Aphiline e contains the aphid parasite Aphidius ervi Haliday, Braconidae, Hymenoptera.
The product is supplied as a mixed mummy and adult product in vials. Purified mummies are packed into vials shortly before despatch, and the first adult parasites emerge in transit. The numbers that emerge in transit will vary depending on temperature and the duration of transit. Each vial contains a food supply to ensure that those adults that do emerge arrive in the best possible condition.
No carrier material is used, so that the emerging adults are able to fully expand their wings, and can quickly reach the available food without becoming exhausted by crawling through a shifting mass of particles. This packaging method also allows the grower to see the product clearly, and judge its quality and purity.
General information
How does it work?
Aphidius ervi females seek out and parasitise aphids. The main targets for this parasitoid in commercial crops are Macrosiphum euphorbiae and Aulacorthum solani. It is also commonly recorded from the Pea Aphid, Acyrthosiphon pisum, and research on the biology has been done on this species and on the Peach Potato Aphid, Myzus persicae. Other aphid species are also attacked, but less information is available about these.
Aphidius ervi is originally a European species, but it has been widely introduced into North and South America, Australia and other regions in recent years as part of biological control programmes for aphids on a variety of crops. Once a female finds an individual aphid or aphid colony, she will palpate the aphids with her antennae. If the aphid she is examining is of the correct size and has not already been parasitised, she rapidly curls her abdomen under her body and stabs the aphid with her ovipositor. This takes less than one second, but in this time the female checks the identity of the aphid with her ovipositor and lays an egg into it if she is satisfied. The egg soon hatches, and the resulting larva begins to feed within the aphid. Initially it will not kill the host, but as it grows it begins to feed on the vital organs so that the aphid dies. When fully grown, the Aphidius larva cuts a slit in the hollowed out shell of its host and attaches the carcass to the substrate with silk. As it spins more silk within the host skin, this gradually takes on a pale grey colour and forms the characteristic ‘aphid mummy’. Within the mummy the larva pupates and after five to ten days an adult is ready to emerge. The adult cuts a circular trap door in the mummy, always on the upper surface at the back, and escapes through this to seek out new hosts.
The life cycle of Aphidius ervi is longer than that of Aphidius colemani at the same temperatures and the parasite is larger and selects larger hosts. Whereas A. colemani reaches adulthood within 14 days at 21°C, A. ervi takes nearly 19 days at the same temperature At 15°C, the duration of the cycle is approximately 20 days for Aphidius colemani, while it is nearly 29 days for A. ervi.
When and where should you use it?
Aphiline e can be used in any crop where Macrosiphum euphorbiae is the principal pest aphid occurring. Although it is a vigorous parasite, which can attack many individual aphids, it will work best when used prophylactically during periods when aphids are expected to arrive in the crop. This will ensure that at least some of the initial aphids colonising the crop will be found and parasitised, so that colonies may grow slowly or be stopped entirely before they reach damaging levels. There will then be fewer large colonies and fewer aphids will develop as winged individuals to spread through the crop and form new foci of infestation.
This prophylactic approach can be achieved using either regular low rate releases of between 0.25/m² and 0.5/m²/week, or by using cereal plants infested with an alternative aphid host which will not attack the principal crop.
These ‘banker plants’ are popular with many growers, but they require horticultural care and may need repeated releases of cereal aphids to function correctly.
This prophylactic approach may entirely avoid aphid outbreaks, but if not it will slow the development of colonies of aphids to allow the grower extra time in which to act. Aphidius ervi can also be released correctively directly onto existing colonies, but the rapid reproductive rate of aphids and the lag between parasitism by Aphidius spp. and death of the host may allow the population to grow beyond the level at which economic damage is caused. It may therefore be necessary to use some other biological agent such as Adalia bipunctata or Chrysoperla carnea, or a compatible chemical agent to reduce localised outbreaks to a manageable level before releasing Aphidius.
How should you use it?
Adults must be released into the crop as soon as possible after receipt, ideally in cool temperatures and low light levels to avoid the risk that they will fly immediately to the roof of the greenhouse. If this is not possible, they should be kept at 6-8°C in darkness until release. Mortality will occur during any period of storage.The Aphiline e product will be delivered as a mixture of adults and mummies. The adults present will have hatched in transit, and there will normally be unhatched mummies present. These should also be released in cool temperatures and low light levels if possible, but will survive short periods of storage.
In both cases release the adults present in the vial amongst the foliage, whilst walking through the crop. Keep the vial almost horizontal to release the wasps slowly: hold it vertically to release the wasps quickly, for example close to a colony of aphids. The former technique should be used for low rate preventive releases on a regular basis, while the latter might be used for higher rate corrective releases. Finish by placing the open bottle in the greenhouse next to a plant in case more hatch. Do not tip the mummies onto the leaves, as this will expose them to lower humidities and reduce the emergence success.
When should you not use it?
Do not use Aphiline e for the control of Myzus persicae or Aphis gossypii. Although there will be parasitism of the former species, the alternative parasitoid Aphidius colemani will be more effective in the majority of cases.
Do not use Aphiline e as the sole means of control where there are very high populations of Macrosiphum euphorbiae or other large aphid species present on the crop. The rate of population growth of the aphid will make it difficult to gain control rapidly in this situation. Control will eventually occur, but not before substantial crop damage has occurred. In this case it is more appropriate to use a compatible chemical treatment, or possibly a predator such as lacewing larvae or Coccinellid beetles, to reduce the population to a more manageable level before using Aphiline e.
What will it not do, and what are the control options?
The product will not control Aphis gossypii and some other aphid species, and it is important to identify the pest if possible before making any releases of aphid parasites. Where the aphid is Aphis gossypii or Myzus persicae use the parasite Aphidius colemani for control.
If there is any doubt as to the identity of the aphid species, it may be advisable to release a mixture of parasites including Aphidius ervi, Aphidius colemani and Aphelinus abdominalis until a determination can be made.
At high population densities it is possible to release the predatory Cecidomyiid Aphidoletes aphidimyza, and some growers favour the use of larvae of the lacewing Chrysoperla carnea (or Chrysoperla rufilabris in North America). The fungal pathogens Verticillium lecani and Beauveria bassiana and the coccinelid beetles Hippodamia convergens and Harmonia axyridis may also be available for aphid control in some countries.
There are also a number of chemicals available for aphid control, which are compatible with other biological control agents. Amongst these are pirimicarb and pymetrozine. Imidacloprid may also be used effectively for spot applications and is best applied as a drench to the roots of the plants. The availability of insecticides varies between countries, as do formulations and methods of application permissible. Always check the availability of a particular compound on the crop and in the country concerned.
Chemical compatibility
A number of insecticides for aphid control are compatible with the use of Aphidius.
Products that kill the host aphid will inevitably reduce parasitoid populations by killing hosts containing feeding parasite larvae, but Aphidius pupae within mummies may survive. Avoid use of insecticides between release of Aphidius and mummy formation on the plants.
Compatible products for control of whitefly, spider mite and Lepidoptera also exist, but the majority of compounds available for thrips control are deleterious.