Melolonthinae is a subfamily of the scarab beetles (family Scarabaeidae). It is a very diverse group; distributed over most of the world, it contains over 11,000 species in over 750 genera.Cave, R.D. & Ratcliffe, B.C. (2008). Scarab beetles (Coleoptera: Scarabaeoidea). In J.F. Capinera (Ed.), Encyclopedia of Entomology (pp. 3273–3286. Heidelberg. Springer. Some authors include the scarab subfamilies Euchirinae and Pachypodinae as tribes in the Melolonthinae.
Unlike some of their relatives, their habitus is usually not bizarre. They resemble the Rutelinae in being fairly plesiomorphic in outward appearance. Like in many Scarabaeidae, males have large fingered antennae, while those of the females are smaller and somewhat knobby. In the Melolonthinae, this sexual dimorphism is particularly pronounced. Many species have striking – though rarely brilliant or iridescent – hues and bold patterns of hairs.
Being often quite sizeable and swarming in numbers at certain times, for example the Amphimallon, Phyllophaga and Polyphylla "June beetles" or the Melolontha cockchafers – all from tribe Melolonthini – feature widely in folklore. Some Melolonthinae are economically significant pests. Other than the Melolonthini, the most diverse tribes are the Ablaberini, Liparetrini, Macrodactylini, Tanyproctini and Sericini.
Description Melolonthinae adults range from 3 to 58 mm in length and are usually brown or black in colour. Some species are shiny, while many are covered in setae or scales. The clypeus, a structure on the head above the mouthparts, is not armed with teeth. There are two antennae, each with 7 to 10 segments, of which the last 3 to 7 segments are elongate and form a club, and the antennal bases are usually concealed from above. The scutellum is exposed at the base of the elytra. The margins of the elytra are straight instead of strongly curved. Each leg ends in a pair of tarsal claws that are often toothed or double.
Larvae are C-shaped with a white/cream body and a darker, well-sclerotised head. They can be distinguished from other scarabaeid larvae by the galea and lacinia either partly fused proximally or fitting tightly together, the mandibles lacking stridulatory areas, the apical segment of the antenna about as wide as its penultimate segment, and the anal cleft usually Y-shaped or angulate.
Life cycle The Melolonthinae life cycle has the four stages of egg, larva, pupa and adult, similar to other beetles. Eggs are laid in soil, which is also where the larval and pupal stages occur. Adults occur above ground. The larval stage is long and may last up to two years, whereas the adult stage is short and lasts only a few days or weeks.
Diet Larval melolonthines feed on plant roots and humus. Known host plants include grasses, clover and sugarcane. Adults may (e.g. Automolius, Diphucephala, Heteronyx, Liparetrus, Phyllotocus and Sericesthis) or may not feed (e.g. Antitrogus and Rhopaea). Adults that feed do so on the leaves of trees, such as eucalypts, or on flowers or pollen.
Behaviour Adults are usually crepuscular or nocturnal, but the flower- and pollen-feeding species are often diurnal. They are often attracted to light.
In feeding species, adults gather on trees and this helps them find each other to mate. In non-feeding species, virgin females emit a sex pheromone so that males can find them.
Pests Larvae of Sericesthis spp. are pasture pests, while larvae of Dermolepida albohirtum, Antitrogus and Lepidiota are sugarcane pests. Lepidiota stigma is another sugarcane pest and also attacks corn, sorghum and various fruits. Adults of Phyllophaga spp. can sometimes cause complete defoliation of deciduous trees.
Systematics
Traditionally, various authors, divided the living Melolonthinae into about 20–30 tribes:
Ablaberini Burmeister, 1855 – including Camentini Automoliini Britton, 1978 Chasmatopterini Lacordaire, 1856 Colymbomorphini Blanchard, 1850 – including Stethaspini and Xylonichini Colymbomorpha Blanchard, 1850 Stethaspis Hope, 1837 Xylonichus Boisduval, 1835 Comophorinini Britton, 1957 – including Comophini Dichelonychini Burmeister 1855 Diphucephalini Britton, 1957 Diphycerini Medvedev, 1952 – sometimes in Macrodactylini Diplotaxini Kirby, 1837 – sometimes in Melolonthini Heteronychini Britton, 1957 Heteronyx Guérin-Méneville, 1838 Hopliini Latreille, 1829 Leucopholini Burmeister, 1855 Lichniini Burmeister, 1844 Liparetrini Burmeister, 1855 – including Allarini, Colpochilini Macrodactylini Kirby, 1837 – including Dichelonyciini Maechidiini Burmeister, 1855 Melolonthini Leach, 1819 – including Rhizotrogini Amphimallon Brahmina Holotrichia Leucopholis Melolontha – cockchafers, May bugs Phyllophaga – May beetles Polyphylla Rhizotrogus Oncerini LeConte, 1861 Pachytrichini Burmeister, 1855 Phyllotocidiini Britton, 1957 Phyllotocus Podolasiini Howden, 1997 – sometimes in Hopliini Scitalini Britton, 1957 Sericini Dalla Torre, 1912 Maladera Sericoidini Burmeister, 1855 Systellopini Sharp, 1877 Tanyproctini Erichson, 1847 – includes Pachydemini
In addition, a prehistoric tribe, the Cretomelolonthini, is only known from fossils.
Several genera are of unclear relations; they are not yet firmly placed in a tribe:
Acoma Conebius Fuavel, 1903 Costelytra – Liparetrini? Hemictenius – Pachydemini? Metascelis Westwood, 1842 Mycernus – Colymbomorphini? Odontria – Liparetrini? Prodontria – Liparetrini? Psilodontria – Colymbomorphini? Scythrodes – Liparetrini? Sericospilus – Liparetrini? XenaclopusOcampo, F.C., Vaz-de-Mello, F.Z. (2008) The genus Xenaclopus Arrow (Coleoptera: Scarabaeidae): redescription and removal from the Aclopinae, with systematic notes. Zootaxa, 1916: 57–62.
"Anonetus" and "Tryssus", both used by Erichson in 1847, are nomina nuda. Holophylla and Hoplorida are of uncertain validity.
Recent studies have revealed that the broad concept of the Melolonthinae, as used before, is paraphyletic. To resolve this, the subfamilies Sericinae Kirby, 1837 and Sericoidinae Erichson, 1847 have been reinstated.A transcriptome-based phylogeny of Scarabaeoidea confirms the sister group relationship of dung beetles and phytophagous pleurostict scarabs (Coleoptera) This results in the following classification: Sericinae Kirby, 1837 Ablaberini Blanchard, 1850 Diphucephalini Laporte, 1840 Sericini Kirby, 1837 Astaenina Burmeister, 1855 Sericina Kirby, 1837 Trochalina Brenske, 1898 Sericoidinae Erichson, 1847 Automoliini Britton, 1978 Heteronychini Lacordaire, 1855 Liparetrini Burmeister, 1855 Maechidiini Burmeister, 1855 Phyllotocini Burmeister, 1855 Scitalini Britton, 1957 Sericoidini Erichson, 1847 Melolonthinae MacLeay, 1819 Acomini Evans & Smith, 2020 Ardellini Paulsen, 2021 Athliini Smith & Evans, 2018 Chasmatopterini Lacordaire, 1855 Chnaunanthini Evans & Smith, 2020 Colymbomorphini Blanchard, 1850 Comophini Britton, 1978 Dichelonychini Kirby, 1837 Diphycerini Medvedev, 1952 Diplotaxini Kirby, 1837 Euchirini Hope, 1840 Heptophyllini Medvedev, 1951 Hopliini Latreille, 1829 Langbianellini Prokofiev, 2015 Leucopholini Burmeister, 1855 Macrodactylini Kirby, 1837 Melolonthini Leach, 1819 Pachypodini Erichson, 1840 Pachytrichini Burmeister, 1855 Phobetusini Evans & Smith, 2020 Phyllotocidiini Britton, 1957 Rhizotrogini Burmeister, 1855 Schizonychini Burmeister, 1855 Systellopini Dalla Torre, 1912 Tanyproctini Erichson, 1847 Warwickiini Evans & Smith, 2020 †Cretomelolonthini Nikolajev, 1998
References
https://web.archive.org/web/20161025112710/http://bug.tamu.edu/research/collection/hallan/test/Arthropoda/Insects/Coleoptera/Family/Scarabaeidae.txt