Pink bollworm
Red bollworm ( Pectinophora gossypiella )
The Red bollworm ( Pectinophora gossypiella ) is a small butterfly of the family of Palpenmotten ( Gelechiidae ). The caterpillars cause by feeding in buds and fruit capsules considerable economic damage to cotton.
- 4.1 Notes and references
Features
The moths have a wingspan of 13 millimeters. The antennae are curled grayish and triple dark. The front wings are especially drawn to the rear half of the wing with irregular dark spots. The hind wings are smoky-gray and fitted with long fringe scales.
The larvae are pale whitish at first, in the third instar larvae are pale colored pink. The individual segments are sparsely provided with bristles to the bristle base is a black spot. The eggs are round and flattened. They are initially light green and darker before hatching of the larva.
Dissemination
The original habitat of the red bollworm is unknown, but is suspected in the Indo-Pakistan region. In Australia, first 1911 copies were observed in Africa ( Tanzania) 1904. In the Western Hemisphere, the parasite was from 1911 to 1913 spread by cottonseed. In the U.S., he first appeared in 1917 in Texas in appearance and could initially be cut again. Since the 1950s, was once again the large-scale propagation. Today, the Red bollworm is found in almost all cotton- growing countries worldwide.
Biology
The moths are nocturnal and mate shortly after hatching. From the third day, the females start laying eggs. It will be stored up to 450 eggs, on average there are 125 The period of oviposition depends on the weather and can take four to 25 days. The first generation develops in the buds and flowers of cotton, subsequent generations live in young or mature seed capsules. The larval stage lasts eight to 14 days, with three larval stages are passed through. The larvae pupate after a short resting phase in the diffusion layer or in the ground, occasionally a tacked on parts of plants cocoon is made. The pupal period lasts six to 20 days. A distinction is made between a short and a long generation cycle. In the former case, the larvae pupate immediately after they are fully grown. A generational cycle then takes about 30 days. In the second case, the larvae insert a eight to ten month diapause and overwinter. Four to six generations are formed per year.
In addition to various species of cotton (Gossypium ) larvae of the red bollworm were detected on the following crops: okra ( Abelmoschus esculentus ), Abutilon indicum, various hibiscus species such as Kenaf (Hibiscus cannabinus ) and Roselle (Hibiscus sabdariffa ), alfalfa (Medicago sativa) and Eibischarten ( Althaea ).
Harmful effects and control
The larval feeding damages the buds and causes the plant yields fruit capsules. In more developed capsules larvae feed on the one hand the seeds from which cotton seed oil is obtained and damage on the other hand, the cotton fibers. The yield losses without plant protection measures was at 80 percent, crop protection measures are carried out, the loss is still at about 37 percent. Due to the high pollutant potential of the red bollworm, the cotton production has become a major market for plant protection products. In addition to the traditional combat with insecticides, this method is used today worldwide to about half of the cultivated area since the introduction of Bt cotton in 1996. In March 2010 it was reported by Indian specimens who have developed resistance to the Cry1Ac toxin of the first generation Bt cotton. Possible causes include insufficient refuge areas or unauthorized propagation of Bt cotton to a low content of Bt - toxin apply.
Natural enemies
From the literature, a variety of natural enemies to which various inter alia slip wasp species ( genus Apanteles, Trichogramma ), brackish wasp species ( genus Bracon, Microchelonus ) Florfliegenarten and beetle species ( collops vittatus, Hippodamia convergens ) is known count. Pathogen act different subspecies of the bacterium Bacillus thuringiensis. Attempts to use natural enemies for the biological control of the cotton bollworm were not successful.