Tomato pinworms are native to South America, and appeared in France in 2009 in the Drôme area. Since then, they have invaded all of France and spread to other European countries as well.
This pest spreads far and wide, and is often credited for destroying many tomato crops nowadays.
Its latin name is Tuta absoluta, and it is part of the Lepidoptera order.
The tiny pinworm larvae start gnawing at tomato leaf edges, then attack stems and finally attack the fruits themselves.
At that stage, tunnels on leaves and stems can be seen, which then appear on tomatoes, especially green ones. White spots appear on the tomato leaves.
Tomato pinworms infest all plants belonging to the solanaceae or nightshade family such as potato or eggplant.
These pinworm larvae reproduce extremely quickly and up to 10 consecutive generations can breed in a single season.
Growing larvae are the ones responsible for digging new tunnels on plants.
Since no curative treatment is available, the choice comes down to which preventive measure to put in place. The table below sums up what each one involves and the moment it is useful.
| Method | What to do | When it helps |
|---|---|---|
| Anti-insect net | Stretch a net of 1/5 inch (5 mm) mesh at most over hoops, keeping it clear of the foliage and leaving no gap wider than 5 mm, even near the ground | Kept on until the risk of attack has passed |
| Destroying infested plants | Pull out every infested plant and every hint of pinworm presence; keep contaminated remains off the compost | As soon as an infestation is spotted, since one larva can start it all again |
| Weeding | Clear the weeds growing around the tomato plants | On a regular basis, as a preventive routine |
| Beneficial insects | Introduce Nesidiocoris tenuis (Nesibug) or Macrolophus caliginosus (Mirical) | Against eggs and young larvae |
| Fermented rhubarb tea | Spray the fermented tea over the tomato plants | Used preventively, before any attack |
Combining a net with strict removal of infested plants gives the tightest protection, the other methods backing it up.
As of today, there are no authorized organic curative tomato pinworm treatments.
However, it is possible to keep them from attacking your tomato plants by providing adequate protection.
First and foremost, the most effective protection is an anti-insect net, with a 1/5 inch (5 mm) mesh at most.
