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Potential dangerous and invadable pests and diseases in Nepal
Yam Kumar Shrestha,Rajiv Das Rajbhandari,Sunita Shrestha 한국응용곤충학회 2018 한국응용곤충학회 학술대회논문집 Vol.2018 No.10
A review was made on notorious insect pests and diseases of crops, resulting about 25-35% yield loss annually in Nepal. Among the insect pests; brown planthopper (Nilaparvata lugens) in rice, cotton bollworm (Helicoverpa armigera) in various crops, armyworm (Mythimna separate) in rice and maize, white stemborer (Xylotrechus quadripes) in coffee, Potato tuber moth (Phthorimaea operculella) and red ants (Dorylus orientalis) in potato are causing periodically havoc. Whiteflies, mealybugs and leaf miners are emerging as major pests. Recently introduced South American tomato leaf miner (Tuta absoluta) in tomato, officially identified in 2016 from Kathmandu valley is reported as possible dangerous pest. Similarly, blast (Magnaporthe grisea) and bacterial leaf blight of rice, late blight and bacterial wilt of tomato and potato, club root and black rot of crucifers, downy mildew and virus complex of cucumber, citrus greening (Liberobacter asiaticum), leaf and stripe rusts of wheat, northern leaf blight of maize, panama wilt of banana etc. are considered as major diseases of economic importance. Bacterial stem rot (Erwinia caratova) of tomato and gray leaf spot (Cercospora zea maydis) of maize are emerging for significant yield loss. The newly introduced coffee rust (Hemileia vastatrix) is now becoming serious threat to coffee plantation. Fall armyworm (Spodoptera frugiperda) and UG99 virulence race of Puccinia graminis need to prevent becoming dangerous from their entry. This review would be helpful to policy planning, future research and extension works.
Yam Kumar Shrestha,Hong-Soo Choi,Kwan-Suk Lee,Chang-Suk Kim,Sukchan Lee,Kyeong-Yeoll Lee 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.10
The oral toxicities of symbiotic bacteria Photorhabdus temperata ssp temperata (Ptt), mutually associated with entomopathogenic nematode Heterorhabditis megidis, and P. luminescens ssp. laumondii (TT01) with H. bacteriophora, were demonstrated to adults of the sweetpotato whitefly Bemisia tabaci. Sucrose solution (25%) containing bacteria-free supernatant of culture media of symbiotic bacteria was ingested into adult whiteflies within the glass tube. Whitefly mortalities were shown similar patterns against two bacterial media. Mortalities were significantly increased to 60-64% at 36 hours and almost 100% at 60 hours after treatments. In addition, We demonstrated the effect of oral ingestion of symbiont culture media on the gene expression of B. tabaci. Several genes fluctuated those expression levels. Our results suggest that oral ingestion of symbiont culture media of entomopathogenic nematodes significantly changed metabolic rates and highly lethal to whiteflies. The use of symbiotic bacteria of entomopathogenic nematodes provides a great potential as an alternative genetic resource of Bacillus thuringiensis, a major resource of microbial insecticide.
Oral toxicity of symbiotic bacteria Photorhabdus spp. against immature stages of insects
Yam Kumar Shrestha,Eun-Kyung Jang,Yeon-Su Yu,Mijo Kwon,JAE-HO SHIN,이경열 한국응용곤충학회 2011 Journal of Asia-Pacific Entomology Vol.14 No.1
The oral toxicity of 5 Photorhabdus spp. strains collected in different regions of Korea was determined in the larvae of Plodia interpunctella, Galleria mellonella, Lucilia caesar, and Culex pipiens pallens. When diet or water containing culture media containing 1 of the 5 different strains was ingested by immature insects, the first instar larvae of both G. mellonella and L. caesar and young larvae of C. pipiens pallens died within 3–5 days after treatment. However, mortality of P. interpunctella neonate larvae was slightly slower and reached 94.4%–100%within 7 days after treatment. The mortality rate of a control group given a diet containing water, the medium without cultured bacteria, or Escherichia coli culture medium was not affected. The mortality rates were 100%,45.3%, 2.8%, and 0% for Galleria, Lucilia, Plodia, and Culex, respectively, in another control group given a culture medium of Photorhabdus luminescens ssp. laumondii (TT01). In addition, culture media containing Photorhabdus strains significantly inhibited molting of third instar Plodia larvae by as much as 88% 7 days after treatment, whereas molting inhibition was reduced by 0%, 4%, and 20% following treatments with water,E. coli, or TT01 culture media, respectively. Our results suggest that the oral administration of Photorhabdus bacterial medium was highly effective for controlling various immature insects.
Yam Kumar Shrestha,Jae-Kyoung Shim,Hae-Son Bang,Jae-Ho Shin,Kyeong-Yeoll Lee 한국응용곤충학회 2010 한국응용곤충학회 학술대회논문집 Vol.2010 No.05
Oral toxicities of 5 Photorhabdus temperata ssp. temperata (Ptt) strains collected in different regions of Korea were determined against the larvae of Plodia interpunctella, Galleria mellonella, Lucilia caesar, Culex pipiens pallens and Paratlanticus ussuriensis. When a diet or water containing culture media of 5 different Ptt strains were ingested to immature insects, mortalities of the first instar larvae of G. mellonella, L. caesar, P. ussuriensis and young nymphs of C. pipiens pallens were rapidly increased and 100% within 3-5 days after treatments. However, mortality of P. interpunctella neonate larvae was slightly slower and 94.4-100% within 7 days after treatments. As controls, a diet containing either water, the medium without culturing bacteria, or E. coli culture medium did not effective on their mortalities. As another control group, the culture medium of P. temperata ssp. laumondii (KACC) were variously effective to mortalities of 4 species, namely, 100, 45.3, 2.8 and 0% to Galleria, Lucilia, Plodia and Culex, respectively. Culture media of Ptt strains inhibited developmental late of late larvae of P. interpunctella. Our results suggest that the oral administration of the culture medium of Ptt symbiotic bacteria was highly effective to control various immature insects.
Genetic diversity and geographic distribution of Bemisia tabaci species complex in Nepal
Acharya Rajendra,Kumar Shrestha Yam,Raj Sharma Sushant,이경열 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.2
Bemisia tabaci species complex comprises at least 44 cryptic species worldwide. Here, we analyze the nucleotide sequences of mitochondrial cytochrome oxidase subunit 1 (COI) gene obtained from 76 samples of B. tabaci collected from 23 districts in Nepal. This is the first genetic and geographic study of B. tabaci species complex in Nepal. Our phylogenetic study identified the presence of three cryptic species—Asia I, Asia II 1, and Asia II 5—with high interspecific but low intraspecific variations. Among the three cryptic species, Asia II 5 was the most prevalent in Nepal, constituting 64.47% of all the sequenced samples. Based on haplotype network analysis of COI sequences, Asia II 1 was more genetically diversified than the other two cryptic species. Our results provided useful information on the genetic diversity and geographic distribution of B. tabaci in Nepal, which help monitor population changes of B. tabaci at cryptic species level and develop sustainable management strategies for its control.