The Pink Bollworm (Pectinophora gossypiella) is a destructive pest that attacks cotton plants and causes significant damage to the plant’s fiber and seeds. It is native to Asia but has spread to cotton-growing regions worldwide. In some parts of India, the pest has developed resistance to first-generation transgenic Bt cotton. Infestations are usually controlled through insecticides, plowing the field after harvest, and mating disruption using chemicals and releases of sterile males.
The adult Pink Bollworm is a small, grayish-brown moth, while the larvae are white caterpillars with pink banding. Female moths lay eggs in cotton bolls, and the larvae cause damage by feeding on the seeds. The feeding affects the Cotton’s quality and provides a pathway for other insects and fungi to enter. Bollworms overwinter in the field and re-infest crops the following season, making control measures necessary for successful cotton farming.
Pink Bollworm management in Cotton
The life cycle of Pink Bollworm
The pink bollworm (Pectinophora gossypiella) lays eggs on cotton bolls and young leaves, and the larvae inflict damage by feeding on the seeds. The incubation period is 3-6 days, and the larvae develop pink color by the third instar. The larval cycle lasts 9-14 days in hot regions, and the pupal period is 8-13 days. The life cycle is completed in 3-6 weeks, with overlapping broods in the late season.
Some larvae enter a state of diapause and spin a rigid, spherical cell called a “hibernaculum” to overwinter. The moths have a lifespan of 56 days for females and 20 days for males. The larvae may spin up on bales of lint, seed bags, or cracks and crevices, making them difficult to control.
Favorable conditions favoring an increased population of Pink Bollworms in the field
- Favorable factors dictate the severity of P. gossypiella: maximum temperature over 33°C in the morning, relative humidity less than 70% in the evening, and relative humidity more than 40% during weeks 40, 41, and 43.
- A low temperature of less than 12°C between weeks 48 and 49 is also a condition.
Identification of the Pink Bollworm
- Larva: Young larvae are white, while late instars are virtually black, brown, or green, with multiple dark and light alternating bands running the entire length.
- Adult: Small moth with forewings that are brown or dull yellow-olive grey with black dots. The edges of the hind wings are heavily fringed.
Symptoms of damage by Pink Bollworm
Pink bollworm larvae cause damage to cotton crops by feeding on the seed kernels inside the cotton bolls. This results in rosette flowers plugged holes of entry filled with excreta and “double seeds” formed by cutting window holes between two adjoining seeds. Immature bolls and attacked buds may also drop off, and the lint can become discolored and have burrowed seeds.
These symptoms lead to reduced yield and quality of the cotton crop. Lint staining around feeding regions, resulting in poor quality. Kapas can be found in open bolls. Improper boll opening is visible, as are damaged seeds. Small circular holes may be noticed on the septa between open boll locules. Lint from pink bollworm-infested bolls is of poor quality.
Impact of Pink Bollworm on Cotton crop
Pink bollworm larvae, Pectinophora gossypiella, destroy cotton squares and bolls. Adults are speckled grey to grayish-brown. They have long, thin