Cornworm moth or corn stem borer was first collected and detected from sugarcane fields in Java about 110 years ago. It is one of the important pests of corn that is spread in the southern and central regions of the country and has several hosts that always prefer cluster corn, corn, sugarcane and Sudan grass to other hosts.
Corn Sesamia Cretica
Introduction of the pest:
Cornworm moth or corn stem borer was first collected and detected from sugarcane fields in Java about 110 years ago. It is one of the important pests of corn that is spread in the southern and central regions of the country and has several hosts that always prefer cluster corn, corn, sugarcane and Sudan grass to other hosts. Once the corn plants are ripe, there is a perfect match between the moth and the plants. The moth rests motionlessly on the bushes for a long time, making it difficult to see the moth on the farm.
How to damage:
In summary, the symptoms of cornworm damage are: Medium leaf wilting, formation of rows of four holes on the leaf, creating a feeding hole on the stem from which often sap comes out, and lack of full growth and damage to the inflorescence.
Early larvae feed mostly on the fresh upper leaves of the corn plant and pierce them. Pest attack on corn fields coincides with the formation of male igneous flowers before its emergence.
The larvae enter the inflorescence by piercing the leaves surrounding it and feed on the male flowers. Whenever feeding from the base of the inflorescence. It causes it to dry out. Cutting the base of the inflorescence causes it to dry out, which is visible from the door. Sometimes the larvae fail to dry the inflorescence and penetrate the stem by feeding on the male flowers. If spawning is done on the lateral pods of the plant, the larvae enter the stem from the same place. A number of larvae enter the ear cluster and feed on it. The larvae enter the cluster sometimes from the upper part, which is cut by feeding on corn cobs, and finally the larvae reach the seeds and while feeding on them, they enter the cob. The larvae do not always enter the cluster from the upper part and sometimes enter it by feeding and piercing the leaves of the cob cover and feed on it. The movement of larvae inside the stem has no definite path. Sometimes it moves from top to bottom and sometimes from bottom to top, but it is closer to the crown part of the plant.
It spends the winter as a full larva in the lateral buds of the plant inside the branches and inside the corn stalks and spends it in the fields. Under favorable conditions, in late spring, the larvae become pupae and then adult insects appear. After mating with the male, the female lays her eggs in large numbers up to 400 in various groups (4-8) under the pods of corn leaves or sugarcane and other hosts. The embryonic period of the egg is about 7-10 days, then the young larvae hatch. Young larvae begin their activity almost side by side, feeding on young leaves close to the pods, which are also brittle and thin. The larvae are able to penetrate into the stem from about the second age. Adult larvae (fifth instar) usually go through the pre-pupal stages before pupation, in which the larvae use saliva and feces to create a special cocoon. Then inside it turns into a pupa. The pupae are usually located between grass, dried leaves and stems, either inside the feeding aisle or under the cob’s skin, or inside clusters and even corn cobs and male inflorescences. After a short time, due to the heat, the pupal period ends and adult sesame seeds appear in both males and females. In any case, males fly earlier than females and work at night in search of females. After mating, females often lay eggs under the leaf sheath at night. Under favorable conditions of the growing season, a period of individual development and sesame appearance from the egg stage to the emergence of a full-fledged insect lasts from 40-45 days. In general, Sesame is a polyvoltine pest and causes from 3 to 5 consecutive generations per year on the plateau of Iran, depending on the region. It has 3-5 generations in corn fields of Isfahan and Tehran provinces, and 4-5 generations in Khuzestan.
Platytelenomus hylas egg parasitoid
Habrobracon hebetor larval parasitoid
Collecting and burning crop residues in the field is effective in reducing the pest population.
In addition to Trichogramma Spp. Reproduced and distributed to combat this pest.