Lasius grandis ant

Systematic position: Lasius grandis belongs to the order Hymenoptera and the family Formicidae. It is a soil-dwelling ant species commonly found in Mediterranean regions, frequently inhabiting agricultural ecosystems and home gardens.

Biology and life cycle: The life cycle of this species is characteristic of the Lasius genus. Colonies are often polygynous, meaning they contain multiple queens, which facilitates rapid population growth. These ants are active during the warmer months, constructing nests in the soil, under rocks, or within the root zone of plants.

Nature of damage and harmfulness: While direct damage to plants by Lasius grandis is rare, it acts as a significant indirect pest. The primary danger lies in its mutualistic relationship with sap-sucking pests, such as aphids and mealybugs. The ants protect these colonies from natural predators in exchange for honeydew, which leads to exponential pest growth.

Crops affected: The pest poses a threat to fruit trees, ornamental shrubs, and vegetable crops. Constant ant activity on stems and leaves supports dense aphid populations, which result in plant nutrient depletion, shoot deformation, and the spread of viral diseases among susceptible plants.

• Application of sticky bands on tree trunks to block ant access to the canopy.
• Regular control of aphid populations to eliminate the ants' primary food source.
• Use of slow-acting toxic baits that are carried back to the nest to eliminate the queen.
• Soil cultivation around nest sites to disrupt colony activity.

Protection measures: Effective management of Lasius grandis requires an integrated approach. Combining physical barriers, such as sticky traps on stems, with systemic gel baits is essential. These baits are the most effective method, as workers transport the insecticide back to the nest, ensuring the destruction of the queen and developing larvae.