The parasitic wasp Aphelinus abdominalis occurs in large areas of Europe and Asia. It is a member of the family Aphelinidae, to which also the whitefly parasites Encarsia formosa and Eretmocerus californicus belong.

An adult Aphelinus abdominalis is on average 3 mm long, and has relatively short legs and short antennae. The female has a black thorax and a yellow abdomen. Males are somehow smaller and have a darker abdomen. Usually, there are as many males as females. Aphelinus does not often fly. When a female is looking for aphids, she walks rapidly groping on the leaf. When she has found an aphid, she scans it with her antennae, turns around, raises her wing tips and injects her oviposito in the aphid.

Oviposition takes about 20 to 60 seconds. Aphelinus can parasitise any aphid stage, even alates (winged aphids). The Aphelinus larva developes in the aphid. At 20°C (68°F) it pupates after 7 days and transforms the aphid into a black mummy. Eight days later an adult Aphelinus leaves the mummy.

Characteristic for Aphelinus is the long effective oviposition period. The first days after emergence the adult female has not yet started to lay eggs at full speed. Oviposition reaches cruising speed on the 3rd or 4th day. From then on she parasitises 5-10 aphids per day, and keeps on doing so for about 8 weeks. Aphelinus abdominalis also feeds on aphids (host feeding), in which case the female punctures an aphid with her ovipositor, turns around and sucks the body contents of her prey. She can also feed on aphid species which she does not parasitize. Moreover, Aphelinus can also eat honeydew.

Aphelinus abdominalis can distinguish parasitized from non-parasitized aphids (host discrimination). Only very rarely the female will deposit a second egg in an aphid that has already been parasitized.

For a good activity Aphelinus requires enough light and sufficiently high temperatures. Although some hyperparasites of Aphelinus are known to exist, in practice it is not a problem, as is the case with Aphidius colemani.

Although Aphelinus abdominalis parasitizes several species of big-sized aphids, it is mainly used for biological control of potato aphid (Macrosiphum euphorbiae) and glasshouse potato aphid (Aulacorthum solani). Aphelinus is applied on several greenhouse crops such as sweet pepper, tomato, eggplant, bean, gerbera, rose, chrysanthemum, ...

The parasitic wasps should be introduced in the greenhouse at the first signs of aphids. They are released in and around beginning hot spots at 0.5-2/m², depending on the crop and the circumstances.

Remember that Aphelinus has a long-lasting but slow activity. For a faster approach the parasitic wasp Aphidius ervi and the gall midge Aphidoletes aphidimyza are more suited. More advanced infestations are tackled with the ladybirds Hippodamia convergens or Harmonia axyridis, or with a chemical treatment with pirimicarb (Pirimor, Rapid, ZZ Aphix, III).

Aphelinus abdominalis is supplied per 100 adults in a tube. The wasps are released low in the crop by tapping softly on the opened tube.

Aphelinus can be stored for a few days at 8-10°C (46.4-50°F).

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