Pink Bollworm
The Pink Bollworm (Pectinophora gossypiella) or lagarta rosada in Spanish, causes serious damage to cotton in many parts of the world. The adult is a small thin gray moth with fringed wings. The eggs, laid on bracts, squares or green bolls, are difficult to find and the larvae rapidly penetrate the fruiting bodies. The female moth lays eggs in a cotton boll, and when the larvae emerge from the eggs they inflict damage through feeding. They chew through the cotton lint to feed on the seeds. The larva, is a dull white eight-legged caterpillar with conspicuous pink banding along its dorsum. The larva reaches one half inch in length. Once inside a boll, the larvae are protected from attack from either predators, parasites or insecticides. Because the moths do not normally fly great distances, preventative control through mating disruption is a particularly appropriate strategy for the pest.
The pink bollworm is native to Asia but has become an invasive species in most of the world's cotton-growing regions. It reached the cotton belt in the southern United States by the 1920s. It is a major pest in the cotton fields of the southern California deserts.
Transgenic Bt cotton is reported as resistant to the pink bollworm. Infestation on susceptible cotton is generally controlled with insecticides. Once a crop has been harvested, the field is ploughed as soon as possible to stop the life cycle of the new generation of bollworm. Unharvested bolls harbour the larvae, so these are destroyed. The plants are ploughed into the earth and the fields are irrigated liberally to drown out remaining pests. Some farmers burn the stubble after harvest. Surviving bollworms will over-winter in the field and reinfest the following season. Populations of bollworms are also controlled with mating disrupting chemicals and releases of sterile males which mate with the females but fail to fertilize their eggs.
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