Vast amounts of information is available for Leptinotarsa decemlineata because of its status as a major pest insect. The information provided here is a general introduction to the biology of Leptinotarsa decemlineata. Further information can be found using the references listed here and the many studies cited within those references.
The primary modalities of perception and communication are olfaction and vision. Chemical signals emitted by host plants can be vital for sexual communication and host selection. Leptinotarsa decemlineata uses plant volatiles for host location at close range, but seems to rely mostly on vision for host and mate location. It is known that adults can sense wavelengths from yellow through the ultraviolet, and probably also sense polarized light. After locating a suitable host, males then emit their aggregation pheromone, (S)-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol [(S)-CPB I], that attracts both males and females to areas of host plants. Colonizing adults use this pheromone as a signal for potential mates. This is one of the few species of insects where it is known that larvae also sense, and are attracted to adult aggregation pheromone. For mating, female Leptinotarsa decemlineata produce a pheromone to attract males.
Communication Channels: visual ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; ultraviolet; polarized light ; chemical
Leptinotarsa decemlineata is not listed as an endangered or threatened species on any local, state, national or international level.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
The last generation of adults of Leptinotarsa decemlineata each year move to the edge of fields, bury slightly in the soil and overwinter. A small percentage of adults remain in diapause and emerge the following season. Fields are colonized by overwintered adults that walk to the field from their overwintering sites or emerge from the soil within the field. Once they have colonized the field, the overwintered beetles first feed and then oviposit within 5 to 6 days depending on temperature.
Development from egg to adult is greatly affected by temperature, varying from 14 to 56 days. The larvae of L. decemlineata go through four instars, typically lasting around 21 days, while continuously feeding on the host plant. Once larvae are mature, they drop from the host plant where they burrow 2 to 3 cm into the soil. After about 2 days they pupate, and then emerge as adults after an average of 5.8 additional days. The optimal temperature for development is within the range of 25 to 32˚C. After development has been completed, adults start mating and laying eggs to complete another generation of beetles. By midsummer, generations are asynchronous and all life stages can be found.
Development - Life Cycle: metamorphosis ; diapause
Leptinotarsa decemlineata is considered one of the most serious pests and agricultural defoliators. The Colorado potato beetle causes significant damage to agricultural plants such as tomatoes, eggplants, and, of course, potatoes. Both larvae and adults feed on the foliage of host plants, skeletonizing the plant, leaving only roots and stems. Because of such devastation, insecticides have been implemented to decrease the destruction that Leptinotarsa decemlineata has on agricultural production, costing farmers millions of dollars each year. This species has been a huge pest problem throughout the country and is a problem annually for farmers. With such heavy insecticide use, populations of this species have developed resistance to nearly all classes of chemicals used as insecticides. It is estimated that this resistance costs growers between $44 and $69 per hectare each year, but no good alternatives are currently available.
Negative Impacts: crop pest
There are no known positive effects of Leptinotarsa decemlineata on humans.
Leptinotarsa decemlineata feeds almost exclusively on Solanum plants, particularly the cultivated potato, Solanum tuberosum. Other suitable hosts include Solanum rostratum, Solanum augustifolium, Solanum dulcamara, Solanum melongena (eggplant), Lycopersicon esculentum (tomato), peppers, tobacco, Solanum carolinense, Solanum sarrachoides, Solanum elaeagnifolium, and Hyoscyamus niger. It is a major agricultural pest and has the potential to significantly defoliate its host plants.
Eggs, larvae, and adults of L. decemlineata can serve as hosts to a variety of parasites and parasitoids. Parasites of the Colorado potato beetle include a couple of mites, Chrysomelobia labidomerae, which feeds under the elytra, and Pyemotes tritici, the straw itch mite, which is an ectoparasite that causes paralysis and death within 2 to 7 days. At least two internal parasites are also known. Bacillus thuringiensis can be used as a control agent, killing larvae, and Beauveria bassiana, a fungus, infects larvae and adults. The parasitic wasp, Edovum puttleri, has been found to parasitize up to 71% to 91% of the eggs in a mass on eggplant hosts, killing 67% to 69% of the egg mass.
Parasitoids of Leptinotarsa decemlineata include species of Diptera (Myiopharus aberrans, Myiopharus australis, Myiopharus doryphorae, Myiopharus macella, all Tachinidae that are larval parasitoids, usually emerging from adults), Coleoptera (larvae of Lebia grandis act as parasitoids on pupae), and Hymenoptera (Edovum puttleri, a Eulophid egg parasitoid; and possibly Brachymeria truncatella, a chalcidoid wasp that may be a hyperparasitoid of the tachinids, and Anaphes fuscipennis, a Mymarid that parasitizes eggs). Leptinotarsa decemlineata is prey to many other insects, including species of Neuroptera, Heteroptera, Coleoptera, and Hymenoptera. Many arachnids also feed on L. decemlineata.
Species Used as Host:
Commensal/Parasitic Species:
Leptinotarsa decemlineata feeds primarily on Solanum plants, skeletonizing the plant and leaving only the roots and stems. The most suitable host for L. decemlineata is now the cultivated potato, Solanum tuberosum, thus the beetle's common name of the Colorado potato beetle. Other suitable hosts include Solanum rostratum and Solanum augustifolium, the insect's original hosts. A European species now widely distributed in North America, Solanum dulcamara is also commonly used in the wild. Solanum melongena (eggplant), Lycopersicon esculentum (tomato), peppers, tobacco, and other wild hosts such as S. carolinense, S. sarrachoides, S. elaeagnifolium, and Hyoscyamus niger are utilized occasionally.
Plant Foods: leaves
Primary Diet: herbivore (Folivore )
Currently, Leptinotarsa decemlineata, the Colorado potato beetle, is distributed widely throughout North America east of the Rockies as well as some of Europe and Asia. Its distribution covers about 8 million km² in the Nearctic Region and about 6 million km² in the Palearctic and Oriental regions. Originally, Leptinotarsa decemlineata was found in the southwestern United States into Mexico. As potatoes were extensively planted for agriculture, the species spread into agricultural areas throughout North America, Europe, and Asia. It is predicted that Leptinotarsa decemlineata could occupy other regions including Korea, Japan, parts of Africa, and most of the temperate Southern Hemisphere.
Biogeographic Regions: nearctic (Native ); palearctic (Introduced ); oriental (Introduced ); neotropical (Native )
Other Geographic Terms: holarctic
The Colorado potato beetle is found mostly in farm fields that specialize in growing agricultural crops in the family Solanaceae, such as potatoes, tomatoes, tobacco, eggplants and peppers. It can also be found on non-agricultural solanaceous plants in open grassland areas.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland
Other Habitat Features: suburban ; agricultural
Most individuals live for at least a few weeks as adults during the summer. The last generation of the year overwinters as adults, and thus has a longer adult lifespan, although they are mostly inactive. A small percentage of adults will remain in diapause for a second winter or even a third winter (recorded in some populations).
Range lifespan
Status: wild: 24 (high) months.
Typical lifespan
Status: wild: 2 to 12 months.
Leptinotarsa decemlineata has the physical features typical of chrysomelid beetles such as 5-5-5 tarsi, an oval shape, and antennae shorter than the body. Adults can reach anywhere from 8 to 10 mm and have five bold, brown stripes along each elytron. The thorax has an intricate pattern of black spots on top of a deep orange complexion. Larvae typically have a row of black spots down the side of the abdomen, which is convex and very stout (large and plump) compared to the rest of the body. Eggs resemble footballs with an orange/yellow color. They are about 1.7 to 1.8 mm long and 0.8 mm wide. The dorsal and ventral surfaces are distinctly non-parallel and deep red in color.
Range length: 8 to 10 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
There are many known predators of Leptinotarsa decemlineata. Predators include arachnids (Phalangium opilio, a phalangid that eats eggs and small larvae; Xysticus kochi, a spider in USSR; Peucetia viridans, Misumena, 2 species in the family Thomisidae, spiders that eat eggs and larvae), Neuroptera (Chrysoperla carnea and Chrysoperla rufilabris, lacewings that eat eggs), Heteropterans (Perillus bioculatus, Podisus maculiventris, Oplomus dichrous, Oplomus severus, Stiretris anchorago, Perilloides confluens, Zicrona coerules, Pinthaeus sanguinipes, all stink bugs that eat larvae and eggs; Nabis roseipennis, Nabis alternatus, Geocoris punctipes, and species of Deraecoris that all prey on eggs), Coleoptera (Lebia grandis and at least 8 other species of Lebia that eat eggs, larvae, and pupae; Pterostichus chalcites and Calledia decora, which feed on larvae; Coleomegilla maculata, Hippodamia convergens, Coccinella septempunctata, Coccinella transversoguttata, Harmonia axyridis, and Aiolocaria miriabilis (in USSR), all Coccinellids that eat eggs and larvae; Collops quadrimaculatus, a Melyrid), Hymenoptera (wasps of Polistes that eat larvae; ants of genus Formica that eat adults and larvae).
In the United States, the lady beetle Coleomegilla maculata is a particularly significant predator that consumes eggs and small larvae of L. decemlineata. When present, C. maculata can kill up to 37.8% of eggs in the first generation and up to 58.1% of eggs for the second generation. Several species have been introduced into Leptinotarsa decemineata populations to suppress the substantial numbers. Predaceous stink bugs such as Perillus bioculatus and Podisus maculiventris attack beetle larvae, significantly decreasing the population by 62%, and reducing the destruction of foliage by 86%. Other beetles such as Lebia grandis feed on eggs and larvae of the Colorado potato beetle, while the larvae of the same species act as parasitoids on the pupae of Leptinotarsa decemlineata.
There is some evidence that the Colorado potato beetle produces a toxin, leptinotarsin, that protects the larvae and adults from predation. This is evidently not sequestered from the host plant, because no sequestered alkaloids have been found. The larvae and adults also have not been demonstrated to be aposematic.
Known Predators:
Both sexes of Leptinotarsa decemlineata mate with multiple individuals over the course of their adult life. Last generation adults typically mate before overwintering, with females storing sperm that can be used in the spring. However, they also mate after emerging from overwintering, usually before entering the fields. Sperm from these spring matings show some precedence, fertilizing the majority of eggs. Males have slightly modified tarsal setae that although them to cling to the elytra of the female. This is a trade-off with the ability to cling to host plants, and females can adhere to hosts more effectively.
Mating System: polygynandrous (promiscuous)
After overwintering in crop fields, gardens, and field margins, the Colorado potato beetle becomes active in the spring, often in May. Adults feed for a very short time, then reproduce. Adult females have high fecundity, producing 300 to 800 eggs, which are laid on the underside of plant leaves. Eggs are clustered into groups of 10 to 30. Egg laying may last several weeks.
Breeding interval: Adults breed continuously after emerging from overwintering.
Breeding season: Leptinotarsa decemlineata breeds from spring through summer.
Range eggs per season: 300 to 800.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous ; sperm-storing
Leptinotarsa decimilineata has little to no parental investment in the offspring, other than provisioning of eggs by females.
Parental Investment: pre-hatching/birth (Provisioning: Female)
The Colorado potato beetle (Leptinotarsa decemlineata), also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug, is a major pest of potato crops. It is about 10 mm (3⁄8 in) 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,[3] it spread rapidly in potato crops across America and then Europe from 1859 onwards.
The Colorado potato beetle was first observed in 1811 by Thomas Nuttall and was formally described in 1824 by American entomologist Thomas Say.[3] The beetles were collected in the Rocky Mountains, where they were feeding on the buffalo bur, Solanum rostratum.[4] The genus Leptinotarsa is assigned to the chrysomelid beetle tribe Chrysomelini (in subfamily Chrysomelinae).
Adult beetles typically are 6–11 mm (0.24–0.43 in) in length and 3 mm (0.12 in) in width. They weigh 50-170 mg.[5] The beetles are orange-yellow in colour with 10 characteristic black stripes on their elytra. The specific name decemlineata, meaning 'ten-lined', derives from this feature.[4][6] Adult beetles may, however, be visually confused with L. juncta, the false potato beetle, which is not an agricultural pest. L. juncta also has alternating black and white strips on its back, but one of the white strips in the center of each wing cover is missing and replaced by a light brown strip.[7]
The orange-pink larvae have a large, 9-segmented abdomen, black head, and prominent spiracles, and may measure up to 15 mm (0.59 in) in length in their final instar stage. The beetle larva has four instar stages. The head remains black throughout these stages, but the pronotum changes colour from black in first- and second-instar larvae to having an orange-brown edge in its third-instar. In fourth-instar larvae, about half the pronotum is coloured light brown.[4][8] This tribe is characterised within the subfamily by round to oval-shaped convex bodies, which are usually brightly coloured, simple claws which separate at the base, open cavities behind the procoxae, and a variable apical segment of the maxillary palp.[9][6]
The beetle is most likely native to the area between Colorado and northern Mexico, and was discovered in 1824 by Thomas Say in the Rocky Mountains. It is found in North America, and is present in every state and province except Alaska, California, Hawaii, and Nevada.[4] It now has a wide distribution across Europe and Asia,[10] totalling over 16 million km2.[11]
Its first association with the potato plant (Solanum tuberosum) was not made until about 1859, when it began destroying potato crops in the region of Omaha, Nebraska. Its spread eastward was rapid, at an average distance of 140 km per year.[12] By 1874 it had reached the Atlantic Coast.[4] From 1871, American entomologist Charles Valentine Riley warned Europeans about the potential for an accidental infestation caused by the transportation of the beetle from America.[12] From 1875, several Western European countries, including Germany, Belgium, France, and Switzerland, banned imports of American potatoes to avoid infestation by L. decemlineata.[13]
These controls proved ineffective, as the beetle soon reached Europe. In 1877, L. decemlineata reached the United Kingdom and was first recorded from Liverpool docks, but it did not become established. Many further outbreaks have occurred; the species has been eradicated in the UK at least 163 times. The last major outbreak was in 1976. It remains as a notifiable quarantine pest in the United Kingdom and is monitored by DEFRA to prevent it from becoming established.[14] A cost-benefit analysis from 1981 suggested that the cost of the measures used to exclude L. decemlineata from the UK was less than the likely costs of control if it became established.[15]
Elsewhere in Europe, the beetle became established near USA military bases in Bordeaux during or immediately following World War I and had proceeded to spread by the beginning of World War II to Belgium, the Netherlands, and Spain. The population increased dramatically during and immediately following World War II and spread eastward, and the beetle is now found over much of the continent. After World War II, in the Soviet occupation zone of Germany, almost half of all potato fields were infested by the beetle by 1950. In East Germany, they were known as Amikäfer ('Yankee beetles') following a governmental claim that the beetles were dropped by American planes. In the European Union, it remains a regulated (quarantine) pest for the Republic of Ireland, Balearic Islands, Cyprus, Malta, and southern parts of Sweden and Finland. It is not established in any of these member states, but occasional infestations can occur when, for example, wind blows adults from Russia to Finland.[16][17]
The beetle has the potential to spread to temperate areas of East Asia, India, South America, Africa, New Zealand, and Australia.[18]
Native range of the potato and native and current range of the Colorado beetle
Expansion of the Colorado potato beetle's range in North America, 1859–1876
Expansion of the Colorado potato beetle's range in Europe, 1921–1964
Colorado potato beetle females are very prolific and are capable of laying over 500 eggs in a 4- to 5-week period.[19] The eggs are yellow to orange, and are about 1 mm (0.039 in) long. They are usually deposited in batches of about 30 on the underside of host leaves. Development of all life stages depends on temperature. After 4–15 days, the eggs hatch into reddish-brown larvae with humped backs and two rows of dark brown spots on either side. They feed on the leaves of their host plants. Larvae progress through four distinct growth stages (instars). First instars measure about 1.50 mm (0.059 in) long, and the last (fourth) instars about 8 mm (0.31 in) long. The first through third instars each last about 2–3 days; the fourth lasts 4–7 days. Upon reaching full size, each fourth instar spends several days as a nonfeeding prepupa, which can be recognized by its inactivity and lighter coloration. The prepupae drop to the soil and burrow to a depth of several inches, then pupate.[4] In 5 to 10 days, the adult beetle emerges to feed and mate. This beetle can thus go from egg to adult in as little as 21 days.[19] Depending on temperature, light conditions, and host quality, the adults may enter diapause and delay emergence until spring. They then return to their host plants to mate and feed; overwintering adults may begin mating within 24 hours of spring emergence.[20] In some locations, three or more generations may occur each growing season.[4]
Eggs laid on the underside of a leaf
First-instar larva after hatching
Early (3rd) instar stage of larvae
Late (4th) instar stage of larva, before pupation
Pupa
Adult beetle after emergence
Mating adult beetles
L. decemlineata has a strong association with plants in the family Solanaceae, particularly those of the genus Solanum. It is directly associated with Solanum cornutum (buffalo-bur), Solanum nigrum (black nightshade), Solanum melongena (eggplant or aubergine), Solanum dulcamara (bittersweet nightshade), Solanum luteum (hairy nightshade), Solanum tuberosum (potato), and Solanum elaeagnifolium (silverleaf nightshade). They are also associated with other plants in this family, namely the species Solanum lycopersicum (tomato) and the genus Capsicum (pepper).[21]
At least 13 insect genera, three spider families, one phalangid (Opiliones), and one mite have been recorded as either generalist or specialized predators of the varying stages of L. decemlineata. These include the ground beetle Lebia grandis, the coccinellid beetles Coleomegilla maculata and Hippodamia convergens, the shield bugs Perillus bioculatus and Podisus maculiventris, various species of the lacewing genus Chrysopa, the wasp genus Polistes, and the damsel bug genus Nabis.[22]
The predatory ground beetle L. grandis is a predator of both the eggs and larvae of L. decemlineata, and its larvae are parasitoids of the pupae. An adult L. grandis may consume up to 23 eggs or 3.3 larvae in a single day.[23]
In a laboratory experiment, Podisus maculiventris was used as a predatory threat to female L. decemlineata specimens, resulting in the production of unviable trophic eggs alongside viable ones; this response to a predator ensured that additional food was available for newly hatched offspring to increase their survival rate. The same experiment also demonstrated the cannibalism of unhatched eggs by newly hatched L. decemlineata larvae as an antipredator response.[24]
Around 1840, L. decemlineata adopted the cultivated potato into its host range and it rapidly became a most destructive pest of potato crops. It is today considered to be the most important insect defoliator of potatoes.[18] It may also cause considerable damage to tomato and eggplant crops with both adults and larvae feeding on the plant's foliage. Larvae may defoliate potato plants resulting in yield losses up to 100% if the damage occurs prior to tuber formation.[35] Larvae may consume 40 cm2 of potato leaves during the entire larval stage, but adults are capable of consuming 10 cm2 of foliage per day.[36]
The economic cost of insecticide resistance is significant, but published data on the subject are minimal.[37] In 1994, total costs of the insecticide and crop losses in the US state of Michigan were $13.3 million, representing 13.7% of the total value of the crop. The estimate of the cost implication of insecticides and crop losses per hectare is $138–368. Long-term increased cost to the Michigan potato industry caused by insecticide resistance in Colorado potato beetle was estimated at $0.9 to $1.4 million each year.[38]
The large-scale use of insecticides in agricultural crops effectively controlled the pest until it became resistant to DDT in 1952 and dieldrin in 1958.[39] Insecticides remain the main method of pest control on commercial farms. However, many chemicals are often unsuccessful when used against this pest because of the beetle's ability to rapidly develop insecticide resistance. Different populations in different geographic regions have, between them, developed resistance to all major classes of insecticide,[40][41] although not every population is resistant to every chemical.[40] The species as a whole has evolved resistance to 56 different chemical insecticides.[42] The mechanisms used include improved metabolism of the chemicals, reduced sensitivity of target sites, less penetration and greater excretion of the pesticides, and some changes in the behavior of the beetles.[40]
CPB has evolved widespread insecticide resistance.[43] No cases without fitness cost or of negative cost are known.[43]
Bacterial insecticides can be effective if application is targeted towards the vulnerable early-instar larvae. Two strains of the bacterium Bacillus thuringiensis produce toxins that kill the larvae.[35] Other forms of pest control, through nonpesticidal management are available. Feeding can be inhibited by applying antifeedants, such as fungicides or products derived from Neem (Azadirachta indica), but these may have negative effects on the plants, as well.[35] The steam distillate of fresh leaves and flowers of tansy (Tanacetum vulgare) contains high levels of camphor and umbellulone, and these chemicals are strongly repellent to L. decemlineata.[44]
Beauveria bassiana (Hyphomycetes) is a pathogenic fungus that infects a wide range of insect species, including the Colorado potato beetle.[45] It has shown to be particularly effective as a biological pesticide for L. decemlineata when used in combination with B. thuringiensis.[46]
Crop rotation is, however, the most important cultural control of L. decemlineata.[18] Rotation may delay the infestation of potatoes and can reduce the build-up of early-season beetle populations because the adults emerging from diapause can only disperse to new food sources by walking.[35] One 1984 study showed that rotating potatoes with nonhost plants reduced the density of early-season adults by 95.8%.[47]
Other cultural controls may be used in combination with crop rotation: Mulching the potato crop with straw early in the growing season may reduce the beetle's ability to locate potato fields, and the mulch creates an environment that favours beetle's predators; Plastic-lined trenches have been used as pitfall traps to catch the beetles as they move toward a field of potatoes in the spring, exploiting their inability to fly immediately after emergence; flamethrowers may also be used to kill the beetles when they are visible at the top of the plant's foliage.[48]
During the Cold War, some countries in the Warsaw Pact claimed that the beetles had been introduced by the CIA in an attempt to reduce food security by destroying the agriculture of the Soviet Union.[49] A widespread campaign was launched against the beetles; posters were put up and school children were mobilized to gather the pests and kill them in benzene or spirit.[49]
L. decemlineata is an iconic species and has been used as an image on stamps because of its association with the recent history of both North America and Europe. For example, in 1956, Romania issued a set of four stamps calling attention to the campaign against insect pests,[51] and it was featured on a 1967 stamp issued in Austria.[52] The beetle also appeared on stamps issued in Benin, Tanzania, the United Arab Emirates, and Mozambique.[53]
Neapolitan mandolins (also called Italian mandolins) are often called tater bugs,[54][55] a nickname given by American luthier Orville Gibson, because the shape and stripes of the different color wood strips resemble the back of the Colorado beetle.[56]
The fans of Alemannia Aachen carry the nickname "Kartoffelkäfer", from the German name for the Colorado beetle, because of striped yellow-black jerseys of the team.[57][58]
During the 2014 pro-Russian unrest in Ukraine, the word kolorady, from the Ukrainian and Russian term for Colorado beetle, (Ukrainian: жук колорадський, Russian: колорадский жук) gained popularity among Ukrainians as a derogatory term to describe pro-Russian separatists in the Donetsk and Luhansk Oblasts (provinces) of Eastern Ukraine. The nickname reflects the similarity of black and orange stripes on St. George's ribbons worn by many of the separatists.[59]
The Colorado potato beetle (Leptinotarsa decemlineata), also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug, is a major pest of potato crops. It is about 10 mm (3⁄8 in) 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.
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