Leaf miners & lettuce

May 2000. Niue reported an outbreak of leaf miner in hydroponically-grown lettuce.

Replies mentioned the need to rear the insect to the adult stage in order to get it identified correctly as well as the correct method of preservation. Drying is needed, rather than preservation in alcohol. In addition, a number of pesticides were mentioned: Perfekthion (Samoa), which is also effective against mites,

The same problem had occurred in Raratonga, Cook Islands in 1999, and the following procedures proved useful in managing the outbreak:

• Pick infested leaves and destroy them;
• Set up yellow sticky traps to catch adult leaf miners, e.g., yellow A4 paper with a dab of Vaseline;
• Use Agrimec (a.i. is Abamectin); this kills the larvae and it is not harmful to beneficial wasps attacking the other stages, but use sparingly to avoid resistance build-up;
• Alternate Agrimec with Cyromazine;
• Monitor on a regular basis.