Annales de la Société Entomologique de France (2005) 41, 81-125
Imre Foldi (2005)
Ground pearls: a generic revision of the Margarodidae sensu stricto (Hemiptera: Sternorrhyncha: Coccoidea)
Annales de la Société Entomologique de France 41 (1), 81-125
Abstract: The ground pearls comprise the scale insect family Margarodidae s. str., and are subterranean plant sucking parasites on roots of a wide variety of plants. Some ground pearls are serious destructive pests of grape vines, sugar cane, oil palms, cotton or lawn grass around the world. Both female and male development is characterised by an apodous, feeding 2nd-instar nymph, called a cyst. The cyst is primarily circular and often colourful, shiny, metallic or pearl-like, from which the common name 'ground pearls' is derived. Other unique features are the strongly developed prothoracic legs for digging, the construction of a protective test from their own liquid excreta in which the cyst is enclosed and a behavioral adaptation by modification of their life-cycle to survive in adverse environmental conditions.
The 10 genera, currently include 105 species, form a monophyletic group with a worldwide distribution. First-instar nymphs and cysts are feeding instars; however, adults male and females lack mouthparts and do not feed. Species of ground pearls reproduce either bisexually or parthenogenetically, parthenogenesis is facultative in Eurhizococcus brasiliensis. Females undergo three, four or five developmental stages, while male have five. During the cyst stage, one, two or three molts may occur. Most species have a single generation each year, although development in Margarodes vitis requires three years including three instars of cysts. This revision redescribes and illustrates the type species of each genus, including Margarodes vitis (Philippi) and provides a key to the genera based on the morphology of adult females. Lectotypes of Dimargarodes mediterraneus (Silvestri), Heteromargarodes arnericanus Jakubski, Promargarodes sinensis Silvestri and Termitococcus carrotai Silvestri are designated. A nomenclatural change is proposed, the genus Sphaeraspis Giard, 1894 is considered to be a synonym of Margarodes Guilding, 1829. This work also provides information on the history of the group of Archaeococcoids; on the biology, economic importance and distribution of the margarodids.
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Research topic(s) for pests/diseases/weeds:
identification/taxonomy
general biology - morphology - evolution
