Scientific name: Agonoscena pistaciae
Family: Aphalaridae

LIFECYCLE

The common pistachio psylla has two distinct seasonal forms that differ morphologically as well as biologically. The winter form is larger and darker and is observed in early October when it migrates towards the sites where it overwinters (tree trunks, wall cracks, field ground). Psyllas become active in late April as they mate and embed their eggs mostly on the upper surface of pistachio leaves by a small pedicel that provides moisture to the egg, but also on the petioles and young shoots. The summer form of the psylla will emerge from those eggs, which are 2-3 mm long with a light-yellow colour. This form develops and mates within a large temperature range and has several generations (4-5) per year. The adults grow better at 30 ^oC whereas the nymphs at 25-32.5 ^oC. The common pistachio psylla passes through 5 nymphal instars which all are mobile followed by a sexually reproducing adult stage.

PLANT INJURIES

Both adults and nymphs pierce and suck the juice from the buds and tender parts of the pistachio tree producing massive quantities of sticky honeydew that forms white solid granules immediately following secretion, which then favours mould development. Heavy populations weaken the trees and affect the current year’s and subsequent year’s yield.

ΚΑΤΑΠΟΛΕΜΗΣΗ

CHEMICAL CONTROL

Treatment with suitable pesticides in July and August. Use of 1% soap and 0.5% alcohol solution is recommended in order to dissolve the sticky honeydew. Repeated after harvest.

BIOLOGICAL CONTROL

• Placement of yellow glue traps in the field.
• Coating of the bark with Bordeaux mixture.
• Protection of all natural predators who feeds on psyllids and their nymphs, such as various ladybugs (Psyllovora spp., Hyperaspis spp., Synharmonia conglobata), spiders, or small wasps (Psyllaephagus pistaciae) which lay their eggs on psylla nymphs.

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Bibliography: Mehrnejad M.R. (2020): Arthropod pests of pistachio, their natural enemies and management. Plant Protect. Sci., 56: 231–260.

Athanasia Chatziperi, Agronomist, Attica Region