Sunflower fruit fly
| Sunflower fruit fly | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Sunflower maggot fly |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Strauzia longipennis | ||||||||||||
| ( Wiedemann , 1830) |
The sunflower fruit fly (Strauzia longipennis , Syn .: Trypeta longipennis , Wiedemann, 1830) is a fly from the family of bored flies (Tephritidae).
It is a from North America originating pest of sunflowers (of the genus Helianthus ). The fly is currently spreading as a neozoon in Europe .
features
The flies are about 6 to 8 millimeters long with a wingspan of about 13 millimeters. The head, trunk and abdomen of the animals are predominantly yellow to orange-yellow in color. The eyes are, however, strongly contrasting, green, less often red in color. The animals have darker drawing elements on the trunk section. The scutellum , the rear, roughly triangular tergite at the back of the trunk, has a dark flaw or a stripe on each side. The metanotum has a somewhat darkened stripe pattern, and the ovipositor of the female is darker than the body. The side sections of the trunk ( pleura ), however, are hardly darkened.
As is characteristic of the bored flies family, the wings have a dark mark on the otherwise crystal-clear ( hyaline ) wing surface, the shape of which is characteristic of the species. It consists of an irregularly lobed longitudinal stripe over the entire length of the wing. The front ( apical ) part of the stripe is characteristic, consisting of a dark transverse band with two longitudinal stripes reaching outwards, a long one along the front edge and a shorter one in the middle of the wing, which together form the shape of the letter "F". This F-mark is usually separated from the basal wing strip by a hyaline space, but can occasionally merge with it.
The larvae reach a length of seven to nine millimeters and have a yellowish-white colored body. It is a typical, worm-like, spindle-shaped fly maggot, somewhat narrowed towards both ends, without recognizable extremities and without a detached, sclerotized head capsule, with two black-colored mouth hooks that can be retracted into the body. On both sides of the first thoracic segment (ringlet) a comma-shaped, dark sclerotized stigma plate can be seen, which has a different number of small papillae. At the rear end there is a somewhat darker-colored stigma plate with six slit-shaped stigmas. The larvae cannot be determined up to the species on the basis of morphological characteristics.
Way of life and life cycle
The larvae of the species (in the broader sense) develop as herbivores on some sunflower species. The following host species are specified: species of sunflowers , namely (common) sunflower ( Helianthus annuus ), Jerusalem artichoke ( Helianthus tuberosus ) including the hybrid Helianthus × laetiflorus, which is occasionally grown as an ornamental plant, and the Helianthus maximiliani Schrad (which is rarely cultivated in Europe). Other host plants are Garden sun-eye ( Heliopsis helianthoides ), as well as Ageratina altissima , known in America as “snakeroot” , as well as three-lobed ragweed Ambrosia trifida L. and possibly other species of Ambrosia .
The species only trains one generation per year. The larvae mine in the soft pith of the stem (stem) into which the female sunk the eggs with her sclerotized ovipositor around mid-June; in the case of Jerusalem artichoke also in the tubers. Eight to ten, up to a maximum of thirty larvae can live in one stem, each in its own mine. The three larval stages will go through in about six weeks of development. The completed third larval stage eats an exit hole in the stem wall and drops to the ground, after which it digs a small cavity in the soil or plant litter about three centimeters deep, in which it pupates. Two different ecotypes exist in sunflowers. Animals from the southern parts of the range overwinter as larvae and pupate in the following year, just before hatching. Animals spread further north pupate immediately and overwinter as a pupa. The adults hatch from the doll's cradle in the ground, depending on the weather conditions, in early to mid-June and can be found until the end of July. The flight time is only about fourteen days.
The adult (imaginal) flies are good fliers and very active in flight. Males occupy individual host plants, from which they undertake brief patrol flights in search of females, and more or less males are attacked and driven away. In bad weather they go to sheltered places and rarely fly. Occasionally the adults can be observed on flowers, where they probably also take up food.
distribution
The sunflower fruit fly lives in western North America, in the north from Ontario in the east to Manitoba in the west, to in the south from South Carolina in the east to Kansas in the west. The species was introduced to Europe from North America as a neozoon and was first discovered in 2010 in Berlin (Germany), in an ornamental bed with sunflowers in the Treptow-Köpenick district. Immediately initiated, more intensive investigations already showed evidence for almost the entire state of Brandenburg for 2011 , predominantly, in a very low density, in agriculturally grown sunflower crops, while in 2012 only a few verifications were obtained. Such a change in mass is not unusual for insect species, depending on the weather conditions. Due to the extremely rapid distribution, it is assumed that the species had been present for some time, but was previously overlooked. So later, further finds from Berlin became known in 2009 and then in 2008. A further spread of the species is considered highly likely. The sunflower is an economically important crop in Brandenburg, with 16,800 to 18,200 hectares (in the years 2003 to 2011) it is about 60–70% of the total German cultivation area.
Harmful effect
The consequence of the infestation of the sunflower ( Helianthus annuus ) by the sunflower fruit fly is a reduced stability of the stems.
As the larvae eat, they rot later on the boreholes and the sunflowers die prematurely. The seeds cannot ripen, are smaller and the shelf life is limited. Up to 37% of sunflower fields in North America are affected. The later the infestation occurs, the better the sunflower can develop.
The species was on the warning list of the European and Mediterranean Plant Protection Organization added (European and Mediterranean Plant Protection Organization EPPO). This is intended to draw attention to the possible infestation across Europe and to stimulate the exchange of data. So far, apart from the German finds, there are no records of the species in Europe.
Combat
Insecticides (list of plant protection products) for combating sunflower fruit flies are permitted in Germany.
Natural control is difficult and time-consuming. The most important measure is the destruction of the plants, whereby they should not be disposed of on the compost heap, but either disposed of with residual waste or, if necessary, burned so that the larvae cannot pupate or overwinter in the soil. Another measure is turning the soil before the flies hatch in order to prevent the flies from hatching or flying out (because they overwinter in the ground as a pupa).
The hanging up of yellow boards , some of which are additionally baited , when the insects are flying (early June to July) can lead to a reduction in population density, but with this method the bycatch of other insects is quite large. In addition, only a reduction in the number of flies can be achieved with yellow panels, but not sufficient control. Kairomone traps from Hungary have also been available since 2014 .
Taxonomy, related species
The species was first described as Trypeta longipennis . Under the synonymous name Strauzia inermis Robineau-Desvoidy, it is the type species of the genus Strauzia in 1830 . This was named in honor of the French researcher Hercule-Eugène Straus-Durckheim. Why the generic name was written with z instead of an s is unknown, but spelling mistakes of this type cannot be corrected in scientific names, the name is described as validly. The genus Strauzia is restricted to North America in its distribution. The species of the genus are very similar to each other and to the genera Euleia (with the European Euleia heraclei ) and Myoleja , and it is difficult to determine the species.
Strauzia longipennis is a morphologically and ecologically variable species, the delimitation of which is scientifically controversial to this day. In contrast to most related species, which only accept one host species as a food plant, several host plants of the species are known. The forms that live on each of them can be differentiated from one another partly on the basis of morphological differences. These forms were also formally described in the rank of varieties , which after morphological addressing can be differentiated from one another in typical cases, but can more or less seamlessly merge into one another in the spectrum of characteristics. Most of these varieties were later raised to species rank by other processors, but this is not accepted by all. The species is therefore described differently by different editors until today.
More detailed investigations, also using genetic methods, have shown that these varieties can be viewed either as host races or as species in the development process that are still imperfectly reproductively isolated from one another . In the Midwest of the United States sympatric occurring Strauzia longipennis var. Typica and Strauzia longipennis var. Vittigera both can occur at sunflowers, both are on a color feature, the expansion of two dark bands on the thorax, distinct, but always intermediate transitional forms exist. Genetic data showed three genetic lines with reduced gene flow (“clusters”), although the coloring characteristics of var. Typica appeared in all three and var. Vittigera in two of them, but these could be distinguished from one another based on the preferred food plants and the time of occurrence . Because of the ongoing gene flow, with introgression of traits between groups, the authors concluded that it was not yet useful to consider them as separate species.
Web links
- North American Insects and Spiders: Sunflower Maggot Fly - Strauzia longipennis
- Pest Fruit Flies of the World: Strauzia longipennis (Wiedemann)
- Radcliffe's IPM World Textbook: Sunflower Insect Pest Management in North America
- NCBI Taxonomy Browser: Strauzia longipennis
- Catalog of Life: 2011 Annual Checklist, species details
Individual evidence
- ↑ a b c d W. Bryan Stoltzfus (1988): The Taxonomy and Biology of Strauzia (Diptera: Tephritidae). Journal of the Iowa Academy of Science 95 (4): 117-126. download
- ↑ a b c Sandra Lerche, Peter Baufeld, Tobias Schober, Birgit Kummer, Margit Naujok, Carmen Büttner (2013): Investigations on the occurrence of Strauzia longipennis Wied. in Berlin and in the state of Brandenburg . Journal for Cultivated Plants 65 (8): 297–308 doi: 10.5073 / JFK.2013.08.01 PDF
- ↑ M. Everatt, H. Anderson, C. Malumphy (2015): Sunflower maggot Strauzia longipennis. Plant Pest Factsheet. UK Department for Environment, Food & Rural affairs. 4 pages
- ↑ C. Brueckner & SV Korneyev (2010): Strauzia longipennis (Diptera: Tephritidae), an important pest of sunflowers recorded for the first time in the Palaearctic Region. Ukrainska Entomofaunistyka 1 (1): 55-57.
- ↑ S. Lerche, T. Schober, P. Baufeld, B. Kummer, C. Büttner: A new, non-endemic sunflower pest in Europe - catches of Strauzia longipennis in Berlin . pdf, poster, Entomologentagung der DGaaE, Berlin 2011.
- ↑ Sandra Lerche, Tobias Schober, Peter Baufeld, Birgit Kummer, Carmen Büttner (2012): A new, non-endemic sunflower pest in Europe - catches of Strauzia longipennis in Berlin. Communications of the German Society for General and Applied Entomology 18: 195. download
- ↑ Michael Woelky & Joachim Ziegler (2013): Record of the sunflower fruit fly Strauzia longipennis (Wiedemann) (Diptera: Tephritidae) in 2008 in Berlin (Germany). Studia dipterologica 20 (2) 2013: 297–298 (short communication 11/2013) PDF
- ↑ EPPO Alert List, data sheet
- ↑ M. Tóth, E. Voigt, B. Baric, I. Pajac, M. Subic, P. Baufeld, S. Lerche (2014): Importance of application of synthetic food lures in trapping of Rhagoletis spp. and Strauzia longipennis Wiedemann. Acta Phytopathologica et Entomologica Hungarica 49 (1): 25-35. doi: 10.1556 / APhyt.49.2014.1.3
- ↑ Peter Baufeld, Sandra Lerche, Miklós Tóth, Linda Molenaar: Monitoring and control options for the sunflower fruit fly (Strauzia longipennis). PDF abstract volume, 59th German Plant Protection Conference Freiburg 2014.
- ↑ Julius Kühn Institute: Guideline for combating Strauzia longipennis download
- ↑ a b G. C. Steyskal (1986): Taxonomy of the Adults of the genus Strauzia Robineau-Desvoidy (Diptera, Tephritidae). Insecta Mundi 529 (Vol 1, no. 3: 101-117). download
- ↑ Heather J. Ax, Jessica L. Harrison, John R. Gammons, Ian G. McNish, Laura D. Blythe, Marty A. Condon (2010): Incipient Speciation in Strauzia longipennis (Diptera: Tephritidae): Two Sympatric Mitochondrial DNA Lineages in Eastern Iowa. Annals of the Entomological Society of America 103 (1): 11-19.
- ↑ Andrew A. Forbes, Patrick H. Kelly, Kara A. Middleton, Marty A. Condon (2013): Genetically differentiated races and speciation-withgene-flow in the sunflower maggot, Strauzia longipennis. Evolutionary Ecology 27: 1017-1032.