Biocontrol in Greenhouse Tomato

Key takeaways

  • Greenhouse tomato production runs on specialty cultivars with distinct pest pressure profiles — build the biocontrol plan around the crop, not a generic IPM template.
  • The strategy — organic or conventional — is the same: keep fruit clean of pests and pesticide residue from the first seedling onward.
  • Top tomato pests to plan for: fungus gnat, whitefly (greenhouse and Bemisia), aphid, leafminer, lepidoptera and spider mite.
  • Preventive releases — Stratiolaelaps on seedlings, weekly Encarsia/Eretmocerus — cost a fraction of curative releases once a colony is established.
  • Match the parasite to the species: Encarsia formosa for greenhouse whitefly, Eretmocerus eremicus for Bemisia or mixed populations, Aphidius colemani for green peach aphid, A. ervi for potato aphid.

Since the tomato entered our diets it has been bred into hundreds of cultivars — and greenhouse tomato production has its own dedicated varieties tuned for protected cropping. Those varieties pair with a pest pressure profile every grower has to plan around, ideally before the first seedling goes in.

Ripening cluster of greenhouse tomatoes on the vine — protected-cropping production
Greenhouse tomato cultivars are bred for protected cropping — biocontrol planning starts with the variety and the production system.

Tomato in the greenhouse

Tomato is one of the most widely produced greenhouse crops in the world, and the cultivars used under glass or poly are not the same as field varieties. Indeterminate vining types dominate, trained vertically and managed for steady fruit set over a long cropping window. That long window is precisely what makes biological pest control so attractive: a single misstep with broad-spectrum chemistry can disrupt months of harvest, while a well-planned biocontrol program keeps beneficial populations working through the entire run.

Strategy

Whether the crop is organic or conventional, the strategy is the same: keep the fruit clean of pests and of pesticide residue. Preventive releases of biocontrol agents at the seedling stage establish a working predator-and-parasite community before pest populations have a chance to take off. Curative releases at higher rates are reserved for the inevitable hot spots that show up mid-season.

Clean fruit means clean of pests and clean of residue. Plan the biocontrol program from the first seedling, not after the first outbreak.

Major pests & biocontrol agents

Fungus gnat

The larvae of fungus gnats damage the roots of young tomato plants and vector the soil-borne disease Pythium. To control, release the predatory soil mite Stratiolaelaps scimitus preventively onto all seedlings. Stratiolaelaps works well in a wide range of substrates — rockwool, coconut fibre, and soilless mixes — making it a fit for most greenhouse propagation systems.

Greenhouse whitefly adult on a tomato leaf — pale wings and visible body
Greenhouse whitefly — one of two whitefly species that drive most tomato infestations worldwide.

Whitefly

Worldwide, two whitefly species infest greenhouse tomato: greenhouse whitefly (Trialeurodes vaporariorum) and Bemisia whitefly (Bemisia tabaci, also called silverleaf or sweet potato whitefly). Larvae cause direct sap-feeding damage; the adults vector multiple plant viruses. Choose the parasitoid that targets the species you have.

The parasitic wasp Encarsia formosa attacks (parasitizes) the young stages of whitefly and also kills young whitefly by host-feeding — the female stings nymphs and feeds on the haemolymph. Use Encarsia against greenhouse whitefly. The parasitoid Eretmocerus eremicus functions similarly; however, E. eremicus attacks both greenhouse and Bemisia whitefly, making it the right choice where Bemisia is present or species ID is uncertain.

Aphid

Most tomato infestations come from green peach aphid (Myzus persicae) or potato aphid (Macrosiphum euphorbiae). Two Aphidius parasitoids handle most of the pressure — choose by species. Aphidius colemani targets green peach aphid; Aphidius ervi targets potato aphid.

Leafminer tunnels visible on a tomato leaf — serpentine mining damage
Leafminer damage — dipteran larvae tunnel through leaf tissue, creating the visible serpentine mines.

Leafminer

The larvae of these dipteran (fly) pests tunnel through leaf tissue, cutting photosynthetic capacity and lowering yield. Diglyphus isaea is the most common parasitoid used against leafminer in greenhouse tomato. Pheromone-baited yellow sticky cards help time releases by signalling adult emergence.

Lepidoptera (caterpillars)

Various lepidopteran pests — tomato fruitworm, tomato pinworm, loopers and others — chew foliage and bore into fruit. The egg parasitoid Trichogramma spp. is released to intercept the pest before larvae hatch. Bacillus thuringiensis (Bt) products are a compatible spray option where pressure builds.

Two-spotted spider mite damage on a tomato leaf — stippling and fine webbing
Spider mite damage on tomato — stippling on the upper leaf surface is the first scouting clue.

Spider mite

Two-spotted spider mite (Tetranychus urticae) is the dominant species on greenhouse tomato. The predatory mite Phytoseiulus persimilis is the curative pick once a hot spot is detected. Tomato cultivars with heavy leaf hairs (glandular trichomes) can slow the predator; pair persimilis with Neoseiulus californicus or other compatible predators where leaf-surface biology limits performance.

Match the parasitoid to the species. Encarsia for greenhouse whitefly. Eretmocerus for Bemisia or mixed populations. Aphidius colemani for green peach aphid. Aphidius ervi for potato aphid.

Preventive release rates

Preventive releases are scheduled before the pest is detected — they establish a working biocontrol community ahead of the population curve. Rates below are the standard preventive baseline for greenhouse tomato.

Preventive applications

Pest Product Rate Frequency
Fungus gnat STRATIOforce™ (Stratiolaelaps scimitus) 5–10 per sq. ft. Once, applied to seedlings
Bemisia whitefly ERETforceâ„¢ (Eretmocerus eremicus) 0.3 per sq. ft. Weekly
Greenhouse whitefly ENCARSIAforceâ„¢, ERETforceâ„¢, or the ENCAR/ERETforceâ„¢ mix 0.3 per sq. ft. Weekly

Curative release rates

Curative releases run at higher rates and continue until the population is back under control. Scout 7–14 days after each release; if counts haven’t turned, repeat before the next pest generation builds.

Curative applications

Pest Product Rate Frequency
Fungus gnat STRATIOforce™ 10–50 per sq. ft. As needed
Bemisia whitefly ERETforce™ 0.5–1.5 per sq. ft. Until control is achieved
Greenhouse whitefly ENCARSIAforce™, ERETforce™, or the ENCAR/ERETforce™ mix 0.5–1.5 per sq. ft. Until control is achieved
Green peach aphid APHIDIUSforceâ„¢ C (A. colemani) 0.1 per sq. ft. Until control is achieved
Potato aphid APHIDIUSforceâ„¢ E (A. ervi) 0.1 per sq. ft. Until control is achieved
Lepidoptera TRICHOforceâ„¢ B or TRICHOforceâ„¢ P 100,000 per acre Until control is achieved
Spider mite PERSIMILISforceâ„¢ (P. persimilis) 20 per sq. ft. Until control is achieved

Note: the above is intended as a guideline and is not a written recommendation. Contact a Beneficial Insectary representative for crop-specific advice.

For over 30 years, Green Methods has been a leader in the production and application of beneficial organisms used in biological pest control and integrated pest management programs.

↑