Delia platura

Bean seed fly

Overview of Bean seed fly

The bean seed fly, officially known as Delia platura, is a common pest that targets bean crops but can attack crucifers, cereals and tubers worldwide. Adult flies lay eggs near the base of bean plants, and upon hatching, the larvae burrow into the soil and feed on the seeds and roots of young plants. Larvae mainly attack seedlings by feeding on emerged roots and cotyledons. Plants that survive are weak and less tolerant to subsequent attacks by other pests and plant pathogens. This feeding activity can significantly reduce crop yields.

Recognize bean seed fly

The adult bean seed fly (Delia platura) is a small, dark-colored fly measuring about 4-5 mm in length. It typically has a shiny black or dark brown body with clear wings. The larvae, on the other hand, are small white maggots that can be found near the base of affected bean plants.

You can recognize if your crop is affected by the bean seed fly through several indicators. Firstly, check the seedling appearance. Infested plants may exhibit wilting, yellowing, or stunted growth compared to healthy young seedlings. Secondly, inspect the seeds for damage. Look for darkened or damaged seeds, as bean seed fly larvae feed on seeds germinating in the ground, causing them to appear shriveled or discolored. Thirdly, search for the presence of larvae. Small, white maggots near the base of affected bean plants are a clear sign of bean seed fly infestation. Finally, observe adult fly activity around your bean crop, especially during periods of egg-laying activity.

Bean seed fly damage

The damage symptoms of bean seed fly infestation include:

  • Wilting or yellowing: Infested bean plants may exhibit wilting or yellowing of leaves, particularly in young seedlings.
  • Poor growth: Bean seedlings may fail to emerge or show stunted growth compared to healthy plants.
  • Damage to seeds: Darkened or damaged seeds, as bean seed fly larvae feed on seeds and can cause significant damage.
  • Presence of larvae: Small, white maggots near the base of affected bean plants. These larvae are a clear indicator of bean seed fly infestation.

By recognizing these symptoms early, you can take prompt action to address the infestation and minimize damage to your crop.


Control bean seed fly with beneficial nematodes

Biological control of the bean seed fly using beneficial nematodes offers a natural and effective solution to manage infestations. Beneficial nematodes, such as Steinernema feltiae (Capirel), are microscopic organisms that parasitize and kill the larvae of the bean seed fly. To implement this method, nematodes are applied to the soil. Growers can use their standard spraying equipment to apply the nematodes. Once introduced, the nematodes actively seek out and penetrate the larvae, releasing bacteria that quickly kill them. This biological control approach is environmentally friendly and poses no harm to humans or other non-target organisms. Regular application of beneficial nematodes can help suppress bean seed fly populations and minimize crop damage, contributing to sustainable pest management practices in bean cultivation.