PICKLEWORM

Name of the pest: Pickleworm (Latin name:Diaphania nitidalis, Pyralidae, Lepidoptera)

Host range: cucumber, squash, watermelon and pumpkin.

Occurrence and importance:
Pickleworm is a tropical insect and appears in United States and Mediterranean The young larvae causes damage to the blossoms and sometimes entrance into the fruit by a small hole.

Symptoms:
The blossom is a favored feeding site, especially for young larvae. In plants with large blossoms, larvae may complete their development without entering fruit. They may also move from blossom to blossom, feeding and destroying the plant's capacity to produce fruit. Very often, however, the larva burrows into the fruit. The larva's entrance is marked by a small hole, through which frass is extruded. The presence of the insect makes fruit unmarketable, and fungal or bacterial diseases often develop once entry has occurred. When all blossoms and fruit have been destroyed, larvae will attack the vines.

Description of the pest:

The white eggs are deposited singly or in small clusters on the foliage, and gradually turn dull yellow before hatching. Their shape varies from spherical to flattened; each egg is about 0.5 mm in diameter. Newly hatched pickleworm larva (about 1.5 mm long) is almost colorless except for slightly darker jaws and a black spot on each side of the head. Third and fourth instar larvae are about 6 to 12 mm long, pale yellow with dark spots. The dark-headed fifth instar larva has a yellow-green body with no spots and may be 25 to 30 mm long. Pupa is enclosed in a thin silken cocoon; the white pupa turns reddish-brown soon after forming. Pupae are about 16 mm long.
The pickleworm moth has a large, pale yellow spot near the centre of each dark brown forewing; the pale yellow hind wings have a wide, dark brown border. Wingspan is more than 25 mm. The tip of the abdomen is tufted with hairs.

Life cycle:
The pickleworm can complete its life cycle in about 30 days. New adults emerge after hibernating in the pupal stage and are active at night, laying tiny eggs in small clusters on leaves, buds, vines and fruits. Hatching occurs in a few days and larvae feed for approximately 2 weeks, then pupate inside silken cocoon on leaves. In 5 days or more, adults appear.

Control:
Covering plants with screen or row covers to prevent moths from depositing eggs has proven helpful in large fields.
It is also possible preventing plant injury through careful timing of cropping cycle. By planting early, it is often possible to harvest part of the crop before pickleworms appear. Pollinators, particularly bees, are very important in melons production, and insecticide application can interfere with pollination by killing bees. If insecticides are to be applied when blossoms are present, it is advisable to use insecticides with little residual activity, and to apply insecticides late in the day, when honeybee activity is minimal. They have several natural enemies, but none reliably suppress damage. It is difficult to scout for this insect and predict its appearance.

Recommended insecticides are present in the following table:

Name of the active ingredient
Effect method
Name of the product
Used rates
Application
Last Application before the harvest
Lambda cyhalothrin 5% EC or WG Contact and stomach Karate 5 EC, Karate 5 WG
0,4-0,6 l /ha
Foliar
7 days
Malathion 50% EC Contact, stomach and respiration Malatox 50 EC, Dipamal 50 EC, Polimal 50 EC 100-200 ml/100 l water
Foliar
4 days