The Wikipedia article for Manduca sexta, or the tobacco hornworm, contained information about its lifecycle. However, no information was provided about its behavior even though there has been recent research about its behavior. I added a Behavior section in the Wikipedia article found here: https://en.wikipedia.org/wiki/Manduca_sexta.
Manduca sexta (Tobacco hornworm). Photo by Daniel Schwen (CC BY-SA 4.0).
Behavior
Feeding
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). [1] 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 the plants since they feed on nectar. [2]
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). [3]
Defense
Nicotine is poisonous to most animals that use muscles to move because nicotine targets the acetylcholine receptor, an important 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 spiders predation (Kumar et al., 2013). [4] (more…)