Sequence Analysis Of RDNA-ITS Of Root-knot Nematodes And Bioactivities Of Pesticide On Root-knot Nematodes (Meloidogyne Spp.)

The rDNA-ITS of 25 root-knot nematode populations was amplified and sequenced through PCR analysis. The results showed that the PCR fragment length of root-knot samples was 768bp in cowpea(RKN-1), tomato(RKN-2), balsam pear(RKN-3), Astragalus adsurgens (RKN-19)and rose(RKN-4) from Beijing, peanut fromWeifang (RKN-7) Yantai(RKN-6) and Jiaozhou(RKN-5) in Shandong, tomato from Hexian(RKN-9), cucumber from Suzhou (RKN-8) and Platycodon grandiflorum from Taihe(RKN-11) in Anhui and two kinds of tomato species(RKN-22,23) from China Central Agricultural University; the PCR fragment length of root-knot samples was 769bp in balsam pear from Ganyu(RKN-10) in Jiangsu, tomato from Kunming(RKN-12) in Yunnan, Langfang (RKN-17)in Hebei, Chengdu(RKN-18) in Sichuan and Suzhou(RKN-21) in Anhui and cucumber from Sixian(RKN-20) in Anhui; the PCR fragment length of root-knot samples was 772bp in guava(RKN-13) and pawpaw (RKN-15) from Hainan; the PCR fragment length of the other two samples was both 766bp in tomato(RKN-24,25) from China Central Agricultural University, and the PCR fragment length of root-knot nematodes in cucumber from Hangzhou in Zhejiang(RKN-16) and pepper from Anding (RKN-14)in Hainan was 767bp and 869bp, respectively.According to sequence cluster analysis of the the tested samples, it indicates that the gene distance of RKN-9, RKN-8, RKN-21, RKN-11, RKN-18 , RKN-20, RKN-17, RKN-22, RKN-23, RKN-24 and RKN-25 to Meloidogyne incognita and Meloidogyne arenaria was very close with homology of 100% and 99%, respectively. They belong to Meloidogyne incognita or Meloidogyne arenaria. The gene distance of RKN-1, RKN-2, RKN-5, RKN-6, RKN-7, RKN-10, RKN-12, and RKN-19 to Meloidogyne hapla and Meloidogyne javanica was close with homology of 100%; The gene distance of RKN-3, RKN-4 and RKN-13, RKN-15 to Meloidogyne hapla and Meloidogyne javanica was close with homology of 99% and 98% compared with Meloidogyne hapla and Meloidogyne javanica, respectively. They belong to Meloidogyne hapla or Meloidogyne javanica. Whereas the sequence of RKN-14 was different significantly from others belonging to Meloidogyne panyuensis with homology of 97% compared with Meloidogyne panyuensis.The economic damage of root-knot nematodes on crops can reach up to tens of billion dollars in world wide, which made it very important to apply for chemical control. The biological activities were assayed with 14 pesticides and three mixtures on southern root-knot nematodes, the results showed that the LC₅₀ of avermectin(5h after treatment), azadirachtin(5h after treatment), fosthiazate (24h after treatment ) and profenofos (24h after treatment ) were 20.883μg/mL, 37.9422μg/mL, 13.4236μg/mL and 6.2538μg/mL respectively, and the three mixtures of avermectin and fosthiazate(24h after treatment) with ratio of 1:20, 2:3 and 3:2 were 0.9953μg/mL, 0.6790μg/mL and 0.6032μg/mL, respectively. The mixtures with different ratio might be optimal pesticide to control southern root-knot nematodes.