Mediterranean fruit fly

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Mediterranean fruit fly
Mediterranean fruit fly (Ceratitis capitata)

Mediterranean fruit fly ( Ceratitis capitata )

Systematics
Order : Fly (Diptera)
Subordination : Flies (Brachycera)
Family : Drill flies (Tephritidae)
Subfamily : Dacinae
Genre : Ceratitis
Type : Mediterranean fruit fly
Scientific name
Ceratitis capitata
( Wiedemann , 1824)

The Mediterranean fruit fly ( Ceratitis capitata ) is one comprehensive to around 4,500 species family of fruit flies (Tephritidae), so it is with the designated also sometimes referred to as "fruit flies" fruit flies (Drosophilidae) no close relatives. Like the majority of bored flies, it is characterized by conspicuously spotted wings and, in the case of females, also by a laying tube . As the world's most economically important species of bored flies, the Mediterranean fruit fly is a particularly feared pest in fruit and vegetable cultivation in the tropics and subtropics, as its polyphagous larvae can develop in the pulp or tissue of numerous plant species. It is also regularly introduced to Central Europe, but without being able to build up permanent populations there .

features

The imago is 3.5 to 5 mm long. The abdomen is yellowish with a brown tinge. The compound eyes are reddish-purple with a greenish tinge. Males have an elongated, spatulate, broadened pair of bristles near the inner edge of their eyes. The strongly humped thorax is whitish to yellowish with characteristic black markings. The ovipositor of the female is stretched 1.2 mm long. The hyaline wings are drawn black and brownish, a broad brownish-yellow band runs through the middle of the wing.

The eggs, about one millimeter long, are slender, curved, smooth and translucent white. The area of ​​the micropyle is bumpy. The larvae are white and around 7 to 9 mm long in the last of their three stages of development. Adult larvae can, when they are removed from fruits, perform several "jumps" of around 25 mm. The pupa is 4 to 4.3 mm long, cylindrical and dark red-brown.

Way of life

The development of the Mediterranean fruit fly from egg to imago is temperature-dependent and takes 16 days at 32 ° C, 30 days at 24 ° C and 100 days at 18 ° C. Florida summer around 21 to 30 days is typical. In Hawaii , which offers year-round favorable conditions, can occur up to 16 generations per year.

The female lays one to ten eggs in a one millimeter deep cavity and can lay up to 22 eggs a day. During its life, there are up to 800 eggs, on average around 300. These are usually deposited under the skin of a ripening fruit, often taking advantage of existing cracks. Ripe fruits are preferred to those that are already ripe. The hatching larvae form tunnels and stay close together almost to the end. The egg, larva and pupa stages of development stagnate when the temperature drops to 10 ° C. In warm conditions, the larvae hatch after 1.5 to 3 days. You go through three development phases. At 25 ° to 26.1 ° C, the entire larval phase only lasts 6 to 10 days, but this also depends on the food. Typical are 10 to 15 days (unripe peach ) to 14 to 26 days (ripe lemon ). Pupation usually takes place in the ground. At 24.4 ° C to 26.1 ° C, the pupae rest for 6 to 13 days.

The adults hatch in warm weather, preferably in the morning. The animals can only fly short distances, but the wind can also move them over several kilometers. Once they have hatched, they are not yet capable of reproduction. Males usually reproduce about five days after hatching, the females can usually be fertilized six to eight days after hatching. Two months after hatching, more than 50% of the hatched animals are usually dead. If no food is available, they die after four days. Some adults can survive six months or more with good nutrition and cool surroundings.

Food crops

In contrast to many other representatives of the drill flies, the food spectrum of the Mediterranean fruit fly is very broad. Over 260 plant species are known to be at least occasionally infected. Thin-skinned, juicy, succulent fruits when ripe are preferred . The pulp is destroyed by the activity of the larvae and liquefied like a paste. Since the larval tunnels serve as entry gates for bacteria and fungi, a secondary microbial infestation is often partly responsible for the destruction of the fruit .

However, vegetables, flowers and nuts are also attacked. The food crops vary depending on the region; some species are only accepted under laboratory conditions, but not in the field. The particularly preferred species include a number of representatives of the citrus family , but also coffee , persimmon , fig , mango and species of the genus Prunus such as peach . Among the species that are occasionally infested are important crops such as peppers , papaya , walnut , cotton and avocado . Species rarely affected are z. B. litchi , banana or date palm .

Origin, distribution and infested areas

The area of ​​origin of the Mediterranean fruit fly is not in the Mediterranean but in sub-Saharan Africa. The exact region is unclear, the species may originate from Kenya . Due to the global fruit trade, however, it now occurs more or less regularly around the world in numerous regions outside of Africa, in addition to the Mediterranean region, for example, in Australia and the states of South and Central America. Since it has a comparatively high adaptability to lower temperatures despite its tropical origin, it not only penetrates as far as the southern states of the USA, but can also reproduce under favorable conditions in Central Europe, where it is regularly introduced, but survives the winter there Not. Since it can cause serious damage in fruit growing, it is fought vigorously in many places, which led to successful extermination in New Zealand , where it appeared in Auckland in 1996 .

Central and Western Europe

The Mediterranean fruit fly appeared in the Frankfurt am Main area by 1937 at the latest . In 1939 and again in 1952 she destroyed the peach harvest there. It also appears regularly in Austria, Switzerland and France. In some fruit-growing areas in the Basel , Paris and Geneva areas , peach cultivation was abandoned because of this type of cultivation.

United States

The fly, often also referred to as "Medfly" for short in the USA, was introduced to Hawaii from Australia around 1907. Their first appearance on the USA mainland is documented in 1929. Affected states have been Texas , California and Florida since then . Massive control has apparently prevented permanent colonization so far, but outbreaks occur again and again, especially in California and Florida.

“Medfly Crisis” in California

In the early 1980s, control measures against the Mediterranean fruit fly triggered the so-called “California Medfly Crisis” in California , which at times took on the form of mass hysteria. In June 1980, flies were found in Santa Clara County . Since high economic damage was feared with permanent establishment of the insect, local control measures were initially taken. Since these remained unsuccessful until the end of 1980, a 6-week, large-scale aerial spraying campaign with the insecticide malathion was planned with the approval of the governor . This led to massive resistance from local environmental groups. Malathion, one of the most widely used pesticides in the home and garden in the United States , has low levels of acute toxicity to humans. However, there were also experts who wanted to deduce a human hazard from some studies. Others argued that the agent was dangerous for bees and fish, and considered that combating it with biological agents would be sufficient, if at all. For a time, conditions arose in public that almost amounted to mass panic. However, a committee of neutral experts came to the conclusion that there was no short-term or long-term risk to the population. Due to massive educational measures, the establishment of a hotline for the population, etc., the alarming reporting in the media gradually subsided. The American Red Cross set up evacuation shelters which, due to lack of interest, were dismantled during the large-scale spraying measures that were carried out. Although these were extended to 6 other counties (total area 1,300 square miles, corresponding to about 3,370 km²), in the meantime general calm had occurred. The fight itself was only completed in September 1982.

In 2007 and 2008, infestations with Mediterranean fruit flies occurred again in California, to which massive measures were taken (spraying pesticides on the bottom and releasing sterile males).

Alternative control methods

In addition to the use of insecticides, an alternative control method is based on the targeted exposure of males that have previously been rendered sterile by irradiation with gamma rays, the so-called sterile insect technique (SIT). Male eggs are selected in the Mediterranean fruit fly by treatment with warm water, which kills the female embryos , unlike the male ones. The population of the next generation is reduced in this way, since females only mate once.

In 2009 a biotechnological control method was described that is based on the introduction of a controllable lethality gene into male individuals. It is only activated after its release and causes the offspring to die off prematurely. Field studies are still pending.

Synonyms

  • Ceratitis citriperda MacLeay
  • Hispanic ceratitis De Brême
  • Paradalaspis asparagi Bezzi
  • Tephritis capitata Wiedemann

swell

literature

  • MC Thomas, JB Heppner, RE Woodruff, HV Weems, GF Steck, TR Fasulo: Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) (Insecta: Diptera: Tephritidae) EENY-214 (IN371) (orig.publ. As DPI Entomology Circulars 4 , 230 and 273), Featured Creatures Series, Entomology and Nematology Dept., Florida Cooperative Extension Service, Inst. Of Food and Agricultural Sciences, Univ. of Florida, 2001. ( online )

Individual evidence

  1. ↑ Urania Animal Kingdom, Vol. 3, Insects. Urania-Verl. Leipzig u. a., 5th edition 1989, ISBN 3-332-00255-4
  2. ↑ Ceratitis capitata Wied. - Mediterranean Fruit Fly ( Memento from July 5, 2008 in the Internet Archive )
  3. ↑ Bernhard Grzimek (Ed.): Grzimeks Tierleben, Vol. 2: Insects. Kindler Verlag, Zurich, 1968, licensed edition German. Taschenbuchverlag, Munich, 1993, pp. 412-413
  4. ^ E. Kahn, RJ Jackson, DO Lyman, JW Stratton: A Crisis of Community Anxiety and Mistrust: The Medfly Eradication Project in Santa Clara County, California, 1981-82 . At the. J. Public Health 1990; 80: 1301-1304, PMC 1404895 (free full text)
  5. ↑ Overview of current control programs, USDA
  6. ^ Marc F. Schetelig, Carlos Caceres, Antigone Zacharopoulou, Gerald Franz, Ernst A. Wimmer: Conditional embryonic lethality to improve the sterile insect technique in Ceratitis capitata (Diptera: Tephritidae) . BMC Biology 2009, 7: 4 (PDF; 2.8 MB)

Web links

Commons : Mediterranean Fruit Fly  - Album with pictures, videos and audio files