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Gratiana pallidula

What do they look like?

As their common name suggests, adult eggplant tortoise beetles are shaped like tortoises. They are a yellowish green color, and their head and claws are hidden from above. The body is also flattened. The elytra, which cover the wings and are extended beyond the body, contain a series of punctures that stretch from the front to the back of the entire body.

Larvae are usually yellow-green in color and 5.5 mm when full grown.

The eggs of G. pallidula are oval shaped and a creamy to light brown color. They are usually 1.3 mm by 0.7 mm. A rectangular, brown, transparent membrane covers the egg. (Blatchely, 1926; Rolston, et al., 1965)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    5 to 5.5 mm
    0.20 to 0.22 in

Where do they live?

Gratiana pallidula, also known as the eggplant tortoise beetle, is found in the Nearctic Region throughout the southern United States. (Olckers and Zimmermann, 1991)

What kind of habitat do they need?

Gratiana pallidula is found wherever host plants of the genus Solanum grow. Solanum melongena, S. carolinese, S. xantii, and S. elaegnifolium are the main host plants. S. melongena is not found in the wild, but is instead grown in gardens. S. carolinese can live in a variety of habitats, including prairies, forest edges, roadsides, fields, and vacant lots. S. elaegnifolium is also a weed-like plant that lives in many habitats. It is found throughout most of the United States. S. xanti grows in the southwestern United States in chaparrals, woodlands and forests. (Blatchely, 1926; Imura, 2003; Olckers and Zimmermann, 1991; Rolston, et al., 1965)

How do they grow?

Gratiana pallidula undergoes complete metamorphosis, and goes through egg, larva, pupa, and adult stages. First generation eggs are laid as early as May by adults that have emerged from hiding during the winter, while a second generation of eggs are laid in June or July. Larvae emerge after about a week or two. The larval stage of G. pallidula consists of five stages called instars. Larvae sometimes leave the host plant before pupating. Pupae form anywhere from a week to 3 weeks later, and attach to host plant leaves for 2 to 10 days. First generation adults usually emerge beginning in late June; second generation adults emerge in early August. From late August to early September they go into hibernation for the winter. One generation generally takes about 30 to 35 days to go from egg to adult. (Rolston, et al., 1965)

How do they reproduce?

Little information is available on the mating systems of Gratiana pallidula.

Each year, G. pallidula has two generations that overlap, with one generation born in May-June, and the other generation born in August. Eggs are laid on the leaves of Horsenettle (Solanum). Usually eggs are laid singly, but are occasionally found in groups of 2. Additionally, G. pallidula is able to cross-breed with another species of tortoise beetle, G. lutescens, and produce offspring. (Olckers and Zimmermann, 1991; Rolston, et al., 1965)

  • How often does reproduction occur?
    Two generations are born during the summer.
  • Breeding season
    The two main breeding times are May-June and August.

Females provide nutrients in the eggs for the offspring to grow and develop. Otherwise, eggs are likely left on plants to hatch on their own, with no care from the parents. (Rolston, et al., 1965)

  • Parental Investment
  • pre-hatching/birth
    • provisioning
      • female

How long do they live?

Little information on lifespan is available, but it takes about 30 to 35 days for G. pallidula to go from egg to adult. Adults then likely live several weeks in the summer. (Rolston, et al., 1965)

How do they behave?

G. pallidula is active during the day. They stay on their host plants during the night. They are less active when it is cloudy and when temperatures are low. (Rolston, et al., 1965)

How do they communicate with each other?

In general, leaf beetles in the Chrysomelidae family use sight, smell, and chemical detection to find host plants. (Fernandez and Hilker, 2007)

What do they eat?

Gratiana pallidula is a herbivore that feeds on Solanum plants, particularly eggplant (S. melongena), common horsenettle (S. carolinese), gray horsenettle (S. xantii) and white horsenettle (S. elaegnifolium). Adults chew small, circular holes in leaves. During early larval instars, larvae feed on old leaves and green stems. The later instars feed on leaves and young growth. Before pupating, larvae live for 1 to 5 days without eating. Toward the end of summer, adults eat less. After emerging in the spring after hiding during the winter, adults eat more than normal. (Blatchely, 1926; Imura, 2003; Olckers and Zimmermann, 1991; Rolston, et al., 1965)

  • Plant Foods
  • leaves

What eats them and how do they avoid being eaten?

The stinkbug Stiretrus anchorago is a predator of G. pallidula larvae. Ants are also known to prey on larvae of the genus Gratiana, and are likely predators of G. pallidula as well. To defend against predators, the larvae of G. pallidula make shields on their backs out of feces. Instead of getting rid of their waste, it collects on a fork that sticks out from the end of their body. Larvae will also collect molted skin in their shields. Predators are more likely to stay away because of this fecal shield. (Eisner and Eisner, 2000; Rolston, et al., 1965; Scholtens, 2012)

What roles do they have in the ecosystem?

Eggplant tortoise beetles feed on Solanum plants, particularly eggplant (S. melongena), common horsenettle (S. carolinese), gray horsenettle (S. xantii) and white horsenettle (S. elaegnifolium). G. pallidula are used as a host by parasitic wasps, Tetrastichus and Spilochalcis. Tetrastichus develops in the eggs G. pallidula and emerges 7 to 15 days later. S. sanguineiventris develops in the pupae of G. pallidula and emerges 12 to 18 days later. (Askew, 1971; Carasi and Teixeira, 2010; Olckers and Zimmermann, 1991; Rolston, et al., 1965)

Species (or larger taxonomic groups) used as hosts by this species
  • Solanum melongena
  • Solanum carolinese
  • Solanum xantii
  • Solanum elaegnifolium
Commensal or parasitic species (or larger taxonomic groups) that use this species as a host

Do they cause problems?

Gratiana pallidula feeds on and infests Solanum plants, particularly eggplant (S. melongena), common horsenettle (S. carolinese), gray horsenettle (S. xantii) and white horsenettle (S. elaegnifolium). Both adults and larvae eat holes in the leaves of host plants, causing damage to the plant. For crops such as eggplant, which are eaten by G. pallidula, this can lead to economic loss on the damaged crops. (Carasi and Teixeira, 2010; Olckers and Zimmermann, 1991)

  • Ways that these animals might be a problem for humans
  • crop pest

How do they interact with us?

There are no known positive effects of G. pallidula on humans.

Are they endangered?

Gratiana pallidula is not an endangered species.

Contributors

Jaclyn Tolchin (author), University of Michigan Biological Station, Angela Miner (editor), Animal Diversity Web Staff.

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.

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.

chaparral

mid-altitude coastal areas with mild, rainy winters and long, dry summers. Dominant plant types are dense, evergreen shrubs.

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.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

animals that have little or no ability to regulate their body temperature, body temperatures fluctuate with the temperature of their environment, often referred to as 'cold-blooded'.

hibernation

the state that some animals enter during winter in which bodily functions slow down, reducing their energy requirements so that they can live through a season with little food.

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.

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
urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

Askew, R. 1971. Parasitic insects. London, Great Britain: Heinemann Educational Books Ltd.

Blatchely, W. 1926. An illustrated descriptive catalogue of the Coleoptera or beetles known to occur in Indiana. Indianapolis, Indiana: WM. B. Burford, Contractor for State Publishing and Printing.

Carasi, S., E. Teixeira. 2010. Immatures of Gratiana conformis (Bohemian) (Coleoptera, Chrysomelidae, Cassidinae). Revista Brasileira de Entomologia, 54: 235-242.

Eisner, T., M. Eisner. 2000. Defensive use of a fecal thatch by a beetle larva (Hemisphaerota cyanea). Proceedings of the National Academy of Sciences of the United States of America, 97/6: 2632-2636.

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

Imura, O. 2003. Herbivorous arthropod community of an alien weed Solanum carolinense L. Applied Entomology and Zoology, 38: 293–300.

Olckers, T., H. Zimmermann. 1991. Biological control of silverleaf nightshade, Solanum elaeagnifolium, and bugweed, Solanum mauritianum, (Solanaceae) in South Africa. Agriculture, Ecosystems and Environment, 37: 137-155.

Rolston, L., R. Mayers, P. Edwards, M. Windfield. 1965. Biology of the eggplant tortoise beetle (Coleoptera: Chrysomelidae). Journal of the Kansas Entomological Society, 38: 362-366.

Scholtens, B. 2012. "Stiretrus anchorago" (On-line). Animal Diversity Web. Accessed July 31, 2012 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Stiretrus_anchorago.html.

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

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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