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Manduca sexta
Manduca sexta is a moth of the family Sphingidae present through much of the Americas. The species was first described by Carl Linnaeus in his 1763 Centuria Insectorum.
Commonly known as the Carolina sphinx moth and the tobacco hawk moth (as adults) and the tobacco hornworm and the Goliath worm (as larvae), 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 larvae of these species can be distinguished by their lateral markings: tomato hornworms have eight V-shaped white markings with no borders, while tobacco hornworms have seven white diagonal lines with a black border. Additionally, tobacco hornworms have red horns, while tomato hornworms have dark blue or black horns. 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.[citation needed]
M. sexta is a common model organism, especially in neurobiology, due to its easily accessible nervous system and short life cycle. Due to its immense size M. sexta is big enough for medical imaging modalities (like CT, MRI, or PET) and used as a model in imaging and gut inflammation. 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.
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. 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 bright green in color and grow up to 100 millimeters in length. The posterior abdominal segment is tipped with a dorsocaudal horn that earns them the name "hornworm". The final instar consists of a cylindrical body covered with fine hairlike setae. The head is equipped with a pair of ocelli and chewing mouthparts. Each of the three thoracic segments bears a pair of true legs, and there is a pair of prolegs on the third, fourth, fifth, sixth, and last abdominal segments in all larval instars. The prothoracic segment bears one pair of spiracles, and additional pairs occur on each of the eight abdominal segments.
The hemolymph (blood) of this species contains insecticyanin, a blue-colored biliprotein. When the larva feeds on its normal diet of plant foliage, it ingests pigmentacious carotenoids, which are primarily yellow in hue. The resulting combination is green. Under laboratory conditions—when fed a wheat-germ-based diet—larvae are turquoise in color due to the lack of carotenoids in their diet.[citation needed]
The caterpillar stage of the tobacco hornworm is quite similar in appearance to that of the closely related tomato hornworm. The larvae of these two species can however be readily distinguished by their lateral markings. Specifically, the M. sexta caterpillar has seven white diagonal lines with a black border at the first seven abdominal segments, and the horn is red or green with a red tip. The M. quinquemaculatacaterpillar has V-shaped white markings with no borders at all eight of its abdominal segments, and the horn is dark blue or black in color.
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Manduca sexta
Manduca sexta is a moth of the family Sphingidae present through much of the Americas. The species was first described by Carl Linnaeus in his 1763 Centuria Insectorum.
Commonly known as the Carolina sphinx moth and the tobacco hawk moth (as adults) and the tobacco hornworm and the Goliath worm (as larvae), 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 larvae of these species can be distinguished by their lateral markings: tomato hornworms have eight V-shaped white markings with no borders, while tobacco hornworms have seven white diagonal lines with a black border. Additionally, tobacco hornworms have red horns, while tomato hornworms have dark blue or black horns. 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.[citation needed]
M. sexta is a common model organism, especially in neurobiology, due to its easily accessible nervous system and short life cycle. Due to its immense size M. sexta is big enough for medical imaging modalities (like CT, MRI, or PET) and used as a model in imaging and gut inflammation. 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.
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. 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 bright green in color and grow up to 100 millimeters in length. The posterior abdominal segment is tipped with a dorsocaudal horn that earns them the name "hornworm". The final instar consists of a cylindrical body covered with fine hairlike setae. The head is equipped with a pair of ocelli and chewing mouthparts. Each of the three thoracic segments bears a pair of true legs, and there is a pair of prolegs on the third, fourth, fifth, sixth, and last abdominal segments in all larval instars. The prothoracic segment bears one pair of spiracles, and additional pairs occur on each of the eight abdominal segments.
The hemolymph (blood) of this species contains insecticyanin, a blue-colored biliprotein. When the larva feeds on its normal diet of plant foliage, it ingests pigmentacious carotenoids, which are primarily yellow in hue. The resulting combination is green. Under laboratory conditions—when fed a wheat-germ-based diet—larvae are turquoise in color due to the lack of carotenoids in their diet.[citation needed]
The caterpillar stage of the tobacco hornworm is quite similar in appearance to that of the closely related tomato hornworm. The larvae of these two species can however be readily distinguished by their lateral markings. Specifically, the M. sexta caterpillar has seven white diagonal lines with a black border at the first seven abdominal segments, and the horn is red or green with a red tip. The M. quinquemaculatacaterpillar has V-shaped white markings with no borders at all eight of its abdominal segments, and the horn is dark blue or black in color.