 |
 |
 |
 |
 |
 |
 |
Cotton Pests -- Pink Bollworm |
|
 |
|
Biology
The pink bollworm, Pectinophora gossypiella, is a small grayish-brown moth with a wing spread of about ¾ of an inch. Moths emerge in the spring and summer from pupae produced by overwintered, diapausing “long-cycle” larvae, and during the summer from pupae produced by seasonal non-diapausing “short-cycle” broods. Moth emergence in the spring usually begins before cotton is fruiting. If no fruiting host plant is available, the emerging adults die without reproducing and the emergence is termed suicidal. Once fruiting cotton is available, eggs are deposited on the plants and the first generation larvae develop in the squares.
The adult short-cycle moths live about 14 days. However, some moths may live as long as 31 days with an average oviposition period of about 7 days. The adults are most active at night, seek shelter during the day, and are seldom seen in an infested field.
Males respond to a pheromone released by the female prior to mating, which may occur the first night after emergence and one or more times thereafter. Most mating takes place after midnight. The greatest oviposition activity in the cotton field occurs in the evening between 8 and 10 p.m. Bolls 10 to 20 days old are the preferred ovipositioning site. Eggs laid on the bolls may be deposited singly or in clusters. Egg clusters on a boll may contain only a few or as many as 75 to 100, overlapped in a shingle-like configuration.
The larva of the pink bollworm is the life stage that is injurious to cotton. It passes through four and sometimes 5 instars before attaining a length of about ½ inch when fully grown. The length of time spent in the larval stage characterizes the individual larva as “short-cycle” (summer brood) or “long-cycle” (resting stage). The newly-hatched larva is almost colorless except for the brown head capsule. It enters the fruiting form of the cotton plant shortly after hatching and is seldom seen outside the fruiting form. Coloration darkens as the larva grows until it reaches a deep pink at maturity. After the short-cycle or non-diapausing larvae complete their feeding period, they leave the fruiting forms and drop to the ground where they spin a silken cocoon and pupate in surface trash or in the soil. Most diapausing larvae remain in the boll. These larvae usually remain in a single seed, but sometimes spin a cocoon tying two seeds together, which resembles a double seed.
The larva spins a cocoon and may or may not pupate. The pupa is reddish brown, about 8 to 10 mm long and covered with fine pubescence. The pupal stage is usually 8 to 10 days.
Images
Select thumbnail for a larger image |
||
 |
 |
|
| Mature pink bollworm larva. Image: Jack Kelly Clark. | Pink bollworm moth. Image: Jack Kelly Clark. | |
Illustration - Pink Bollworm Life Cycle
Host
Cotton is the preferred host, but 46 plant species (mostly in the mallow family) have been recorded as hosts in the U.S. and northern Mexico. Cultivated okra is second in importance to cotton as a pink bollworm host.
Distribution
Generally distributed in all of the major cotton producing countries of the world except Mexico and the U.S., where it is established only in certain areas.
Chronology of the pest in the United States
The pink bollworm was first reported in Arizona on infested seed from Egypt in 1913. The first pink bollworm infestation in the U.S. was found in a cotton field near Hearne, Texas, in 1917. By 1952, new infestations were reported from various locations in Texas, Louisiana, Oklahoma, New Mexico, Arkansas, and Arizona.
Technical Working Group
Technical Advisory Committee (serves as part of the National Cotton Council’s Pink Bollworm Action Committee)
Research
Limited research is being conducted as the program moves toward completion, although work continues on resistance monitoring, alternative pheromone formulations and release rates, and genetic markers for easily identifying lab-reared, sterile moths from native moths captured in traps.
