Preventive Control

Natural enemies

Parasitoids

1. Braconid
   Dacnusa sibirica is a Braconid wasp species that is commercially available and widely distributed in Europe, Siberia, and North America. The females deposit eggs on all larval instars of a wide variety of leafminer species. The eggs develop inside the host while the host is still inside the leaf. Its lifecycle is completed in about 16 days (Olkowski; Daar; Olkowski, 1991: p. 390).
2. Trichogramma
   Diglyphus isaea is a chalcid which kills its host by opening a hole through which it feeds on tissues. Such kind of feeding is essential to obtain protein for the egg development of the females. She parasitizes the host with her ovipositor. It lays an egg or more on or near the host. The host larva becomes brown and flaccid. The developing larva consolidates its pupal chamber as a protection when the leaf dries out. D. isaea is abundant in Europe, North America, and Japan (Olkowski; Daar; Olkowski, 1991: p. 390).

Predators

1. Dragonfly
2. Hoverfly
3. Lacewing
4. Minute pirate bug
5. Spider
6. Weaver ant

Management and cultural practices

1. Conservation of the natural enemies is an important aspect of leafminer management. Maintain flowering grasses around field margins to provide habitat and food for natural enemies.
2. Proper field sanitation. Remove and burn all crop residues after harvests. Burning is very effective to prevent emergence of eggs and larvae remaining in the leaves (CABI, 2003).
3. Plow-under remaining plant residues, to expose pupae to ground predators, and to sunlight. Flooding the field is another method to kill the pupae.
4. Practice crop rotation or grow different crops in one season. Carrots and beets are good companion crops to potatoes (Braun; Shepard, 1997: p.5).
5. Plant resistant varieties, transplant only non-infested seedlings.
6. Immediately remove and destroy any leafminer infested leaves. Do not put infested leaves in compost.