Combating black vine weevils and other weevils with parasitic nematodes

Black vine weevils and other weevils can be combated speedily and effectively by using parasitic nematodes.

There is no known resistance to the use of parasitic nematodes, so they can be used without restriction. They work speedily and effectively and are safe for the user.

The best way to control weevil larvae is to use Larvanem. Larvanem contains the nematode Heterorhabditis bacteriophora and is effective against the larvae (mobium) and pupae of the black vine weevil. Larvanem is up to 100% effective at higher soil temperatures. In practice, people have often used nematodes at lower soil temperatures. In this case Entonem is recommended. Steinernema feltiae (Entonem) is a good supplement for controlling black vine weevil larvae in cooler periods.

How the products work
After application the nematodes go in search of the weevil larvae and enter them through naturally occurring body openings. The nematodes feed on the contents of the larvae, excreting specific bacteria from their digestive tracts. These bacteria convert host tissue into products that the nematodes can easily ingest. The larvae die within a few days. The development of the nematodes in the prey depends on the quantities used and the size of the prey.

Effectiveness depends on the time and method of application
Larvanem is an effective solution against weevils, including black vine weevils, but is effective only if it is used correctly!

For complete directions for the use of these products, read our product leaflet ‘Combating black vine weevil – quickly and effectively’.

Here are some important points to note:

  • All the sieves in the equipment used must be removed to prevent blockages
  • Do not expose the nematodes to direct sunlight
  • Nematodes must be mixed continually to prevent them from sinking (also when spraying!)
  • Spray the crop with water before and after application
  • Keep the soil moist for the first two weeks after application

The product can be used both in container cultivation and in open field cultivation. Please note: in open field cultivation in dry weather, the ground must be sprayed with water before using the nematodes. The best time to use the nematodes is late August or early September when the temperature of the soil is high. Other possible application periods – if conditions are favourable – are April and May.

Weevils
Worldwide there are around 60,000 species of weevil. Many of them feed on leaves, and the larvae feed on the roots of all kinds of crops. Around 600 species are active in the Netherlands, some of which can damage crops. One of the most common species of weevil in the Netherlands is the black vine weevil (Otiorhynchus sulcatus).

Black vine weevils
Black vine weevils are only active at night. They take round bites out of leaves, starting at the edge. This reduces the plant’s ornamental value. The weevils sometimes cause damage to shrubs and young trees by eating the buds and the soft bark.

Larvae cause the most damage. Young larvae feed mostly on root hairs. Older larvae eat the bigger roots and also damage the stem base. This stunts the growth of the plant, which becomes yellow and ultimately withers. One larva can be enough to kill a plant by, for example, gnawing at the stem base, stopping the sap from flowing through the plant.

More information
The complete directions for the use of Larvanem and Entonem are enclosed in the packaging and are also available on our website. You will also find the sales addresses of suppliers on the website.