Pteromalus puparum

Pteromalus puparum is a species of hymenopteran insect belonging to the family Pteromalidae. Far from being a plant pest, this organism is a well-known parasitoid, functioning as a natural biological control agent against various Lepidoptera species that pose threats to agricultural crops worldwide.

The biology of this species is characterized by its reliance on pupae of butterflies, most notably the cabbage white butterfly (*Pieris brassicae*). The female wasp uses her ovipositor to penetrate the pupal shell of the host, depositing multiple eggs inside. The developing larvae then feed on the host's internal tissues, effectively neutralizing the pest before it can emerge as an adult.

This parasitoid is particularly effective in controlling pest populations on cruciferous crops. By targeting the pupal stage, *Pteromalus puparum* acts as a significant limiting factor for pest outbreaks, often reducing the need for chemical interventions in cabbage, kale, and oilseed rape cultivation.

While the insect is not a crop pest, its presence is a key indicator of a healthy ecosystem. Damage to crops is often caused by the larvae of the host insects (caterpillars) that this wasp helps to manage. Therefore, preserving the wasp's habitat is a strategic goal for integrated pest management (IPM) programs.

To protect *Pteromalus puparum* in the field, it is recommended to implement selective pest control strategies:

• avoid broad-spectrum synthetic pesticides;
• use biological insecticides when necessary;
• maintain flower strips to provide nectar sources for adult wasps;
• time application of treatments to avoid peak parasitoid activity.