Aphelinus abdominalis is a parasitic wasp used for the biological control of aphids in greenhouse and indoor growing environments. It is especially effective against the foxglove and the potato aphid, which can be difficult to manage with predators or sprays alone.

Unlike predatory insects that consume aphids directly, Aphelinus abdominalis controls pests by parasitizing them from the inside. Female wasps lay their eggs inside aphids, where the developing larva feeds internally, eventually killing the host. Adult wasps also feed on aphids, providing an additional level of suppression.

This dual action makes Aphelinus abdominalis a powerful tool for growers dealing with persistent aphid pressure.

Here’s What They Look Like At Different Stages of Their Life:

Because parasitic wasps are small and discreet, many new growers are unfamiliar with what they are releasing in their crop.

• Egg: Eggs are laid inside the aphid and cannot be seen from the outside.
  
• Larval: The larva develops inside the aphid, feeding internally. During this time, the aphid gradually stops growing and becomes less active.
  
• Pupal (mummy): As the larva matures, the aphid turns into a hardened, swollen shell known as an aphid “mummy.” These mummies are typically darker in color and remain attached to the leaf.
  
• Adult: Adult Aphelinus abdominalis are tiny parasitic wasps, measuring about 2–3 mm long. Females have a black thorax and a yellow abdomen. Males are slightly smaller, and their abdomen is a somewhat darker color.

Behavior: Adult wasps prefer to walk rather than fly, and will jump if irritated.

Why Growers Love It:

• Targets the foxglove and the potato aphid, which are harder to control with predators alone
• Provides dual control through parasitism and host feeding
• Fits well into integrated pest management programs
• Safe for people, plants, pollinators, and the environment

Timing is critical to achieving success with parasitic wasps. They perform best when introduced before pests reach outbreak levels.

Preventive use:

• ID aphid to ensure it is either the Foxglove or the Potato Aphid
• Introduce early when aphids are first detected to prevent populations from building.

Curative use:

• Effective when Foxglove and Potato Aphid populations are already present.
• Multiple releases will be required if pest pressure is high or crop is mature and dense.

Environmental Conditions:

• Performs best at temperatures between 15–35°C, with activity slowing below 15°C.
• Suitable for a wide range of greenhouse crops including ornamentals, vegetables, herbs, and indoor plants.
• Better than Aphidius species at high temperatures (above 28°C/82°F).

Note: Monitoring is essential. After 14-21 days from the first release, inspect leaves, flowers, and fruit clusters to determine if additional releases are required. Specifically look for adults and mummified aphids.

Proper release techniques ensure Aphelinus abdominalis establish quickly and begin controlling pests effectively:

1. Distribute the product: Release mummies near infested plants. A. abdominalis is not very mobile. Spread material on rock wool slabs or in application boxes (Dibox). Make sure the material remains dry and stays at its introduction site for a few days.
2. Recommended density: Release rates typically range from 0.25 to 4 adults per m², depending on crop type, infestation level and crop stage.
3. Follow‑up releases: In curative situations or severe infestations, multiple releases, every 7–14 days often improves establishment and control.
4. Avoid interference: Do not release immediately before or after broad‑spectrum insecticide applications. If treatments are needed, choose only those compatible with beneficial insects.

Tips for Selecting Rate:

• For dense crops, high pest pressure or curative use → choose a higher rate and repeat releases, weekly or bi-weekly (every 7-14 days).
• For preventive use in low‑pressure crops → choose a lower preventative rate, and watch for product establishment.
• Always match release strategy to crop size, foliage density, pest risk, and environment.

Visual checks: After 14-21 days from the first release, inspect leaves, flowers, and fruit clusters to determine if additional releases are required. Specifically look for adults and mummified aphids.

Supplemental releases: If aphid count remains high or increases, consider additional releases or review your IPM plan for gaps (e.g., residual pesticide effects, low humidity zones, new pest introduction).

Record‑keeping: Track release dates, environmental conditions, pest levels and predator observations to refine future programs.

What to Expect After Release:

• First week: Adult wasps begin parasitizing aphids and feeding on hosts.
• 2-3 weeks: Aphid mummies become visible, indicating successful parasitism.
• Ongoing: New adult wasps emerge from mummies, continuing aphid control across the crop.

Because parasitic wasps work biologically, control is progressive, not instant. Monitoring aphid levels and mummy formation is the best way to track success.

• Start releases early for best aphid suppression
• Focus monitoring on aphid mummies, not adult wasps
• Maintain suitable temperatures for optimal activity
• Combine with cultural controls like removing heavily infested plant material and other predatory insects like Chrysoperla carnea for instant control.
• Use as part of a balanced IPM strategy for long-term aphid management