Verticillium lecanii (Lecanicillium lecanii)

Introduction

Verticillium lecanii, now classified as Lecanicillium lecanii, is an entomopathogenic fungus that specializes in parasitizing soft-bodied insect pests such as aphids, whiteflies, thrips, and mealybugs. It’s widely used in horticulture and protected cultivation systems (e.g., greenhouses) due to its specificity, safety, and effectiveness in humid conditions. Lecanicillium provides a critical option for integrated pest management (IPM) where chemical control is limited or undesirable.

Scientific Description

Lecanicillium lecanii is a fungus belonging to the order Hypocreales. Its infection process involves adhesion of spores to the insect cuticle, penetration through enzymatic activity, internal colonization, and eventual host death. The fungus then sporulates on the cadaver, allowing transmission to adjacent pests under favorable humidity.

Mechanism of action:

• Cuticle Penetration: Spores adhere to the waxy insect surface and secrete enzymes (proteases, lipases, chitinases).
• Proliferation: Fungal hyphae invade insect tissues, consuming nutrients and disrupting metabolism.
• Toxin Release: Produces insect-specific toxins that accelerate mortality.
• External Sporulation: White fungal growth emerges from cadavers, spreading spores to nearby insects.

Benefits

• Highly Targeted Pest Control: Ideal for aphids, whiteflies, mealybugs, and soft scales.
• Safe for Beneficials: Doesn’t harm pollinators, parasitoids, or vertebrates.
• No Residues: Suitable for residue-free produce in export-oriented or organic markets.
• Compatible with IPM: Can be combined with neem, botanical oils, or predatory insects.
• Multiplicative Effect: Under humid conditions, the fungus spreads across the pest population.

Uses

• Target Pests: Aphids, whiteflies, mealybugs, soft scales, thrips (partial efficacy).
• Crops: Tomato, brinjal, chili, capsicum, cabbage, banana, cotton, tea, coffee, floriculture crops.
• Application Methods:
  • Foliar spray: 5 g/L or 5 mL/L water with wetting agent; repeat every 7–10 days
  • Greenhouse use: Works very well in controlled environments with >70% humidity
  • Nursery dips: For young plants prone to aphid and whitefly attack
• Environmental Needs: Works best at 25–30°C and relative humidity above 70%
• Reapplication: Recommended at regular intervals during pest pressure due to limited persistence outdoors

Trivia

• First isolated from aphid cadavers in tea plantations in India.
• The name “Verticillium” refers to the whorled (verticillate) arrangement of its spore-producing structures.
• Now reclassified into the genus Lecanicillium based on molecular data.
• Often used in greenhouse IPM programs in Europe and Southeast Asia.