Adelgidae
| Adelgidae | ||||||||||||
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Adelges tsugae , Exulis stage |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Adelgidae | ||||||||||||
| Annand , 1928 |
The Adelgidae are a family of aphids (Aphidoidea) comprising around 70 species , of which 24 species also occur in Europe. All species live on conifers of the pine family (Pinaceae), many are forest pests of high economic importance. The "pineapple galls" produced by many species on the host trees (spruce species) are far more striking than the tiny insects themselves.
Life cycle
The life cycle of most species of Adelgid is of rare complexity. Several generations with different physique and different lifestyles follow one another, one of which reproduces sexually and the other asexually parthenogenetically , usually on two different host species. In species with a full life cycle (called holocycle), five morphologically and life-style distinguishable stages follow one another, three of them on the primary host - this is the host species on which sexual reproduction also takes place - two on the secondary host. Further parthenogenetic generations with the same morphology can be inserted into the life cycle. A holocycle takes two full years to complete. The primary host is always a species of spruce ( Picea ), the secondary host is another conifer; a fir ( Abies ), larch ( Larix ), Douglas fir ( Pseudotsuga ), hemlock ( Tsuga ) or pine ( Pinus ). Most Adelgidenarten are highly host-specific ( monophag ), not only the genus, but a certain species is required. In some cases, however, the species has migrated to new host species after being moved to other regions, e.g. B. Dreyfusia piceae in North America or Dreyfusia nordmannianae in Central Europe.
The change from the secondary host to the primary host takes place via a winged stage called the sexupara. When the Sexuparae reach a suitable species of spruce, they begin to lay eggs. They then die, leaving the corpse stuck to protect the eggs. Nymphs hatch from the eggs and develop into a new generation, called Sexualis, over four nymph stages. This consists of particularly small, wingless males and females with short proboscis. The males are smaller than the females, but more active to run, so that they can also reach neighboring clutches. After mating, the sexualis female lays a single egg (possibly after migrating to another plant organ). From this, a generation consisting exclusively of females develops, called the Fundatrix. The Fundatrix nymph crawls around on the host plant until it has reached a shoot bud and hibernates there.
In the following spring, sucking the fundatrix on the bud causes it to swell. After three nymph stages, the imaginal fundatrix lays a large egg clutch on the bud. A new stage called Gallicola develops from the eggs. Sucking the Gallicolae causes the already swollen bud to develop into a bile . The bile, called pineapple bile after its shape, consists of the swollen and reshaped needle base and the adjacent shoot. Usually (more or less normal looking) needles grow out of the swollen, compressed shoot. A chamber is formed at the base of each needle, and a Gallicola nymph sits in each chamber of the bile. The bile tissue is richer in nutrients and has fewer antibodies (phytochemicals) than normal tissue, it serves as a food base for the four nymph stages of Gallicola. In the middle of summer, the bile stops growing. It dries up, with its chambers opening outwards. The Gallicolae climb out and transform into a winged stage in a final molt. The winged Gallicolae leave the spruce and fly off to reach the conifer that serves as their secondary host.
When the winged Gallicolae reach a suitable tree, they lay eggs immediately and die after a few hours. From the eggs, another, parthenogenetic (i.e. consisting only of females) develops, which is now called Exulis. Depending on the species and environmental influences, the Exulies nymphs either overwinter in the first nymph stage (then called sistens), or they develop (after four moults) into adult females (then called progressiens). In some species these stages follow one another according to law, others are flexible in their development. In both cases the first nymph stage of the exules is very mobile, with long legs. It can therefore colonize new parts of the host tree. Older nymphs and adults, on the other hand, are almost immobile. As a rule, they are covered and enveloped in dense wax deposits that they produce in wax glands that sit all over the body. Numerous generations of progressions can now follow one another on the secondary host until finally overwintering sistentes are produced. After hibernating, some sistentes develop into winged sexuparae, which fly off in search of the primary host. This completes the cycle.
As if this wasn't complicated enough, there are some Adelgid species that deviate from this cycle. With them, the cycle is simplified in that the change of host has been abandoned. Depending on the species, they develop either exclusively on the primary host or exclusively on the secondary host, called the Anholo cycle. All anholocyclic species have given up sexual reproduction and reproduce exclusively parthenogenetically. Either Gallicola and Fundatrix generations always follow one another directly on the primary host (gall-producing species), or only exules are formed on the secondary host (non-gall-producing species). A common anholocyclic species in Europe is, for example, Pineus pini on Scots pine ( Pinus sylvestris ).
The complicated life cycle with up to five morphologically distinguishable stages on two tree species has resulted in numerous species of the Adelgidae having been described several times in different stages. There are therefore numerous synonyms. A corresponding case in Japan was only cleared up in 2011.
features
The Adelgidae, together with the species of the Phylloxeridae family , are the only aphids that lay egg in all stages. All other aphid species are viviparous in all parthenogenetic generations ( vivipar ). Another thing they have in common with the Phylloxeridae is the lack of siphons or siphunculi, a pair of ring-shaped or long tubular organs that are found on the abdomen of most other aphids and that emit an alarm pheromone .
Adelgidae are small aphids, they reach body lengths between about 0.7 and 1.5 millimeters. Winged animals have only three oblique veins in the front wing (in addition to the longitudinal veins on the wing leading edge) (the radius artery Rs is missing). In the fore wing, the two branches of the cubitus are separated from the base, in the hind wing only one oblique vein is formed. In the resting position, the wings are carried like a roof over the abdomen. The antennae of the winged stages have five segments, with the last three carrying a conspicuous sensory field (sensorium, here called rhinarium). The proboscis (rostrum) remains relatively short for aphids. All imaginal females still have a conical, partially reduced, ovipositor , which has been lost in the other aphids. Six pairs of stigmas sit on the abdomen , one of which is difficult to see.
The wingless stages and nymphs have a rounded to short oval body outline; they are domed with a flat underside. All stages (including the winged ones ) have numerous small sclerites with wax glands in the center, which are segmentally arranged in rows. The living animal is usually more or less covered by separated wax threads. The adults and nymphs have three antennae (four in Sexuales and their nymph stages) with two rhinaria.
Taxonomy
After that of Carl Linnaeus described genus Chermes the family has long called time Chermidae. The name was suppressed because the type species of the genus does not refer to an aphid ( Chermes alni L., today Psylla alni ), but belongs to the leaf fleas (Psylloidea).
The taxonomy of the Adelgidae is confused. This is because there are two systems of naming, both of which are used to this day. The American system recognizes only two genera, Adelges and Pineus , which then both monotypically form a subfamily (Adelginae, Pineinae); these are differentiated according to the spiracles on the sixth abdominal segment ( absent in Pineus ). According to the European system, the genus Pineus is understood in the same way (the sub-genus Pineodes was rarely seen as a genus), but within the Adelginae (following a suggestion by Carl Börner ) a number of other genera are distinguished, which according to the other system only have the rank of sub-genera comes to. The following list with some exemplary species is based on the European system.
- Subfamily Pineinae
- Genus Pineus
- Subfamily Adelginae
- Genus Adelges
- Genus Aphrastasia
- Genus Cholodkovskya
- Genus Dreyfusia
- Pine stem louse ( Dreyfusia piceae )
- White fir tree louse ( Dreyfusia nordmannianae )
- Genus Gilletteella
- Genus Sacchipanthes
- Green spruce gall louse ( Sacchiphantes viridis )
The Adelgidae, along with the Phylloxeridae, are segregated from the other aphids in a number of characteristics, most notably the fact that the females in both families lay eggs. Many authors combine both families in a common group, usually as a superfamily, then called Phylloxeroidea. According to others, the close relationship of the two families is not certain. They then place the Adelgidae in their own superfamily Adelgoidea. This system (modern e.g. after Heie & Wegierek) is followed here. The Adelgoidea are monotypical as far as living families are concerned, but the extinct families Mesozoicaphididae Heie & Pike, 1992 and Elektraphididae Steffan, 1968 , which have only survived in fossil form , are assigned to them.
Individual evidence
- ^ A b Nathan P. Havill & Robert G. Foottit (2007): Biology and Evolution of Adelgidae. Annual Review of Entomology 52: 325-349. doi : 10.1146 / annurev.ento.52.110405.091303
- ↑ Barbara Osiadacz & Roman Halaj (2011): Alien and invasive species of oviparous aphids (Aphidomorpha: Adelgoidea, Phylloxeroidea) in Poland: characteristics and review. Aphids an other hemipterous insects Vol 17: 29-38.
- ↑ Masakazu Sano, Nathan P. Havill, Kenichi Ozaki (2011): Taxonomic identity of a galling adelgid (Hemiptera: Adelgidae) from three spruce species in Central Japan. Entomological Science 14: 94-99. doi : 10.1111 / j.1479-8298.2010.00417.x
- ↑ OE Heie & P. Wegierek (2009): Diagnoses of the higher taxa of Aphidomorpha (Hemiptera Sternorrhyncha). Redia XCII: 261-269 download
- ^ PA Lehr (editor) (1988): Keys to the insects of the far east of the USSR. Volume II: Homoptera and Heteroptera. Leningrad (Nauka Publishing). Transliteration of the Russian title: Opredelitel 'nasekomykh Dal'nego Vostoka SSSR v shesti tomakh. Vol. 2. Ravnokrylye i poluzhestkokrylye. Translation by AV Stekolshchikov
- ^ Manya B. Stoetzel (1998): Antennal and other characters useful in identification of the Aphidoidea (Homoptera). Proceedings of the Entomological Society of Washington 100 (3): 588-593.
- ↑ Adelgidae at Aphid speciesfile org
- ^ Matthew S. Wallace: A historical review of adelgid nomenclature. Third symposium on hemlock wholly adelgid. Presentations.
- ↑ Ole E. Heie & Piotr Wegierek (2009): A classification of the Aphidomorpha (Hemiptera, Sternorrhyncha). Redia XCII: 69-77. download
