Cereal capuchins
| Cereal capuchins | ||||||||||||
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Grain capuchin ( Rhyzopertha dominica ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Rhyzopertha dominica | ||||||||||||
| ( Fabricius , 1792) |
The Grain Capuchin ( Rhyzopertha dominica , Syn . : Rhizopertha dominica ) is a beetle from the family of the drill beetle (Bostrichidae). It owes to the fact its German name, that his neck shield the head hood-like covering and both the adult animals and the larvae feed on corn. The beetle can cause great damage in granaries and mills .
features
The cereal capuchin becomes 2 to 3 millimeters long. The upper side is mostly chestnut to dark brown in color, the color can also be very dark to black. The legs and the belly side are light brown. Its domed pronotum, under which the head is hidden, is as wide as the body, which gives the beetle an overall cylindrical shape. The wings are only slightly hairy, but provided with longitudinal rows of recessed coarse points that become finer towards the rear. There are also such depressions on the pronotum, but there the individual points are usually fused to form furrows. At the rear end the wings are rounded. This is one of the most important distinguishing features to the large corn borer ( Prostephanus truncatus ), which has truncated, almost rectangular shaped ends on the wing covers. The last three links of the ten-link antennae are club-shaped in the grain capuchin as well as in the large corn borer and are significantly larger than the rest.
distribution
The grain capuchin is originally from Southeast Asia . In the tropical and subtropical climate it finds the best conditions for rapid reproduction. In the countries of this region, a population can increase twenty-fold each month and cause considerable damage to stored grain, especially unpeeled rice, but also to other food supplies. The beetle was able to spread worldwide with the transport of food. Today it lives as a neozoon in all warmer areas of Asia, in all of Australia, in Europe including large parts of Northern Europe , in Africa and in South and North America to the south of Canada . In the United States , the grain capuchin, which is called the Lesser Grain Borer , was brought in with grain deliveries from Australia during the First World War .
Way of life
In addition to a variety of grains such as rice, corn, and wheat, the cereal capuchin can also utilize other food sources, including various nuts, cocoa beans , legumes, sunflower seeds, and even dried fish. With the help of its strong mouthparts, it can also penetrate packaging made of paper, cardboard or plastic film. In addition to the damage to the grains, the food is also affected by the excretions of the larvae and beetles, which have an adverse effect on the smell and taste.
Endosymbionts , which are housed in two mycetomas on either side of the beetle's intestinal tract, help the beetles to break down the vegetable food . The predispositions for these mycetomas are already formed in the embryo and the microorganisms are transferred to the offspring via the ovaries in the egg stage.
The grain capuchin, however, is not only dependent on human supplies in its way of life. The beetles can undertake long migratory flights, covering a kilometer in one or two days. In temperate latitudes , such flights occur mainly in spring and autumn, as studies in Kansas (USA) have shown. In autumn, the beetles do not migrate near fields and storage sheds, but rather into the forests, where they hibernate like their wood-boring relatives from the family of the beetle . The spread of the beetles from the forests back to the supply stores in the following spring makes control of the grain weevils difficult.
development
The development cycle of the cereal capuchin only lasts around 25 days under optimal conditions. This requires a temperature of more than 30 ° C and a relative humidity of 70 percent. These values can only be achieved in the tropics, but the cereal capuchin can survive and reproduce under much less favorable conditions at around 20 ° C and at least 30 percent humidity. At a temperature of 25 ° C, its development cycle takes around two months. The moisture of the grain must not permanently fall below 9 percent.
The females lay the elongated, translucent white eggs individually or in groups of up to 20 between the grains. Under optimal conditions, a female can lay 500 eggs within the fertile phase of around six months. Older eggs are slightly pink in color and the egg shell consists of two layers. The larvae hatch after 6 to 14 days. They are white to cream in color and usually immediately dig into the grain, but can only do this in places where the grain is already damaged. In the third larval stage at the latest, however, all larvae have bored into the grain. There they feed mainly on the protein and less on the starch , which is transported to the outside as flour through the holes in the shell of the grain. The larvae that have not yet bored into a grain can feed on this flour, but their development slows down considerably as a result of this way of life.
The larvae become less and less agile from molt to molt and develop more and more from the maggot shape towards a c-shaped beetle larva. After the fourth larval stage, pupation also takes place within the grain of the cereal that was previously hollowed out by the larva. The pupal stage lasts five to six days at a temperature of 28 ° C and eight days at 25 ° C. After leaving the pupal shell, the beetle can spend a few more days in the protection of the grain until the chitin shell has hardened. A few days later the next generation cycle begins.
Taxonomy
The genus Rhyzopertha is often misrepresented as Rhizopertha , after a synonym introduced by Agassiz and Erichson in 1845, but not a priority over the name Rhyzopertha by Stephens in 1830 . Therefore, one often reads the scientific name Rhizopertha dominica in the literature , but it is not valid.
swell
literature
- Michael Chinery: Parey's Book of Insects. A field guide of European insects. Paul Parey Publishing House, Hamburg and Berlin, 1993 ISBN 3-490-23118-X
Individual evidence
- ^ Dennis S. Hill: Pests of Crops in Warmer Climates and Their Control. Springer Netherlands, 2007, p. 290 ISBN 1-4020-6737-2
- ↑ K. Mansour: On the Intracellular Microorganisms of some Bostrychid Beetles. Quart. Journ. Micr. Sci., 77, pp. 243-255, 1934
- ↑ Paul Buchner : Studies on intracellular symbionts VIII. The symbiotic institutions of the bostrychids (apatids) . In: Journal for Morphology and Ecology of Animals . tape 42 , no. 6-7 , 1954, pp. 550-633 , doi : 10.1007 / BF00406635 .
- ↑ JF Campbell, GP Ching'oma, MD Toews, SB Ramaswamy: Spatial distribution and movement patterns of stored-product insects. In: Proceedings of the 9th International Working Conference on Stored Product Protection, 15 to 18 October 2006, Campinas, Sao Paulo, Brazil, pp. 361–370, ABRAPOS, Brazil 2006 PDF (English)
- ↑ Grain Capuchin Profile of the Institute for Pest Science
- ↑ Navaid Shabir Qazi: Geography of the World. APH Publishing Corporation, 2007, p. 384 ISBN 8-1313-0192-3
- ↑ Lesser Grain Borer Rhyzopertha dominica Plant Biosecurity Toolbox, PaDIL, 2011 (PDF, English)
- ↑ Lesser grain borer ( Rhyzopertha dominica ) - Stages of Development ( 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 notice. Pest and Diseases Image Library, Australia
- ↑ Development cycle of the Getreidekapuziners ( 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 notice. Figure, US Department of Agriculture, Agricultural Research Service (PDF, English; 210 kB)
Web links
- Rhyzopertha dominica at Fauna Europaea
- Rhyzoperta dominica in the Crop Protection Compendium
- Higher resolution image in the Atlas of Beetles of Russia