Parasitic Wasps Against Aphids And Whitefly

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The beneficial insects can be used as a natural method of combating plant pests. We reveal how parasitic wasps can be used successfully against aphids, whiteflies, and the like.

Ichneumonidae are beneficial insects that live as parasites. They lay their eggs to develop in insects or insect larvae, which causes them to die after the larvae hatch. As soon as all host insects have been killed, the parasitic wasp no longer holds anything on the scene and it disappears almost unnoticed. This makes it an elegant and ecological alternative to chemical crop protection.

But the use of parasitic wasps should be well prepared: The useful little helpers are very specific when it comes to the choice of their host. However, you shouldn’t be put off by the high host specificity. Most parasitic wasp suppliers also provide comprehensive advice and help you make the right choice. We’ll tell you in which areas and how exactly you can use parasitic wasps.

Parasitic wasps are a very species-rich family of insects. Due to a large number of different species, parasitic wasps can also be used against various pests. They are useful against both aphids (Aphidoidea) and scale insects (Coccoidea) and whitefly (Aleyrodoidea), better known as whitefly. They can be used both in closed rooms such as greenhouses or living rooms as well as outdoors. In closed rooms, the little helpers do not migrate so quickly, which is why their use is particularly effective here. Ichneumon wasps can be used at air temperatures of 15 to 30 ° C. It is therefore not recommended to use it until late spring.

Parasitic wasps against aphids

Aphids belong to the plant lice (Sternorrhyncha) and are annoying companions in every garden. With their stinging mouthparts, aphids suck on the phloem sap of the plants, which is very sugary. However, the aphids cannot use all of the sugar in addition to the other valuable phloem components. Therefore, they excrete a large part of the sugar as honeydew. This creates a sticky, shiny film on leaves or your windowsill.

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The ichneumon wasp is inconspicuous at around three millimeters in length, but very effective against aphids. A female can parasitize around 500 aphids in a short time. It lays an egg with its sting in the previously anesthetized aphid. A larva then grows out of the egg and kills the aphid as it grows – what is left is what is known as an “aphid mummy”.

If the aphid infestation is very widespread, the parasitic wasps are even able to track down and parasitize individual animals, which is why they also have a preventive character in control. However, if you have problems with a very dense infestation, it is advisable to include other beneficial insects such as ladybirds (Coccinellidae).

Parasitic wasps against aphids & whitefly: tips for use

Note: Some species of aphids are “milked” by ants, which means that the ants obtain the sugary honeydew from the aphids for their own food. To protect their “aphid herd”, the ants defend their lice against enemies such as the ichneumon wasp. Some parasitic wasp species, for example, Lysiphlebus testaceipes, can imitate the smell of aphids by excreting fragrances so that they are camouflaged and are not attacked by the ants.

Here is a brief overview of the most important aphid species and their most effective opponents:

Aphid species Ichneumonid wasp for control
Pea louse ( Acyrthosiphon Pisum ) Prawn involucre
Green peach aphid ( Myzus persicae ) Aphidius colemani
Great raspberry louse (Amphorophora idaei ) Praon volucre
Potato mouse (Macrosiphum euphorbiae ) Aphidius matricariae
Great rose aphid ( Macrosiphum rosae ) Aphelinus abdominalis
Black bean louse ( Aphis fabae ) Lysiphlebus testaceipes

Tip: ichneumon wasps are sold in the ice stage. The beneficial insect eggs, which are used on a large scale, are applied to cardboard or small paper balls and are therefore immediately ready for application. The dispatch takes place only between 5 and 30 ° C and is reasonably only processed on a few fixed days of the week to always guarantee fresh parasitic wasps.

The fact that you may have to wait longer for your animals can therefore be a sign of quality! As soon as the beneficial insects have arrived, you should get them out of their packaging as soon as possible. In any case, we recommend being careful with the little helpers so as not to crush them. Please also note: Depending on the degree of infestation and the spatial situation – i.e. outdoors, winter garden, or greenhouse – a repeated order every two weeks is necessary to sustainably decimate the plant lice.

Parasitic wasps against scale insects

Scale insects (Coccoidae) particularly affect your plants by sucking out the sap. The males are usually winged and appear as single individuals. The females of most species, however, have an eponymous flat and shield-shaped body. The females of the cup scale insects (Coccidae) have a very strongly arched back and therefore have a more spherical body.

Mealybugs (Pseudococcidae), which are also known as mealybugs, also count among the scale insects, but instead of the shield-shaped body, they have a striking white “hair” made of wax threads. Female scale insects live in colonies and diligently suckle on the phloem of the plant. They also lay their eggs under their shield on the leaves of the infested plant, from which new adult pests later develop.

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Since the scale insect family includes many different species, it is important to select the right little helpers for pest control. The parasitic wasp Metaphycus flavus, for example, feeds on eggs and young scale insect nymphs. It also lays eggs under scale nymphs, from which parasitic wasp larvae hatch. These penetrate the pest and help you to get rid of the scale insects. New beneficial insects develop in the parasitized cocoons. The parasitic wasp species with the greatest successes in the control of scale insects is Metaphycus flavus. But other parasitoid species such as Coccophagus lycimnia and Aphytis melinus are also showing good results.

Parasitic wasps against aphids & whitefly: tips for use

Important: If you have problems precisely identifying the small parasites, beneficial insect sellers offer support. The host specificity of the beneficial insects is the decisive factor, whether control is crowned with success or not.

Ichneumon fly against whitefly

The term “whitefly” does not actually mean a fly, but rather a trivial name for some representatives of the whitefly (Aleyrodidae). The most important pests, known as whitefly, are the cabbage whitefly (Aleurodes proletella ) and the greenhouse whitefly (Trialeurodes vaporariorum ). Whiteflies are one to two millimeters in size, their wings are covered with white wax dust. The larvae of the pest are particularly feared in the greenhouse, but they can be brought under control through the use of beneficial insects.

The spatial limitation prevents the parasitic wasps from migrating to other hosts and can thus be used in a very targeted manner. The temperature in the greenhouse must be optimal. The ideal temperature, depending on the parasitic wasp species, is between 18 and 22 ° C and is crucial for the development of the parasitic wasp population. You can ensure that the little helpers feel comfortable by ventilating them regularly.

The parasitic wasp Encarsia Formosa has proven to be particularly valuable when it comes to combating whitefly. It is doubly useful: Older development stages of the larvae are parasitized and serve as a host for the next generation of Encarsia Formosa. Younger stages of development are used as food by adult parasitic wasps.

Parasitic wasps against aphids & whitefly: tips for use

Summary: Use parasitic wasps against plant lice

  • Parasitic wasps can be used against various plant lice, namely aphids, scale insects, and whiteflies.
  • Parasitic wasps only parasitize certain lice, which is why you should make sure that the parasitic wasp matches the pest when using them specifically. The beneficial insect dealers will be happy to advise you on this.
  • The use is possible in closed rooms and in the open field, whereby the use in rooms is much more effective.
  • The air temperature should be between 15 and 30 ° C for successful use.
  • Temperatures between 18 and 22 ° C and regular ventilation ensure that the ichneumon wasps stay healthy and hard-working.

Alternative control method: pest-free neem

If house plants are heavily infested with aphids, scale insects, or whiteflies, beneficial insects such as parasitic wasps are sometimes not sufficient. The targeted use of beneficial insects is also often difficult in the field. In these cases, we recommend the use of a biological pesticide. Such biological pesticides protect the naturally occurring beneficial insects in the field so that they can continue to “work for you” as a preventive measure instead of being harmed. Unfortunately, this does not usually apply to synthetic pesticides against plant lice. You should make sure that you do not use beneficial insects and pesticides at the same time, not even biological agents.

Neem-based preparations are a very effective way to naturally control aphids, scale insects, or whiteflies. The neem oil from the seeds of the neem tree contains the active ingredient azadirachtin, which is ideal for use against plant lice. Organic pest-free neem is based on this valuable neem oil and offers you the possibility of controlling the pests purely plant-based. The active ingredient is absorbed by the lice when they suckle on the plant and causes the sucking activity to stop quickly.

The development of the larvae is disturbed so that the entire population is damaged and disappears. Organic pest-free neem is simply mixed with water and the emulsion is sprayed onto the infected plant. You can use organic pest-free neem both indoors and outdoors – it is not dangerous to bees. Please note that you use our organic pest-free neem as specified in the application recommendation. Therefore, please read the instruction leaflet before use.

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Tip: Organic pest-free neem is not only effective against aphids, scale insects, and whiteflies but also helps you to fight spider mites naturally.

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