Adalia bipunctata is a predatory beetle which is best known for feeding on aphids. It is a specialist at exploiting the rapid growth of aphid colonies, arriving when the colony is large and plenty of food is available, and moving on to the next colony as the food supply diminishes. Adults are typical ladybird beetles, with shiny, brightly coloured and boldly patterned wing cases which protect the membranous wings. The wings are carefully folded beneath these cases when not in use, and it may take several seconds for a ladybird to unfold its wings so that it can fly.
Larvae are very different in appearance, with relatively long bodies which taper towards the rear end, and three pairs of prominent, dark legs which project outwards from the front third of the body. They are usually grey in colour with some dark and some orange spots. This form is typical of the larvae of beetles in the family Coccinellidae.
Adult females lay clusters of bright, orange - yellow eggs on plants. After a few days, these eggs darken and produce small larvae which initially cluster around the egg mass. They quickly move away in search of food.
When fully fed, the larvae anchor themselves to a leaf or other surface to form a pupa. During this non-feeding stage, the larval tissues are re-organised to form the adult, a process known as metamorphosis. At the end of this stage, an adult beetle will emerge from the pupal case. Initially these adults are soft and pale, and unable to feed or fly, but over a day or two their cuticle hardens and darkens to produce the typical form described above.
Both adults and larvae are predatory. and will eat many types of small insects, not only aphids. They can consume very large numbers of prey, and destroy quite large colonies of aphids. If food is not available, they are strongly cannibalistic: adult beetles will eat eggs, and larvae will eat eggs and other larvae.
When and where should you use it?
Adalline b can be used as a spot treatment to reduce localised outbreaks of aphids. It is normally used in conjunction with other aphid predators such as Aphidoletes aphidimyza, or with aphid parasitoids such as Aphidius colemani, Aphidius ervi, or Aphelinus abdominalis.
It will eat many species of aphids, and so can also be used when the identity of the aphids in uncertain, or when more than one species is present.
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. Adults will often chose to fly away once released, even in the presence of large numbers of aphids.
Larvae should be used as soon as possible. Their cannibalistic nature means that they will begin to eat each other as soon as the food provided for them during transport is exhausted. Take care when releasing them that any carrier material does not fall to the floor: it is important that it remains on the leaves initially so that the larvae can move onto the plants.
Release adults or larvae directly into the colonies of aphids which you wish to control. Rates of use will depend upon the level of infestation by the pest: high rates will give rapid reductions in aphid numbers, whilst lower rates may allow the aphids to persist and multiply. More than one release may be necessary, especially where larvae are used, because the first individuals may reach full size and turn into non-feeding pupae before the aphid infestation is controlled. If this happens, there will be no control of the aphid population until fresh adults emerge from the pupae.
When should you not use it?
Adalline b is not recommended for preventive use.
What will it do?
Adalline will support non-chemical control of aphids as part of a programme using aphid parasitoids. It is ideally suited to the clean-up of outbreaks of aphids within an otherwise successful control programme. Note, however, that parasitised aphids may also be consumed by Adalia bipunctata and other Coccinellid beetles.
It will consume many species of aphid, some of which are not controlled by commercially available parasitoids such as Aphidius spp.
What will it not do, and what are the control options?
Adalline b will not prevent aphid infestations, nor will it eradicate aphids in most situations. It is a specialist at exploiting the rapid growth of aphid colonies, arriving when the colony is large and plenty of food is available, and moving on to the next colony as the food supply diminishes. As such, some aphids normally remain in any colony, and populations can rapidly increase again.
It should be used as part of a programme with aphid parasitoids and other aphid predators. Where the principal aphid is Myzus persicae or Aphis gossypii, use Aphidius colemani preventively or curatively. For Macrosiphum euphorbiae or Aulacorthum solani, use Aphidius ervi. Aphelinus abdominalis is also available for control of Macrosiphum euphorbiae. Where the aphid species is unknown, or mixed species are present, there are two options available:
- Aphiline ACE mix contains a mixture of all the three parasitoids mentioned
- Aphidoline a contains the predatory midge Aphidoletes aphidimyza, which has a broad host range and will attack and kill many species of aphids
The latter is the preferred option on crops such as strawberries, where several species of aphids occur which cannot be controlled adequately with commercially available parasitoids.
There are also a number of chemicals available for aphid controls that are compatible with biological control agents, such as pymetrozine. Neonicotinoids such as thiamethoxam may also be used effectively for spot applications and are 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