Coccinellidae (/ˌkɒksɪˈnɛlɪdiː/)[3] is a widespreadfamily of smallbeetles. They are commonly known asladybugs in North America andladybirds in the United Kingdom; "lady" refers tomother Mary.Entomologists use the namesladybird beetles orlady beetles to avoid confusion withtrue bugs. The more than 6,000 described species have a global distribution and are found in a variety of habitats. They are oval beetles with a domed back and flat underside. Many of the species have conspicuousaposematic (warning) colours and patterns, such as red with black spots, that warn potentialpredators that they taste bad.
Most coccinellid species arecarnivorous predators, preying on insects such asaphids andscale insects. Other species are known to consume non-animal matter, including plants and fungi. They arepromiscuous breeders, reproducing in spring and summer in temperate regions and during thewet season in tropical regions. Many predatory species lay their eggs near colonies of prey, providing their larvae with a food source. Like most insects, theydevelop fromlarva topupa to adult. Temperate specieshibernate anddiapause during the winter; tropical species are dormant during thedry season. Coccinellids migrate between dormancy and breeding sites.
Species that prey on agricultural pests are consideredbeneficial insects. Several species have been introduced outside their range asbiological control agents, with varying degrees of success. Some species are pests themselves and attack agricultural crops, or can infest people's homes, particularly in winter. Invasive species likeHarmonia axyridis can pose an ecological threat to native coccinellid species. Other threats to coccinellids includeclimate change andhabitat destruction. These insects have played roles infolklore, religion and poetry, and are particularly popular innursery rhymes.
Etymology
The nameCoccinellidae, created byPierre André Latreille in 1807,[4] is derived from the Latin wordcoccineus meaning'scarlet'.[5] The common English nameladybird originated in Britain where the insects became known as "Our Lady's birds".[6][7]Mary ("Our Lady") was often depicted wearing a red cloak in early art, and the seven spots of the speciesCoccinella septempunctata (the most common in Europe) were said to represent herseven joys andseven sorrows.[8] In the United States, the name was popularly adapted toladybug.[9]Entomologists prefer the names ladybird beetles or lady beetles to avoid confusion withtrue bugs.[9][10][11][12] Names in some other countries may be similar; for example, in Germany they are known asMarienkäfer meaning'Marybeetle' or'ladybeetle'.[9]
Description
Coccinellids range in size from 0.8 to 18 mm (0.03–0.7 in).[13] Adult females tend to be slightly larger than males.[14] They are generally oval with domed backs and flattened undersides.[7] They have largecompound eyes and clubbedantennae with seven to eleven segments. The powerfulmandibles (equivalent to jaws) typically have pairs of "teeth" which face each other.[15] The coccinellidprothorax (front of thorax) is broad and convex, and can cover the back of the head.[16][17] Being beetles, they have hardened, non-overlappingforewings, known aselytra, which cover up the more fragilehindwings when the insects are not in flight. Theirlegs are relatively short,[16] with atarsal formula of 4-4-4 (may appear 3-3-3 because the third segment of each tarsus is reduced).[18][19] Thetarsus (end of leg) has two claws at the tip.[16]
As adults, these beetles differ from their closest relatives with the followingmorphological characteristics:[20]
Coxal cavities (holes where the leg articulates with the thorax) that open from the back in the front of the thorax and from the front in the middle of the thorax
Epimeron (corner plates) on the metathorax with parallel edges
Coccinellids are often distinctively coloured and patterned. The elytron may be light with dark spots or dark with light spots. Light areas are typically yellow, red, orange or brown, and the spots vary in size and shape and numbers. Some species have striped orcheckered patterns. The pigmentcarotene creates the lighter colours, andmelanins create darker colours. Other parts of the body also vary in colouration.[7][21] These colour patterns typically serve aswarning colouration, but some can act ascamouflage, attract mates or even regulate heat.[7][22] Several individual species may displaypolymorphism and even change colour between seasons.[7]
Coccinellidlarvae are elongated with square heads.[23] They are covered in hairs orsetae, the abdominal segments, in particular, each having six divided into pairs, and one to three segmented antennae.[20][7] Their colouration varies from grey, blue-grey, grey-brown or brown and spotted with white, yellow, red or orange. They tend to brighten as they get closer to adulthood.[24]
Over 6,000 living species of Coccinellidae have been described.[13] They are sparsely preserved in the fossil record.[25] Althoughmolecular clock estimates have placed their origin in theCretaceous, the oldest fossils of the group are known from theOise amber of France, dating to the EarlyEocene (Ypresian) around 53 million years ago, which belong to the extant generaRhyzobius andNephus.[26] The greatest number of fossils comes from the younger EoceneBaltic amber, including members of the extant generaSerangium[27] andRhyzobius as well as extinct genera belonging to the tribesMicroweiseini (Baltosidis)[28] andSticholotidini (Electrolotis).[25]
The Coccinellidae are within the superfamilyCoccinelloidea, which in turn is part of the infraorderCucujiformia, a group containing most of the plant-eating beetles. The ladybirds form the majority of the species in the Coccinelloidea; many of the rest are fungus-feeding beetles orscavengers.[29]
A 2021 genetic study sampling many species, identified three subfamilies, Microweiseinae (with three tribes), Coccinellinae (26 tribes) and a newly identified group, theMonocoryninae (one tribe). All three subfamilies were strongly supported, but the study noted that although the tribes are mostly monophyletic, their relationships are only weakly supported. The study suggests that thecrown group appeared some 143Mya in theEarly Cretaceous, and that the group diversified rapidly during the Late Cretaceous, perhaps because the growth in diversity ofangiosperm plants then encouraged the radiation of insects of the cladeSternorrhyncha such asaphids, on which ladybirds could feed.[32]
An earlier 2009 study concluded that consumption ofscale insects is the mostbasal diet of Coccinellidae. Aphid-eating evolved three separate times and leaf-eating evolved twice, one of which evolved from a clade that contains both aphid-eating andpollen-eating. The fungi-eating also evolved from aphid-eating.[30]
Biology and ecology
Flight
Coccinellids mostly fly during the day.[33] Springy, cylindrical veins in the hindwings stiffen when in flight and bend when folding. Folding of the wings is further aided by creases in the membrane.[34] These beetles maymigrate long distances to hibernation and breeding sites, and areas with more food. They appear to be drawn to recognisable landmarks.[35] The more crowded an area is, the more individuals leave, but will remain if there are enough prey species to feed on.[36] "Trivial flights" refer to flying while foraging or when finding a place to lay eggs.[35] One study of species in Britain found that coccinellids can fly as far as 120 km (75 mi). They flew at speeds of 30 km/h (19 mph) and could reach altitudes close to 1,100 m (3,600 ft).[37]
In temperate climates, coccinellids typically breed from late spring to early summer. In warmer temperate regions, reproduction may occur in spring, fall and winter; tropical species reproduce during thewet season.[7][38] Mating ispromiscuous. In some species, females appear to be selective in their partners, preferring males of a certain size and colour. Males producesperm packets each with 14,000 sperm, and insert three of them into the female, even though she can only hold 18,000 sperm. This is likely a form ofsperm competition.[7][39] Like other insects, coccinellidsdevelop from egg, to larva, topupa and finally adult. Eggs tend to be bright yellow, and the females lay them close together, standing upright and near where they can access food.[7] The number of eggs in a cluster can vary depending on the species; it is typically in the double digits but some species can lay over a thousand eggs in their lifetime.[40]
After hatching, the larvae will begin eating, including the other eggs in their clutch.[7] Certain species lay extra infertiletrophic eggs with the fertile eggs, providing a backup food source for the larvae when they hatch. The ratio of infertile to fertile eggs increases with scarcity of food at the time of egg laying.[41] Larvae typically have fourinstar stages with threemoults between them.[42] The larva eventually transitions into a pupa; which involves the development of a hunch, the fusion of the legs to the body, and the attachment of the posterior to the surface.[7][20][42]
Pupae may be uncovered, partially covered or fully covered by larval skin depending on the species. The pupa is mostly immobile, but the head can move in response to irritation. When the adult emerges, it has its hindwings, while the elytron starts out softer and lighter in colour, with no patterns.[43] The length of each development stage varies based on climate and between species. ForAdalia bipunctata, eggs hatch after four to eight days, the larva stage lasts around three weeks and the pupa lasts seven to ten days.[7] Adult coccinellids develop much of their final colouration within hours, but may not fully darken for weeks or months.[44] The lifespan of an adult reaches up to a year.[7]
In temperate areas, coccinellids mayhibernate or enterdiapause during the winter. Individuals during this period gather in clumps, large or small depending on the species. Overwintering insects can be found both in lowland areas, aggregating under dead vegetation, and at the tops of hills, hibernating under rocks and ongrass tussocks.[45] In areas with particularly hot summers, the insects experience summer dormancy oraestivation; in the tropics, coccinellids enter dormancy during thedry season.[7]
Coccinellids act both as predators, prey andparasitichosts infood webs.[46] The majority of coccinellids arecarnivorous andpredatory, typically preying on Sternorrhyncha insects like aphids, scale insects,whiteflies,psyllids andadelgids. Some species feed on the larvae ofmoths and other beetles, as well asmites. Since much of their prey are agricultural pests, coccinellids are considered to bebeneficial insects.[47][48][49] A 2009metastudy by Hodek and Honěk found that aphid-eaters constituted around 68 percent of species that live in temperate areas but only 20 percent of species worldwide. Around 36 percent of total species mostly feed on scale insects.[49] Larvae and adults eat the same foods, unlike in other insect groups.[7]
Ladybird species vary in dietaryspecificity. An example of a specialist species is those of the genusStethorus, which feed onspider mites. Aphid-eaters tend to be generalist; they have a high voracity and can multiply quickly in response to outbreaks, and switch to other prey when theephemeral aphids become scarce. Predators of scale insects tend to be less voracious and are slower breeders and developers; matching their prey.[50] Under pressure from coccinellid predation, aphid species have evolved to become more toxic, forcing coccinellids to develop immunities.[51] Coccinellid predators of aphids need to defend themselves against ants that tend and defend aphids for their honeydew,[52] and coccinellid eggs laid near aphids are disposed of.[46] Some species includingCoccinella magnifica andDiomus have adapted to grow within ant nests as larvae, and some likeDiomus thoracicus are predators of the brood of the antWasmannia auropunctata.[53][54]
Cannibalism has been recorded in several species; which includes larvae eating eggs or other larvae, and adults feeding on individuals of any life stage.[55] Some coccinellids are mostly non-predatory, such as some species in the generaEpilachna andHenosepilachna.[56][57] The majority of predatory species may also supplement their diet with other sources of food both in their larval and adult stages.[58] Non-animal matter consumed include leaves, pollen,nectar,sap, fungi, andhoneydew.[47][58][59] Members of the tribe Halyziini of the subfamily Coccinellinae are obligate fungus feeders.[60]
The bright warning colouration of many coccinellidsdiscourage potential predators, warning of theirtoxicity. A 2015 study of five ladybird species found that their colourationhonestly signalled their toxicity, implying the warning is genuine. Species with more contrast with the background environment tended to be more toxic.[65] Coccinellidhaemolymph (blood) contains toxicalkaloids, azamacrolides andpolyamines, as well as foul-smellingpyrazines.[66] Coccinellids can produce at least 50 types of alkaloids. When disturbed, ladybirds further defend themselves withreflex bleeding, exuding drops from their tibio-femoral (knee) joints, effectively presenting predators with a sample of their toxic and bitter body fluid.[61] Predator-deterring poisons are particularly important for the immobile pupa.[67] Access to food can affect the concentration of both pigments and toxins.[68]
The similarity of coccinellid patterning in red and orange with black markings has led to suggestions that they and some species of chrysomelids[69] formMüllerian mimicry rings[70] particularly to defend them from birds.[71] Despite their chemical defenses, coccinellids are preyed on by someclerid beetles in the genusEnoclerus, several species of which are brightly coloured in red and black, and which possibly sequester the toxins of the prey to defend themselves against other predators.[72]
As an anti-predator defense, spiders of the genusEresus, known as ladybird spiders, have evolved to replicate the patterns of coccinellids. This is a form ofBatesian mimicry, as the spiders lack the chemicals. This resemblance is limited to adult male spiders which are actively searching for females and exposed – unlike the females and young, which remain sheltered in burrows.[73]
Distribution and status
The widespread and invasiveHarmonia axyridis
Coccinellidae are found on every continent except Antarctica.[74] Asian and African species are less studied than others.[75] Coccinellids can be found in a variety of habitats, both on the ground and in the trees. They may specialise using certain plants. Some species can live in extreme environments such as high mountains, arid deserts and cold regions.[76] Several of the most famous species have wide ranges, but others are moreendemic and possibly threatened.[75]
Threats to coccinellids includeclimate change, agriculture, urbanisation, andinvasive species. Coccinellid biodiversity will likely be affected by the rising of both average temperatures and heat fluctuations. Climate change may lead to smaller larvae, as well as increase energy and metabolic needs and interspecific predation. Agriculture and urbanisation threatens these insects thoughhabitat destruction and homogenisation and the use ofpesticides. Invasive threats include other coccinellids, particularlyC. septempunctata in North America andH. axyridis globally.[75] These invaders outcompete the native species as well as eat their eggs.[75][77]
As of 2022, theIUCN Red List does not list the conservation status for any coccinellid, though there is an IUCN SSC Ladybird Specialist Group. Conservationists have suggested several measures for protecting the insects, includingcitizen science and education programs, habitat preservation and restoration, prevention of the spread of invasive species and a global monitoring program.[75]
Coccinellids have been valued inbiological pest control, as they prey on agricultural pests such as aphids and scale insects. Their importance in controlling pests was noted as far back as 1814 in England.[7] Their efficiency can vary: sometimes they have a relatively small effect on aphid populations; at others they cause significant seasonal declines.[78]
Several species have beenintroduced to areas outside their native range; the first being the vedalia beetle,Novius cardinalis.[7] The larva of the species was introduced to California in 1887 from Australia, to protectcitrus trees fromcottony cushion scale. The project was markedly successful, costing $1,500 in 1889,[79] making it "a textbook example of the great potential of classical biological control as a tactic for suppressing invasive pests." The beetle was then used in 29 countries, again with success; reasons for this include its high prey specificity, fast development, multiple generations each year, efficient discovery of host patches, and larval development completed on a single host insect.[80]
There have been many further attempts to use ladybird species against pests, with varying degrees of success.[81][7] Scale insect-eating coccinellids have been more successfully used than aphid predators.[7] Out of 155 deliberate introductions meant to control aphids by the year 2000, only one was deemed to be "substantially successful". This is due to aphid-eating species being fast-breeding, generalist and voracious, and thus difficult to control.[82]
As pests
Cluster of invasive Asian lady beetles inside a farm building after the fall harvest in South Dakota
Coccinellids can also act as pests.Harmonia axyridis is native to East Asia, but has been introduced to the Americas, Europe and Africa.[75] In North America, this species begins to appear indoors in the autumn when they leave their summer feeding sites to search out places to stay for winter. Typically, when temperatures warm to the mid-60s °F (around 18 °C) in the late afternoon, they swarm onto or into buildings illuminated by the sun from nearby fields and forests.[83][84] After an abnormally long period of hot, dry weather in thesummer of 1976 in the UK, a marked increase in the aphid population was followed by a "plague" of the nativeCoccinella septempunctata; there were many reports of people being bitten as the supply of aphids dwindled.[85][86][87]
H. axyridis,C. septempunctata andHippodamia convergens are the most common causes ofladybird taint in wine. As few as 1.3 to 1.5 coccinellids per 1 kilogram (2.2 lb) of grapes can affect wine quality when they are present during the wine-making process.[88] TheMexican bean beetle is an agricultural pest as it primarily feeds on plants, especiallylegumes, instead of insects.[89]
In culture
Coccinellids have had important roles in culture and religion, being associated with luck, love, fertility and prophecy. "Ladybird" is an affectionate term for someone, such as a loved one. InEuropean folklore, an insect acts as a matchmaker, crawling on a woman and then flying to their true love. Coccinellids have been said to predict the future, particularly weather conditions and how well the crops will grow.[90][91]
In Christianity, coccinellids have been seen as the literal gatekeepers of Heaven. A Swedish name for the insects,Himmelska nycla, means "Keys of Heaven". Jews have referred to the insects as the "Cow ofMoses our Teacher". TheCherokee have revered them as the "Great Beloved Woman"; this was used as a title for the highest-ranking woman in the government, who would be painted in the colours and patterns of the insect during ceremonies.[92]
Coccinellids have been popularly featured in poems andnursery rhymes, the most famous beingLadybird! Ladybird!. This has come in several forms, including:[93]
Ladybird, ladybird, fly away home, Thy house is on fire, thy children all roam, Except little Nan, who sits on herpan, Weaving gold laces as fast as she can.
Card cutout ladybirds for a children's nature trail
^abcdefghijklmnopqrsMajerus, Michael E. N. (2003). "Ladybugs". In Resh, Vincent H.; Cardé, Ring T. (eds.).Encyclopedia of Insects. Academic Press. pp. 618–622.ISBN0-12-586990-8.
^Holland, Mary (2016).Naturally curious day by day : a photographic field guide and daily visit to the forests, fields, and wetlands of Eastern North America. Stackpole Books. p. 173.ISBN978-0811714129.
^Johnson, Ken (4 June 2020)."Ladybug, Ladybug".extension.illinois.edu. University of Illinois Extension. Retrieved17 January 2023.
^Kirejtshuk, A. G.; Nel, A. (2012). "The oldest representatives of the family Coccinellidae (Coleoptera: Polyphaga) from the lowermost Eocene Oise amber (France)".Zoosystematica Rossica.21 (21):131–144.doi:10.31610/zsr/2012.21.1.131.
^Magro, A; Lecompte, E; Magné, F; Hemptinne, J. L.; Crouau-Roy, B (2010). "Phylogeny of ladybirds (Coleoptera: Coccinellidae): Are the subfamilies monophyletic?".Molecular Phylogenetics and Evolution.54 (3):833–848.Bibcode:2010MolPE..54..833M.doi:10.1016/j.ympev.2009.10.022.PMID19903531.
^Obrycki, J. J.; Harwood, J. D.; Kring, T. J.; O'Neil, R. J. (2009). "Aphidophagy by Coccinellidae: Application of biological control in agroecosystems".Biological Control.51 (2):244–254.Bibcode:2009BiolC..51..244O.doi:10.1016/j.biocontrol.2009.05.009.
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