Psylla pyricola Forster Pear sucker

This psyllid is an important pest of pear, and heavy infestations often result in fruit distortion and premature leaf-fall; summer infestations may have a deleterious effect on fruit-bud development and can check tree growth. Nymphs of the first generation can also cause direct damage to blossoms, the petals turning brown. Foliage and fruits are contaminated by honeydew, excreted in profusion by the nymphs, and by sooty moulds that subsequently develop on the honey-dew; affected fruits may be unmarketable unless washed or wiped clean.

BIOLOGY

Unlike apple sucker, this species is multivoltine and overwinters in the adult stage. The adults are active in sunny weather, even in mid-winter. They invade pear orchards from February onwards, eggs then being deposited on shoots and spurs. The eggs hatch in late March and April. First-instar nymphs invade the opening buds and blossom trusses; they then begin to feed. There are usually three generations each year and pest numbers typically increase at each generation and reach a peak in the late summer. Summer eggs are usually deposited on the underside of fully expanded leaves, often clustered in large numbers along the mid-rib. In autumn, adults of the final generation fly away from pear trees to seek overwintering sites in nearby hedges and other shelter.

DESCRIPTION

Adult 1.5-2.0mm long, brownish-black to reddish-brown; wings transparent (Fig. 187); winter form darker, with cloudy patches on the wings. Egg 0.3 mm long, elongate-oval and lemon-yellow to orange; pedicel moderately long. Nymph pinkish to orange, with dark brown to blackish markings; older individuals, and nymphs of the first generation, tend to be darkest.

NOTE In parts of continental Europe, Psylla pyri (L.) is the main psyllid pest of pear; its biology is similar to that of P. pyricola, with adults overwintering, but

Fig. 187 Pear sucker, Psylla pyricola (x25).

Fig. 187 Pear sucker, Psylla pyricola (x25).

there are up to six generations annually. Psylla pyri is of no pest status in the British Isles.

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