Polydesmus angustus

Polydesmus angustus is a species of flat-backed millipede belonging to the class Diplopoda and the family Polydesmidae. These soil-dwelling invertebrates are commonly found in habitats with high moisture levels and rich organic content, such as compost heaps, damp garden soils, and commercial greenhouse environments.

This millipede is considered a pest because it feeds on a variety of agricultural and horticultural crops. It primarily targets germinating seeds, young seedlings, and the subterranean parts of established plants. Carrots, potatoes, and various root vegetables are particularly susceptible to the feeding activities of this species.

The biology of Polydesmus angustus revolves around moisture dependence. Females construct small, mud-based nests in the soil to lay their eggs. The life cycle progresses through several nymphal stages, with individuals adding body segments as they moult. They are nocturnal and shy away from direct light, preferring to stay buried in moist soil during the day.

Damage is characterized by irregular pits and deep excavations in root crops, which often ruins the marketability of produce. In seedlings, the millipedes chew through the stems at the soil line, leading to plant collapse. Furthermore, the damage caused by their feeding often facilitates secondary infections by fungi and bacteria, leading to rot.

Managing populations requires a combination of cultural and chemical interventions:

• Improving soil drainage to create a less favorable environment for the pests.
• Reducing the amount of decaying organic matter near vulnerable seedlings.
• Using physical barriers or traps to monitor and reduce local populations.
• Applying soil-based insecticides during peak activity periods if damage is severe.