TECHNOLOGY FOR BIOLOGICAL PROTECTION OF FOREST AND PARK PLANTATIONS USING INDUSTRIAL TRICHOGRAMMA CROPS

The scientific and research activity of Organic Invest Bio Protection Ltd. is aimed at solving a strategically important problem — protection of plants from pests.

We have the technology for mass industrial cultivation of Trichogramma ,a parasitoid less than 1 mm in size. It parasitizes the eggs of over 180 species of butterflies. After becoming imago, the trichogramma finds the eggs of enemies and lays in them. Parasitoid larvae hatch in the egg of the enemy and eat its insides.

Sunset in the forest at springtime

The proportion of butterflies (Lepidoptera) species in forest plantations is over 40% of the total number of pests.

In the European fauna there are about a thousand species of leafroller moths (Tortricidae), in Bulgaria there are more than 50 species.  Bulgarian forests are dominated by more than 16 species. Of all the species diversity of forest pests, the trichogramma parasitizes primarily the eggs of leafroller moths. Winter moths are also in this group.

Leafroller moth caterpillars lead a hidden lifestyle. In some species, the caterpillars twist the leaves like a tube and feed hidden, in others — they mine the leaves, damage buds, flowers, stems, roots, make tunnels under the bark or feed in the seeds and fruits.

Females lay eggs singly, rarely in groups, on leaves, fruits, on the bark of trees or under the scales of buds, in cracks, wounds.  In many species the eggs are covered with secretion secreted from special glands in female butterflies, or with scales secreted from the wings.

Most leafroller moths are very dangerous pests of forest and park plantations, orchards, vineyards and berry crops.

It is important to know that apart from the damage that leafroller moth caterpillars cause to trees, they play a very important positive role. It is a fact that the diapausing trichogramma overwinters in the eggs of these leafroller moths, both the natural populations and the trichogramma we colonize in the summer.

This is a very important part of our technology. In early spring, viable trichogrammas from natural populations hatch from parasitized leafroller moth eggs and intensively search for eggs in the canopy of trees, both leafroller moths and other butterfly species. Therefore, the technology we propose includes a universal mechanism for self — regulation of forest ecosystems. In the industrial/laboratory culture technology trichogramma displacement takes place during the period of mass laying of leafroller moths.

The leafhopper species listed here are the primary resource for breeding and displacement of trichogramma in forests. This resource practically disappears when using chemicals that massively destroy the caterpillars of leafroller moths, but also all entomophages, including trichogramma. This is another very important advantage of the technology we offer. The necessary economic efficiency is not achieved by the complete eradication of all species, but by the long — term dynamic maintenance of pest numbers at a sub — threshold level.

Species composition of the most dangerous species of leafroller moths in forest and park plantations in Bulgaria.

Species of leafroller moths overwintering in the egg stage:

  • Brown oak tortrix Archips crataegana Gb
  • Rose tortrix Archips rosana L
  • Variegated golden tortrix Archips xylosteana L
  • Exopatecongelatella Cl
  • Aleimma loefligiana Cl
  • Green oak tortrix Tortrix viridana L
  • Acleris rhombana
  • Acleris varidana

Leafroller moths overwintering in the caterpillar stage:

  • Summer fruit tortrix Adoxophyes orana F
  • Physholoma leheana l
  • Torteicodes tortricella Hb
  • Vine Tortrix Moth Sparganothis pilleriana Den
  • Bud moth Spilonota ocellana F
  • Cherrybark tortrix Enarmonia formosana Scop
  • Rusty oak moth (Laspeyresia amplana)
  • Chestnut tortrix (Laspeyresia splendana)
  • Laspeyresia splendana)

We emphasize that trichogramma infects all leafhopper eggs equally effectively. We pay attention to tree and shrub species that are attacked by leafhopper caterpillars: oak, birch, maples, ash, acacia, mountain pine, fir, conifers, all fruit crops, berries.

The damage from leafroller moths is significant. Their massive spread is accompanied by physiological weakening of trees and the colonization of enemies on the stems — bark beetles, fruit — tree bark — beetles, etc. In addition, weakened trees are also attacked by disease agents and are much more susceptible to disease — phytopathogenic fungi, bacteria and viruses.

Essence of bio protection technology:

In Bulgaria, similar protection of forest and park stands and plantations was applied with the use of Trichogramma until the early 1990s.

  1. Surveillance — visually and with pheromones and holy catches. Collection, analysis and species identification of collected leafroller moths.
  2. Determine the level of viability and potential harmfulness. Establishing mean population densities.
  3. Determination on this basis of the norms, timing and frequency of colonization of the trichogramma
  4. Preparation of the necessary equipment for aerial displacement (colonization) of the trichogramma on trees by uniform displacement.
  5. Evaluation of the effectiveness of the technology according to certain criteria: biological — parasitized eggs of leafroller moths (%); economic — damaged plants, leaves, fruits (%); ecological — species diversity of entomophagous per unit area — adults and larvae of predators such as ladybirds, predatory mites, larvae of syrphid flies and other species.

Typically, 1–2 displacements (colonisations) per trichogramma are carried out to protect forest stands from leafroller moths and related pests.