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Verticillium Lecanii

Lecanicillium lecanii

Microbial Pathogens Beneficial Hyphae 2–3 µm diameter; conidia 2–4 µm × 1–2 µm

📖 Description

Lecanicillium lecanii (formerly classified as Verticillium lecanii) is one of the most important entomopathogenic fungi used in Indian biological control programmes. The species was first described in 1861 from scale insects on glasshouse plants in Europe, and was first commercially developed as a biopesticide in the 1980s by Tate & Lyle in the UK (under the trade name ‘Vertalec’ for aphid control and ‘Mycotal’ for whitefly control). In India, NBAIR Bangalore and several private companies produce L. lecanii formulations, used on approximately 100,000 ha per year for management of aphids, whiteflies, and mealybugs on vegetables, cotton, spices, and plantation crops. The species is particularly valuable because it attacks sap-sucking insects that are difficult to control with conventional insecticides (due to resistance development) — including Bemisia tabaci (whitefly), Aphis gossypii (cotton aphid), Myzus persicae (peach-potato aphid), and Planococcus citri (citrus mealybug). The fungus’s mode of infection (cuticular penetration) makes it effective against insects that have developed resistance to chemical insecticides. Lecanicillium lecanii is also notable as a natural pathogen of coffee green scale (Coccus viridis) in Indian coffee plantations — natural epizootics in 1970s Kerala coffee tracts inspired much of the early Indian research on this species.

⚠️ Symptoms to watch for

In susceptible insects: conidia adhere to the insect cuticle, germinate, and penetrate through the cuticle using a combination of mechanical pressure (appressorium) and enzymatic degradation (proteases, chitinases, lipases); once inside the haemocoel, the fungus multiplies as blastospores, consuming the insect's nutrients; toxins (destruxins, efrapeptins) produced by the fungus suppress the insect's immune system; insect dies within 5–10 days of infection; after death, the fungus emerges through the cuticle and sporulates, covering the cadaver with a characteristic white-to-yellowish mould. Infected aphids and whiteflies are often seen stuck to leaves, surrounded by a halo of fungal growth.

🩹 Treatment

Apply Lecanicillium lecanii at 5 g/L (1×10^8 CFU/g formulation) for control of aphids, whiteflies, and mealybugs. Apply in the evening or early morning to avoid UV degradation. Maintain humidity >70 % for 12–24 hours after application for optimal spore germination and infection. Use a wetting agent to improve coverage on waxy leaf surfaces. Repeat at 7–14 day intervals during peak pest activity. Most effective under humid conditions — limited efficacy in dry weather.

🌿 Organic treatments

Lecanicillium lecanii is itself an organic biological insecticide. Apply at 5 g/L (1×10^8 CFU/g) in the evening. Add a non-ionic surfactant at 0.1 % to improve coverage. Apply when humidity is high (post-monsoon, or use overhead misting in polyhouses). Repeat at 7–14 day intervals. Compatible with most other organic inputs (neem, Bacillus thuringiensis, predatory insects, parasitic wasps) — does not harm beneficial insects at recommended doses. However, avoid tank-mixing with fungicides, which can kill the biocontrol agent.

🧪 Chemical treatments

Not applicable — Lecanicillium lecanii is itself a biological insecticide. However, in conventional programmes, L. lecanii can be tank-mixed with most chemical insecticides. Always check the product label for specific compatibility information. Avoid tank-mixing with fungicides (carbendazim, mancozeb, copper oxychloride, sulphur) — fungicides kill the biocontrol agent. Maintain a 7–10 day interval between fungicide application and L. lecanii release.

🛡️ Prevention

Not applicable — this is a beneficial microbial biocontrol agent applied as needed for pest management, not prevented. Conservation strategies: integrate L. lecanii with other IPM tools (predatory insects, parasitic wasps, cultural practices). Maintain field humidity through irrigation and mulching to favour natural epizootics. Avoid fungicide applications in fields where L. lecanii is being used. In polyhouses, maintain humidity >70 % to favour L. lecanii efficacy.

🪴 Affected plants

Not a plant pest — entomopathogenic fungus attacking insects. Used for biological control of aphids, whiteflies, scale insects, mealybugs, thrips, and mites on a wide range of crops including vegetables, cotton, fruits, ornamentals, spices, and plantation crops. Different strains have different host ranges — some are specialised for aphids, others for whiteflies, others for scales.

🦋 Natural predators

Not applicable — Lecanicillium lecanii is itself a pathogen of insects. In the environment, L. lecanii is degraded by UV radiation (sunlight), high temperature (>35 °C), low humidity (<50 % RH), and antagonistic soil microorganisms (Trichoderma spp., Pseudomonas spp.). Conidia remain viable on plant surfaces for 7–14 days under humid conditions, 1–3 days in dry sunny conditions.

🌱 Host plants

Not host-specific to plants — entomopathogenic fungus attacking insects. Applied as a biological insecticide on vegetables (tomato, brinjal, cabbage, okra), cotton, fruits (citrus, mango, grapes, pomegranate), ornamentals (rose, jasmine, chrysanthemum), spices (black pepper, cardamom), and plantation crops (coffee, coconut, tea).

🔄 Lifecycle

Lecanicillium lecanii is a fungus — it does not have a 'lifecycle' in the conventional entomological sense.
Infection cycle: conidium adheres to insect cuticle → germinates (12–24 hours) → penetrates cuticle (24–48 hours) → multiplies as blastospores in haemocoel (3–7 days) → kills insect (5–10 days) → emerges through cuticle → sporulates on cadaver → produces conidia that disperse to infect new hosts.
In commercial production: L.
lecanii is mass-produced by submerged fermentation or solid-state fermentation on grains (rice, sorghum), harvested as spore powder, formulated with UV protectants and stickers, and packaged for application.

📅 Season

Applied throughout the year as needed for pest management.
Most effective under humid conditions (>70 % relative humidity) — monsoon and post-monsoon months in tropical India (June–November).
Limited efficacy in dry hot weather (April–June).
In polyhouses, can be used year-round with humidity management.
Field persistence is 7–14 days in humid conditions, 1–3 days in dry conditions.

🔎 Appearance

Lecanicillium lecanii (formerly Verticillium lecanii) is a filamentous entomopathogenic fungus.
On infected insects: the cadaver becomes mummified and is covered with a characteristic white-to-yellowish powdery mould consisting of conidiophores (branched filaments bearing spore-producing cells) and conidia (asexual spores).
On artificial media: colonies are white to pale yellow, slow-growing (1–2 mm/day), with a velvety or powdery texture.
Conidiophores are slender, vertically oriented, and bear whorls of 2–4 conidiogenous cells (phialides) — giving the genus name 'Verticillium' (whorled).
Conidia are elongate-ellipsoidal, single-celled, and produced in slime heads at the tips of phialides.

💥 Damage level

Beneficial

🔁 Reproduction rate

Moderate

🗺️ Geographic regions

Cosmopolitan — Lecanicillium lecanii is naturally present in soils and on insects worldwide. In India
L. lecanii formulations are produced by NBAIR Bangalore
several agricultural universities (TNAU Coimbatore
UAS Bangalore)
and private companies including Bio-green
Pest Control India
and International Panaacea. Applied across all states where target pests occur — particularly important in Karnataka (coffee)
Kerala (spices
coconut)
Tamil Nadu (vegetables
cotton)
Andhra Pradesh (cotton
vegetables)
and Maharashtra (cotton
fruits).

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