Umbonia

Diversity

The genus Umbonia , comprised of four known species, consists of plant-sucking insects. These insects are also known as "thorn bugs" due to their thorn-like appearance, resulting from the growth of their pronotum extending back over their abdomen. This particular genera has one prominent "horn" curving upward and two smaller "horns" on either side of the head. The adult's body size can be between 9mm-14 mm. These insects are often green, light blue, or yellow in overall coloration with striping being yellow-orange, dark green, or red. Umbonia are unique for their social behavior and brood care. They can be considered pests when large groupings of them congregate on tropical plants. Umbonia can be found almost year-round from southeastern United States all the way to Brazil.

Geographic Range

Umbonia are found in humid, tropical areas of the Neotropical and Nearctic regions of the world (i.e. southern Florida, Central America, Brazil), but over the last decade have become more prominent in the Nearctic region due to global warming.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
  • native native
• neotropical neotropical
  • native native

Habitat

Umbonia thrive in warm, tropical climates in low elevations. They are regularly found in southern Florida, Mexico, and throughout Central and South America. They live off of host plants found in these areas such as acacia, calliandra, mimosa, and inga, congregating around their branches and stems. Reproduction, brood care, and foraging all take place on host plants.

• Habitat Regions
• temperate temperate
• tropical tropical

• Terrestrial Biomes
• forest forest
• rainforest rainforest

• Other Habitat Features
• agricultural agricultural

Systematic and Taxonomic History

Umbonia was originally called Physoplia by Amyot and Serville in 1843 but was given its modern name by Burmeister in 1835 due to a violation of ICZN (International Commission on Zoological Nomenclature). Based on maternal care studies and pronotum structure, Umbonia is more closely related to the genus Platycotis , another group of treehoppers within the tribe Hoplophorionini . Genera within this tribe are characterized by their unique kicking anti-predator defense and geographic region ranging from Canada to Chile. Umbonia species are one of the most derived genera of the family Membracidae .

Physical Description

Umbonia treehoppers generally grow to roughly half an inch (about 10 mm). They vary in color and patterns, but are most often a green or light blue color with red, brown, and/or green markings. They are most notable for their pronotum, which grows perpendicularly to their body in a thorn-like shape so to be mistaken for a thorn on a plant. Males and females are the same size (with a few exceptions in some species where females are smaller) and pattern, but are easily told apart by the shape of the pronotum growth on their backside. Females' are slightly longer and flatten out towards the tip of the thorn to a blunt end. Males' stay pointed and are usually shorter in comparison. Nymphs look like smaller versions of the parents, but with more prominently pointed "side horns" and no wings. Because adults can be either bright green or light blue, species are often mistaken with each other. There is no seasonal variation, and they are active year-round.

• Other Physical Features
• polymorphic polymorphic

• Sexual Dimorphism
• sexes shaped differently

Development

Umbonia displays incomplete metamorphosis or are hemimetabolous, meaning there is no pupal stage in their growth from larva to adult. After mating, females lay their eggs and it takes about 14-20 days for them to hatch. After hatching, the nymphs continue to grow for the next four weeks and complete five molts before they are at the adult stage. Each molt allows the nymphs to become larger in size and have more developed wings.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

Males within Umbonia must compete for a female, as females often only mate once in their lifetime. Males and females are often seen in congregations together on plants, but there is no visible display of males warding off others from their female(s) of choice. Females have been seen to choose males based on age, wherein older males are preferred. Males will attract females by making calls or clicks using their abdominal muscles. While males spend their time hopping from plant to plant in search of mating opportunities, females stay together to help protect and raise their young.

• Mating System
• polygynous polygynous
• cooperative breeder cooperative breeder

After mating, females will lay about 100 eggs into plants' stems or leaves and stay with the clutch until the hatched nymphs fully mature. Eggs hatch about 20 days after laying, and out of the 100-count egg clutch, only 15-20 nymphs will survive. Although females only mate once in their lifetime, four generations are produced every year. Depending on the host plant, a large congregation of Umbonia species/individuals can create a resource shortage; therefore, when the nymphs have matured, they can be much smaller than average. This does not affect females, but smaller males often have a difficult time finding mates.

• Key Reproductive Features
• year-round breeding year-round breeding
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Umbonia females exhibit maternal care for their young. Males are uninvolved after fertilization. Females do not hunt or teach their young skills, but they do protect their egg clutch until her offspring are all mature adults. If the mother dies or is unable to protect her young before they are mature, another female can adopt the clutch. Nymphs only communicate with their caretaker when they sense a threat nearby by creating vibrations through the host plant. The nymphs must work together to create these vibrations, otherwise the female will ignore the call. Once the nymphs have matured, they often leave the host plant in search of a new host and/or mating opportunities to avoid inbreeding.

• Parental Investment
• female parental care female parental care
• pre-fertilization
  • protecting
    • female
• pre-hatching/birth
  • protecting
    • female
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

Umbonia individuals in the wild only live to be a few months old, just long enough to develop, reproduce, and raise young (if they are a female). Ultimately, lifespan is affected by how many resources are available at time of hatching through adulthood.

Behavior

Umbonia consists of social species that often remain in the same general area throughout their lifespan. Males are more solitary than females but are still in congregations when trying to attract a female. Females often stay together to assist in raising young. Males communicate with females via their abdominal muscles for mating purposes, and nymphs communicate with females through plants for alerting purposes.

Hence their common name "treehoppers," this genus is well-known for the species' odd way of jumping from plant to plant, often doing a summersault mid-air in the process. They can also fly, which is more efficient than jumping, but with age they lose this ability.

• Key Behaviors
• arboreal arboreal
• saltatorial saltatorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social

Communication and Perception

Treehoppers rely heavily on communication through vibration detection. They have two large, compound eyes for focusing images and ocelli to distinguish sunlight from shadow, but vibrations have proven to be more reliable. The calls and clicks males make when attracting a female create vibrations, and nymphs communicate using vibrations within the plants they occupy.

Since their body is in the shape of a thorn on the stem of a plant, these species utilize camouflage to hide from predators.

• Communication Channels
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations

Food Habits

Treehoppers are herbivores. They have piercing-sucking mouthparts that assist in stabbing soft plant stems and sucking the sappy substance out of them. Umbonia species have a wide array of plant hosts, including but not limited to tamarinds ( Tamarindus indica ), bottlebrushes ( Callistemon sp. ), Madras thornes ( Pilhecellobium dulce ), and silk plants ( Albizzia lebbeck ).

• Primary Diet
• herbivore herbivore

Predation

Umbonia species' thorn-like body plans and camouflaging colorations protect them from predators. They also create a chemical repellent that is passed from parents to offspring which makes them distasteful to predators.

Treehoppers are prey to various birds, lizards, spiders, and assassin bugs species. Their primary threat, however, are wasps.

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

Umbonia species are a food source for many insectivores, both vertebrates and invertebrates. Since treehoppers are sap-sucking herbivores, they are responsible for killing plants when in large enough congregations. They have been known to disrupt pollinators, but have the ability to be pollinators themselves, although it is very uncommon.

Economic Importance for Humans: Positive

Treehoppers are a very important prey type for various bird, lizard, and insect species. Although they do not positively affect the human economy directly, they indirectly do by serving as a food source for other animals that do affect humans.

• Positive Impacts
• food food
• research and education

Economic Importance for Humans: Negative

In some regions, Umbonia species can be considered a pest. Since they are widespread and spend their lives on plant stems eating and reproducing, large enough congregations can kill plant hosts. They are easy to get rid of with conventional pesticides if there are too many in one area. Otherwise, treehoppers do not bite or sting, making them relatively harmless.

• Negative Impacts
• crop pest

Conservation Status

There is no known conservation status for Umbonia , but Umbonia species do not seem to be significantly threatened in any manner.

Other Comments

There is not a lot of available taxonomic publications relevant to this genus. Most studies that revolve around Umbonia species focus on the species' unique parental behaviors and their impacts as a pest for plant species. Genetic taxonomic hypotheses are based primarily on behavioral genetics relating to parental investment.

Additional Links

Encyclopedia of Life

Contributors

Amanda Sieps (author), Colorado State University, Audrey Bowman (editor), Colorado State University, Sydney Collins (editor), Colorado State University.

References

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