Manduca sexta has been developed as a model system for biological study, and is used in laboratories investigating a broad spectrum of topics such as neurobiology, flight mechanics, larval nicotine resistance, and regulation of development. It has several advantages for study, including its large size, short life cycle and the fact that it is easily reared in lab conditions. In the lab the caterpillars are blue because the artificial wheat germ diet they are fed does not contain the yellow carotenoid pigments that normally combine with insecticyanins to turn their bodies green. The tobacco hornworm has also been used for research projects and teaching science in secondary and college classrooms (http://www.manducaproject.com/; http://www.acad.carleton.edu/curricular/BIOL/resources/rlink/).
(Villanueva 1998; Lange and Bronson 1981; Wikipedia 2011)
The Carolina sphinx moth (Manduca sexta) is also known as the tobacco hornworm, hummingbird moth, six-spotted sphinx, and the tobacco fly.
The Carolina sphinx moth has six pairs of yellow bands on its abdomen; indistinct black, brown, and white markings on its forewing with wing fringes spotted with white; and black and white bands and two black zigzag lines on its hindwing. The forewings are long and narrow and larger than the hindwings. These moths have a wing span of two to 12 cm. The caterpillar, known as a tobacco hornworm because the caterpillars feed on the tobacco plant (Nicotiana attenuate), is cylindrical with seven straight white lines with black edges on each side and has a red-tipped horn at the end of its abdomen.
This species is found in tobacco fields, vegetable gardens, and a wide variety of other habitats. The Carolina sphinx moth is found in Massachusetts west across southern Michigan to Minnesota, central Colorado, and northern California; south to Florida, the Gulf Coast, Texas, New Mexico, Arizona, and southern California. It is secure globally, though may be rare in parts of its range.
This information is based an ongoing project dedicated to the inventory and dissemination of information on lepidopteran larvae, their host plants, and their parasitoids in a Costa Rican tropical wet forest and an Ecuadorian montane cloud forest.
N=1 rearing as of 2012, eclosed.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) The overall range is from near Boston, Massachusetts southwest into Chile. In the US, the normal limit seems to be roughly a line from Boston though southern most Ontario, southern Wisconsin, about half of Nebraska, to north-central Colorado and the rest of eastern Colorado, contracting eastward to southern Texas then northwest along the border to southern California, including much of the desert Southwest. In the US it is probably most common along the Gulf Coast, up through the Mississippi Valley and along the East Coast to Maryland and New Jersey. Pupae can survive winters in New Jersey and Connecticut (Schweitzer, 2006) and the species appears to be resident virtually to its northeastern limit. It occurs in southern California and north into the San Joaquin Valley (Hodges, 1971). Other than Colorado and along the southern border, this species is not widespread in the West.
Collected in Heredia Province, Costa Rica.
Comments: Extremely variable regionally. In most of eastern North America this is primarily a pest of solanaceous crops, especially tomato and tobacco, of farms and gardens, although in New Jersey larvae also occur and mature (Dale Schweitzer) on introduced nightshades (Solanum) and Datura which is possibly native. It seem unlikely the species could occur in most of the east based only on wild plants. Going southwest, this moth is clearly part of the native fauna of the greater Sonoran desert region where it has several native foodplants, mostly, but not entirely Solanaceae (Tuttle, 2009), breeding mainly in riparian areas during the summer rainy season. Eastern North American populations do not appear to be commonly migratory (discussed by Schweitzer, 2006). South of the USA, habitats apparently include a variety of tropical scrub, forest, and woodlands, as well as agricultural lands.
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Unlike the related M. quinquemaculatus and Agrias cingulatus, M. sexta is very rarely found outside of its normal range or during the fall when migrants most typically reach up the east coast into Canada. Instead the species seems to have a stable range and well adpated phenology.
Comments: Over the vast range, larvae use an array of Solanaceous plants and a very few form other families (see Robinson et al., 2002, Tuttle, 2009), but in eastern North America almost, or quite, entirely crops and exotic weeds. Adults visit many kinds of flowers and probably are important pollinators of some, such as native tobaccos, agave, and mescal.
Flowering Plants Visited by Manduca sexta in Illinois
(observations are from Sheviak & Bowles and Bertin; this moth is referred to as the 'Tobacco Hornworm' and 'Carolina Sphinx')
Bignoniaceae: Campsis radicans sn (Brt); Orchidaceae: Platanthera leucophaea sn (SB)
Rubiaceae: Hamelia patens
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 81 to >300
Comments: Estimate thousands of occurrences.
10,000 to >1,000,000 individuals
Comments: This was one of our commonest hawkmoths (Holland, 1915) but is less abundant now with the widespread use of insecticides on farms. Still this is a very widespread moth and it larva is well-known to most persons who have grown tomatoes from Connecticut to Florida and westward. The species is probably most common along the Gulf Coast, up through the Mississippi Valley and along the east coast to MD and NJ (Hodges, 1971). A pest (Covell, 1984).
Manduca sexta is probably an important pollinator in desert regions and of Platanthera orchids elsewhere. In the American Southwest, this and other Manduca are native, resident species, breeding mostly in riparian habitats during the summer rainy season. This moth is usually not associated with natural habitats east of about Texas, although Datura growing in recently abandoned or at least recently plowed, old fields are used as foodplants as far east as New Jersey (Dale Schweitzer), where some of these might be native. Manduca sexta is primarily a crop pest (the most common hornworm on tomato) eastward where it is usually controlled by insecticides, native parasitoids, and plowing of the pupae, in farmlands to the extent it is common, but does not reach high densities. Despite dependence on anthropogenic habitats, eastern US populations are apparently not dependent on migration, and pupae do survive in regions with cold winters (Schweitzer, 2006). Phenology is well-adapted to local climate and crop phenology. In eastern North America, Manduca sexta has probably evolved as primarily a crop pest for thousands of years, at first mostly on tobaccos, later on tomatoes, potatoes and others. Adaptation to the short mid summer growing season of the arid southwestern USA and northern Mexico probably facilitated adaptation to the somewhat longer summer tobacco growing season farther east. In practice then if this species were identified as an important pollinator northeast of the southwestern desert regions, managing for it would be problamatic to impractical since no natural communities would likely support larvae. In desert regions maintaining healthy populations of native Solanaceae (and he exotic tree tobacco) should suffice for M. sexta.
Life History and Behavior
Comments: In North America only pupae are present for most of the year. While Tuttle states the species is univoltine northward, there is a partial second brood in about mid or late August very near the northeastern limit of the range in Connecticut and New Jersey (both Dale Schweitzer), where adults occur throughout July and August, sometimes late June in New Jersey,and not after about 12 September. Phenology is similar in Arizona, although perhaps there is no second brood (Tuttle, 2009). In the far southern US, where appearance of adults in April or May is normal, there probably are three or four broods, but nearly all larvae complete feeding before October. In Louisiana, 96% of 2129 records of adults at light traps are from May through September, with a peak in August (Brou and Brou, 1997). Presumably all stages occur year round in wet tropical regions, although Tuttle (2009) could not verify such claims for southern Florida. Adults are not present among stray or migrating hawk moths, in recent decades mostly Agrius cingulatus, that reach the northeast coast in September to early November. From egg to pupa takes under month, and if the pupae does not diapause, adults eclose in about three weeks.
Females lay a single egg on the upperside of a host plant leaf. Hostplants include potato, tobacco, tomato, and other plants in the nightshade (Family: Solanaceae) family. The female will lay up to 100 eggs in a season. Eggs hatch in two to eight days and the larva emerges. Caterpillars pupate and overwinter in burrows in the soil for one to 25 weeks. An adult emerges and lives for several weeks. The life cycle has between two and four generations per year and the insects are typically active in late summer through fall.
Molecular Biology and Genetics
Barcode data: Manduca sexta
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Manduca sexta
Public Records: 13
Specimens with Barcodes: 33
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Described as a "pest" and "one of our commonest hawkmoths" (Covell, 1984; Holland, 1915). This highly vagile species may be less susceptible to habitat loss or alteration than species with low vagility.
Other Considerations: Relatively highly vagile adults can be recorded far from breeding and larval habitats.
Global Short Term Trend: Increase of 10 to >25%
Comments: A pest species that is increasing due to association with land converted for agriculture.
Relevance to Humans and Ecosystems
These moths are important pollinators of deep-throated, night-blooming flowers. The moth extends its long proboscis (a hollow straw-like organ) up to 10 cm into the flower to collect nectar. As the moth removes its proboscis from the flower, pollen grains stick to it and become entrapped on the scales of the moth's body. As it nectars on other plants, it inadvertently deposits this pollen on other flowers and pollinates the plant.
Hawk moths are such good pollinators that some plants have developed distinct pollination syndromes to attract them. One example is the large white petunia (Petunia axillaris), that emits a strong odor during the night to attract hawk moths. Other examples of plants pollinated by the Carolina sphinx moth include Colorado four-o'clock (Mirabilis froebelii), periwinkles (Mandevilla longiflora, Mandevilla petraea), wild tobacco (Nicotiana attenuata), agaves (Agave spp.), and jimsonweed (Datura wrightii). An interesting mutualism has developed between the Carolina sphinx moth and jimsonweed. Larvae are major herbivores of jimsonweed, feasting on the leaves. However, the plant has developed mechanisms to deal with this herbivory - the plant stores resources in its massive roots that can be allocated to new leaf production. In return, the moth is a major pollinator of jimsonweed, whose large white funnel-shaped flowers bloom at night and are filled with nectar. Jimsonweed plants pollinated by the moth have heartier seedlings than those plants that are self-pollinated.
However, the larval stage of this species is considered an agricultural pest. Larvae can defoliate a plant overnight including crop plants like tobacco, tomatoes, potatoes, peppers, and eggplants.
Manduca sexta is a moth of the family Sphingidae present through much of the American continent. Commonly known as the tobacco hornworm and the goliath worm, it is closely related to and often confused with the very similar tomato hornworm (Manduca quinquemaculata); the larvae of both feed on the foliage of various plants of the family Solanaceae. The tobacco hornworm is sometimes kept as a pet by children throughout its range. It can be distinguished by its seven diagonal lines on its sides; tomato hornworms have eight V-shaped markings. A mnemonic to remember the markings is tobacco hornworms have straight white lines like cigarettes, while tomato hornworms have V-shaped markings (as in "vine-ripened" tomatoes). M. sexta has mechanisms for selectively sequestering and secreting the neurotoxin nicotine present in tobacco.
M. sexta is a common model organism, especially in neurobiology, due to its easily accessible nervous system and short life cycle. It is used in a variety of biomedical and biological scientific experiments. It can be easily raised on a wheat-germ-based diet. The larva is large, and thus it is relatively easy to dissect it and isolate its organs.
- Manduca sexta caestri (Blanchard, 1854) (Chile)
- Manduca sexta jamaicensis (Butler, 1875) (Caribbean)
- Manduca sexta leucoptera (Rothschild & Jordan, 1903) (Galápagos Islands)
- Manduca sexta paphus (Cramer, 1779) (South America)
- Manduca sexta saliensis (Kernbach, 1964) (Argentina)
- Manduca sexta sexta (Americas)
M. sexta has a short life cycle, lasting about 30 to 50 days. In most areas, M. sexta has about two generations per year, but can have three or four generations per year in Florida.
M. sexta eggs are spherical, approximately 1.5 millimeters in diameter, and translucent green in color. They typically hatch two to four days after they are laid. Eggs are normally found on the underside of foliage, but can also be found on the upper surface.
M. sexta larvae are green in color and grow up to 70 millimeters in length. Under laboratory conditions, when fed a wheat-germ based diet, larvae are turquoise due to a lack of pigments in their diet. M. sexta blood contains the blue-colored protein insecticyanin. When the larva feeds on plants, it ingests pigmentacious carotenoids. Carotenoids are primarily yellow in hue. The resulting combination is green.
During the larval stage, M. sexta caterpillars feed on plants of the family Solanaceae, principally tobacco, tomatoes and members of the genus Datura. M. sexta has five larval instars, which are separated by ecdysis (molting), but may add larval instars when nutrient conditions are poor. Near the end of this stage, the caterpillar seeks a location for pupation, burrows underground, and pupates. The searching behaviour is known as "wandering". The imminence of pupation suggested behaviorally by the wandering can be anatomically confirmed by spotting the heart (aorta), which is a long, pulsating vessel running along the length of the caterpillar's dorsal side. The heart appears just as the caterpillar is reaching the end of the final instar.
A common biological control for hornworms is the parasitic braconid wasp Cotesia congregata, which lays its eggs in the bodies of the hornworms. The wasp larvae feed internally and emerge from the body to spin their cocoons. Parasitized hornworms are often seen covered with multiple white, cottony wasp cocoons, which are often mistaken for large eggs. Another wasp species, Polistes erythrocephalus, feeds on hornworm larvae.
Before the larva pupates, it goes through a stage called the pre-pupa, where its shrinks considerably and prepares to pupate. Often people mistake this stage for a dead or dying caterpillar.
The pupal stage lasts approximately 18 days under laboratory conditions (17 hours light, 7 hours dark, 27 °C). When reared on a short-day photoperiod (12 hours light, 12 hours dark), pupae enter a state of diapause that can last several months. During the pupal stage, structures of the adult moth form within the pupal case, which is shed during eclosion (adult emergence).
Adult M. sexta are known as Carolina sphinx moths. M. sexta moths are nectarivorous and feed on flowers, demonstrating a remarkable ability to hover.
Adult males and females are sexually dimorphic. Males are identifiable by their broader antennae and the presence of claspers at the end of the abdomen. Female moths are typically ready to mate one week after eclosion, and do so only once. Males may mate many times. Mating generally occurs on a vertical surface at night, and can last several hours, with the male and female facing in opposite positions, their posterior ends touching. After mating, females deposit their fertilized eggs on foliage, usually on the underside of leaves.
Like Drosophila melanogaster, M. sexta is commonly used as a model organism for experiments. They are frequently studied in the laboratory due to their large size and relative ease of rearing. They may be reared on host plants, such as tobacco and tobacco relatives, tomato plants, or wheat-germ-based artificial diet. Their rearing is straightforward, as long as they receive a "long day" (i.e., 14 hour) daylight cycle during development to prevent diapause.
Eggs are rinsed for one to five minutes in dilute household bleach for disinfection.
Eggs are placed on diet cubes or host plants. The eggs hatch and develop at different speeds depending on temperature. The larvae are moved to fresh diet or leaves as their food spoils or is consumed. When they start to "wander", they are about to pupate, so are placed in a pupation chamber. Pupation chambers are holes drilled into a wood board. The Manduca larvae are sealed in the chamber using a stopper and allowed to pupate. After pupation, the pupae are placed in a breeding or colony chamber to eclose. Providing a cup of sugar water and a tobacco (or related) plant will allow mated females to oviposit fertile eggs, which can then be reared.
When fed an artificial diet, Manduca larvae do not consume the xanthophyll needed to produce their green coloration; instead they appear blue. On some diets, they have very little pigment and pigment precursors, so are a very pale blue-white. As vitamin A and other carotenoids are necessary for the visual pigments (rhodopsin), an artificial-diet-reared hornworm may have poor vision due to lack of carotenoids in the diet.
Tobacco hornworms are facultative specialists; the larvae can grow and develop on any host plants. However, the larvae prefer solanaceous plants, such as tobacco and tomato plants. On these types of plants, larvae grow and develop faster. The lateral and medial sensilla styloconia, which are sensory receptors, on their mouthparts help them to identify solanaceous plants by recognizing indioside D, a steroidal glycoside found in those particular plants (del Campo et al., 2001). Tobacco hornworms are considered pests because they feed on the upper leaves of tobacco plants and leave green or black droppings on the plants. As adults, they do not damage plants since they feed on nectar.
Tobacco hornworm larvae prefer humid environments. When dehydrated, tobacco hornworm larvae will move towards a source of water or to an area with a high relative level of humidity. They use their antennae to locate water to drink (Rowley and Hanson, 2007).
Nicotine is poisonous to most animals that use muscles to move because nicotine targets the acetylcholine receptor at the neuromuscular junction. However, the tobacco hornworm is capable of metabolizing nicotine from the tobacco plant and using nicotine as a defense against predators. It possesses a gene called cytochrome P450 6B46 (CYP6B46) that converts nicotine into a metabolite. About 0.65% of nicotine metabolites are transported from the gut to the hemolymph, where they are reconverted to nicotine and released into the air from the tobacco hornworm’s spiracles. The emitted nicotine is used as a way to deter spiders, a practice known as “toxic halitosis.” In one study, tobacco hornworms that fed from nicotine-deficient plants or expressed low levels of CYP6B46 were more susceptible to wolf spider predation (Kumar et al., 2013).
Tobacco hornworm caterpillars emit short clicking sounds from their mandibles when they are being attacked. This sound production is believed to be a type of acoustic aposematism, or warning sounds that let predators know that trying to eat them will be troublesome; tobacco hornworms have been observed to thrash and bite predators after producing those clicking sounds. These clicks can be heard at a close distance with a frequency range of 5 to 50 kHz. The intensity of clicks increases with the number of attacks (Bura et al., 2012).
Manduca sexta parasitized by Braconidae wasp larvae
- "CATE Creating a Taxonomic eScience – Sphingidae". Cate-sphingidae.org. Archived from the original on 2012-11-14. Retrieved June 16, 2011.
- Villanueva, Raul (June 2009). "Featured Creatures". University of Florida / IFAS. Retrieved 12 October 2012.
- Eichman, Aaron; Weston Tripp; Matt Edwards (2000). "Manduca sexta "Carolina sphinx"". Archived from the original on 2006-09-08. Retrieved October 21, 2006.
- "Biologia y comportamiento de Polistes erythrocephalus". Biology. . Retrieved 2014-10-14.
- del Campo, M.L.; Miles, C.I.; Schroeder, F.C.; Mueller, C.; Booker, R.; Renwick, J.A. (2001). "Host recognition by the tobacco hornworm is mediated by a host plant compound". Nature 411 (6834): 186–189. doi:10.1038/35075559.
- Puvuk, Dan (September 23, 2009). "The Tomato Hornworm and the Tobacco Hornworm". Michigan State University. Retrieved 20 April 2014.
- Rowley, M.; Hanson, F. (2007). "Humidity detection and hygropreference behavior in larvae of the tobacco hornworm, Manduca sexta". Journal of Insect Science 7: 1–10. doi:10.1673/031.007.3901. PMC 2999434. PMID 20302460.
- Kumar, P.; Pandit, S.S.; Steppuhn, A.; Baldwin, I.T. (2013). "Natural history-driven, plant-mediated RNAi-based study reveals CYP6B46’s role in a nicotine-mediated antipredator herbivore defense". PNAS: 1–8.
- Bura, V.L.; Hnain, A.K.; Hick, J.N.; Yack, J.E. (2012). "Defensive sound production in the tobacco hornworm, Manduca sexta (Bombycoidea: Sphingidae)". Journal of Insect Behavior 25: 114–126. doi:10.1007/s10905-011-9282-8.
- Van Griethuijsen, L. I.; Banks, K. M.; Trimmer, B. A. (2013). "Spatial accuracy of a rapid defense behavior in caterpillars". Journal of Experimental Biology 216 (3): 379. doi:10.1242/jeb.070896.
- Bura, Veronica L.; Hnain, Antoine K.; Hick, Justin N.; Yack, Jayne E. (2011). "Defensive Sound Production in the Tobacco Hornworm, Manduca sexta (Bombycoidea: Sphingidae)". Journal of Insect Behavior 25 (2): 114. doi:10.1007/s10905-011-9282-8.
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