fisicosm's Identifications

Scientific & Common Name(s): The hemipteran Oncopeltus fasciatus, commonly known as the Large milkweed bug (LMB) or milkweed bug, has a noticeable red-orange and black colouration (Milkweed Bugs, 2010). They can be observed in nature as well as in the laboratory, as they are commonly used for research purposes (Palmer & Dingle,1986).

Habitat & Geographic Range: Small groups of the milkweed bug are found in temperate to tropical climates, in habitats such as meadows and fields that contain milkweed (Asclepias) or dogbane (Apocyum) (Dingle, 1968). They can be observed on the stems, leaves and seeds of the milkweed plant or less commonly on other related species. The milkweed bug is native to North America and spans geographically from Costa Rica, California, Florida to southern Canada in areas such as Ontario and New Brunswick (Ralph, 1976). They can be found year round in some parts of the geographic range, such as in California and Texas however in other places such as southern Canada they are found in late summer and fall (Iowa State University, 2016). Typically, Oncopeltus fasciatus are separated into non-migrators and migrators, depending on the geographic area in which they live, with northern populations being highly migratory (Palmer & Dingle, 1986).

Size /Weight & Lifespan: The main phases of development of the large milkweed bug are the egg, nymph and adult and at each phase the length from back of the head to the abdomen can vary (Palmer & Dingle, 1986). The nymph phase can range in length from 3-8mm while the adult can range from 9-18mm (Palmer & Dingle, 1986). Oncopeltus fasciatus weight depends on which phase of development that it is in typically, the range is between 0.3-0.6g (Leslie, 1990). As stated the large milkweed bug is separated into migratory and non-migratory, populations found in tropical climates may be observed and reproduce year-round (Leslie, 1990). While, populations in the middle to upper latitudes, migrate south to reproduce during the warmer months. Once an egg is hatched the nymphal stages to the final adult stage is around 4-8 weeks with the adult typically living for one month (Large milkweed bug (Oncopeltus fasciatus), 2016).

Diet: Oncopeltus fasciatus are herbivores that consume the milkweed plant but can feed on seeds of relatives to the milkweed. Using their mouthparts, the late nymphs and adults can pierce through the pods of the milkweed and suck on the contents of the seeds (The Xerces Society for Invertebrate Conservation, 2014). To eat the seeds, they use a long rostrum in order to inject saliva to pre-digest the seeds. Young nymphs usually feed on pods that are damaged as they can’t penetrate through the thick walls. Although the seeds of the milkweed are the main food source they do consume the stems and leaves of the plant (The Xerces Society for Invertebrate Conservation, 2014).

Reproduction & Communication: Oncopeltus fasciatus is a hemimetabolous and goes through incomplete metamorphosis, as it has 5 instar stages, they are called nymphs and in these stages they appear similar to adults but lack full wings and have a coloration that differs slightly (The Xerces Society for Invertebrate Conservation, 2014). During these stages they shed their exoskeleton, through a process called molting, until they reach the fifth phase of molting and become a fully mature adult. During reproduction the male and female can be observed as being attached end-to-end for up to 30 minutes, after this the female lays eggs, with an average of 30 eggs a day which is approximately 2000 eggs over the one month lifespan of an adult (The Xerces Society for Invertebrate Conservation, 2014) For communication the O. Fasciatus is thought to secrete phenomes from their glands (Aldrich et al., 2009).

Predation: The coloration of the large milkweed bug, it’s reddish-orange and black markings, serve as a warning signal, an aposematic trait, that predators associate with distastefulness (Iowa State University, 2016). Further, the milkweed contains toxic cardiac glycosides that the milkweed bug can consume without being poisoned. This poisonous compound is used as a defense mechanism, as predators who consume them such as Robbins, sparrows and cardinals would get sick and thus a taste aversion response would be established (Milkweed Bugs, 2010). Therefore, most predators avoid these insects due to their aposematic colouration and potential to sicken predators with the stored toxic chemical.

Conservation Status: The large milkweed bug is widespread and often used in laboratory for studies, thus they currently do not have a conservation status (Large milkweed bug, 2016). Further, the lack of predators that consume the milkweed bug as stated above ensure that it is not under threat of becoming extinct.

Did You Know: that female O. fasciatus have the ability to resorb oocytes (oosorption) during unfavourable environmental conditions and transfer this resource for survival rather than reproduction? (Moore & Attisano, 2011). A study by Moore & Attisano (2011) found that female large milkweed bugs responded to environments with poor food quality, those fed with pumpkin seeds, had ovarian apoptosis that occurred at higher levels than that of the control. These individuals that increased oosorption had lower reproduction output, however, under these poor conditions had no significant difference in life span. Further, a study by Attisano et al. (2013) found that populations of O. fasciatus that migrated had lower levels of oosorption in comparison to resident females that used this mechanism to survive poor environmental conditions.
References

Aldrich, J. R., Oliver, J. E., Taghizadeh, T., Ferreira, J. T. B., & Liewehr, D. (1999). Pheromones and colonization: reassessment of the milkweed bug migration model (Heteroptera: Lygaeidae: Lygaeinae). Chemoecology, 9(2), 63-71. doi: 10.1007/s000490050035

Attisano, A.,Tregenza, T., Moore, A.J., Moore, P.J. (2013). Oosorption and migratory strategy of the milkweed bug, Oncopeltus fasciatus. Science Direct. 86(3), 651-657. Retrieved from http://www.sciencedirect.com/science/article/pii/S0003347213003357

Dingle, H. (1968). Life History and Population Consequences of Density, Photo-Period, and Temperature in a Migrant Insect, the Milkweed Bug Oncopeltus. The American Naturalist, 102(924), 149-163. Retrieved from http://www.jstor.org/stable/2459082

Iowa State University. (2016). Species Oncopeltus fasciatus-Large milkweed bug. Bug Guide. Retrieved from http://bugguide.net/node/view/504#range

Large milkweed bug (Oncopeltus fasciatus). (2016). Biology at Illinois. Retrieved from http://www.life.illinois.edu/ib/109/Insect%20rearing/milkweedbug.html

Large milkweed bug. (2016). Nature Tourism in Minnesota. Retrieved from http://minnesotaseasons.com/Insects/large_milkweed_bug.html

Leslie, J. (1990). Geographical and Genetic Structure of Life-History Variation in Milkweed Bugs (Hemiptera: Lygaeidae: Oncopeltus). Evolution, 44(2), 295-304. doi: 10.2307/2409408

Milkweed Bugs. (2010). Missouri Botanical Garden. Retrieved from http://www.missouribotanicalgarden.org

Moore, P.J., Attisano, A. (2011). Oosorption in response to poor food: complexity in the trade- off between reproduction and survival. Ecology and Evolution. 1, 37–45. doi:10.1002/ece3.4

Palmer, J., & Dingle, H. (1986). Direct and Correlated Responses to Selection Among Life- History Traits in Milkweed Bugs (Oncopeltus fasciatus). Evolution, 40(4), 767-777. doi: 10.2307/2408461

Ralph, C. (1976). Natural Food Requirements of the Large Milkweed Bug, Oncopeltus fasciatus (Hemiptera: Lygaeidae), and Their Relation to Gregariousness and Host Plant Morphology. Oecologia, 26(2), 157-175. Retrieved from http://www.jstor.org/stable/4215349

The Xerces Society for Invertebrate Conservation. (2014). Milkweeds-A Conservation Practitioner’s Guide. Oregon, DC: Borders B., Lee-Mader E.

Species Identification: The species of interest is the Lophocampa caryae, commonly referred to as the Hickory Tussock Moth or the Hickory Tiger Moth due to its appearance.

Description and Lifespan: The Hickory Tiger Moth has ochre-yellow wings spanning about 37-55 millimeters (Herrick 123), and a body length between 20-28 millimeters (Beadle and Seabrooke 305). The moths can be naturally observed during May and June when they lay about a hundred eggs on the underside of a leaf (Bartlett). The eggs hatch about 2 weeks later, giving life to numerous caterpillars with a coat of white and black urticating hairs (Herrick 123). These larvae measure 1.5 inches in length and are present between July to late September (Herrick 124). They weigh about 0.01 grams and pass through eight or nine developmental phases, and feed for 60 to 100 days before spinning a cocoon (Herrick 123). Weighing about 0.1 grams and varying in size (Tripi et al. 125), the cocoon is spun using their hairs, among leaves or in protected areas, to increase their probability of surviving the winter (Herrick 124). The winter is spent as a pupa, before emerging as a moth in April or May for reproduction (Pohl). The average weight of the moth is unknown (Pohl et al.), and it now lacks hairs on its body, as studies show hairs cannot regenerate (Lamy et al. 352). Overall, there are three stages in this species one year life, including the larva, pupa and adult, thus experiencing complete metamorphosis (Bartlett).

Geographic Range: Found most commonly in the Americas in areas ranging west of the Atlantic Ocean to Missouri and south to North Carolina (Herrick 122), this species is frequently seen in northeastern United States and adjacent Canadian provinces - between the boundaries of the Atlantic Ocean and Saskatchewan (Herrick 122). Its terrestrial habitat ranges drastically between its vast geographic range, usually involving temperate woodlands and forests where food is plentiful as seen in Southern Ontario, or even mountains like in Nebraska (Herrick 122). Generally, caterpillars are found on or near their food source (Pohl et al.).

Diet: The larvae typically feed on deciduous trees, including ash, elm, maple, oak, and most importantly, the hickory tree, thus the name “Hickory Tussock” (Beadle and Seabrooke 305). They also feed on hop plants, berries and sumac, when available (Bartlett), and walnuts, butternuts and pomaceous fruit trees (Herrick 123). The newborn caterpillars are gregarious, typically feed in groups, yet later feed on their own (Herrick 123). Although pupa do not feed, the moths feed on their larval lipid reserves and liquids similar to butterflies; anything that can dissolve in water (Pohl et al.). The moths are very attracted to the sodium component of sweat, which is vital for their reproduction and why they occasionally land on humans (Pohl et al.).

Reproduction and Communication: Lepidoptera, the order of the Hickory Tussock Moth, are well known for their sense of smell, and they use chemical senses as their primary source of communication (Pohl et al.). Females produce pheromones, which can be detected by males for location and courtship (Pohl et al.). The moth senses these pheromones when the compound comes in contact with the sensilla trichodea, the sensory hairs located on the antennae, causing a neural signal to be transduced via action potentials (Baker 253). The moths then use either optomotor anemotaxis (flying according to the wind), or self-steering, to locate the source of pheromones (Baker 257). Once the male locates a receptive female, he creates high frequency clicks via his thorax tymbal organ, and if this courtship behaviour interests her, copulation will occur (Weller 563). Breeding season is between April and May, after hatching from cocoons (Pohl et al.). There is also a sexual dimorphism between the two sexes, as females are larger, and there is parental investment by her only (Pohl et al.). Therefore, this species follows Bateman’s Hypothesis as female fitness is limited by egg production, and male success by the number of partners (Nordell).

Predation: The Hickory Tussock Moth’s most vital defense mechanism involves urticating setae during the larvae and pupa stages, involving the caterpillar being covered in setae, and setae are woven into pupa cocoons for protection (Beadle and Seabrooke 305). These hairs have barbs at the end that attach to predators on contact, along with a venom gland embedded in the base of the hairs (Beadle and Seabrooke 305). This venom causes an allergic reaction similar to poison ivy, and usually causes the predator to spit the species out (Beadle and Seabrooke 305). These setae also affect humans who come in contact with it, yet Kuspis’ results show that removing spines via hair-removing wax or adhesive tape solved most cases. These moths also have distinctive colouration patterns to warn possible predators of venomous abilities via aposematic strategies (Pohl et al.). There are a few parasites known to attack these Tussock moths including Scambus pedalis, Theronia melanocephala, and Amblyteles malacus (Herrick 124). Also, main enemies of larvae include various birds, large ground beetles, and Polistes paper wasps, and birds and bats are common predators of the moth (Hall and Buss).

Did you Know?: To protect themselves from bats, Tusscok Moths have evolved to detect bat sonars to listen to their echolocation communication (Pohl et al.). Thus, their adaptation of ultrasound allows them to sense the bat within 20 feet, and then either drop out of the bat’s path, or travel randomly so the bat cannot follow (Pohl et al.). This species of moth also has scales on their wings that disrupt the deflection of the bat’s sonar and camouflages them (Pohl et al.).

Conservation Status: This native species has drastically declined in population over the past 30 years, as museum records prove that this species was once more abundant (Conner). As previously mentioned, this animal is quite common in North America, and due to vast geographic and habitat range, is not considered in need of protection.

Works Cited
Baker, Troy C. "Sex Pheromone Communication in the Lepidoptera: New Research Progress." Experientia 45.3 (1989): 248-62. Springer Nature. Springer International Publishing. Web. 21 Oct. 2016. http://link.springer.com/article/10.1007%2FBF01951811?LI=true.
Bartlett, Troy. "Lophocampa Caryae - Hickory Tussock Moth." The Bug Guide. Iowa State University- Department of Entomology, 9 Aug. 2004. Web. 21 Oct. 2016. http://bugguide.net/node/view/5690.
Beadle, David, and Seabrooke Leckie. "Species Accounts." Peterson Field Guide to Moths of Northeastern North America. 1st ed. Boston: Houghton Mifflin Harcourt Pub, 2012. 305-06. Print.
Conner, William E. Tiger Moths and Woolly Bears: Behavior, Ecology, and Evolution of the Arctiidae. Oxford: Oxford UP, 2009. Print.
Hall, Donald W., and Lyle Buss. "Tussock Moths - Orygia Spp." Featured Creatures- Entomology and Nematology. University of Florida, Feb. 2014. Web. 21 Oct. 2016. http://entnemdept.ufl.edu/creatures/URBAN/MEDICAL/tussock_moths.htm.
Herrick, Glenn W. "Insect Enemies of the Hickory." Insets; Enemies of Trees. 2nd ed. New Delhi: Logos, 1999. 122-24. Print.
Kuspis, Denise A., J. E. Rawlins, and Edward P. Krenzelok. "Human Exposures to Stinging Caterpillar: Lophocampa Care Exposures." The American Journal of Emergency Medicine 19.5 (2001): 396-98. Science Direct. Saunders Company. Web. 21 Oct. 2016. http://www.sciencedirect.com/science/article/pii/S0735675701050197.
Lamy, Michel, Marie-Hélène Pastureaud, Françoise Novak, Georges Ducombs, Philippe Vincedeau, Jean Maleville, and Lucien Texier. "Thaumetopoein: An Urticating Protein from the Hairs and Integument of the Pine Processionary Caterpillar (Thaumetopoea Pityocampa Schiff., Lepidoptera, Thaumetopoeidae)." Toxicon 24.4 (1986): 347-56. Science Direct. Web. 21 Oct. 2016.
Nordell, Shawn E., and Thomas J. Valone. Animal Behaviour: Concepts, Methods, and Applications. 1st ed. New York: Oxford UP, 2014. Print.
Pohl, Greg, Gary Anweiler, Christian Schmidt, and Norbert Kondla. "Lepidoptera." Encyclopedia of Life. University of Michigan, 2010. Web. 21 Oct. 2016. http://eol.org/pages/747/details.
Tripi, P. A., R. Lee, J. B. Keiper, A. W. Jones, and J. E. Arnold. "An Unusual Case of Ingestion of a Moth Cocoon in a 14-month-old Girl." American Journal of Otolaryngol 31.2 (2010): 123-26. NCBI. Web. 21 Oct. 2016.
Weller, S. "The Evolution of Chemical Defences and Mating Systems in Tiger Moths (Lepidoptera: Arctiidae)." Biological Journal of the Linnean Society 68.4 (1999): 557-78. Wiley. Web. 21 Oct. 2016.