Cacopsylla

Ossiannilsson, 1970

jumping plant lice, pear psyllids

Species Guides

Cacopsylla is a of jumping plant lice ( Psyllidae) comprising that are significant agricultural pests, particularly of fruit trees. The genus includes most psyllids within Psyllinae that cause economic damage to orchards. Several species act as for phytoplasma-associated including Apple Proliferation, European Stone Fruit Yellows, and . Phylogenetic studies reveal two major clades that diverged in the Miocene, with Clade I predominantly species that overwinter on conifers. Vector competence has evolved independently rather than through shared ancestry.

Cacopsylla magnicauda by (c) Rebecca Ray, some rights reserved (CC BY), uploaded by Rebecca Ray. Used under a CC-BY license.

Cacopsylla by (c) Christian Back, some rights reserved (CC BY), uploaded by Christian Back. Used under a CC-BY license.

Cacopsylla by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Cacopsylla: //ˌkækəˈsɪlə//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Identification to level requires examination of morphological characters, often supplemented by molecular methods. A diagnostic tool targeting the mitochondrial Control Region has been developed to discriminate closely related species such as Cacopsylla melanoneura and C. affinis. Genetic variants within species exist; for example, C. melanoneura has two forms distinguished by a 56 indel (WI and WOI variants) that may differ in phytoplasma transmission ability.

Images

Habitat

Associated with plants in the Rosaceae including apple, pear, plum, and hawthorn. Clade I overwinter on conifers. Some species utilize non-host plants as temporary "whistle stops" for shelter and nutrients when primary hosts are unavailable.

Distribution

Europe, with particular study focus on Italy (Aosta Valley, northern Italy). Records also from Denmark, Norway, Sweden, and the United States (Vermont).

Seasonality

Activity patterns vary by . species (one per year) in Clade I migrate to conifers for . Species with multiple , such as those on pear, are active through the growing season with present from late spring into summer.

Diet

Phloem-feeding; nymphs and insert into plant vascular tissue to extract sap.

Host Associations

Malus - primary apple; C. melanoneura and C. picta are primary of 'Ca. Phytoplasma mali'
Pyrus - primary pear; C. pyricola and related develop exclusively on this
Prunus - primary plum and stone fruits; C. pruni of 'Ca. Phytoplasma prunorum'
Crataegus - primary hawthorn; C. melanoneura and C. affinis feed on this
Buxus - primary boxwood; C. buxi causes characteristic cupped leaf damage
Cercis - primary Judas tree; C. pulchella feeds on C. siliquastrum
Conifers - Clade I migrate to conifers for as or

Life Cycle

patterns differ between clades. Clade I are predominantly , with from deciduous to conifers for . Some species can develop on multiple related Rosaceae hosts. C. buxi has one per year with laid in terminal buds, nymphs developing in cupped leaves, and emerging in late spring.

Behavior

are capable of jumping and flying; disturbance of foliage causes adults to jump off plants in large numbers. Some demonstrate extensive landscape movement between agricultural and non-agricultural . Nymphs of some species produce conspicuous white waxy filaments for protection.

Ecological Role

of phytoplasma causing significant agricultural . C. melanoneura and C. picta transmit 'Candidatus Phytoplasma mali' (Apple Proliferation disease). C. pruni transmits 'Ca. Phytoplasma prunorum' (European Stone Fruit Yellows). C. pyricola and related transmit pathogens causing . of phytoplasmas has been demonstrated in C. pruni. The serves as for complexes that may provide .

Human Relevance

Major agricultural pests causing yield reductions and tree in European orchards. Monitoring and management are complicated by the difficulty of tracking movements between crop and non-crop . -based gut content analysis has been developed to identify prior feeding plants and predict crop risk. Some cause cosmetic damage to ornamental boxwoods.

Similar Taxa

BactericeraAlso containing agricultural pests (e.g., B. cockerelli, the potato/tomato psyllid); distinguished by different associations and phylogenetic placement
DiaphorinaContains the Asian citrus psyllid D. citri, a major citrus pest; differs in specificity and geographic distribution

More Details

Phylogenetic Structure

Two major clades identified: Clade I (including C. melanoneura, C. picta, C. pruni) diverged from Clade II (including C. mali) in Early to Middle Miocene. sizes vary significantly: 438 Mb in C. melanoneura versus 631 Mb in C. picta, largely due to repetitive element expansion.

Vector Competence Evolution

Ability to transmit phytoplasmas reflects independent evolutionary trajectories rather than shared ancestry, as closely related (C. melanoneura and C. pruni) differ in competence from C. picta despite shared Clade I membership.

Genetic Variation

C. melanoneura exhibits two genetic variants (WI with 56 indel, WOI without) that may differ in phytoplasma transmission and plant ability.