Diaphorina citri

Kuwayama, 1907

Asian citrus psyllid, ACP

, the , is a small hemipteran insect and one of two confirmed of Huanglongbing (HLB), also known as , caused by the bacterium Candidatus Liberibacter asiaticus. Native to southern Asia, it has spread to citrus-growing regions worldwide including the Americas, Middle East, and Oceania, posing a severe threat to global citrus production. The insect feeds on phloem sap of new citrus growth and has become the focus of intensive , monitoring, and genomic research efforts due to its economic impact.

Diaphorina citri by no rights reserved, uploaded by Jesse Rorabaugh. Used under a CC0 license.

Diaphorina citri by no rights reserved, uploaded by 余世文. Used under a CC0 license.

Pronunciation

How to pronounce Diaphorina citri: //ˌdaɪəfəˈraɪnə ˈsɪtraɪ//

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

Identification

Distinguished from the African citrus (Trioza erytreae) by wing shape and color pattern. Separated from aphids by jumping , ten-segmented , and absence of abdominal cornicles. The waxy secretion and mottled coloration separate it from other psyllid . Nymphs lack abdominal spots present in some related species.

Images

Habitat

Citrus orchards and residential citrus plantings; specifically associated with new flush growth of citrus and related Rutaceae. Found in tropical, subtropical, and warm temperate climates where citrus occurs.

Distribution

Native to southern Asia; established in Middle East, South and Central America, Mexico, Caribbean, and United States (Florida since 1998, California since 2008, plus Louisiana, Georgia, Arizona, South Carolina, Texas, Hawaii). Present in Oceania (American Samoa, Guam, Northern Mariana Islands, Papua New Guinea). Under programs in some California regions.

Seasonality

Activity coincides with citrus flush growth periods; in California, major flushes occur spring and fall with young trees and lemons producing periodic growth during warm weather. Development cycle takes 2–7 weeks depending on temperature.

Diet

Feeds on phloem sap of new leaf growth (feather flush) of citrus and related plants in Rutaceae; specifically targets tender new shoots and unfolding leaves.

Host Associations

Citrus spp. - primary All commercial citrus including oranges, lemons, mandarins, grapefruit
Murraya paniculata - alternate Orange jessamine; highly attractive for oviposition
Murraya koenigii - alternate Curry leaf plant; fastest completion observed
Citrus aurantifolia - Himalayan lime
Citrus reticulata - Mandarin

Life Cycle

laid on tips of growing shoots between and near unfolding leaves; female may lay up to 800 eggs over several months. Nymph passes through five instars. Whole development cycle completed in 2–7 weeks depending on temperature and season. Eggs hatch into nymphs that develop through five before becoming winged .

Behavior

Adopts characteristic -down, tail-up posture while feeding. Highly mobile, jumping insect compared to sedentary aphids. Aggregated distribution pattern on flushes within trees. Does not avoid plants with predatory mites even after experiencing . Attracted to yellow color and UV wavelengths; probing stimulated by formic acid and acetic acid on leaf surface.

Ecological Role

Primary of Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing (), one of the most devastating citrus globally. Also implicated in transmitting Tristeza virus. Serves as prey for various agents including and predatory insects.

Human Relevance

Major economic pest threatening multibillion-dollar citrus industries worldwide. Subject to restrictions and programs in multiple jurisdictions. Intensive research focus for RNAi , -based trapping systems, and . California Department of Food and Agriculture maintains hotline (1-800-491-1899) for public reporting.

Similar Taxa

Trioza erytreaeAfrican citrus ; distinguished by different wing shape and color pattern
Aphids (Aphididae)Often co-occur on citrus; distinguished by sedentary , 4–6 segmented , and presence of cornicles

More Details

Genomic resources

Complete sequenced (Diaci v3.0 -level assembly released 2023–2024); transcriptome identifies over 25,600 predicted genes. Genome enabled development of RNAi and antisense oligonucleotide control strategies.

Endosymbionts

Houses specialized bacteriome organ containing Candidatus Carsonella ruddii (nutrition) and Candidatus Profftella armatura (nutrition, defense toxins, ). Also associated with and can harbor Candidatus Liberibacter asiaticus.

Biological control agents

Primary Tamarixia radiata successfully established in multiple countries; Diaphorencyrtus aligarhensis less successful due to competition. Predatory mites (Amblyseius herbicolus), lady beetles, and fungal entomopathogens (Isaria fumosorosea, citriformis) also used.

Pheromone discovery

identified by Walter Leal team (2017); acetic acid-based lures capture approximately three times more individuals than standard yellow sticky traps, particularly effective at low densities.