Cotton boll beetle
| Cotton boll beetle | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Cotton boll beetle |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Anthonomus grandis | ||||||||||||
| Boheman , 1843 |
The cotton boll beetle ( Anthonomus grandis ) is a species of the weevil family that feeds on the buds and flowers of the cotton plant . It is mainly attracted by the cotton nectar and destroys the cotton bolls.
Originally at home in Central America, it spread to the cotton-growing areas in the southern United States in the late 19th and early 20th centuries, causing serious damage to the local economy. In the late 20th century, it became a serious pest in South America as well. A large-scale control program has been running in the USA since 1978, which has made it possible to resume cotton cultivation in many regions.
The cotton boll beetle belongs to the group of flowers and is widespread. It is not to be confused with the cotton drill , a species of butterfly.
features
The adults are initially light-colored and become darker over time. They are reddish brown to gray and dense pale yellow hairy. Their body length is 5 to 5.5 mm, depending on the food available, more extreme values can occur in exceptional cases (2.5 to 7 mm). The beetles are elongated oval, with elongated wing-coverts , which are parallel- sided in the front section and rounded at the rear end. In the male, the last section ( Pygidium ) is free and not covered by the elytra , typical of the genus . The wing covers have deep and distinct longitudinal stripes that are roughly dotted. In contrast to many other species of the large genus, they are not marked and only slightly indistinctly cloudy due to the condensed hair. A light vertical stripe on the pronotum formed by the hair is typical . The prothorax is a little narrower than the elytra and half wider than it is long. Its sides are parallel with clear rear corners, narrowing towards the front rounded.
The proboscis characteristic of the weevil (an extension of the head capsule that carries the mouthparts at its tip) is long and slender. The antennae are pivoted in near the tip of the Rüssl, they consist of a long shaft link (scapus), an antenna whip and an oval, three-part antennae lobe. The antenna whip in this species is seven-limbed, with limbs widening towards the tip. As with almost all species of the genus, the femora (thighs) of the front and middle legs have clear, pointed thorns on the abdomen. In this species, the legs are thickened towards the tip and the thorns are two-pointed with a strong outer pin and a small inner pin.
distribution
Originally the species was widespread in Mexico and Central America. With the cultivation of cotton, its range has expanded significantly to the north and south. The beetles were first detected north of the Rio Grande in 1892, and Alabama was reached in 1915. In the 1920s they spread at a speed of 60 to 250 kilometers per year to all cotton-growing areas in the north of the USA and are still the most important pests in cotton cultivation there today.
The cotton boll beetle first appeared in Venezuela in 1949 and in Colombia in 1950. For a long time, the Amazon region with its rainforests was thought to be a barrier to spread, but in 1983 the beetles were first found in Brazil, where they now infest an estimated 90% of the cotton plantations. International organizations have already initiated control programs similar to those in the US.
Reproduction
The adult beetles hibernate in porous soil regions near cotton plantations. The plants are attacked between early spring and midsummer, with the peak of the attack occurring in late spring. Immature cotton seed pods are eaten. The females lay about 200 eggs on the flower buds within 10–12 days. From these eggs, larvae hatch within a few days , live within the flower buds and pupate after one to one and a half weeks. The adult beetles hatch from the pupae after a further week. In this way, under ideal conditions, eight to ten generations of beetles can be run through each year. In this case, a pair of cotton boll beetles can produce 134 million offspring between early spring and first frost.
Natural enemies
Cotton boll beetles begin to die at temperatures below -5 ° C. According to research by the University of Missouri, the beetles are unable to survive for more than an hour at -15 ° C. Accordingly, thermal insulation through dry leaves, crop residues and a blanket of snow plays an elementary role in their survival.
Extreme heat and drought also damage the beetles. Their natural enemies include fire ants , the ore wasp Catolaccus grandis , other insects , arachnids and birds .
Harmful effect
The inside of the flower buds and seed pods of the cotton are eaten by the larvae of the beetle, which ultimately prevents them from producing seeds and fibers. The damage it has caused since its appearance is estimated at around 13 billion US dollars. Currently, the damage it causes is around $ 300 million a year.
In the 1920s, the cotton boll beetle caused a serious crisis in cotton cultivation in the southern United States, which was exacerbated by the global economic crisis in the 1920s.
Mose Austin from South Carolina reports on the harmful effects of the beetle :
- De cotton come up and started to growin ', and, suh, befo' de middle of May I looks down one day and sees de boll weevil settin 'up dere in de top of dem little cotton stalks waitin' for de squares to fo ' m. So all dat gewano us hauled and put down in 1922 made nuttin 'but a crop of boll weevils.
- “The cotton fell out and began to grow, but then - between early and mid-May - I looked at it one day and saw that beetles were crawling over the young twigs, looking for buds. In 1922 the harvest consisted only of cotton boll beetles. "
Even so, Austin Mose's employer continued to grow cotton the following year and eventually had to give up his farm. However, the cotton boll weevil plague in the southern United States has ultimately promoted agricultural diversification.
Combat
The first report of the occurrence of the boll weevil in Corpus Christi (Texas) reached the Bureau of Entomology , a division of the US Department of Agriculture , in October 1894. The entomologist C. H. Tyler Townsend was commissioned to explore the life of the boll weevil in Mexico and Texas and seek countermeasures. Townsend proposed a combination of cultivation measures: the beetle's rate of reproduction should be reduced by removing fallen leaves and increasing the spacing between the plants, but above all the cotton fields should be burned or plowed under after the main picking in early autumn. As a result, the boll beetle would have been deprived of food at the time when it is usually spreading and looking for hibernation opportunities. For the farmers, this would have meant foregoing the "top crop" for another picking, which was possible in some years when the frost set in late. The measures could only have been successful if all farmers in a region had participated. Laws that could have obliged them to do so were politically unenforceable.
In 1918 employees of the Bureau of Entomology discovered the effectiveness of calcium arsenate against the cotton boll beetle. They observed that the adult beetles drink dew drops in the morning . The dew was poisoned by the application of finely powdered calcium arsenate. Most of the overwintering beetles were killed with an initial treatment in spring, and additional dusting kept the cotton boll beetle below the economic damage threshold . This method of chemical control was promoted by the Bureau of Entomology and quickly adopted by farmers. While only 50,000 pounds (about 23 tons) of calcium arsenate were sold in the USA in 1918, it was already ten million pounds (about 4,540 tons) in 1920 . Consumption then continued to rise, for example one of the first agricultural aviation companies applied the insecticide in 1927 on an area of over 2000 km² of cotton fields.
After the Second World War, the then new pesticides were used against the cotton boll beetle. DDT proved to be extremely effective, but the beetles became resistant to the insecticide as early as the mid-1950s. As a result, organophosphoric acid esters such as parathion and malathion as well as pyrethroids were used, but the beetles soon developed resistance here too. In addition, there was growing environmental awareness, so that the control strategy was changed. In 1978, attempts were made in North Carolina to eradicate the cotton boll beetle in the growing areas. This was the basis for large-scale control programs in the 1980s supported by the US Department of Agriculture. This has enabled the boll beetle to be wiped out in Virginia , North and South Carolina, Georgia , Florida , California and Arizona, as well as in parts of Alabama. This is also being pushed for the rest of the USA. Bans on unlicensed cotton cultivation and precise stock monitoring also play an important role here.
However, the decline in the boll beetle is also partially attributed to the spread of the fire ant, another invasive species . In addition, the spread of the beetle is restricted by planting resistant cotton plants, the ore wasp Catolaccus grandis , the fungus Beauveria bassiana and the Chilo iridescent virus . Genetically modified Bt cotton is not resistant to the cotton boll beetle.
Cultural
The US blues musician Brook Benton dedicated the Boll Weevil Song , which is about a fictional conversation between a cotton planter and a cotton boll beetle , to the cotton boll beetle .
In Enterprise, Alabama , the beetle was honored with the Boll Weevil Monument .
Individual evidence
- ↑ Section: Pests and Diseases ( Memento of the original from April 29, 2009 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. . Retrieved January 15, 2012
- ^ William G. Dietz (1891): Revision of the Genera and Species of Anthonomini Inhabiting North America. In: Transactions of the American Entomological Society Vol. 18, No. 2/3: 177-276.
- ↑ Vincent H. Resh, Ring T. Cardé: Encyclopedia of Insects. Elsevier Science & Technology, 2009, ISBN 978-0-12-374144-8 , pp. 116-117.
- ^ A b Mississippi State University: History of the Boll Weevil in the United States . Retrieved November 15, 2013.
- ↑ ICAC: Integrated Pest Management Of The Cotton Boll Weevil In Argentina, Brazil, And Paraguay (PDF; 68 kB) Archived from the original on October 5, 2006. 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. Retrieved December 28, 2011.
- ^ Thad Sitton, Dan Utley: From Can See to Can't
- ↑ "Always Agin It" Place Chapin, South Carolina, John L. Dove, interviewer, January 24, 1939. American Life Histories, 1936-1940
- ^ Thomas R. Dunlap: DDT: Scientists, Citizens and Public Policy . Princeton University Press, 1981, pp. 25-31, ISBN 0-691-04680-8
- ↑ Timothy D. Schowalter: Insect Ecology: An Ecosystem Approach . Academic Press, May 31, 2011, ISBN 978-0-12-381351-0 , p. 482 (accessed November 8, 2011).
- ↑ DA Fillman, WL Sterling: Killing power of the red imported fire ant [Hym .: Formicidae]: a key predator of the boll weevil [Col .: Curculionidae]. In: Entomophaga. 28, 1983, p. 339, doi : 10.1007 / BF02372186 .
- ↑ Hedin, PA and McCarty, JC: Weevil-resistant strains of cotton . Journal of agricultural and food chemistry : 1995, vol. 43, no10, pp. 2735-2739 (19 ref.). Retrieved December 28, 2011.
- ↑ Catolaccus grandis (Burks) (Hymenoptera: Pteromalidae) ( Memento from May 20, 2009 in the Internet Archive )
- ↑ AL Nussenbaum, RE Lecuona: Selection of Beauveria bassiana sensu lato and Metarhizium anisopliae sensu lato isolates as microbial control agents against the boll weevil (Anthonomus grandis) in Argentina. In: Journal of invertebrate pathology. Volume 110, number 1, May 2012, ISSN 1096-0805 , pp. 1-7, doi : 10.1016 / j.jip.2012.01.010 , PMID 22326392 .
- ^ Extract from the National Register of Historic Places . Retrieved March 13, 2011
- ^ Science Online . Memorial to the cotton boll beetle. Retrieved January 15, 2012
