Poplar leaf roller
| Poplar leaf roller | ||||||||||||
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Female rolling a poplar leaf |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Byctiscus populi | ||||||||||||
| ( Linnaeus , 1758) |
| Comparison of the two Byctiscus species | |
| Poplar leaf roller | Vine cutter |
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| Fig. 1: Forehead B. populi | Fig. 2: Forehead B. betulae |
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Fig. 3: Underside always blue-black ( B. populi ) |
Fig. 4: Upper side is the same color as the lower side ( B. betulae ) |
| Pictures of the poplar leaf roller | |
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Fig. 5: Male, upper side with pronotum spine |
Fig. 6: Underside, same individual |
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| Fig. 7: Video | Fig. 8: Couple |
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Poplar leaves
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| Fig. 9: Feed track ( B. populi ) | |
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Fig. 10: Eggs (roll rolled up) |
Fig. 11: Leaf wrap made from single leaf (poplar) |
The poplar leaf roller ( Byctiscus populi , syn .: Bytiscus populi ) is a beetle from the family of the leaf roller , subfamily Triebstecher or Rhynchitinae, which belongs to the relationship of the weevils . The genus Byctiscus is represented in Europe with two very similar species , the poplar leaf roller and the grapevine . The females of the lively green-gold, red-violet or blue-gold shiny animal roll the leaves of various poplar species, on which the larvae feed.
In Saxony-Anhalt the species is classified as endangered (category 3).
Notes on the name
The species was first described by Linnaeus in 1758 as the 33rd species of the genus Curculio under the name Curculio Populi . Linnè adds to the description: Habitat in Populo, Corylo ( Latin: Lives on poplar, hazel). This explains the species name populi (Latin for poplar). The German name Pappelblattroller refers to the fact that the beetle rolls the leaves of the poplar into a roll.
Later the species of the genus Attelabus was synonymous with Rhinomacer . When this genus was split further, the species was assigned to Rhynchites because of the longer trunk . The genus Byctiscus was finally separated from Rhynchites and the species was given the current name Byctiscus populi . The genus name Byctiscus is from Altgr. βύκτην býkten, densely packed, and the ending ίσκος ískos formed. He alludes to the fact that the elytra are dotted with tightly tangled dots .
In Europe the genus Byctiscus is represented with only two species, worldwide with eight species.
Characteristics of the beetle
The beetle, four to 5.5 millimeters long, is on average slightly smaller than the closely related grapevine . The body is compact. The top of both species shines gold-green, violet or metallic blue, but the bottom of the poplar leaf roller is always black-blue (Fig. 3/4 and 5/6). With the poplar leaf roller, the entire body is hairless, including on the wing cover.
The head is drawn out forward to a trunk of medium thickness, which lowers forward and is broadened at the tip. The mouthparts sit at the tip of this trunk. The palpitations are rigid, the upper lip is missing. The eyes are slightly arched. The eleven-link antennae are pivoted in front of the middle of the trunk. The short feeler pit is on the top of the trunk. The antennae are not kneeled and end in a loose tripartite club. The temples do not narrow backwards. With the poplar leaf roller, the forehead is not only slightly indented between the eyes, but deepened into a groove. The puncture of the head between the eyes has not flowed into longitudinal wrinkles as with the vine prick (Figs. 1 and 2).
The pronotum is about as wide as the head in front. It then widens and reaches the greatest width just before the constricted base. The males have a pointed, forward-facing thorn on either side (Fig. 5), which the female lacks (taxo picture).
The elytra are wider than the pronotum and have pronounced shoulders. Their sides are largely parallel. They drop off steeply to the sides and back. They have dense, at most partially confused rows of points.
All legs end in four-limbed tarsi . The claws are not grown together and are toothed inside. The hair on the tarsal soles enables a secure hold.
larva
The larvae are maggot-shaped and slightly curved. In this state they measure 1.3 to 2.5 millimeters in the first stage, 1.8 to 3.5 millimeters in the second and 2.5 to seven millimeters in the third and final stage. To determine the stage, the width of the head capsule is used, in which there is no overlap between the different stages. The width of the head capsule in individuals in the first stage is between 0.34 and 0.48 millimeters, in the second stage between 0.52 and 0.66 millimeters and in the third stage between 0.67 and 0.93 millimeters.
egg
The oval eggs are on average just over 0.8 millimeters long and 0.6 millimeters thick. They are pale yellow, shiny and slightly sticky (Fig. 10).
biology
The species occurs in very different habitats. They can be found on various types of poplar, especially the quaking aspen on river banks, lakes and ponds, but also in parks and heathland areas.
The diurnal beetles appear in Central Europe in mid-April and can be found until September. Males and females are equally common and appear simultaneously in spring. These are initially last year's adults who hatched in the previous year and stayed in the pupal chamber over the winter or visited the host plants in autumn of the previous year and then overwintered in the litter. These previous year's animals die about two months after their appearance, the males earlier. From mid-August, young animals appear that have completed their development in the current year.
The maximum activity of the adult beetles is in the afternoons on warm, sunny days with little wind. At over 20 ° C, the beetles are happy to fly. They fly relatively straight and fast, but rather clumsy. Flight distances of over a hundred meters have been observed. When in danger, the beetles often flee to the underside of the leaves or they drop and after a while, fly up from the ground.
When eating, the animals scrape small holes in the surface of the leaves of the host plant, whereby the epidermis of the underside of the leaves is preserved (Fig. 9). The holes are lined up in a row so that colorless feeding strips are created. The stripes are one to fifteen millimeters long and almost constant a millimeter wide. The strips usually run parallel to the main vein or other leaf veins so that no veins are damaged. In addition to the leaves, non-woody shoots are also gnawed. The host plants are mainly the trembling aspen , but other poplar species and a few other deciduous trees are also used for food intake. In feeding experiments there was a clear preference for quivering aspen, only poplars were used for laying eggs. Poplar bushes up to a maximum height of two meters are preferred.
After a maturation feeding of several days, the animals reach sexual maturity. In spring, the captive animals copulate three to six times during the day and one to three times at night. Copulation lasts between three and fifteen minutes.
As a form of brood care, the females begin after fertilization to roll individual leaves or several leaves into a roll that serves as food for the larvae (Fig. 11 and video Fig. 7). The leaves are rolled parallel to the main vein of the leaf (longitudinal roller). They are not cut, as is the case with the hazel leaf roller , for example . The beetle first drills into the leaf stalk or into not yet lignified shoots, which initiates the wilting of the leaves and makes rolling easier. The following details emerged from several years of research in the Czech Republic.
From the second half of June to the end of July, the growth of the leaves is already well advanced. Then only young single sheets are used for the wraps. The petioles are pricked or pierced from above near the base of the leaf, which causes the leaf to wilt. This process takes about ten minutes, with the beetle's head facing away from the leaf blade as it widens the opening in the petiole into a hole that is about 0.54 by 0.37 millimeters and 0.55 millimeters deep. Usually the female leaves the leaf after that and returns after twenty to forty minutes. She begins to roll up the sheet from the edge of the page. If the leaf is not wilted enough, it is waited or the hole in the stem enlarged. The leaf is rolled very tightly parallel to the main axis of the leaf, creating a long, slender roll. (With the vine prick the wraps are rolled much more loosely.) The tarsi on one side of the body adhere to the already rolled part of the leaf, those on the other side of the body on the not yet rolled part, then the legs are brought closer to each other and the wrap is enlarged. The trunk presses the top layer of the lap onto the one below by constant knocking (about twice a second). The abdomen is also used to press the new position of the roll. The actual winding process takes about an hour on average, but sometimes a roll succeeds in half an hour or, if the winding unrolls again, the female struggles for well over two hours. Then the edges are glued to the wrap in two to five places with excretions on the abdomen. This takes another ten minutes on average. About two thirds of the wraps have the upper side of the leaf on the outside. The finished wraps are open at the top and bottom. They are about two and a half millimeters in diameter and the length of the leaf used.
However, wraps are rolled as early as the end of May. Then the young shoots are not yet lignified. At this time, in addition to winding from single sheets, also winding from several sheets are made. In this case, it is not the leaf stalks but the shoots in the upper area that are drilled, thereby initiating the wilting of the leaves above the injured area. Usually the female begins to roll the largest leaf, but uses up to three other leaves at the same time or wraps them around the initial coil, sometimes even perpendicular to its main vein. These wraps are then on average thicker and usually looser the more leaves are used. However, they are about the same length. They can differ significantly from the shape of an ordinary wrap and be up to half a centimeter thick. They are also glued in significantly more places than the wraps from a sheet. At the beginning of the growing season, the multi-leaf packs can make up a significant part of the packs. In the aforementioned study, 27.5% of the wraps were rolled from two sheets, about ten percent consisted of three sheets, and about two percent of the wraps had four sheets processed.
Each female makes twenty to thirty wraps and lays about thirty to forty eggs in total. The eggs are positioned near the winding axis between two layers of the winding. During the study period, only one egg was laid per wrap in over 76% of the cases, two eggs were found in just under seventeen percent of the wraps and three eggs were found in two percent of the wraps. In the case of multiple eggs, they were at least four millimeters apart. In the laboratory, up to eight eggs per wrap were found in individual cases. Several eggs are preferably in larger coils. It should be noted that several females often work together to produce a lap, so the eggs in a lap do not necessarily come from the same female. There were no eggs in about five percent of the wraps.
Up to four wraps are made per day and up to six eggs are laid in them. It takes a female about two hours to make a wrap from piercing to gluing. Unfinished wraps are rarely found in nature. In about a third of the cases, after the winding is made, the petiole is bitten through, so that the winding falls to the ground. The remaining laps fall off by themselves later.
The females die two to eight days after they finish laying eggs. The larvae only eat part of the inner layers of the wrap. In the third stage, the larvae pupate in the ground at a depth of several centimeters. The observed development time from egg through three larval stages to pupa was between 26 and 38 days in nature and between 17 and 23 days in the laboratory. The embryonic development took six to ten days, the first larval stage lasted about six days, the second seven days, and the third eight to twelve days. If the weather is good, the young beetles appear in October; if the weather is bad, some of them overwinter in the pupa chamber.
Harmfulness
Normally, the damage to the leaves from eating and making the wraps is negligible. Only in pure poplar cultures with young plants can piercing the shoots in spring lead to noticeable damage in the event of mass infestation. In the laboratory experiment with the aspen, the larvae ate a little more than 2 cm² of leaf area in the third stage, about half a square centimeter in the second stage and minimally in the first stage. An adult beetle damages about 17 cm² of leaf area in its entire life.
The beetle population is declining in the UK and protective measures are planned to conserve populations.
distribution
The distribution area extends over the whole of Europe and to the east over Siberia to China . The beetle is relatively common in Central Europe.
literature
- Heinz joy , Karl Wilhelm Harde , Gustav Adolf Lohse (ed.): The beetles of Central Europe . tape 10 : Bruchidae – Curculionidae 1 . Goecke & Evers , Krefeld 1981, ISBN 3-87263-029-6 .
- Klaus Koch : The Beetles of Central Europe . Ed .: Heinz Freude . tape 3 : ecology . Goecke & Evers, Krefeld 1992, ISBN 3-87263-042-3 . P. 175
Individual evidence
- ^ Byctiscus populi in Fauna Europaea. Retrieved August 12, 2012
- ↑ a b Byctiscus at Fauna Europaea. Retrieved March 9, 2013
- ↑ Red lists at BioNetworkX
- ↑ C.Linnaeus: Systema Naturae per Regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata Stockholm 1758 first description page 385: 381
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (species)
- ↑ GA Olivier: Entomologie, ou histoire naturelle des insectes, avec leurs caractères génériques et specifiques, leur description, leur synonymie et leur figure enluminée Coléoptères. Tome second Paris 1790 p. 21 No. 29 Synonyms for Bytiscus betulae until 1795
- ↑ Sigmund Schenkling: Explanation of the scientific beetle names (genus)
- ↑ Species of the genus Byctiscus at BioLib
- ↑ a b c d e f g h J. URBAN: Biology of Byctiscus populi (L.) (Coleoptera, Attelabidae) . Part II. Leafrolls, larvae and this year's imagoes Acta univ. Agric. et silvic. Mendel. Brun., 2012, LX, No. 1, pp. 155-166
- ↑ a b c d e f g J. URBAN: Biology of Byctiscus populi (L.) (Coleoptera, Attelabidae) . Part I. Last year's imagoes Acta univ. Agric. et silvic. Mendel. Brun., 2012, LX, No. 1, pp. 145-154
- ↑ Protective measures for Byctiscus populi in Warwickshire, Great Britain ( Memento of the original from October 10, 2011 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. (PDF; 132 kB)
Web links
- Species description at the insect box