Asian Psyllid, Kuwayama (: ) ... http://link.springer.com/referenceworkentry/10.1007/978-1-4020-6359-6...

John L. Capinera Encyclopedia of Entomology 10.1007/978-1-4020-6359-6_10360 © Springer Science+Business Media B.V. 2008

James H. Tsai 1

(1) University of Florida, Ft. Lauderdale, FL, USA

The Asian citrus psyllid Diaphorina citri, is of Far Eastern origin and is also called the oriental citrus psyllid. Its known range of distribution covers tropical and subtropical Asia including India, Burma, Thailand, Nepal, Sikkim, Hong Kong, Ryukyn Islands, the Philippines, Malaysia, Indonesia, Ceylon, Pakistan, Afghanistan, Reunion, and Mauritius. It is also found in Saudi Arabia in the Near East, and Brazil in South America. This was first discovered in the United States in 1998, and is now widespread in southern Florida.

Diaphorina citri causes severe damage to citrus by: (i) withdrawal of a large quantity of sap from the foliage, affecting the overall growth of citrus, and promotion of sooty mold on honeydew secreted onto leaves, which results in reduction of photosynthesis; and (ii) efficient transmission of greening bacterium (Liberobacter asiaticum) by D. citri. The greening disease (Huanglungbin) is a limiting factor in citrus production in the Far East, though it does not occur in Florida. Citrus infected by the greening agent initially shows leaf mottling and chlorosis symptoms, followed by stunted growth, unseasonable bloom and leaf and fruit drops. Eventually, branch dieback and a general decline will result. Fruits from infected trees are small, uneven in size, off color, and having objectionable flavor. In Southeast Asia, mandarins and oranges are the main citrus trees planted in commercial groves, and they are the most susceptible cultivars. Liberobactor asiaticum is a phloem- limited, gram-negative bacterium which also can be readily transmitted by grafting and propagating with infected plant material. Both the nymph and adult can transmit the greening agent in 15 min acquisition feeding time. The incubation period in the vector is about 3 weeks. The infectious vector can retain the pathogen for life.

The length of the life cycle of Asian citrus psyllid varies from 27 to 117 days, depending on rearing temperature and host plants. The average developmental time for the immature stages is from 14 to 49 days within 15–28°C. D. citri nymphs undergo five instars. The adult longevity averages from 34

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to 88 days within the temperature range of 15–30°C. The maximal longevity of individual females is 117 and 51 days at 15 and 30°C, respectively. The individual female may lay more than 748 eggs at 28°C. A total of 1,378 eggs have been reported to be deposited by a single female on grapefruit. Asian citrus psyllid can feed and breed on most citrus spp., two species of Murraya and three genera of Rutaceae. The developmental time of immature stages on various host plants varies significantly, ranging from 69 days on sour orange to 85 days on grapefruit. The average adult longevity on rough lemon is significantly longer than those on orange jassamine, grapefruit and sour orange. However, the females preferentially lay more eggs (averaging 858 eggs/female) on grapefruit than the other hosts mentioned above. The egg incubation period is about 4 days regardless of host plants. Eggs are deposited within 2 cm lengths of terminal tissue, including leaf folds, petioles, axillary buds, upper and lower surfaces of young leaves and tender stem. The egg is anchored on a slender stock-like process arising from the plant tissue. The egg is elongate, with a broad basal end and tapering towards its distal and curved end. The average size of egg measures 0.31 mm long and 0.14 mm wide. Freshly deposited eggs are light yellow, turning bright orange with 2 distinct red eye spots at maturity. First and 2nd instar nymphs mostly aggregate and feed on the inside of folded leaves, the terminal stem and between the axillary bud and the stem of tender shoots. Young nymphs are quite docile and they only move when disturbed or overcrowded. The nymphs continuously secrete a copious amount of honeydew from the anus, and thread-like waxy substance from the circumanal glands, resulting in the growth of black sooty mold on the lower leaves. The average size of 1st instars measures 0.30 mm in length and 0.17 mm in width with light pink body and a pair of red compound eyes. The measurement of 2nd instars averages 0.45 mm long and 0.25 mm wide. The rudimentary wing pads are visible on thoracic dorsum. The average size of 3rd instars is 0.74 mm long and 0.43 mm wide. The wing pads are well developed and the segmentation of antenna is evident. The 4th instar averages 1.01 mm long and 0.70 mm wide. The wing pads are well developed; the mesothoracic wing pads extend towards 1/3 of compound eyes and the metathoracic wing pads extend to 3rd abdominal segment. The 5th instar averages 1.60 mm long and 1.02 mm wide. The mesothoracic wing pads extend towards the front of compound eyes; the metathoracic wing pads extend to 4th abdominal segment. In some mature nymphs, the abdominal color turned bluish green instead of pale orange.

Adults of D. citri (Fig. 87) are often found to rest on the terminal portion of plants, especially on the lower side of the leaves, with their heads pointing to the leaf surface at a 30° angle. When disturbed, they readily take flight to a short distance. The females only oviposit on the tender shoots. In the absence of suitable tissue, oviposition ceases temporarily. The average size of the adult female is 3.3 mm in length and 1.0 mm in width; the mean size of the adult male is 2.7 mm long and 0.8 mm wide.

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Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), Figure 87 Adult Asian citrus psyllid, Diaphorina citri (photo J. Tsai).

Control of Asian citrus psyllid can be achieved by insecticide application. It is advisable to target the nymphs, (Fig. 88) as they are less mobile and concentrated on terminal tissue. However, other non-chemical control methods have been widely accepted; they include the use of such natural enemies as syrphids, chrysopids, coccinellids and parasitic wasps. The success in Reunion of using the eulophid (Tamarixia radiata Waterston) to control Asian citrus psyllid is a good example of biological control. Other control measures, such as injecting infected trees with tetracyline antibiotics, establishing disease free nursery and monitoring and removing diseased trees from the grove are also known to be effective.

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Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), Figure 88 Nymphs of Asian citrus psyllid (photo Lucy Skelley, University of Florida).

Liu YH, Tsai JH (2000) Effects of temperature on biology and life table parameters of the Asian citrus psyllid Diaphorina citri Kuwayama (Homoptera: Psyllidae) . Ann Appl Biol 137:201–206 CrossRef

Mead FW (1977) The Asiatic citrus psyllid, Diaphorina citri Kuwayama (Homoptera: Psyllidae). Florida Department of Agriculture and Consumer Services, Division Plant Industry, July 1977

Pande YD (1971) Biology of citrus psyllid, Diaphorina citri Kum (Hemiptera: Psyllidae). Israel J Entomol 5: 307–311

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Tsai JH, Chen ZY, Shen CY, Jin KX (1988) Mycoplasmas and fastidious vascular prokaryotes associated with tree diseases in China. In: Hiruki C (ed) Tree mycoplasmas and mycoplasma disease. The University of Alberta Press, AB, Canada, pp 69–240

Tsai JH, Liu YH (2000) Biology of Diaphorina citri (Homoptera: Psyllidae) on four host plants. J Econ Entomol 93:1721–1725 PubMed CrossRef

Tsai JH, Wang JJ, Liu YH (2000) Sampling of Diaphorina citri (Homoptera: Psyllidae) on orange jassamine in south Florida. Fla Entomol 83:446–459 CrossRef

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