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Elasmucha grisea, common name parent bug, is a species of shield bugs or stink bugs belonging to the family Acanthosomatidae. The term parent bugs includes also the other species of the genus Elasmucha and some species of the family Acanthosomatidae.<ref>Template:Cite journal</ref>
SubspeciesEdit
Subspecies within Elasmucha grisea include:<ref>EU-Nomen</ref>
- Elasmucha grisea cypria Josifov, 1971
- Elasmucha grisea grisea (Linnaeus, 1758)
DistributionEdit
Elasmucha grisea is a rather common and widespread species present in most of Europe.<ref name=Fauneur>Fauna europaea</ref>
DescriptionEdit
Elasmucha grisea can reach a length of Template:Convert. Males are smaller than females. These medium-sized shield bugs are usually brown-reddish, but there are also gray (hence the Latin species name grisea) and green-brown specimens. The connexiva are black and white. The upper side is covered with several dark dots. The scutellum usually shows an evident black patch.<ref name=BB>British Bugs</ref> The ventral face is largely punctuated with black. The lateral corners of the pronotum are simply beveled. The front corners of the pronotum show a more pronounced tooth. Antennae are blackish in the male, dark brown in the female.<ref name=Cle>François Dusoulier, Claire Mouquet Clé de détermination des Acanthosomatidae Signoret, 1864 du Massif armoricain (Hemiptera, Heteroptera).</ref>
This species, like other parent bugs, possesses metathoracic and abdominal glands, which discharge a foul smelling secretion.<ref name="roth">Roth S, Adaschkiewitz, Fischer C (2006) Notes on the bionomics of Elasmucha grisea (LINNAEUS 1758) (Heteroptera, Acanthosomatidae) with special regard to joint brood guarding. zugleich Kataloge der OÖ, Landesmuseen Neue Serie 50:1153–1167</ref><ref name="hanelova">Hanelova J, Vilimova J (2013) Behaviour of the central European Acanthosomatidae (Hemiptera: Heteroptera: Pentatomoidea) during oviposition and parental care Acta Musei Moraviae, Scientiae biologicae 98:433-457</ref> This secretion is used to deter potential enemies and is sometimes released when the bug is disturbed.
Life cycleEdit
Adults of E. grisea can be found all year around. In fact this species overwinters as an adult. Mating occurs in the spring and new adults can be found in August.<ref name=BB/> These shield bugs feed on various woody plants, preferably on birch (Betula sp.), but also on alder (Alnus sp.), beech (Fagus sp.), holly (Ilex sp.), spruce (Picea sp.), etc.<ref name=Cle/> Like most shield bugs, E. grisea and other parent bugs suck plant sap and require symbiotic bacteria for their digestion.<ref name="fischer">Fischer C (2006) The biological context and evolution of Pendergrast’s organs of Acanthosomatidae (Heteroptera, Pentatomoidea) 50:1041-1054</ref> They obtain symbionts at an early age: the mother covers her eggs with bacteria so that the nymphs ingest them as they feed on the egg case.<ref name="fischer"/> Both adults and nymphs readily feed on developing seeds, and breeding individuals can be observed on host plants with many young catkins.<ref name="mappes1">Template:Cite journal</ref> However, they seem to avoid trees with a high predation risk.
Parental careEdit
The common name of "parent bug" comes from the relatively rare insect behaviour of prolonged caring for eggs and juveniles, exhibited by females of this species. Predators, such as bugs, beetles, earwigs and ants, can eliminate all the offspring of the parent bug if there is no maternal care. The repertoire of female defensive behaviours includes wing fanning, body jerking, tilting towards the enemy and, finally, releasing of 'nasty' odours from the scent glands,<ref name="mappes1"/><ref>Jordan KHC (1958) Die Biologie von Elasmucha grisea L. (Heteroptera: Acanthosomatidae). Beitr Entomol 8:385-397</ref><ref>Melber A, Hölsher L, Schmidt GH (1980) Further studies on the social behaviour and the ecological significance in Elasmucha grisea L. (Hem.-Het.: Acanthostomatidae) Zool Anz Jena 205:27-38</ref>
After oviposition, the parent bug female stands over the egg batch and shields it throughout egg development. Predation appears to limit the clutch size in E. grisea. Experiments have shown that large females lay larger egg clutches than small females. However, when the clutch size was manipulated, small females protecting large clutches lost significantly more eggs than large females guarding small clutches or females in the control groups (guarding clutches of optimal size).<ref>Template:Cite journal</ref>
After hatching, larvae of the parent bug remain in a tight aggregation, feeding on their empty egg shells.<ref name="hanelova"/> When any larva tries to abandon the aggregation, the female tilts her body, stretches her antennae to reach the larva and pushes the larva back to the aggregation.<ref name="roth"/> During the second and third instar they move, for food, towards catkins then back to the leaf with the female in close attendance.<ref name="hanelova"/> The female keeps a lookout for the larvae constantly and manages them with touches of her antennae. Finally, larvae form smaller groups and disperse at the end of the third instar, at which point the female leaves them.
It has been noted that, in E. grisea, moultings during the early instar stages can be asynchronous.<ref name="roth"/> While some larvae are still at the first instar stage, others have already moulted to the stage of second instar larvae and abandon the brood leaf for food. Under such circumstances, the female is no longer able to provide effective protection for all her larvae. The offspring of different females make contact with each other and form mixed groups. There is no kin-recognition in this species. Both single and joint guarding females provide parental care for their own larvae or other females' offspring. Larvae are likely to benefit from 'kindergartens', when their mothers disappear or die.<ref name="roth"/> Moreover, joint-guarding females defend the egg clutches much more successfully than single females.<ref>Template:Cite journal</ref>
The tachinid fly, Subclytia rotundiventris, is a specialist endoparasite of the parent bug females.<ref name="mappes2">Template:Cite journal</ref> The parasite inserts a single egg through the upper prothorax of an E. grisea female and, after hatching, the larva feeds on its host. At the beginning the parasite feeds only on the non-vital parts of the bug, but finally it kills it and pupates outside the host. The larva ‘permits’ the parent bug to continue caring for the juveniles until their third stage. In experiments, the wing-fanning (regarded as the most effective defensive behaviour of the parent bug) did not differ significantly between parasited and non-parasited females until the nymphs were at the second instar stage. However, with older nymphs, females were much less effective in their defensive behaviour and often died before the end of maternal care. Considering that the older nymphs are more mobile and may escape from predators, some offspring of the parasited females of the parent bug probably survive and may also be potential hosts for the new generation of the parasite.<ref name="mappes2"/>
GalleryEdit
- Elasmucha grisea (Parent bug), Arnhem, the Netherlands - 3.jpg
Elasmucha grisea with eggs
- Elasmucha grisea f3.jpg
A female is guarding her nest.
- Elasmucha grisea (Parent bug), Arnhem, the Netherlands.jpg
Aggregation of nymphs
- Elasmucha grisea nymph.jpg
Young nymph
See alsoEdit
ReferencesEdit
External linksEdit
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