Identification Of Parasitic Nematode Species And Investigation On Nematode Diseases Of Longan, Litchi And Guava In Fujian, China

During2011~2013, thorough investigation on nematode diseases and identification ofphytonematode species from longan, litchi and guava were carried out in Fujian province. Thenematode species including Meloidogyne, Pratylenchus, Hoplolaimidae, Cricomenatidea,Xiphinema and Trichodoridae were found important or potential threats to the fruit trees. Thesymptoms of the root-knot diseases of longan, litchi, and guava and the Pratylenchus diseaseof guava were described, the pathogenic nematodes of the diseases thoroughly indentifiedaccording to the characterization of morphology, biochemistry and molecular biology, makingclear the severity and distribution of the diseases in Fujian. The research on the morphologicaland genetic variations of Meloidogyne enterolobii populations from Fujian was carried outthrough observations by light microscrope, scanning electrical microsccrope and analysis byrDNA-ITS and RAPD. The primary results are as follows:1The symptom of the root-knot disease of litchi was first described in detail, it wassure that litchi was a host of new record to Meloidogyne enterolobii. The disease was found inQuanzhou, the pathogenic nematode was identified as Meloidogyne enterolobii Yang&Eisenback,1983.2. The symptoms of the root-knot disease of longan were described in detail, and2pathogenic nematodes were identified. The pathogen of the root-knot disease of longan fromQuanzhou was identified as Meloidogyne incognita(Kofoid&White,1919)Chitwood,1949,and the one from Fuzhou was identified as Meloidogyne javanica(Treub,1885)Chitwood,1949. The damages of the2nematodes to longan were first reported. It was observed that thesymptom caused by M. incognita was different from that by M. javanica.3. The symptom of the Pratylenchus disease of guava were first described in detail.The disease was found in Zhangzhou, the pathogenic nematode was identified asPratylenchus brachyurus(Godfrey,1929)Filipjev&Schuurmans Stekhoven,1941.4. The root-knot diseases of guava was a new record in Fujian. The symptom and thedamage of the disease was described in detail, the pathogenic nematode was identified asMeloidogyne enterolobii Yang&Eisenback,1983. The root-knot disease of guava distributedwidely in Fujian causing serious damage to guava, the main cultivars in production were allinfected, the age of the damaged guava ranged from3months to13years, the diseasepertentage and the severity of most plantations were up to100%and more than50respectively.5. Meloidogyne enterolobii was a new record in Fujian, of which the morphologicaland genetic variations were studied. The result of morphological research showed that theimportant diagnostic characters of M. enterolobii were stable, the result also providedscanning electric microscope photographs and complementary descriptions for themorphology and the variation of the female lip region. The genetic variations of M.enterolobii were analysed by rDNA-ITS sequences and RAPD technique, it was demonstratedthat M. enterolobii populations from Fujian were clustered into2different gene typesbelonging to Hainan populations and Cost Arica populations respectively, the genetic diversity of M. enterolobii populations was significantly correlated with the geographicdistribution of the populations.6. The species of phytonematodes of longan, litchi and guava in Fujian werethoroughly investigated and identified.44species of nematodes were described, out of whichthe species of new record in China were6and the species of new record in Fujian were20.The species of new record in China are as follows: Tylenchus elegans, Cephalenchushexalineatus, Coslenchus costatus, Mesocriconema brevistylus, HemiCriconemoides gaddi,Gracilacus mutabilis. The species of new record in Fujian are as follows: Tylenchus elegans,Filenchus australis, F. descrepans, F. facultativus, F. misellus, Cephalenchus hexalineatus,C. leptus, Aglenchus agricola, Coslenchus costatus, Basiria graminophila, B. tumida, B.ritteri, Tylenchorhynchus malinus, Pararotylenchus pini, Meloidogyne enterolobii, Criconemamutabile, Mesocriconema brevistylus, HemiCriconemoides gaddi, Gracilacus mutabilis,Pratylenchus brachyurus.There were25genera35species found from longan, among which26species were thefirst records on longan: Tylenchus elegans, Filenchus australis, F. descrepans, F. facultativus,F. misellus, Aglenchus agricola, Coslenchus costatus, Basiria graminophila, B. tumida,Pratylenchus zeae, Hoplolaimus seinhorsti, Scutellonema brachyurus, Pararotylenchus pini,Rotylenchus reniformis, Meloidogyne incognita, M. javanica, Criconema mutabile,Mesocriconema xenoplax, Discocriconemella limitanea, HemiCriconemoides gaddi,Paratylenchus minutus, Gracilacus mutabilis, Aphelenchoides composticola, Xiphinemabrevicollum, Paratrichodorus minor.There were16genera20species found from litchi, among which8species were the firstrecords on litchi: F. misellus, Cephalenchus hexalineatus, C. leptus, Basiria graminophila, B.tumida, Meloidogyne enterolobii, Paratylenchus minutus, Xiphinema insigne.There were11genera17spcies found from guava, among which7species were the firstrecords on guava: Filenchus descrepans, F. misellus, Basiria tumida, Tylenchorhynchusannulatus, T. malinus, Mesocriconema brevistylus, M. xenoplax.7. The predominant nematode species in the roots of the3fruit trees were analysed. Inall the species identified, Meloidogyne nematodes and Pratylenchus nematodes causedsignificant damage to the trees. Filenchus descrepans and F. misellus were the most commonspecies in the family Tylenchidae but caused little damage to the trees. Helicotylenchusdihystera and Rotylenchus reniformis were the most common species in the familyHoplolaimidae, T. leviterminalis was in the genus Tylenchorhynchus, X. brevicollum in thegenus Xiphinema, T. pakistanensis from longan and litchi in Quanzhou and Fuzhou in thefamily Trichodoridae, they were often found in the trees’ rhizosphere at high level ofpopulation indensity, so the further study of their damage to the trees was needed;Hemicriconemoides mangiferae was the most common species in the family Criconematoidea,it was potential to cause growth decline of longan and litchi.