Xun Yan

Zhongkai University of Agriculture and Engineering · College of Agriculture and Biology

Alternatives to hazardous insecticides are urgently needed for an environmentally friendly and effective management of insect pests. One such option is the use of entomopathogenic nematodes (EPN). To increase the availability of EPN with potential for biocontrol, we surveyed agricultural soils in the Republic of Rwanda and collected two Steinernema...

Entomopathogenic nematodes (EPN) are biological control agents used to control different insect pests. Indigenous EPN resources are important for the successful control of endemic pests. A native EPN isolate collected in Yunnan, China that showed high virulence against Spodoptera litura was identified and studied for virulence and production potent...

Spodoptera litura (F.) is an obnoxious cosmopolitan pest that causes serious damage to different economic crops. Entomopathogenic nematodes (EPN) have the potential to control the S. litura larvae. Fifteen EPN isolates were screened, and Steinernema sp. (Qiu, Hu, Zhou, Mei & Pang) 64-2, four isolates of S. carpocapsae (Weiser), S. longicaudum (Shen...

Bradysia odoriphaga is a major pest that causes damage to chive production, and which has developed resistance to highly toxic chemical insecticides. Entomopathogenic nematodes (EPN) show a high potential for B. odoriphaga control. This study aimed to develop an effective management method against B. odoriphaga larvae, using EPN with low-toxicity i...

White grubs are largely unsolved problems in vegetable and tuber production in East Africa. Novel Rwandan as well as international entomopathogenic nematodes (EPNs) were screened in nine laboratory bioassays and two small-scale field trials in 2014 and 2015. Soil-based laboratory bioassays revealed that all EPNs were able to infect Anomala graueri...

The biological and biocontrol traits of two entomopathogenic nematode isolates, Steinernema pakistanense 94-1 (Sp94-1) and Heterorhabditis indica 212-2 (Hi212-2), were evaluated. The highest yield of infective juveniles (IJ) in monoxenic sponge culture system for Sp94-1 and Hi212-2 was 3.52 (± 0.45) × 10⁵ and 7.08 (± 0.11) × 10⁵ IJ g⁻¹, respectivel...

The effects of carriers, temperatures, concentrations of the infective juveniles (IJ) and a fungicide on the survival and infectivity of five nematode species, Steinernema carpocapsae, S. feltiae, S. longicaudum, Heterorhabditis bacteriophora and H. indica, were evaluated to establish the adapted formulations for these nematodes. Vermiculite and hu...

Entomopathogenic nematodes (Steinernema spp. and Heterorhabditis spp.) and the slug-killing nematode Phasmarhabditis hermaphodita have advanced from niche products to key biopesticides within the past 30. years. They can be produced either on their hosts or on artificial solid or liquid medium. All three methods are still used for Steinernema and H...

Combinations of entomopathogenic nematodes Steinernema longicaudum X-7 and Heterorhabditis bacteriophora H06 with chlorantraniliprole, diflubenzuron, and imidacloprid insecticides at different rates for the control of the white grub, Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae), were evaluated both in the laboratory and in peanut fields...

Five field surveys for indigenous entomopathogenic nematodes were conducted in 22 semi-natural and 17 small-holder farming habitats across 16 districts of different altitudes in the northern, eastern, southern and Kigali city provinces of Rwanda. In 2014, 216 mixed soil samples were collected and subsamples thereof baited with Galleria mellonella o...

The white grub Holotrichia oblita Faldermann (Coleoptera: Scarabaeidae) causes serious damage in peanut fields in China. The development of an environmentally friendly control method for this pest is urgently needed. The efficacy of entomopathogenic nematodes against this pest in the laboratory and peanut fields was evaluated in this study. Both St...

We present here the 5.6-Mb genome sequence of Photorhabdus luminescens strain LN2, a Gram-negative bacterium that is a symbiont of Heterorhabditis indica LN2 and shows nematicidal activity against Heterorhabditis bacteriophora H06 nematodes. Copyright © 2014 Qiu et al.

A new species of Steinernema is described herein as S. bifurcatum n. sp. It is characterised by the presence of a male gubernaculum that is bifurcate at both proximal and distal ends, a key diagnostic feature. Steinernema bifurcatum n. sp. belongs to the bicornutum group by having two horn-like structures on the labial region of the infective juven...

Entomopathogenic nematodes (EPN) have good application prospects for the control of the black cutworm, Agrotis ipsilon. In the present study, the effects of isolate, exposure rate, temperature and larval stage on EPN infectivity to A. ipsilon were evaluated. Results of in vitro tests showed that Steinernema carpocapsae Mex and Heterorhabditis indic...

The efficacy of entomopathogenic nematodes (EPNs) against the white grub Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae) in the peanut (Arachis hypogaea L.) fields was evaluated. In the first experiment with a high initial white grub population (24.65 +/- 2.44 larvae per m2) in the field, Steinernema longicaudum X-7 and Heterorhabditis...

The striped flea beetle, Phyllotreta striolata (F.) (Coleoptera: Chrysomelidae) is a key pest of crucifer vegetables in Southern China. The use of entomopathogenic nematodes (EPNs) within an integrated pest management approach may offer an effective and environmentally safe strategy to suppress outbreaks of this pest. In the present study, the effi...

The expression patterns of fat-2 and sod-2 after osmotic induction were studied in four species of EPN, Steinernema carpocapsae, S. loci, Heterorhabditis bacteriophora and H. indica, which represented a good and a weak desiccation tolerant species from each genus, respectively. The expression of fat-2 was significantly different between the four sp...

Combining environmentally friendly insecticides with entomopathogenic nematodes may constitute an effective alternative to conventional chemical control of many insect pests. The objective of this laboratory study was to evaluate the effects of selected insecticides which are commonly used for pest control in vegetables in China on osmotically trea...

Rifampin resistant (Rif(R)) mutants of the insect pathogenic bacterium Photorhabdus luminescens LN2 from entomopathogenic nematode Heterorhabditis indica LN2 were genetically and proteomically characterized. The Rif(R) mutants showed typical phase one characters of Photorhabdus bacteria, and insecticidal activity against Galleria mellonella larvae,...

2-DE map of total cell proteins from P. luminescens LN2 RifR mutant LN2-R2. A representative gel shows the identified differentially expressed protein spots. 350 µg of total cell proteins was loaded onto a 17 cm pH 3–10 NL IPG strip, separated in the second dimension by SDS-polyacrylamide gel electrophoresis on a 12% gel and stained with silver nit...

2-DE map of total cell proteins from P. luminescens LN2 RifR mutant LN2-R16. A representative gel shows the identified differentially expressed protein spots. 350 µg of total cell proteins was loaded onto a 17 cm pH 3–10 NL IPG strip, separated in the second dimension by SDS-polyacrylamide gel electrophoresis on a 12% gel and stained with silver ni...

2-DE map of total cell proteins from P. luminescens LN2 RifR mutant LN2-R33. A representative gel shows the identified differentially expressed protein spots. 350 µg of total cell proteins was loaded onto a 17 cm pH 3–10 NL IPG strip, separated in the second dimension by SDS-polyacrylamide gel electrophoresis on a 12% gel and stained with silver ni...

2-DE map of total cell proteins from P. luminescens LN2 wild type strain. A representative gel shows the identified differentially expressed protein spots. 350 µg of total cell proteins was loaded onto a 17 cm pH 3–10 NL IPG strip, separated in the second dimension by SDS-polyacrylamide gel electrophoresis on a 12% gel and stained with silver nitra...

2-DE map of total cell proteins from P. luminescens LN2 RifR mutant LN2-R31. A representative gel shows the identified differentially expressed protein spots. 350 µg of total cell proteins was loaded onto a 17 cm pH 3–10 NL IPG strip, separated in the second dimension by SDS-polyacrylamide gel electrophoresis on a 12% gel and stained with silver ni...

Oligonucleotide sequences used to generate Photorhabdus luminescens LN2 mutant constructs in this study. (DOC)

Populations of Apis mellifera and Apis cerana in China were surveyed for seven bee viruses: acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Kashmir bee virus (KBV), sacbrood virus (SBV), and Isreal acute paralysis virus (IAPV). No KBV was detected from any samples of th...

A solution consisting of a mixture of glycerol and fortified artificial seawater was used to induce partial anhydrobiosis at 15°C in different strains of Steinernema carpocapsae. All the strains tested were tolerant to the osmotic solution and the survival and infectivity of the nematodes were not influenced. The osmotic treatment greatly improved...

Israel acute paralysis virus (IAPV) is associated with colony collapse disorder of honey bees. An isolate of IAPV was detected in China. Its genome was analyzed and compared with other IAPV isolates from different countries. The results revealed that the Chinese IAPV carried a 9482 nt RNA genome in positive orientation, with two open reading frames...

Chinese sacbrood virus (CSBV) is the pathogen of Chinese sacbrood disease, which poses a serious threat to honeybee Apis cerana, and tends to cause bee colony and even the whole apiary collapse. Here we report on prevention of CSBV infection by feeding second instar larvae of A. cerana with specific sequences of CSBV double-stranded RNA (dsRNA). Pr...

The osmotic tolerance of different species and isolates of entomopathogenic nematodes of the genera Steinernema and Heterorhabditis was examined using an osmotic solution to induce anhydrobiosis in these nematodes. Infective juveniles (IJs) of the species and isolates were exposed for 72 h to the osmotic solution consisting of a mixture of fortifie...

The transgenicEnterobacter cloacae with the insecticidal tcdA1B1 from symbiotic bacteria of entomopathogenic nematodes was constructed and showed high toxic potential against Coptotermesformosanus Shiraki in the laboratory. In this study, the efficacy of this transgenic E. cloacae against C.formosanus colonies in the field was evaluated. Colonies o...

Photorhabdus luminescens subsp. akhurstii LN2 from Heterorhabditis indica LN2 showed nematicidal activity against axenic Heterorhabditis bacteriophora H06 infective juveniles (IJs). Transposon mutagenesis identified an LN2 mutant that supports the growth of H06 nematodes. Tn5 disrupted the namA gene, encoding a novel 364-residue protein and involvi...

Two pairs of primers were used to detect Chinese sacbrood virus (CSBV) from different stages of honeybees (Apis cerana) collected from different regions in Guangdong, China. PCR products of the CSBV were sequenced and compared. The results showed that the primers were sensitive enough to detect CSBV in honeybees even without obvious symptoms. This...

Workers and broods of the honeybee Apis mellifera were collected in apiaries in Guangdong Province, China, where high worker mortalities were displayed. They were screened for the presence of 6 honey bee viruses, including the Israel acute paralysis virus (IAPV), by the RT-PCR method. Two viruses were detected, including Deformed wing virus (DWV) f...

Enterobacter cloacae, one of the indigenous gut bacteria of the Formosan subterranean termite (Coptotermes formosanus), was genetically modified with a transposon Tn5 vector containing genes (tcdA1 and tcdB1) encoding orally insecticidal proteins from the entomopathogenic bacterium Photorhabdus luminescens subsp. laumondii TT01, a symbiont of the e...

A new species of entomopathogenic nematode, Steinernema aciari sp. n. was described. It was recovered from a soil sample collected from Haimen town, Shantou district in the eastern coast of Guangdong province, the People's Republic of China during a survey for entomopathogenic nematodes. S. aciari sp. n. belongs to the Steinernema glaseri group. It...