Insect Note #33 (Revised)

Prepared by:
Dr. Kenneth A. Sorensen, Extension Entomologist

Dated 4/94
Placed on the Web by the Department of Entomology, NCSU
Revised: 03/05

Tomato Pinworm

Keiferia lycopersicella (Walsingham) Lepidoptera: Gelechiidae

The tomato pinworm is a small, microlepidopteran moth that is often confused with other insects which have similar habits, i.e., serpentine leafminer and potato tuberworm.

Distribution

The tomato pinworm is found in the warm agricultural areas of Florida, California, Texas, Hawaii, Mexico, Cuba, Haiti, and the Bahamas. It has also been reported on greenhouse tomatoes grown in Delaware, Mississippi, Missouri, Ohio, Pennsylvania, Virginia and North Carolina. Tomato plants grown in a pinworm-infested greenhouse have been carried to the field on transplants in western North Carolina.

Hosts

Plants of the nightshade family (Solanaceae) are the preferred hosts of pinworms. Tomato is most commonly infested, but eggplant and potato also are attacked. Ornamental plants and weeds in the Solanaceae also serve as suitable hosts.

Economic Importance

Larvae damage tomatoes by the feeding on leaves, stems, and fruit. Initial injury is slight and appears as a small leaf mine. Later injury includes leaf folding and leaf tying. Mature larvae may bore into the fruit particularly under the calyx, leaving a small 'pin'-size hole. Plant tissues become infected by secondary pathogens and the fruit rots. Seedlings may be killed.

Life History

Developmental time for each stage from egg to adult depends upon temperature. The insect completes its development faster at higher temperatures than at lower temperatures. Average times at 79 degrees F- 90 degrees F are shown in the table (Lin & Trumble 1985). Eggs are laid singly or grouped in two's and three's on the undersides of foliage of the host plant. Eggs are opaque white to pale yellow when laid but turn orange before hatching. First instar larvae spin a tent of silk over themselves and tunnel into the leaf. The third and fourth larval stages feed from within tied leaves, folded portions of a leaf, or enter stems or fruit. Mature larvae form a loose pupal cell of sand grains near the soil surface and pupate. From this pupal cell, the adult emerges 2 to 4 weeks later.

Although the cycle is lengthy, generations overlap and infestations may quickly mount to damaging levels. Two or three generations or more per year can be expected under field conditions. In the greenhouse, a life cycle may be completed every 30 days.

Developmental Stage Number of Days Average (79þF) Required (90þF)
     
Egg Incubation 5.6 3.8
Leaf mining 5.8 5.1
Leaf folding 6.2 5.3
Pupa 8.4 6.6
     
Egg to adult 26.0 20.8

Management

Tomato pinworm populations can be monitored by using sex pheromone traps. Pherocon wing traps using tomato pinworm sex pheromones can be placed at 3 per acre or area. These traps will attract male moths for up to 4 weeks at which time pheromones can be replaced. Record number of moths trapped at least 3 times per week. Replace sticky bottoms as needed. Treatments with insecticides can be made when traps indicate collection of 5 or more moths. Mating disruption is also effective. Plastic laminate clip-ons or spiral plastic rings can be placed equally at 200 per acre. This will confuse males and control pinworms by mating disruption. One application is effective for some 60 days provided no gravid moths move in from adjacent areas. It is important to begin mating disruption early and when plants are small. Mating disruption is not effective when nearby areas have pinworms or under greenhouse conditions.

Control

Infestations most often result from movement of pinworm-infested plants or seedlings or from populations carried over on plants left in the greenhouse after harvest. Use transplants that are free of eggs and larvae when set and destroy all plant debris after harvest. In greenhouses, avoid solanaceous ornamental plants which may be infested. Hand picking and destruction of infested leaves is helpful. Populations may be chemically controlled early during the first or second larval stages by using one of the following:
Insecticide and Formulation Amt. Form. per acre Active Ingredient/Acre Time Limitation to Harvest (Days)
       
methomyl (Lannate) liquid 1.8 lb/gal 1-2qt 0.45-0.90lb 1
endolsulfan (Thiodan/Phaser) 3lb/gal EC 1 qt 0.75lb 2 (5 applications/year)
esfenvalerate (Asana XL) 0.66 EC 4.8-9.6oz 0.03-0.05lb 1
abamectin (Agri-mek) 0.15 EC 8 to 16oz

0.01 to 0.02lb

 7
cyfluthrin (Baythroid) 2 E 1.6 to 2.8oz 0.025 to 0.044lb 0
emamectin benzoate (Proclaim) 5 WDG 2.4 to 4.8oz 0.0075 to 0.015lb 1
indoxacarb (Avaunt) 30 DG 2.5 to 3.5oz 0.045 to 0.065lb 3
lambda-cyhalothrin (Warrior) 1 EC 2.6 to 3.8 oz 0.02 to 0.03lb 5
spinosad (SpinTor) 2 SC 4 to 8 oz 0.062 to 0.13lb 1
zeta-cypermethrin (Mustang MAX) 0.8 EC 3.2 to 4.0 oz 0.02 to 0.025lb 1

Control of older larvae is more difficult because full-grown larvae are protected within leaf folds or fruit. Control is contingent upon frequent and thorough examination of tomato leaves for pinworm mines.

The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsements by the North Carolina Cooperative Extension Service nor discrimination against similar products or services not mentioned. All pesticide recommendations provided in this publication apply to pest control in North Carolina. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain information about product usage in your locale and examine a current product label before applying any chemical. The information presented on pest biology is based on conditions in North Carolina and may not be applicable to your locale. For further information, we recommend that you contact the Cooperative Extension Service office in your county.