The tomato fruitworm (Helicoverpa zea) is a destructive pest that affects various crops, including tomatoes, cotton, and corn. It is a moth species with distinctive physical characteristics such as a pale tan to medium brown color with marked front wings and a hind wing with a dark gray band. The larvae of this species start as creamy white caterpillars with blackheads, tubercles, and hairs.
They can vary in color as they grow, developing fine white lines and stubby spines on their body segments. The eggs of the tomato fruitworm are easily recognizable due to their spherical shape, coarse striations, and reddish-brown ring that develops 24 hours after being laid. Identifying and controlling this pest is important to protect crops from damage.
Fruitworm management in Tomato
The life cycle of Tomato Fruitworm
- Egg stage: Tomato fruitworm moths lay eggs individually on leaf tissue and corn silks. The eggs hatch in 3-4 days.
- Larval stage: After hatching, larvae feed on foliage and fruiting structures, with older larvae becoming cannibalistic. The larvae develop through 5-6 instars throughout 14 to 21 days.
- Pupal stage: Once fully grown, larvae fall into the ground and burrow in the soil to pupate. This stage lasts about 13 days in the summer and serves as the overwintering stage in the late fall.
- Adult stage: After pupation, adults emerge from the ground, mate, and lay eggs to start the cycle over again.
Identification of Tomato Fruitworm in Tomato field
- Tomato fruitworm larvae are creamy white caterpillars with blackheads and prominent black tubercles and hairs when they hatch.
- Larger larvae range from yellowish green to nearly black, with fine white lines running down the body but black spots at the base of bristlelike hairs remaining.
- Older larvae have patches of stubby spines on their body segments, which are much shorter than the bristles and are best seen with a hand lens.
- The tops of the tiny, spherical eggs are flattened, with coarse striations or ribs running from base to tip. They are easily confused with looper eggs, but their striations are finer.
Damage symptoms of Tomato Fruitworm in Tomato field
- The larvae cause the damage symptoms of tomato fruit worms in tomato fields.
- The larvae have chewing mouthparts and remove plant tissue, causing holes and gouges in the leaves and fruit.
- They prefer to feed on reproductive structures, such as Tomato and pepper fruit, but can also damage leaf tissue.
- A single larva can damage multiple fruits. Early instar larvae can attack fruit without any leaf feeding, causing significant damage to the crop.
Cultural control of Tomato Fruitworm
Cultural controls are practices aimed at reducing the population of tomato fruit worms and limiting their damage to crops. Some of the cultural control measures include:
- Starting with a clean field by avoiding planting Tomato and pepper fields near post-silking corn fields