''Zygogramma exclamationis'', commonly known as the sunflower beetle, is a species of

leaf beetle The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...

belonging to the family

Zygogramma ''Zygogramma'' is a large genus of leaf beetles in the subfamily Chrysomelinae, which includes approximately 100 species. 13 species occur north of Mexico. Adults and larvae are herbivorous on various host plants. '' Zygogramma exclamationis'' is ...

. It is regarded as a pest of

sunflower The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as ...

crops in North America.

Description

''Z. exclamationis'' is a small

, 6–12 mm in length, 2–4 mm wide, with a brown

pronotum The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum (dorsal), the prosternum (ventral), and the propleuron (lateral) on ea ...

and yellow

elytra An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

marked with three, elongated brown stripes and a single, shorter, lateral stripe ending at the middle of the wing in a small dot that resembles an exclamation point. This arrangement bears similarities to the

exclamation mark The exclamation mark, , or exclamation point (American English), is a punctuation mark usually used after an interjection or exclamation to indicate strong feelings or to show emphasis. The exclamation mark often marks the end of a sentence, f ...

from where this species gets its Latin name. Adult beetles are morphological similar to the

Colorado potato beetle The Colorado potato beetle (''Leptinotarsa decemlineata''), also known as the Colorado beetle, the ten-striped spearman, the ten-lined potato beetle, or the potato bug, is a major pest of potato crops. It is about long, with a bright yellow/o ...

, a pest of potato crops. The larvae are humpbacked in appearance, yellow-green in colour, and may measure in length at maturity. File:Zygogramma exclamationis - lateral.jpg, Lateral view File:Zygogramma exclamationis - posterior.jpg, Posterior view File:Zygogramma exclamationis - head (side).jpg, Head (side) File:Zygogramma exclamationis - head (front).jpg, Head (front) File:Zygogramma exclamationis - antenna.jpg, Antenna

Distribution and Habitat

''Z. exclamationis'' is native to North America. Adult beetles are phytophagus and associated with the

species ''

Helianthus annuus The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as b ...

'' (common sunflower), '' H. giganteus'' (giant sunflower), and '' H. petiolaris'' (prairie sunflower). It is a major economic pest to sunflower production in North America.

Lifecycle

Overwintering adults emerge in late May or early June. Shortly after emergence, the beetles begin to feed, mate and lay eggs singly on stems and undersides of leaves. Adults live for about 8 weeks and are capable of laying eggs for most of this period. Each female lays approximately 850 eggs, with a range of 200 to 2,000 eggs. Eggs hatch into larvae after about one week; the young larvae feed on the leaves at night. They hide among the bracts of the flower bud and amongst leaves during the day. The larvae feed for about two weeks but, because of the long egg laying period, larvae may be present in the field for about six weeks in June or July. The larvae have four

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

s. When mature, the larvae enter the soil to

pupate A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

in earthen cells. The pupal stage lasts from 10 days to two weeks. Adults of the new generation emerge and feed for a short period on the sunflower head or on the uppermost leaves of the plant; they do not mate or lay eggs before re-entering the soil to overwinter.

Behaviour and ecology

Predation

There are many predators of ''Z. exclamationis'' in its different life stages. Eggs are predated by the melyrid beetle '' Collops vittatus'', the thirteen spotted ladybird ''

Hippodamia tredecimpunctata ''Hippodamia tredecimpunctata'', commonly known as the thirteen-spot ladybeetle, is a species of lady beetle. Description Adult ''H. tredecimpunctata'' have domed backs, mainly oval, often shiny with short legs and antennae. They have two wing ...

'', and the convergent ladybird '' H. convergens''. Larvae of the common green lacewing ''

Chrysoperla carnea ''Chrysoperla carnea'', one of the species of common green lacewing, is an insect in the Chrysopidae family. Although the adults feed on nectar, pollen and aphid honeydew, the larvae are active predators and feed on aphids and other small ins ...

'' consume both eggs and larvae. The spined soldier bug '' Podius maculiventris'' predates both larvae and adults.

Parasites

Eggs of ''Z. exclamationis'' are parasitised by the pteromalid wasp '' Erixestus winnemana'', larvae by the

tachinid The Tachinidae are a large and variable family of true flies within the insect order Diptera, with more than 8,200 known species and many more to be discovered. Over 1,300 species have been described in North America alone. Insects in this family ...

fly species '' Myiopharus macellus'' and '' M. doryphorae''. The rate of parasitisation is high in some fields in Canada and the USA can be as high as 70-100%.

As pest of sunflower crops

The sunflower beetle is considered to be one of the most damaging defoliators of cultivated sunflowers in North America. Advice published by

Kansas State University Kansas State University (KSU, Kansas State, or K-State) is a public land-grant research university with its main campus in Manhattan, Kansas, United States. It was opened as the state's land-grant college in 1863 and was the first public instit ...

in 2016 recommends the use of insecticide treatment of sunflower crops if any of the following conditions are met: one adult beetle is present per seedling, larvae reach numbers of 10-15 per plant on upper leaves, or 25 percent defoliation occurs and pupation has not begun. Given the short larval and adult lifecycle, delayed planting of sunflower crops is effective in preventing yield reductions caused by sunflower beetle. Recommended insecticides for infested crops include: Beta-cyfluthrin,

Carbaryl Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin tradem ...

Deltamethrin Deltamethrin is a pyrethroid ester insecticide. Deltamethrin plays a key role in controlling malaria vectors, and is used in the manufacture of long-lasting insecticidal mosquito nets; however, resistance of mosquitos and bed bugs to deltamethrin ...

Esfenvalerate Esfenvalerate is a synthetic pyrethroid insecticide marketed under the brand Asana. It is the (''S'')-enantiomer of fenvalerate Fenvalerate is a synthetic pyrethroid insecticide. It is a mixture of four optical isomers which have different in ...

, Gamma-cyhalothrin,

Lambda-cyhalothrin Cyhalothrin is the ISO common name for an organic compound that, in specific isomeric forms, is used as a pesticide. It is a pyrethroid, a class of synthetic insecticides that mimic the structure and properties of the naturally occurring insectici ...

, and Zeta-cypermethrin.

References

External links

Multiple images of ''Zygogramma exclamationis''List of publication for ''Zygogramma exclamationis'' at Biodiversity Heritage Library
{{Taxonbar, from=Q14933167 Chrysomelinae Beetles described in 1798 Beetles of North America Agricultural pest insects Taxa named by Johan Christian Fabricius