Chrysochus
Chrysochus is a genus of leaf beetles in the subfamily Eumolpinae. It is known from North America, Europe and Asia.
Etymology
The name of the genus is derived from the Greek word , meaning "goldsmith".Taxonomic history
In 1836, the genus Chrysochus was first established by Louis Alexandre Auguste Chevrolat in Pierre [François Marie Auguste Dejean|Dejean]'s Catalogue des Coléoptères, including the species Chrysomela asiatica Pallas, 1771, C. aurata Fabricius, 1775 and C. pretiosa Fabricius, 1792. Chrysomela praetiosa was designated as the type species of the genus by Sylvain Auguste de Marseul in 1864.The generic name Chrysochus Chevrolat in Dejean, 1836 is a conserved name. It was threatened by Eumolpus in the sense used by Kugelann in Johann [Karl Wilhelm Illiger|Illiger], 1798, which included Chrysomela praetiosa. An application to conserve Chrysochus and other names by suppressing Eumolpus Illiger, 1798 was accepted by the International Commission on Zoological Nomenclature in 2012.
Species
There are at least eight described species in Chrysochus. Six are found in the Palearctic realm, and only two are found in North America.| Scientific name | Authority | Range | Common name | Image |
| Chrysochus asclepiadeus | Widespread across Europe, also found in Kazakhstan and Turkey | |||
| Chrysochus auratus | Eastern North America | Dogbane beetle | ||
| Chrysochus brevefasciatus | Pic, 1934 | Shanghai, China | ||
| Chrysochus chinensis | Baly, 1859 | Central, North and Northeast China, Japan, Mongolia and the Russian Far East | ||
| Chrysochus cobaltinus | LeConte, 1857 | Western United States and British Columbia | Blue milkweed beetle | |
| Chrysochus globicollis | Lefèvre, 1888 | Northeast China, the Russian Far East and North Korea | ||
| Chrysochus goniostoma | Weise, 1889 | North and Northeast China, Mongolia, and the Russian Far East | ||
| Chrysochus sikhima | Jacoby, 1908 | Sikkim, India |
Another species, Chrysochus mniszechi, was described in 1877 by Édouard Lefèvre, from three specimens he had seen. While he did not know where the specimens were collected from, Lefèvre thought that they probably came from North America.
The following species, all from the Oriental realm, were formerly included in Chrysochus. They were transferred to the genera Parheminodes and Platycorynus in 2021:Chrysochus conspectus Lefèvre, 1890: moved to ParheminodesChrysochus hageni Jacoby, 1884: moved to ParheminodesChrysochus languei Lefèvre, 1893: moved to PlatycorynusChrysochus massiei Lefèvre, 1893: moved to ParheminodesChrysochus mouhoti Baly, 1864: moved to ParheminodesChrysochus nilgiriensis Jacoby, 1908: moved to ParheminodesChrysochus pulcher Baly, 1864: moved to ''Parheminodes''
Biology
All species of Chryochus feed on plants in the Apocynaceae and Asclepiadaceae families. A small mutation has allowed the two North American species, C. auratus and C. cobaltinus, in particular to feed on the plant species containing cardenolides, while all other species of the genus feed on plant species without cardenolides.Chryochus beetles by location differ in their exoskeleton color due to varying factors such as temperature, humidity, diet, and adaptation to predators. For example, Chryochus larvae as they pupate regulate the chemicals involved in pigment control that depend on the temperature.