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In general, leaf beetles in the Chrysomelidae family use visual, olfactory and chemical cues when colonizing a host plant.
Communication Channels: visual ; chemical
Perception Channels: visual ; chemical
The IUCN Red List, CITES appendicies, the US Federal list or the State of Michigan list have no special status on G. pallidula.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Gratiana pallidula is holometabolous and goes through egg, larva, pupa, and adult stages. First generation eggs are laid as early as May by adults that have overwintered, 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 instars. Larvae sometimes leave the host plant before pupating. Pupae form anywhere from a week to 3 weeks later, and attach to the upper surface of 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.
Development - Life Cycle: metamorphosis ; diapause
Gratiana pallidula feed on and infest 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, but larvae cause the most damage.
Negative Impacts: crop pest
There are no known benefits of G. pallidula to humans.
Eggplant tortoise beetles feed on and infest Solanum plants, particularly eggplant (S. melongena), common horsenettle (S. carolinese), gray horsenettle (S. xantii) and white horsenettle (S. elaegnifolium). G. pallidula serves as a host to parasitic wasps, Tetrastichus and Spilochalcis. Tetrastichus parasitize eggs and emerge 7 to 15 days later. S. sanguineiventris parasitize pupae and emerge 12 to 18 days later.
Species Used as Host:
Commensal/Parasitic Species:
Gratiana pallidula is a herbivorous oligophage 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 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 feeding. Toward the end of summer, adult feeding rates decrease, and then increase in early spring after diapause.
Plant Foods: leaves
Primary Diet: herbivore (Folivore )
Gratiana pallidula, also known as the eggplant tortoise beetle, is found in the Nearctic Region througout the southern United States.
Biogeographic Regions: nearctic (Native )
Gratiana pallidula is found where host plants are found. Solanum plants, such as S. melongena, S. carolinese, S. xantii, and S. elaegnifolium are the main host plants. S. melongena is not found in the wild, but is instead maintained in cultivated gardens. S. carolinese often takes advantages of disturbed areas and can thrive 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.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; scrub forest
Other Habitat Features: urban ; suburban ; agricultural
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.
As their common name may suggest, adult eggplant tortoise beetles are shaped like tortoises. They are a yellowish green color with a concealed head and claws, which differentiates G. pallidula from other North American species of tortoise beetles. The body is also flattened, with a broad, expanded pronotum and elytral margins. The elytra contain a series of coarse punctures that stretch from the front to the back of the entire body.
Larvae are recognized by 16 pairs of subspiracular scoli, an anal fork, and retracted head. They are usually yellow-green in color and 5.5 mm when full grown.
The eggs of G. pallidula are capsular, oblong, 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.
Range length: 5 to 5.5 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
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. In defense, like all larvae of tortoise beetles in the family Cassinidae, the larvae of G. pallidula build fecal shields on their backs. Instead of getting rid of their waste, it accumulates on a fork that projects from the tip of the abdomen, forming a shield that effectively deters enemies. In addition to feces, larvae of G. pallidula will also accumulate molted larval skin in their shields.
Known Predators:
Little information is available on the mating systems of Gratiana pallidula.
Each year, G. pallidula has two full generations that overlap. Eggs are laid on Horsenettle (Solanum) foliage, usually on the upper surface of a leaf or near the leaf terminals. Usually eggs are laid singly, but are occasionally found in groups, rarely containing more than two eggs. Additionally, G. pallidula is able to cross-breed with G. lutescens and produce fertile offspring.
Breeding interval: Two generations are born during the summer.
Breeding season: The two main breeding times are May-June and August.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
Females provide eggs with nutrients, but otherwise it is likely that eggs are left on plants to mature on their own.
Parental Investment: pre-hatching/birth (Provisioning: Female)
Gratiana pallidula, the eggplant tortoise beetle, is a species of tortoise beetle in the family Chrysomelidae. It is found in Central America and North America.[1][2][3]
Adult: in most live individuals, pronotum light green, elytra light golden brown with explanate, transparent margins; color of dead specimens mostly medium brown with lighter brownish-yellow margins; body oblong; elytral margins almost parallel-sided for more than half of their length; elytral disc with many small surface pits arranged in several longitudinal rows.
Larva: may be at least partly green, and carry a fecal shield above its back.[4]
Gratiana pallidula, the eggplant tortoise beetle, is a species of tortoise beetle in the family Chrysomelidae. It is found in Central America and North America.
Adult: in most live individuals, pronotum light green, elytra light golden brown with explanate, transparent margins; color of dead specimens mostly medium brown with lighter brownish-yellow margins; body oblong; elytral margins almost parallel-sided for more than half of their length; elytral disc with many small surface pits arranged in several longitudinal rows.
Larva: may be at least partly green, and carry a fecal shield above its back.
