By Gene McAvoy
The pepper weevil adult (Anthonomus eugenii) is a small (1/6 inch) black or grey beetle with a long snout (proboscis) and elbowed antennae. Adults use the mandibles at the end of the proboscis to feed on leaf or flower buds.
The major form of damage comes via destruction of blossom buds and immature pods. Both adult and larval feeding causes bud drop. Adult feeding punctures appear as dark specks on the fruit, and are not very damaging. Sometimes the fruit is deformed.
Larval feeding within the mature pod is another important form of damage, causing the core to become brown, moldy and hence unmarketable. The stem of pods infested by larvae turn yellow, and the pod turns yellow or red prematurely. Fruit drop is common and is perhaps the most obvious sign of infestation. In the absence of pepper blossom and fruit, adults may feed on leaves and stem material of pepper. Damage by pepper weevil also may allow the fungus Alternaria alternata, an otherwise weak pathogen, to infect fruit resulting in extensive fungal growth within pods.
Survival And Spread
The females bore a small hole in developing fruit or flower buds. The hole is plugged with fecal matter (frass) after an egg is deposited. Females deposit five to seven eggs per day, and may lay 300 to 600 during their life. The larvae are white to gray in color, with a yellowish-brown head. They lack thoracic legs and have few large hairs or bristles. The larva hatches from the egg and eats its way toward the seed core of the fruit where it feeds on seeds and pulp, passing through larval growth stages or instars. There are three instars. Pupation takes place inside the fruit within a small cell created by larval feeding. The emerging adult may feed within the fruit for a while before escaping through a circular hole chewed in the wall of the fruit.
Black nightshade may serve as a secondary host. Since adults will migrate readily from old fields to new plantings, populations generally build up during the season.
Adults tend to move to lower, more protected and less visible plant parts as temperatures increase, scouting efforts should concentrate on a search for adults in leaf whorls, flowers, and fruit during morning hours. Commercially available pheromone traps also may aid in early detection.
Chemical control of this pest is difficult because all stages but the adult are protected within the fruit. Frequent sprays may be necessary starting in the initial stages of infestation in order to avoid unacceptable levels of damage. Spraying needs to commence at the first sign of weevils or with flowering in fields with a history of problems. Vydate (oxamyl, DuPont Crop Protection) has been the standard control and has given pretty good results when sprayed weekly in trials at the Southwest Florida Research and Education Center.
Other chemistries that have performed well in trials include Capture (bifenithrin, FMC Corp.), Kryocide (cryolite, United Phosphorus Inc.), and Actara (thiomethoxam, Syngenta).
Gene McAvoy is regional vegetable Extension specialist IV for UF/IFAS