable pest control agent in agricultural settings. Additionally, the beetle has wing dimorphism which has contributed to its increasing distribution across North America. [2]

Contents

Pterostichus melanarius
Pterostichus melanarius01.jpg
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Coleoptera
Suborder:
Adephaga
Family:
Carabidae
Genus:
Pterostichus
Species:
P. melanarius
Binomial name
Pterostichus melanarius
(Illiger, 1798)

The larvae of this species of beetle have been observed exhibiting cannibalistic behaviorisms in high population densities. [3] The rain beetle's habitat is influenced by their hunger level, with starved beetles preferring larger prey ranges compared to satiated beetles. [4]

Description

Adults of P. melanarius grow to be 12–18mm long. They appear black with straight striations on their elytra. They "are distinguished from other Pterostichus species by their laterobasal carina and denticulate posterior angles of the pronotum." [2] Adults have wing dimorphism, characterized by brachypterous beetles and macropterous beetles. Brachypterous beetles have shortened hind wings and are unable to fly. Macropterous beetles have mature hind wings and are able to fly. [5] Eggs are translucent white immediately after oviposition, but darken before hatching. The larvae have a hard dark reddish-brown head. The appearance of pupae is not well documented. [2]

Distribution

P. melanarius is found in a wide geographical range across Europe, the United States, and Canada. It can be found in "natural, anthropogenic, and agricultural biotopes." [6] Beetles in similar geographical ranges tend to have similar development and life cycle stages, which differs from beetles in other geographical ranges. [6] P. melanarius can traverse 2.5-5m daily, which can increase during the summer in search of mates. In addition to walking, flight capabilities resulting from wing dimorphism contribute to the beetle's ability to traverse wide ranges. [2]

P. melanarius photographed in Ontario, Canada. Note the straight striations on the back on the beetle and the shiny black appearance. Rain Beetle (Pterostichus melanarius) - Guelph, Ontario 2017-07-08.jpg
P. melanarius photographed in Ontario, Canada. Note the straight striations on the back on the beetle and the shiny black appearance.

In Europe, the beetle can be found in Scandinavia, Italy, Greece, Ireland, Russia, and Serbia. In North America, the beetle is found on both the west and east coasts of the continent, but has been documented to have a steady movement into the center of the US. It is important to study this varying distribution to build an understanding how P. melanarius might affect its new habitats. [2]

Habitat

P. melanarius is hydrophilic and eurythermic, meaning it is able to tolerate wet environments with a wide ranges of temperatures. The beetle can inhabit habitats including forests, meadows, urban areas, and arable land. [2] Researchers explain that the consequence of the variability of habitats is that "the total duration of individual development may vary even within one natural climatic zone, which may result in different variants of the life cycle in the local populations occupying different biotopes." [7] In other words, the beetle is able to adapt stages of its life cycle to sync with its various habitat. The main conditions that would have to be met for the beetle to colonize and thrive in a habitat are temperatures suitable to larvae development and availability of food resources. [7]

Since the beetle's reproduction and development is temperature dependent, climate change presents a challenge to the fecundity of the beetles. A study in 2021 modeled the expected distribution of P. melanarius based using several RCP scenarios.The study confirms that the most important factors influencing changes in the beetle's distribution are mean temperature during the warmest and coldest times of the year, as well as precipitation levels during the driest periods of the year. With RCP 8.5 scenario, which is known as the worst-case climate change scenario, a sharp reduction in the Southern European and Mediterranean population of the beetle by 2070 is predicted. Less drastic changes in the distributions of the beetle was predicted in the more moderate RCP scenarios. [8]

Life cycle

Mating of P. melanarius occurs during early fall months closely followed by oviposition. To maximize probability of larvae surviving and having access to resources with needing to travel, female beetles select shaded and wet environments to lay their eggs. Females typically lay about 130 eggs at a time. All larval stages happen in the soil. [2] Colder temperatures are necessary for the larvae to develop into adults and warmer temperatures are necessary for the transition from final larval to pupae. Based on this developmental timeline, fully-developed adults emerge during late May to June. [2]

Behavior

The gray garden slug, the preferred prey of P. melanarius. Deroceras reticulatum 01.JPG
The gray garden slug, the preferred prey of P. melanarius.

P. melanarius, as larvae and adults, is an omnivorous predatory beetle that feeds on insects, invertebrates, and plants. Among a wide range of prey, the most common prey of the beetles are ants, caterpillars, mollusks, seeds, and plant tissue. [2] Additionally, several studies have verified that the beetle's have a special preference for consuming slugs. [2] Specifically, it has been suggested that it prefers the gray garden slug, Derocera reticulatum , which is an invasive slug species. The beetle often detects prey using olfactory cues. [3] The behavior of the beetles is often studied using pitfall trapping, which is a type of sampling method used to explore the behavior of species like beetles. It provides insight into their spatial distribution and abundance in different habitats. [4] The results of one study that used pitfall trapping indicate that the beetles utilize their habitats based on their hunger level and habitat quality. So, starved beetles will be found in habitats with a wider range of prey compared to satiated beetles, meaning that foraging in their habitats is dictated by hunger level. [4] Another study explains that starved beetles practice "conspecific odour-trail avoidance", which means that the P. melanarius beetles avoid searching for prey in locations that other individuals of P. melanarius have visited. [9] This behavior is characteristic of Lévy-flight patterns, which are optimal for widely dispersed prey that may not always be fully consumed at one time, such as slugs. [9]

Larvae are documented to feed on slugs and also practice cannibalism. [3]

Competition

Competition between P. melanarius and other carabid beetles depends on the region. In Europe, laboratory observations indicate that competition exists between P. melanarius and other carabid species like, P. cristatus, and that P. melanarius dominates. To decrease competition in the wild, the two species inhabit different habitats. [2] Interestingly, in Canada, where P. melanarius is an invasive species, there has been substantial evidence of competition between P. melanarius and other carabid beetles. P. melanarius does not appear to negatively impact the diversity or abundance of other carabid beetles. It is hypothesized that this is due to the beetles filling empty ecological niches. [2] [3] [10]

Competition between P. melanarius and primary prey, slugs, is significant. Dense aggregations of P. melanarius are known to be associated with dense aggregations of slugs and the beetle is capable of reducing the distribution and abundance of slug populations. [3] [11] Slugs can avoid attacks by the beetle by using their slime and by strategically moving through the soil to avoid predation. [9] Despite these tactics, the beetles are such avid predators of slugs that they are considered to be of great importance for biologically controlling slug populations, which are often harmful to agriculture. [2] [3]

Competition between P. melanarius and their predators is also significant. The beetles have many predators, primarily birds, but also "mice, bats, hedgehogs, shrews, frogs, toads, and occasionally moles." [3] Additionally, adults beetles and larvae are parasitized by "mites, wasps, flies, and nematodes." [3]

Relevance to agriculture

Heavy machinery is used to till fields and this can be disturbing to beetles in the soil. Tilling the fields - geograph.org.uk - 5865818.jpg
Heavy machinery is used to till fields and this can be disturbing to beetles in the soil.

Since P. melanarius inhabit arable fields, they are vulnerable to agricultural practices such as tilling fields and the use of insecticides. [2] Tilling can be harmful to the life cycle and development of the beetles as it can occur during the fall and spring, which coincide with the oviposition and final development stages of the beetles. Tillage in the spring can disturb larvae and pupae in the soil, resulting in a decrease in the number of fully developed adults able to breed that emerge later in the fall. Some studies suggest that tillage has no effect on the beetles, but the contradictory results may be due to study methodology differences. [2]

The use of insecticides on fields that are inhabited by P. melanarius has negative consequences for the beetle because the insecticide is harmful to the beetles and its prey. Direct exposure to insecticides reduces the beetle population and their activity levels. The beetles can also be indirectly exposed to insecticides through consumption of prey affected by insecticides. According to one study, the consumption of affect prey results in total mortality for a beetle, a risk which was only slightly reduced when consuming the affected prey several days after it was exposed to insecticide. [2] Further, insecticides can cause mortality in the beetle's prey, reducing food availability and potentially resulting in starvation of the beetles. Since beetles that are starved spend more time foraging for food, P. melanarius has increased activity in insecticide treated fields. [2]

An important method to decrease the negative impacts of harmful agricultural practices is to utilize cover crops and intercropping. In fields that used these agricultural control methods, which often require less tillage and chemical use, there was a greater abundance and activity levels of P. melanarius. [2] [3] Moreover, these habitats are ideal for female P. melanarius, which prefer to oviposit in "structurally complex environments" to provide more protection their eggs and larvae. [3]

Wing dimorphism

Several studies have determined that P. melanarius have had more rapid and expansive distribution in regions of Canada compared to other invasive carabid species. A possible explanation is that the macropterous (capable of flight) beetles help establish new beetle population in favorable habitats. After establishment, the majority of those beetles are replaced by brachypterous (flightless) beetles. [10] [5] Both morphs are inherited according to Mendelian genetics, with the flightless morph being the dominant gene and the flight morph being the recessive gene. In the process of establishing a new beetle colony in a new habitat, the flight morph has a competitive advantage, but after the new colony is established, the flightless morph has the competitive advantage and a greater portion of the population will present in this morph. [10]

Related Research Articles

<span class="mw-page-title-main">Beetle</span> Order of insects

Beetles are insects that form the order Coleoptera, in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described species, is the largest of all orders, constituting almost 40% of described insects and 25% of all known animal species; new species are discovered frequently, with estimates suggesting that there are between 0.9 and 2.1 million total species. Found in almost every habitat except the sea and the polar regions, they interact with their ecosystems in several ways: beetles often feed on plants and fungi, break down animal and plant debris, and eat other invertebrates. Some species are serious agricultural pests, such as the Colorado potato beetle, while others such as Coccinellidae eat aphids, scale insects, thrips, and other plant-sucking insects that damage crops.

<span class="mw-page-title-main">Colorado potato beetle</span> Species of beetle

The Colorado potato beetle is also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug. It is a major pest of potato crops. It is about 10 mm long, with a bright yellow/orange body and five bold brown stripes along the length of each of its elytra. Native to the Rocky Mountains, it spread rapidly in potato crops across America and then Europe from 1859 onwards.

<span class="mw-page-title-main">Adephaga</span> Suborder of beetles

The Adephaga are a suborder of beetles, and with more than 40,000 recorded species in 10 families, the second-largest of the four beetle suborders. Members of this suborder are collectively known as adephagans. The largest family is Carabidae which comprises most of the suborder with over 40,000 species. Adephaga also includes a variety of aquatic beetles, such as predaceous diving beetles and whirligig beetles.

<span class="mw-page-title-main">Harpalinae</span> Subfamily of insects in the Ground beetle family (Carabidae)

Harpalinae is the largest subfamily of ground beetles, containing more than 19,000 species worldwide.

<span class="mw-page-title-main">Salt Creek tiger beetle</span> Subspecies of beetle

The Salt Creek tiger beetle is a critically endangered subspecies of tiger beetle endemic to the saline wetlands of northern Lancaster County, Nebraska, adjacent to and immediately to the north of the city of Lincoln, Nebraska. It is a predatory insect, using its mandibles to catch other insects. The beetle is one of the rarest insects in North America; surveys showed that 194 adults existed in 2009, down from 263 in 2008, and 777 in 2000. However, efforts are continuing to boost the population, which in 2013 numbered 365 beetles: one beetle for each day in a regular year. The adult beetles can move very fast to catch the prey.

<span class="mw-page-title-main">Cleridae</span> Checkered beetles

Cleridae are a family of beetles of the superfamily Cleroidea. They are commonly known as checkered beetles. The family Cleridae has a worldwide distribution, and a variety of habitats and feeding preferences.

<i>Neocicindela tuberculata</i> Species of beetle

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.

<i>Deroceras reticulatum</i> Species of gastropod

Deroceras reticulatum, common names the "grey field slug", "grey garden slug", and "milky slug", is a species of small air-breathing land slug, a terrestrial pulmonate gastropod mollusc in the family Agriolimacidae. This species is an important agricultural pest.

<span class="mw-page-title-main">Brachyptery</span> Condition of an animal having short wings

Brachyptery is an anatomical condition in which an animal has very reduced wings. Such animals or their wings may be described as "brachypterous". Another descriptor for very small wings is microptery. Brachypterous wings generally are not functional as organs of flight and often seem to be totally functionless and vestigial. In some species, however, flightless wings may have other functions, such as aposematic display in some Orthoptera and Phasmatodea. Brachyptery occurs commonly among insects. An insect species might evolve towards brachyptery by reducing its flight muscles and their associated energy demands, or by avoiding the hazards of flight in windy conditions on oceanic islands, in which flying insects are prone to drowning. Brachyptery also is common in ectoparasitic insects that have no use for wings, and inquiline insects with socially parasitic life strategies that do not require functional wings.

<i>Nebria brevicollis</i> Species of beetle

Nebria brevicollis, belonging to the Carabidae family, is a ground beetle. With nearly 500 species and over 100 subspecies, N. brevicollis is the most diverse genus within the Nebriini tribe of ground beetles. Members of the genus occupy a wide range of habitats. Nebria brevicollis is native to Europe and the Near East but has been introduced to the western United States and Canada. Its rapid expansion in North America is characteristic of an invasive species. Due to the variation in habitat, their diet consists of small arthropods including Collembola, Diptera, earthworms, mites, and spiders.

<i>Broscus cephalotes</i> Species of beetle

Broscus cephalotes is a species of nocturnal, coastal ground beetle found throughout most of Europe. Its range spans from western Europe into western Siberia. The species was introduced recently in the eastern areas of Canada and has spread farther south and west into the United States. 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.

<span class="mw-page-title-main">Bean leaf beetle</span> Species of beetle

Cerotoma trifurcata is a species of beetle in the Chrysomelidae family that can be found in the Eastern and West United States.

<i>Epomis</i> Subgenus of beetles

Epomis is a subgenus of ground beetle genus Chlaenius. The larvae of this subgenus are notable for being obligate role-reversal predators. Amphibians such as frogs are normally predators of beetles; however, Epomis larvae feed exclusively on amphibians.

<i>Chlaenius circumscriptus</i> Species of beetle

Chlaenius circumscriptus is a species of ground beetle native to the Palearctic, the Near East, and North Africa.

<i>Megadromus antarcticus</i> Species of beetle

Megadromus antarcticus, also known as the “Alexander beetle”, is a member of the Carabidae family and only found in the Canterbury region of New Zealand. Megadromus antarcticus are easily recognized by their iridescent green colouration.

<i>Chlaenius dejeanii</i> Species of beetle

Chlaenius dejeanii is a species of ground beetle native to the Palearctic and the Middle East. It is known from Bosnia and Herzegovina, Greece, Hungary, Israel, Italy, Russia, Syria, Turkey, and Ukraine.

<i>Anisodactylus binotatus</i> Species of beetle

Anisodactylus binotatus is a species of ground beetle native to Europe. It was discovered as being introduced to Canterbury, New Zealand in 1938. Anisodactylus binotatus is a species of Carabidae, also known as the ground beetle family. Although this species of beetle has no official recorded common names, literature from England refers to it as the common shortspur beetle.

<i>Calleida viridipennis</i> Species of ground beetle

The Calleida viridipennis is a species of ground beetle belonging to the Carabidae family, and are referred to as carabid beetles. It is found in various states, including New York, New Mexico, Louisiana, and Florida. Habitat preferences include forests and swamps. C. virdipennis is a particular carabid beetle that is, on average, 10 mm long. Recognizable by a green-black metallic exoskeleton, it has a trapezoidal head shape. Its large eyes are also characteristic of the species. Below the exoskeleton reside functional wings, giving the beetle flight capacity.

<i>Mecodema howitti</i> Species of beetle

Mecodema howitti, termed the Large Banks Peninsula ground beetle, is a carnivorous forest ground beetle in the genus Mecodema. It is endemic to Banks Peninsula, Canterbury, New Zealand, and is the largest of the 16 carabids found in the area.

<i>Rivacindela hudsoni</i> Species of beetle

Rivacindela hudsoni is an Australian species of the family Cicindelinae or "tiger beetle" and is the fastest running insect. The genus Rivacindela is contentiously treated as a subgenus of the broader Cicindela and are typically found in salty habitats such as dry salt lakes and salt streams. The species was discovered in South Australia and described in 1997, with an adult form of approximately 20–21mm in length and a running speed of 2.49m/s, or 120 body lengths per second.

References

  1. ↑ "Pterostichus melanarius (PTESML)[Overview]| EPPO Global Database". gd.eppo.int. Retrieved 2024-04-05.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Busch, Anna K; Wham, Briana E; Tooker, John F (2021-09-07). "Life History, Biology, and Distribution ofPterostichus melanarius(Coleoptera: Carabidae) in North America". Environmental Entomology. 50 (6): 1257–1266. doi:10.1093/ee/nvab090. ISSN   0046-225X. PMID   34492115.
  3. 1 2 3 4 5 6 7 8 9 10 Busch, Anna (2016). "Life history of Pterostichus melanarius (Coleoptera: Carabidae) and its importance for biological control in field crops".
  4. 1 2 3 Fournier, Elisabeth; Loreau, Michel (2002-01-01). "Foraging activity of the carabid beetle Pterostichus melanarius Ill. in field margin habitats". Agriculture, Ecosystems & Environment. 89 (3): 253–259. doi:10.1016/S0167-8809(01)00216-X. ISSN   0167-8809.
  5. 1 2 Hill, Benjamin T. (2012). "Extensive Schweinefreilandhaltung und ihre Auswirkung auf tierische Lebensgemeinschaften am Beispiel der Laufkäfer (Coleoptera: Carabidae)". archiv.ub.uni-marburg.de (in German). doi:10.17192/z2013.0228 . Retrieved 2024-04-02.
  6. 1 2 Matalin, A. V. (2006-05-01). "Geographic variability of the life cycle in Pterostichus melanarius (Coleoptera, Carabidae)". Entomological Review. 86 (4): 409–422. doi:10.1134/S0013873806040051. ISSN   1555-6689.
  7. 1 2 Trushitsyna, O. S.; Matalin, A. V. (2016-04-01). "Specific features of the life cycle of Pterostichus melanarius (Coleoptera, Carabidae) in mosaic floodplain meadows". Entomological Review. 96 (2): 144–159. doi:10.1134/S0013873816020020. ISSN   1555-6689.
  8. ↑ Avtaeva, T. A.; Sukhodolskaya, R. A.; Brygadyrenko, V. V. (2021-06-15). "Modeling the bioclimatic range of Pterostichus melanarius (Coleoptera, Carabidae) in conditions of global climate change". Biosystems Diversity. 29 (2): 140–150. doi:10.15421/012119. ISSN   2520-2529.
  9. 1 2 3 Guy, Adam G.; Bohan, David A.; Powers, Stephen J.; Reynolds, Andrew M. (2008-09-01). "Avoidance of conspecific odour by carabid beetles: a mechanism for the emergence of scale-free searching patterns". Animal Behaviour. 76 (3): 585–591. doi:10.1016/j.anbehav.2008.04.004. ISSN   0003-3472.
  10. 1 2 3 Bourassa, Stephane; Spence, John; Hartley, Dustin J.; Lee, Seung Il (2011-11-16). "Wing-dimorphism and population expansion of Pterostichus melanarius (Illiger, 1798) at small and large scales in central Alberta, Canada (Coleoptera, Carabidae, Pterostichini)". ZooKeys (147): 545–558. doi: 10.3897/zookeys.147.2097 . ISSN   1313-2970. PMC   3286251 . PMID   22379390.
  11. ↑ Symondson, W. O. C.; Glen, D. M.; Wiltshire, C. W.; Langdon, C. J.; Liddell, J. E. (1996). "Effects of Cultivation Techniques and Methods of Straw Disposal on Predation by Pterostichus melanarius (Coleoptera: Carabidae) Upon Slugs (Gastropoda: Pulmonata) in an Arable Field". Journal of Applied Ecology. 33 (4): 741–753. doi:10.2307/2404945. ISSN   0021-8901. JSTOR   2404945.


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