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Common green capsid – additional information

Life cycle

Common green capsid overwinters as eggs inserted into the bark of young, tender shoots of woody hosts, including apple, pear, currant and gooseberry.

  • The eggs hatch in April over an extended period of several weeks between the pink bud growth stage and the end of blossom of apple.
  • The nymphs are active and feed in the growing points of shoots and on young developing fruits until early May when they migrate to herbaceous hosts such as potato, strawberry and many weeds.
  • Here they continue their development until the adult stage.
  • Adults are very active and frequently fly in sunshine.
  • In late June and July, eggs are laid in the stems of summer herbaceous hosts such as potato, bindweed, dandelion, nettle, dock and many other weeds.
  • A second generation develops on these hosts reaching adulthood by the autumn.
  • A return migration to woody winter hosts occurs where eggs are eventually laid, especially in young, tender shoots.

Pest status

It is frequently a damaging pest of apples and sometimes pears. More serious outbreaks seem to occur in certain years, with the pest being much less important in others.

Other hosts

All fruit crops can be attacked as well as certain arable crops, notably potatoes.

Varietal susceptibility

All apple and pear varieties are susceptible.

Distribution

Widespread and abundant.

Damage

  • Adults and nymphs make small feeding punctures in leaves, mainly in the young leaves in shoot tips around the mid-vein.
  • The punctures turn brown and eventually black.
  • Leaves grow unevenly and become distorted and puckered.
  • Nymphs also feed on young developing fruitlets causing similar puncture marks.
  • As the fruitlets grow, irregular corky scars are formed and the fruit is misshaped.

Recognition

Adult
5.0-6.5 mm long. Bright green with a dusky yellow pubescence.

Nymph
Pale to bright green, tips of antennae orange-red. Fast moving

Egg
1.3 mm long, banana-shaped, cream, smooth and shiny. Inserted into the stems of plants.

Other pests with which the common green capsid may be confused

Other capsids

  • Adults and nymphs of the apple capsid, Plesiocoris rugicollis, are very similar in appearance to those of the common green capsid.
  • However, the apple capsid is uncommon in commercial apple orchards as it is sensitive to insecticides and does not occur on a wide range of other host plants.
  • It is more common in unsprayed and organic apple orchards where it can be an important pest.

Green apple aphid and apple grass aphid

  • These aphids have a green appearance and are found in the growing points of plants.
  • However, aphids are slow moving or sedentary and often occur in colonies.
  • They have honey tubes (siphunculi) whereas capsids do not.
  • Aphids do not cause the chlorotic feeding puncture marks that are characteristic of capsids

Monitoring

Common green capsid is usually most abundant at the edges of orchards next to hedgerows, woodland or alder windbreaks and especially on apple trees with rootstock sucker growths. The tender shoots of such sucker growths are favoured sites for oviposition by adults the previous autumn and usually show signs of infestation first.

  • The suckers on trees at the edges of orchards can be inspected in the dormant period for the characteristic bumps indicating where eggs have been inserted into the stem.
  • The tips of rootstock sucker growths are often a good indicator of presence or absence of capsids in an orchard.
  • They can be inspected on 2 3 occasions for damage from late green cluster to petal fall to determine when egg hatch has started.
  • However, best practice is to remove them in winter (see Cultural control).

The best method of assessing levels of common green capsid is by using the beating method [hyperlink to this in the Introductory section, pest and disease assessment], which can detect the pest at low levels before significant damage is done.

  • A sample of at least 25 (preferably 50) beats should be made per orchard when the pest assessment is done at the late blossom growth stage of apple.
  • If any capsid is collected, beat sampling should continue to confirm the level present.
  • The treatment threshold is 3 capsids per 50 beats.
  • This method is time-consuming and seldom used in practice.
  • As an alternative, the 25 trees should be visually inspected for signs of capsid feeding damage.
  • If significant damage is detected, an insecticide treatment should be applied promptly at petal fall.

Work is in progress at East Malling Research and Natural Resources Institute currently to develop a pheromone lure and trap for monitoring common green capsid.

Forecasting

In the Netherlands, a phonological forecasting model has been developed for the common green capsid bug but it is not generally available.

  • Work in the Netherlands has suggested that the time to monitor for the third instar nymphs which are most damaging to apples is when daily temperature sums above 4oC accumulated from 1 January amount to 568 2.05*DTs245  where DTs245 indicates the day on which 245 day-degrees is reached

Chemical control

A spray of an approved insecticide should be applied promptly at petal fall if damaging infestations are detected.

  • Thiacloprid (Calypso) applied for control of rosy apple aphid at this stage will  control capsids as well as other petal fall pests including apple sawfly.
  • Several other novel insecticides recently approved for control of aphids on apple and/or pear in the UK may have useful activity against capsid bugs including acetamiprid (Gazelle), flonicamid (Mainman) and pyrethrins (Spruzit).

In other European countries in the past, mineral oil was applied just before bloom to kill the eggs just before emergence at around 200 day-degrees above 4 deg C after 1 January.

  • This was effective but timing was crucial.
  • Late application  resulted in leaf burning and application too early was not effective.
  • A local application was advised in places where damage by the capsids often occurred.

Cultural and biological control

Cultural control measures can significantly reduce common green capsid outbreaks in orchards.

  • Rootstock sucker growths, which often harbour the pest, should be removed and destroyed in winter.
  • Unfortunately, other beneficial capsid bugs, such as Blepharidopterus angulatus, deposit their eggs in the same place.
  • Weeds growing in the herbicide strip under the tree, especially Compositae (e.g. mayweed), act as a summer host for the pest.
  • These should be mown or destroyed before the second generation of adults mature in the late summer or autumn.
  • Isolation from hedgerows, woodland and windbreaks reduces the incidence of the pest, but the benefits of proximity to such habitats and the shelter they provide is usually considered to be a net benefit, because of the occurrence of beneficial insects.

Natural enemies

Predatory insects and spiders
Capsid bugs appear to have few natural enemies. They are preyed on by nabid bugs and spiders.

Pathogenic fungi
Outbreaks of pathogenic fungal diseases during wet periods in summer can greatly reduce capsid populations.

Biological control

Biological control approaches have not been developed for common green capsid.

Biotechnological control

The female common green capsid is known to produce a sex pheromone which attracts males for mating. The chemical structures of the pheromone components have not been identified though some progress has recently been made in the Netherlands.

  • The insect is attracted to white or yellow sticky traps, though these are not attractive enough in themselves to use for monitoring or control.
  • When the pheromone has been characterised, it may be possible to use it for monitoring and even possibly for control in combination with coloured sticky traps.

Further reading

Blommers, L. H. M. 1997. Life history, seasonal adaptations and monitoring of the common green capsid Lygocoris pabulinus (L.)(Hemiptera: Miridae). Journal of Applied Entomology 121, 389-398.

Groot, A. T.2000. Sexual behaviour of the green capsid bug. PhD thesis, Wageningen University, The Netherlands. 156pp.

Petherbridge, F. R. & Thorpe, W. H. 1928. The common green capsid bug (Lygus pabulinus). Annals of Applied Biology 15, 446-472.