Tomato Fruit Borer

  • Symptoms

  • Trigger

  • Biological Control

  • Chemical Control

  • Preventive Measures

Tomato Fruit Borer

Helicoverpa armigera

Insect


In a Nutshell

  • Feeding damage on flowers and fruits, and to a lesser degree on leaves.
  • Holes bored into reproductive structures and young fruits.
  • Growth of secondary pathogens such as bacteria and fungi lead to the rotting of tissues and fruits.

Hosts

Tomato

Symptoms

Eggs of the tomato fruit borer can often be found on the top canpy of the plant. They are yellow-white to brown, about 0.5 mm in diameter and are laid in clusters around floral structures and young leaves. Larvae can feed on any plant tissue but are most likely to attack flowers and fruits. Young larvae scrape the tomato foliage, causing little damage. Older ones bores into flowers or the young fruit, making it unfit for marketing and causing serious damage. Frass is visible around the feeding holes. The growth of secondary pathogens on the wounds and frass lead to the rotting of the affected tissues. One caterpillar is capable of destroying 2-8 fruits, making of H. armigera one of the most destructive pests of tomato.

Trigger

Damage is caused by the tomato fruit borer, Helicoverpa armigera. Adults are usually light brown, about 35 mm long, with brown forewings mottled with darker patterns. Hindwings are whitish gray, with black "veins" and a large black patch on the edges. Females lay eggs singly on the upper and lower leaf surfaces, mainly on the top canopy. The aspect of the larvae varies from dark-green to reddish black depending on maturation stage. Their body is speckled with little black spots and they have a dark head. At later maturity stages, lines and bands develop along their back and flanks. Its life cycle is influenced by weather conditions and diet. Population normally peaks during fruit development, which results in high yield loss.

Biological Control

Trichogramma wasps parasitize the eggs. Microplitis, Heteropelma and Netelia wasps parasitize the larvae. Predatory bugs and ants, spiders, robber flies and some predatory flies also attack the larvae. You can also apply bio-insecticides based on spinosad, nucleopolyhedrovirus (NPV), Neem seed kernel extract or Bacillus thuringiensis (Bt) to control the larvae. Use of African marigold (Tagitus erecta) as a trap crop is also useful against this pest. Finally, the placement of bird perches will favor the presence of birds that feed on the fruit borer.

Chemical Control

Always consider an integrated approach with preventive measures together with biological treatments if available. Selective insecticide treatment is the best option to rid the field from the pest without affecting beneficial insects. Use the insecticides chlorantraniliprole, flubendiamide, cypermethrin or alpha- and zeta-cypermethrin to reduce populations. The first spray should be at the flowering stage and followed by sprays at either 10 or 15 days interval.

Preventive Measures

Use resistant or tolerant varieties if available.,Plant early to avoid population peaks of the pest.,Use light or pheromone traps to monitor or mass-catch the moths.,Check plants for eggs and damage to flowers and fruits.,Hand-pick larvae and leaves with eggs.,Remove infected plants from fields.,Plow deeply after harvesting to expose the pupae for natural predators and solar rays.