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Chrysochus auratus

What do they look like?

Adult dogbane beetles are iridescent blue-green beetles with copper-colored shine on their front wings. The legs and antennae are really dark blue that is almost black. Their heads and upper parts of their bodies have small, deep holes. They have long antennae between their eyes that have 12 joints each. Their front mouthparts, called mandibles, are flat and adapted to eating plants. The left side is longer, and actually fits into a groove on the right. Their mouthparts are also adapted to lapping up juice from milkweed plants. Dogbane beelte larvae have white bodies and brown heads. (Blatchely, 1926; Wilson, 1934)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    8 to 11 mm
    0.31 to 0.43 in

Where do they live?

Dogbane beetles live in the eastern United States and southern Canada. They are found as far West as the Rocky Mountains, Utah, and Arizona. (Blatchely, 1926; Peterson, et al., 2001)

What kind of habitat do they need?

Dogbane beetles are found wherever the plants they live on are found. Most often, they feed and live on dogbane plants, especially Indian hemp and spreading dogbane. Indian hemp is found throughout the entire United States and is often thought of as a weed. It prefers open habitats where it can spread. It lives along the side of roads, fields, railroad tracks, lakeshores, and places that have been disturbed. Spreading dogbane is found in the northeastern United States. Spreading dogbane lives in forests, at the edge of forests, along the banks of streams, and in fields with sand or gravel soil. (Dobler and Farrell, 1999; Peterson, et al., 2001; Schultz and Burnside, 1979; Wilson, 1934)

How do they grow?

Larvae in the first stage of development, or first instar, hatch from eggs in midsummer. They burrow into the soil and eat the roots of the plant they live on. They develop in a chamber in the soil, and wait for their bodies to harden before they dig their way back up to the surface. Adult dogbane beetles mate and lay eggs during the rest of the summer. (Peterson, et al., 2005)

How do they reproduce?

Dogbane beetles mate about once a day, usually early in the day. Males search for and choose females to mate with. After mating, males ride on the backs of the females to guard them. Dogbane beetles have more than one mate. In the West, dogbane beetles sometimes mate and cross with cobalt milkweed beetles. The mixed beetles are blue-green to brown-purple, but are not able to reproduce. (Peterson, et al., 2001; Peterson, et al., 2005; Schwartz and Peterson, 2006)

Dogbane beetles lay eggs on leaves and stems of the plants where they live or on nearby plants. They lay eggs in large groups of cases, called capsules, that are usually 3 mm wide by 2 mm tall. (Peterson, et al., 2005; Zabriskie, 1895)

  • How often does reproduction occur?
    Dogbane beetles produce one generation each year.
  • Breeding season
    Adults mate from mid to late summer.

Female dogbane beetles lay eggs in capsules, which are cases that protect them. The eggs are left on plants to develop and hatch by themselves.

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female

How long do they live?

Adult dogbane beetles emerge in early summer and live as adults for 6 to 8 weeks. (Peterson, et al., 2005)

  • Typical lifespan
    Status: wild
    42 to 56 days

How do they behave?

Dogbane beetles live in small groups in different places because they cannot travel very far and are not very good at colonizing new places. (Williams, 1992)

Home Range

Dogbane beetles move between plants within a particular area of plants it lives on.

How do they communicate with each other?

Leaf beetles use visual, chemical, and scent information about their environment when moving into their host plant. Dogbane leaf beetles use chemical signals to communicate with each other in mating. The chemicals are specific to dogbane leaf beetles, and make it less likely that they would mate with other beetles like cobalt milkweed beetles. (Fernandez and Hilker, 2007; Peterson, et al., 2007)

What do they eat?

Dogbane beetles mostly eat dogbane plants, usually Indian hemp and spreading dogbane. They also eat milkweed. To protect themselves from being eaten, dogbane plants give off a milky liquid that dries and makes the mouthparts of insects sticky. Dogbane beetles eat the outside parts of the leaves that have less latex and also rub it off on the leaves. They leave sticky bits of latex on dogbane plants. Dogbane beetle larvae mostly eat the roots of the same plants. (Peterson, et al., 2001)

  • Plant Foods
  • leaves
  • roots and tubers
  • flowers

What eats them and how do they avoid being eaten?

Dogbane plants that dogbane beetles eat have contain chemicals called cardenolides, which partially protect them from diseases and animals. Cardenolides are bitter and toxic to insects. However, many insects that eat plants have adapted to be able to consume and store these chemicals in their bodies. If the beetle is bothered, it releases the chemicals, which puts off predators. Larvae that have a lot of these chemicals are not bothered as much by parasitic wasps. (Dobler, et al., 1998; Dobler, et al., 2011; Labeyrie and Dobler, 2003)

  • These animal colors help protect them
  • aposematic

What roles do they have in the ecosystem?

Dogbane beetles eat and live on dogbane plants, especially Indian hemp and spreading dogbane, and sometimes live on and eat milkweed plants. (Peterson, et al., 2001; Williams, 1992; Wilson, 1934)

Species (or larger taxonomic groups) used as hosts by this species
  • dogbanes (Apocynum cannabinum)
  • Indian hemp (Apocynum cannabinum)
  • spreading dogbane (Apocynum androsaemifolium)
  • milkweed (Asclepiadaceae)

Do they cause problems?

There are no known negative economic impacts of dogbane beetles on humans.

How do they interact with us?

There are no known positive economic impacts of dogbane beetles on humans.

Are they endangered?

Dogbane beetles are not endangered.

Contributors

Jaclyn Tolchin (author), University of Michigan Biological Station, Catherine Kent (editor), Special Projects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

aposematic

having colors that act to protect the animal, often from predators. For example: animals that are bright red or yellow are often toxic or distasteful, their colors discourage predators from eating them.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.

chemical

uses smells or other chemicals to communicate

diapause

a period of time when growth or development is suspended in insects and other invertebrates, it can usually only be ended the appropriate environmental stimulus.

diurnal
  1. active during the day, 2. lasting for one day.
ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

fertilization

union of egg and spermatozoan

folivore

an animal that mainly eats leaves.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

internal fertilization

fertilization takes place within the female's body

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland
savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland
visual

uses sight to communicate

References

Blatchely, W. 1926. Catalogue of the Coleoptera of Indiana. Indianapolis, Indiana: WM. B. Burford, Contractor for State Publishing and Printing.

Dobler, S., D. Daloze, J. Pasteels. 1998. Sequestration of plant compounds in a leaf beetle’s defensive secretion: cardenolides in Chrysochus. Chemoecology, 8: 111-118.

Dobler, S., B. Farrell. 1999. Host use evolution in Chrysochus milkweed beetles: evidence from behaviour, population genetics and phylogeny. Molecular Ecology, 8: 1297–1307.

Dobler, S., G. Petschenka, H. Pankoke. 2011. Coping with toxic plant compounds – The insect’s perspective on iridoid glycosides and cardenolides. Phytochemistry, 72: 1593–1604.

Fernandez, P., M. Hilker. 2007. Host plant location by Chrysomelidae. Basic and Applied Ecology, 8: 97-116.

Labeyrie, E., S. Dobler. 2003. Molecular Adaptation of Chrysochus Leaf Beetles to Toxic Compounds in Their Food Plants. Molecular Biology and Evolution, 21: 218-221.

Peterson, M., S. Dobler, J. Holland, L. Tantalo, S. Locke. 2001. Behavioral, molecular and morphological evidence for a hybrid zone between Chrysochus auratus and C. cobaltinus (Coleoptera: Chrysomelidae). Annals of the Entomological Society of America, 94: 1-9.

Peterson, M., S. Dobler, E. Larson, D. Juarez, T. Schlarbaum, K. Monsen, F. Wittko. 2007. Profiles of cuticular hydrocarbons mediate male mate choice and sexual isolation between hybridising Chrysochus (Coleoptera: Chrysomelidae). Chemoecology, 17: 87-96.

Peterson, M., E. Larson, M. Brassil, K. Buckingham, D. Juarez, J. Deas, D. Manglona, M. White, J. Maslan, A. Schweitzer, K. Monsen. 2011. Cryptic gametic interactions confer both conspecific and heterospecific advantages in the Chrysochus (Coleoptera: Chrysomelidae) hybrid zone. Genetica, 139: 663-676.

Peterson, M., K. Monsen, H. Pedersen, T. McFarland, J. Bearden. 2005. Direct and indirect analysis of the fitness of Chrysochus (Coleoptera: Chrysomelidae) hybrids.. Biological Journal of the Linnean Society, 84: 273-286.

Schultz, M., O. Burnside. 1979. Distribution, Competition, and Phenology of Hemp Dogbane (Apocynum cannabinum) in Nebraska. Weed Science, 27: 565-570.

Schwartz, S., M. Peterson. 2006. Strong material benefits and no longevity costs of multiple mating in an extremely polyandrous leaf beetle, Chrysochus cobaltinus (Coleoptera: Chrysomelidae). Behavioral Ecology, 17: 1004-1010.

Williams, C. 1991. Host plant latex and the feeding behavior of Chrysochus auratus (Coleoptera: Chrysomelidae). The Coleopterists Bulletin, 45: 195-196.

Williams, C. 1992. Movement of the Dogbane Beetle, Chrysochus aura/us (Coleoptera: Chrysomelidae), in a Patchy Environment. Banisteria, 1: 8-10.

Wilson, S. 1934. The anatomy of Chrysochus auratus, Fab., Coleoptera: (Chrysomelidae) with an extended discussion on the wing venation. Journal of the New York Entomological Society, 42: 65-85.

Zabriskie, J. 1895. Egg-capsules of Chrysochus auratus (Fab.). Journal of the New York Entomological Society, 3: 192. Accessed July 25, 2012 at http://www.jstor.org.proxy.lib.umich.edu/stable/10.2307/25002685?origin=api.

 
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Tolchin, J. 2013. "Chrysochus auratus" (On-line), Animal Diversity Web. Accessed April 24, 2014 at http://www.biokids.umich.edu/accounts/Chrysochus_auratus/

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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