Picnic beetle
| Picnic beetle | ||||||||||||
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Picnic |
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| Glischrochilus quadrisignatus | ||||||||||||
| ( Say , 1835) |
The picnic beetle ( Glischrochilus quadrisignatus ) is a beetle from the species-rich family of gloss beetles . The genus Glischrochilus is represented in Europe with six species , all of which are black and have four yellowish spots.
The species name quadrisignatus (from Latin "quattuor", in combinations "quádri-" "four-" and "signātus" "drawn") names the four blemishes on the wing covers. However, there are two other European species, Glischrochilus quadriguttatus and Glischrochilus quadripunctatus , whose names also refer to the four blemishes. The genus name Glischrochilus from Altgr. γλίσχρος “glis-chrós” for “sticky” and χῦλός “chilós” for “juice” indicates the use of draining tree sap as a source of food. The rarely used name "picnic beetle" is the translation of the name "picnic beetle", which is established in the English-speaking world, and is explained by the fact that the species often flies to picnics outdoors. However, the English name is common for several species in the genus.
The beetle of North American origin could also become a major pest on various crops in Europe.
Characteristics of the beetle
   
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| Fig. 1: different views | |
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| Fig. 2: Splint and tarsus of the middle bone from the inside |
Fig. 3: Prosternal process |
 
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| Fig. 4: Head, slightly inclined on the left, more on the right, same specimen |
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The elongated oval beetle has a strongly varying length from four to six, exceptionally also up to eight millimeters. The deep brown to black body is elongated oval and slightly arched. It is hairless and shiny. The four flaws on the wing coverts are due to a lack of pigment, the wing coverts are transparent in the flaw area.
The head is large and triangular (Fig. 4). The mouthparts point forward. The bilobed upper lip is fused with the head shield . The lower jaw has only one drawer. The upper jaws have two teeth at the top and a small molar at the base. The end link of the lip switch is cylindrical and trimmed at the tip (Fig. 1). The eleven-part antennae end in an oval, three-part, flattened club. When it is turned in, there arises a feeler groove that initially runs downwards (Fig. 1) and converges under the head (Fig. 1, bottom left). In front of the pronotum, the head is indented in a line, the impression is often formed as a seam. However, it is only visible when the head is tilted sufficiently; when the head is raised, it visually coincides with the front edge of the pronotum (Fig. 4).
The pronotum is trapezoidal with a slightly curved and fluted side edge. The back angles are slightly greater than ninety degrees. The base is about one and a half times as long as the height.
The glossy elytra are about 1.25 times as long as they are together wide. In both sexes, they do not end individually rounded, but more or less straight together. They leave part of the pygidium uncovered. Each wing cover has two pale yellow or red-yellow spots. The front shoulder spot (humeral blemish) is far away from the suture of the wing cover and surrounds the shoulder bump in a ribbon-like manner inwards and backwards, not three-branched. On the outside, it almost reaches the edge groove of the elytra. The apical blemish lies in the rear third of the wing cover and is closer to the wing cover seam. Their contours are vaguely reminiscent of the continent of Australia . The label is rounded and very wide (Fig. 1 top left).
The legs are short and strong, the tarsi all five-limbed and yellowish-brown. The fourth tarsal link is short, the claw link about as long as the first to fourth tarsal link together. The front tarsi are dilated in the male. The outer edge of the middle rail is not nearly straight, but all rails are slightly curved on the outside and clearly drawn out tooth-shaped at the end (Fig. 2). The front chest is elongated backwards between the front hips (prosternal process). The end of the prosternal process is not truncated but rather rounded (Fig. 3). The middle and rear hips are broadly separated (Fig. 1, bottom left).
biology
The species occurs in very different biotopes . Animals have been found in ruderal areas and fields, in gardens and on the edges of forests, both on dry slopes and on swampy meadows. While in Europe the early finds come from "bleeding trees" or from their surroundings, reports from corn plantations followed.
The females are relatively long-lived. A fertilized female can lay eggs for about seventy days. Up to 439 eggs, usually around three hundred eggs, are deposited individually or in small packets up to 2.5 centimeters deep in the soil, which is interspersed with decomposing plant parts. The eggs can also be laid directly on rotting plant material, for example in compost heaps with spent grains and fruit or on corn on the cob, potatoes or onions that remain in the fields after harvest and begin to rot. The larvae feed polyphagously on rotting plant material.
Under laboratory conditions at 21 ° C, the larvae hatched about four days after oviposition; larval development took 21 to 22 days. There are three larval stages. In the last stage, the larvae grow up to six millimeters long. The pupal stage lasted almost twelve days, the hatched beetles remained in the ground for about 11 days. For breeding to be successful, the humidity must be kept at a high level and fungal attack must be prevented. A minimum temperature of 10 ° C is required for complete development to the pupil, cold spells of up to 5 ° C are tolerated. The pupa needs at least 10.5 ° C to molt. Up to four generations can be bred per year. In the wild, eggs are laid in spring. The beetle produces one generation per year in the northern part of its American range, and two generations in the south. Two generations per year have also been found in Hungary ; one to three generations per year are assumed for other European countries. In any case, in late summer newly hatched beetles and previous year's females can be found at the same time. It could be shown that breeding duration and breeding success strongly depend on the feed used. With a natural diet, males are more common than females.
The adults feed on ripe or damaged fruits, vegetables, maize, mushrooms, as well as tree sap ( maple , oak ) flowing out . In the case of tomatoes, at least, it has been shown that damaged fruits are more attractive to the beetles within three days, the more the decomposition progresses. The approaching animals did not land directly on the fruit, but on the ground near them, in order to then crawl to reach them. Chemicals found in ripe fruits act as attractants and are also used for traps.
For wintering, the imago hides under the bark, in plants or in the ground in plant remains. The great tolerance to heat and moisture promotes the ability of the species to spread.
The collection shows that the species, which originated in North America, is displacing native species. The effects of displacement have not yet been studied. Experiments have also confirmed that the beetles transmit phytopathogenic fungi to raspberries.
The presence of Glischrochilus quadrisignatus , on the other hand, reduces the harmful effects of the European corn borer , presumably through mechanical damage to the larvae and the consumption of dying larvae.
Harmfulness and control
Larvae and adults damage useful plants by eating, the larvae only plant material that is no longer economically usable. In addition, the feeding tunnels allow further pests and pathogens to penetrate. Finally, cases of direct transmission of fungal diseases by the beetles have been observed. While in America the damage to corn, tomatoes and various types of fruit (apples, pears, apricots, peaches, raspberries) can be considerable with losses of up to forty percent, the species has so far only occurred to a limited extent as a corn pest in Europe. The beetle bites the young, still milky grains and eats them up. When the grain shell becomes harder, it stops feeding.
In the USA the species is controlled chemically twice a year. However, agrotechnical measures such as rapid destruction of infested crops, early plowing deep under after harvest and removal of maize residues are also successful.
In the USA, both entomopathogenic fungi and various parasitic insects ( Braconidae , Tachinidae ) were used as natural enemies . Less susceptible varieties can also be obtained through breeding.
distribution
The species, which originates from North America, was first discovered in Berlin after the Second World War. Presumably it was introduced during the airlift . In 1948 the Beetle was reported from other locations in Germany. Since then it has spread towards Southeast Europe (Austria, Bohemia, Moravia, Slovakia, Hungary, Serbia, Croatia, Slovenia, Romania, Bulgaria). Then western Russia, Switzerland and Italy were also reached. The first reports from Poland date between 1989 and 1995. In the meantime, numerous sites are known there. Today the species is widespread in almost all of Europe. It is absent on the Iberian Peninsula , in Northern Europe and Ireland , as well as in Belgium . The beetle was first reported from the Baltic states in 2007. The expansion of the range of this adventivart is possibly related to global warming.
literature
- Heinz joy, Karl Wilhelm Harde, Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 7 . Clavicornia. Spektrum Akademischer Verlag, Munich 1967, ISBN 3-8274-0681-1 .
- Gustav Jäger (Ed.): CG Calwer's Käferbuch. 3rd edition, K. Thienemanns, Stuttgart 1876.
- Klaus Koch : The Beetles of Central Europe Ecology . 1st edition. tape 2 . Goecke & Evers, Krefeld 1989, ISBN 3-87263-040-7 .
Individual evidence
- ↑ a b Glischrochilus quadrisignatus in Fauna Europaea. Retrieved October 9, 2012
- ↑ Glischrochilus at Fauna Europaea. Retrieved October 9, 2012
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (kind).
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus).
- ^ A b C. Windels, M. Windels, Th. Kommedahl: Association of Fusarium Species With Picnic Beetles on Corn Ears. In: Phytopathology. 66, pp. 328-331 ( apsnet.org PDF).
- ↑ News from the Iowa State University Extension ( Memento of the original from June 13, 2013 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b Klaus Koch : Die Käfer Mitteleuropas Ökologie . 1st edition. tape 2 . Goecke & Evers, Krefeld 1989, ISBN 3-87263-040-7 .
- ↑ a b c d e f iop.krakow.pl Detailed description (Polish).
- ↑ a b c American information page on biology ( Memento of the original from December 28, 2015 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ Sándor Keszthely: Evaluation of flight phenology and number of generations of the four-spotted sap beetle, Glischrochilus quadrisignatus in Europe In: Bulletin of Insectology. 65, No. 1, pp. 9-16, 2012 ISSN 1721-8861 ( bulletinofinsectology.org PDF).
- ↑ WH Foott, PR Timmins: The Rearing and Biology of Glischrochilus quadrisignatus (Coleoptera: Nitidulidae) in the Laboratory . In: The Canadian Entomologist . tape 111 , no. December 12 , 1979, ISSN 1918-3240 , pp. 1337-1344 , doi : 10.4039 / Ent1111337-12 .
- ↑ Chengwang Peng, Roger N. Williams: Influence of Food on Development, Survival, Fecundity, Longevity, and Sex Ratio of Glischrochilus quadrisignatus (Coleoptera: Nitidulidae) . In: Environmental Entomology . tape 20 , no. 1 , January 1991, ISSN 1938-2936 , pp. 205-210 , doi : 10.1093 / ee / 20.1.205 .
- ↑ WH Foott: Use of Fluorescent Powders to Monitor Flight Activities of Adult Glischrochilus quadrisignatus (Coleoptera: Nitidulidae) . In: The Canadian Entomologist . tape 108 , no. October 10 , 1976, ISSN 1918-3240 , pp. 1041-1044 , doi : 10.4039 / Ent1081041-10 .
- ↑ CE Mccoy, TA Brindley: Biology of the Four-Spotted Fungus Beetle, Glischrochilus q. quadrisignatus and its Effect on European Corn Borer Populations . In: Journal of Economic Entomology . tape 54 , no. 4 , August 1961, ISSN 1938-291X , p. 713-717 , doi : 10.1093 / jee / 54.4.713 .
- ↑ WH Foott, PR Timmins: Importance of field corn as a reproductive site for Glischrochilus quadrisignatus (Say) (Coleoptera: Nitidulidae) In: Journal Proceedings of the Entomological Society of Ontario. Volume 101, 1971, pp. 73-75 ISSN 0071-0768 ( cabdirect.org ).
- ↑ Influences of climate change on agricultural pests and beneficial insects in organic farming in Eastern Austria. Final report on the project StartClim2005.C3-a ( austroclim.at PDF).
- ↑ Romas Ferenca, Povilas Ivinskis, Vytautas Tamutis: New and rare for Lithuania beetles (Coleoptera) species. In: Acta Biol. Univ. Daugavp. 7, No. 2, 2007 ISSN 1407-8953 ( biology.lv ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this note. PDF).
- ↑ EM Frauenschuh, B. Kromp: Influences of climate change on agricultural pests in organic farming in Eastern Austria ( orgprints.org PDF).
