The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（ME...The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（MED）.In an extensive field survey of the B.tabaci complex present throughout part of China from 2004 to 2007,we obtained 93 samples of B.tabaci from 22 provinces.We determined that these Chinese haplotypes included 2 invasive species（MEAM1 and MED）,and 4 indigenous cryptic species（Asia II 1,Asia II 3,China 3 and Asia II 7）by sequencing mitochondrial cytochrome oxidose one gene（mtCOI）.The diversity and genetic differentiation of a subset of 19 populations of B.tabaci were studied using cDNA amplified fragment length polymorphism（AFLP）.Prior to 2007,MEAM1 was a dominant species in many provinces in China.By 2007,MED was dominant in 11 provinces.Both invasive and indigenous species were simultaneously found in some regions.Indigenous species of B.tabaci were found in six provinces in southern China.MED and MEAM1 have broad ranges of host plants,and indigenous species appeared to have much narrower host ranges.All Asia II 3 samples were found on cotton except one on aubergine.China 3 has more host plants than Asia II 3.Twelve samples of China 3 were collected from sweet potato,Japanese hop,squash and cotton.A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained.The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%.Unweighted pair-group method analysis indicated that the clustering was independent of the different species.MED showed the lowest degree of similarity than the other species.The data indicate that both MEAM1and MED were rapidly established in China.展开更多
The epidemiology of Tomato chlorosis virus(ToCV)in China is closely associated with its vector whitefly,Bemisia tabaci(Gennadius)MED.However,the transmission characteristics of ToCV by B.tabaci MED remain poorly under...The epidemiology of Tomato chlorosis virus(ToCV)in China is closely associated with its vector whitefly,Bemisia tabaci(Gennadius)MED.However,the transmission characteristics of ToCV by B.tabaci MED remain poorly understood.In this study,we analyzed:1)the horizontal and vertical transmission of ToCV by B.tabaci MED whiteflies;2)the acquisition of ToCV by male and female B.tabaci MED whiteflies after different feeding durations;3)the transmission efficacy of viruliferous male and female B.tabaci MED whiteflies after different inoculation access periods(IAPs);4)the retention of ToCV by viruliferous male and female B.tabaci MED whiteflies after a 48 h acquisition access period(AAP);and 5)the effects of ToCV on host choice of healthy or ToCV-infected tomato plant of viruliferous and non-viruliferous B.tabaci MED at different time points.Our results showed that:1)viruliferous males could not transfer ToCV to non-viruliferous females,and vice versa,viruliferous females could not pass on ToCV to non-viruliferous males.ToCV could not be detected in the F1 generation adults;2)ToCV could be detected within 4.0%of females or males after a 20 min AAP;3)ToCV could be detected in 33.3%of tomato plants inoculated by 10 viruliferous males or females with IAPs of 20 or 30 min;4)the maximum retention time in females was 7 and 5 days in males;and 5)non-viruliferous B.tabaci MED did not show a preference for ToCV-infected tomato plants or healthy tomato plants.However,viruliferous B.tabaci MED whiteflies did prefer to settle on healthy tomato plants over ToCV-infected tomato plants.These findings will be helpful to better understand the epidemiology of the recently emerged plant virus,ToCV,in tomato fields in China.展开更多
Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects,and heat shock proteins（Hsps）play important roles in the temperature adaptation of various organisms.To better underst...Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects,and heat shock proteins（Hsps）play important roles in the temperature adaptation of various organisms.To better understand the temperature tolerance of the indigenous ZHJ2-biotype of whitefly Bemisia tabaci species complex,we obtained complete cDNA sequences for hsp90,hsp70,and hsp20 and analyzed their expression profiles under different high temperature treatments by real-time quantitative polymerase chain reaction.The high temperature tolerance of B.tabaci ZHJ2-biotype was determined by survival rate after exposure to different high temperatures for 1 h.The results showed that after 41°C heat-shock treatment for 1 h,the survival rates of ZHJ2 adults declined significantly and the estimated temperature required to cause 50% mortality（LT50）is 42.85°C for 1 h.Temperatures for onset（Ton）or maximal（Tmax）induction of hsps expression in B.tabaci ZHJ2-biotype were 35 and 39°C（or 41°C）.Compared with previous studies,indigenous ZHJ2-biotype exhibits lower heat temperature stress tolerance and Ton（or Tmax）than the invasive B-biotype.展开更多
Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to ...Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to compare the proteomes of F2 genotypes of Schizaphis graminum segregating for virus transmission ability,we recently discovered a panel of protein biomarkers that predict vector competency.Here we used aphid and whitefly nucleotide and expressed sequence tag database mining to test whether these biomarkers are conserved in other homopteran insects.S.graminum gene homologs that shared a high degree of predicted amino acid identity were discovered in two other aphid species and in the whitefly Bemisia tabaci.Selected reaction monitoring mass spectrometry was used to validate the expression of these biomarkers proteins in multiple aphid vector species.The conservation of these proteins in multiple insect taxa that transmit plant viruses along the circulative transmission pathway creates the opportunity to use these biomarkers to rapidly identify insect populations that are the most efficient vectors and allow them to be targeted for control prior to the spread of virus within a crop.展开更多
The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into n...The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into new regions,their impacts on human society are likely to increase in the years to come.展开更多
Whiteflies cause problems in vegetable production on a global scale. The primary worldwide whitefly pest is Bemisia tabaci (Gennadius). Insecticides are commonly used to mitigate the whitefly problem in vegetable crop...Whiteflies cause problems in vegetable production on a global scale. The primary worldwide whitefly pest is Bemisia tabaci (Gennadius). Insecticides are commonly used to mitigate the whitefly problem in vegetable crops. In limited-resource crop production, operator-carried spray applicators are commonly used for pesticide treatments. Three single-nozzle operator-carried spray applicators were assessed for their efficacies for whitefly (B. tabaci) control on summer squash (Cucurbita pepo L.) in Egypt. Each knapsack spray equipment was evaluated with five biorational and conventional insecticides. Counts of whitefly nymphs (first, second, third and fourth instars) on leaf samples were taken on 3, 9, 15 and 21 days after treatments with the insecticides. Nymphal mortality varied about 10% among the three spray equipment treatments. The Economy Micro Ulva sprayer resulted in significantly more nymphal mortality as compared with the Arimitsu sprayer and the CZP-3 sprayer, respectively. All insecticides greatly suppressed the whitefly populations;mean mortality ranged from 73% to 95% for all nymphs combined by day for a given treatment. These results provide pest management practitioners with performance assessment of the three operator-carried pesticide applicators for whitefly management with selected foliar insecticides.展开更多
The whitefly is well-known as a serious pest on many economic vegetable crops. It feeds by absorbing plant sap which includes many important nutrients for plant,＇;. An experiment was carried out to investigate the ef...The whitefly is well-known as a serious pest on many economic vegetable crops. It feeds by absorbing plant sap which includes many important nutrients for plant,＇;. An experiment was carried out to investigate the effect of whitefly, B. tabaci （Gennadius）, infestation on the micronutrients; Manganese, Zinc, Copper and Molybdenum, in three plant varieties; cantaloupe （Cucumis melo L.）, cucumber （Cucumis sativus L.） and zucchini （Cucurbita pepo L.） that were planted in a greenhouse at the Agricultural Research Station in Hada AI Sham, north east of Jeddah in Saudi Arabia. Results of this investigation showed that, in general whitefly infestation reduced micronutrients content in plants. Mean content of total micronutrients in each of infested cucumber and zucchini were less than control plants significantly, but the infestation did not vary total micronutrients content in cantaloupe significantly. Feeding of the whitefly reduced mean content of each Zinc and Molybdenum in infested plants significantly, but did not vary Manganese and Copper content significantly.展开更多
The density seasonal dynamics of Bemisia tabaci MED were evaluated over two years in a cotton-growing area in Langfang, Hebei Province, northern China on cotton （Gossypium hirsutum L.） and six other co-occurring com...The density seasonal dynamics of Bemisia tabaci MED were evaluated over two years in a cotton-growing area in Langfang, Hebei Province, northern China on cotton （Gossypium hirsutum L.） and six other co-occurring common plants, common ragweed （Ambrosia artemisiifolia L.）, piemarker （Abutilon theophrasti Medicus）, sunflower （Helianthus annuus L.）, sweet potato （Ipomoea batatas L.）, soybean （Glycine max L.）, and maize （Zea mays L.）. The whitefly species identity was repeatedly tested and confirmed; seasonal dynamics on the various host plants were standardized by the quartile method. B. tabaci MED appeared on weeds （the common ragweed and piemarker） about 10 days earlier than on cotton, or the other cultivated plants. The peak population densities were observed over a span of 2 to 3 weeks on cotton, starting in early （2010） or mid-August （2011）. The common ragweed growing adjacent to cotton supported the highest B. tabaci densities （no. on 100 cm2 leaf surface）, 12-22 fold higher than on cotton itself. Sunflower supported more B. tabaci than the other plants, and about 1.5-2 fold higher than cotton did, Our results indicate that weeds （esp. the common ragweed） around cotton fields could increase the population density of B. tabaci MED on cotton, while sunflower could act as a trap crop for decreasing pest pressure on cotton.展开更多
Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with di...Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with different fingerprints.Host-plant and region of collection were then used to select 25 individuals for PCR amplification and sequencing of their partial mitochondrial cytochrome oxidase subunit one（mtCOI）genes.Pairwise comparisons with mtCOI consensus sequences showed that the majority of these samples had 〈3.5% sequence divergence from groups currently termed Asia I,Asia II-5,Asia II-7,and Asia II-8.The biotype-B B.tabaci from India clustered into the Middle East-Asia Minor 1 group.A new group of B.tabaci from Coimbatore,collected from pumpkin,was related most closely to the Asia I group（6.2% sequence divergence from the consensus Asia I sequence）.To increase our understanding of the epidemiology of tomato leaf curl disease（ToLCD）and the key B.tabaci genetic groups involved in virus spread,the indigenous Asia I and the exotic biotype-B population from South India were used to carry out transmission experiments using Tomato leaf curl Bangalore virus（ToLCBV）.The acquisition access periods（AAP）,inoculation access periods（IAP）,latent periods（LP）,and ToLCBV transmission efficiencies of the two populations were compared and the biotype-B had the more efficient transmission characteristics.These results are discussed in relation to recent changes in the epidemiology of tomato leaf curl disease in South India.展开更多
In this study, the activities of phenylalanine ammonia lyase （PAL）, polyphenoloxidase （PPO）, and peroxidase （POD） were assayed in cucumber seedlings （Cucumis sativus L.） at 0, 6, 12, 24, 48, 72, and 96 h after...In this study, the activities of phenylalanine ammonia lyase （PAL）, polyphenoloxidase （PPO）, and peroxidase （POD） were assayed in cucumber seedlings （Cucumis sativus L.） at 0, 6, 12, 24, 48, 72, and 96 h after they were infested by Bemisia tabaci （Gennadius） using spectrophotometric analysis. The results indicated that herbivore infestation increased the activities of PAL, PPO, and POD. The enzymes showed different activity levels at different times after the infestation. The PAL activity reached the first high peak by 23.1% at 6 h and the highest peak by 29.1% at 48 h compared to the control. The PPO activity reached the first high peak by 22.7% at 6 h and the highest peak by 52.6% at 24 h, and the POD activity reached the highest peak by 213.2% at 6 h and another higher peak value by 135.2% at 96 h. The results suggest that the enhanced activities of the enzymes may contribute to bioprotection of cucumber plants against B. tabaci infestation.展开更多
The polyphagous B-biotype of Bemisia tabaci （Gennadius） has demonstrated a high capacity to adapt to numerous hosts from diverse plant families. To illustrate induced responses by the host plant, biochemical researc...The polyphagous B-biotype of Bemisia tabaci （Gennadius） has demonstrated a high capacity to adapt to numerous hosts from diverse plant families. To illustrate induced responses by the host plant, biochemical research on eight plant-insect interaction correlative enzymes, representing detoxifying, antioxidant and digestive pathways, were investigated. Transferring whitefly adults to Zhongmian 23 from the pre-adapted host Zhongmian 41 induced activities of carboxylesterase （by 1.80-fold）, glutathione S-transferase （by 3.79-fold）, proteinase （by 1.62-fold） and amylase （by 2.41-fold） activities, hut decreased polyphenol oxidase （by 1.89-fold） and peroxidase （by 1.88-fold）. However, transferring whitefly adults to the favorite host abutilon from Zhongmian 41 was associated with increased activities of cytochrome P450 monooxygenase （by 1.61-fold） and amylase （by 1.42-fold）, and decreased activities of polyphenol oxidase （by 2.96-fold） and peroxidase （by 2.07-fold）. Our results, together with previous studies, proved that multiple pathways are involved in coping with host shifts by polyphagous herbivores, and the taxonomic status and preference of the host transferred would affect which pathway would be induced. These results would represent a key challenge in developing long-term sustainable insect control strategies.展开更多
Bemisia tabaci(Gennadius) is a serious pest in many cropping systems worldwide and occurs in different biotypes. ThemtDNA COI gene of the 12 Bemisia tabaci (Gennadius) populations from different regions and countries ...Bemisia tabaci(Gennadius) is a serious pest in many cropping systems worldwide and occurs in different biotypes. ThemtDNA COI gene of the 12 Bemisia tabaci (Gennadius) populations from different regions and countries were analyzed.Based on mtDNA COI sequences, their biotypes were characterized and phylogenetic relationships among thesepopulations were established with the method of UPGMA. The results indicated the genetic similarity between thosepopulations from Beijing, Zhengzhou, Zaozhuang, Nanjing, Shanghai, Haikou, and the B-biotype populations fromCalifornia, Texas, Arizona reached 99.8-100%, which meant the nation-wide infested populations of B.tabaci in China inrecent years were B-biotypes. Another population collected from Kunming of Yunnan Province showed very high similaritywith Q-biotype B.tabaci from Spain and Morocco, which meant the Kunming population was Q-biotype. This is the firstreport on the invasion of Q-biotype into China.展开更多
基金funded by the National Basic Research and Development Program ofChina(2009CB119200)the National Natural Science Foundation of China(31071683)the Earmarked Fund forModern Agro-Industry Technology Research System,China(CARS-27)
文摘The whitefly Bemisia tabaci are considered as a taxonomically complex that contained some destructive pests.Two of the most prevalent cryptic species are B.tabaci Middle East-Asia Minor 1（MEAM1）and Mediterranean（MED）.In an extensive field survey of the B.tabaci complex present throughout part of China from 2004 to 2007,we obtained 93 samples of B.tabaci from 22 provinces.We determined that these Chinese haplotypes included 2 invasive species（MEAM1 and MED）,and 4 indigenous cryptic species（Asia II 1,Asia II 3,China 3 and Asia II 7）by sequencing mitochondrial cytochrome oxidose one gene（mtCOI）.The diversity and genetic differentiation of a subset of 19 populations of B.tabaci were studied using cDNA amplified fragment length polymorphism（AFLP）.Prior to 2007,MEAM1 was a dominant species in many provinces in China.By 2007,MED was dominant in 11 provinces.Both invasive and indigenous species were simultaneously found in some regions.Indigenous species of B.tabaci were found in six provinces in southern China.MED and MEAM1 have broad ranges of host plants,and indigenous species appeared to have much narrower host ranges.All Asia II 3 samples were found on cotton except one on aubergine.China 3 has more host plants than Asia II 3.Twelve samples of China 3 were collected from sweet potato,Japanese hop,squash and cotton.A total of 677 reproducible bands amplified with 5 AFLP primer combinations were obtained.The highest proportion of polymorphic bands was 98.7% and the lowest was 91.9%.Unweighted pair-group method analysis indicated that the clustering was independent of the different species.MED showed the lowest degree of similarity than the other species.The data indicate that both MEAM1and MED were rapidly established in China.
基金supported by the National Key Research and Development Program of China (2016YFC1201200)the Taishan Mountain Scholar Constructive Engineering Foundation of Shandong, China (tsqn20161040)the National Natural Science Foundation of China (31572064)
文摘The epidemiology of Tomato chlorosis virus(ToCV)in China is closely associated with its vector whitefly,Bemisia tabaci(Gennadius)MED.However,the transmission characteristics of ToCV by B.tabaci MED remain poorly understood.In this study,we analyzed:1)the horizontal and vertical transmission of ToCV by B.tabaci MED whiteflies;2)the acquisition of ToCV by male and female B.tabaci MED whiteflies after different feeding durations;3)the transmission efficacy of viruliferous male and female B.tabaci MED whiteflies after different inoculation access periods(IAPs);4)the retention of ToCV by viruliferous male and female B.tabaci MED whiteflies after a 48 h acquisition access period(AAP);and 5)the effects of ToCV on host choice of healthy or ToCV-infected tomato plant of viruliferous and non-viruliferous B.tabaci MED at different time points.Our results showed that:1)viruliferous males could not transfer ToCV to non-viruliferous females,and vice versa,viruliferous females could not pass on ToCV to non-viruliferous males.ToCV could not be detected in the F1 generation adults;2)ToCV could be detected within 4.0%of females or males after a 20 min AAP;3)ToCV could be detected in 33.3%of tomato plants inoculated by 10 viruliferous males or females with IAPs of 20 or 30 min;4)the maximum retention time in females was 7 and 5 days in males;and 5)non-viruliferous B.tabaci MED did not show a preference for ToCV-infected tomato plants or healthy tomato plants.However,viruliferous B.tabaci MED whiteflies did prefer to settle on healthy tomato plants over ToCV-infected tomato plants.These findings will be helpful to better understand the epidemiology of the recently emerged plant virus,ToCV,in tomato fields in China.
基金supported by the National Basic R&D Program of China(2009CB119200)the National Natural Science Foundation of China(30800722)
文摘Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects,and heat shock proteins（Hsps）play important roles in the temperature adaptation of various organisms.To better understand the temperature tolerance of the indigenous ZHJ2-biotype of whitefly Bemisia tabaci species complex,we obtained complete cDNA sequences for hsp90,hsp70,and hsp20 and analyzed their expression profiles under different high temperature treatments by real-time quantitative polymerase chain reaction.The high temperature tolerance of B.tabaci ZHJ2-biotype was determined by survival rate after exposure to different high temperatures for 1 h.The results showed that after 41°C heat-shock treatment for 1 h,the survival rates of ZHJ2 adults declined significantly and the estimated temperature required to cause 50% mortality（LT50）is 42.85°C for 1 h.Temperatures for onset（Ton）or maximal（Tmax）induction of hsps expression in B.tabaci ZHJ2-biotype were 35 and 39°C（or 41°C）.Compared with previous studies,indigenous ZHJ2-biotype exhibits lower heat temperature stress tolerance and Ton（or Tmax）than the invasive B-biotype.
基金supported by NSF BREAD IOS:1109989,USDA-NRI 2007-04567,NSFDBI-0606596USDA-ARS 764 CRIS projects1907-101-16,1907-21000-024/25-00DNIH/NCRR funded Yeast Resource Center P41RR01182
文摘Plant viruses in the families Luteoviridae and Geminiviridae are phloem restricted and are transmitted in a persistent,circulative manner by homopteran insects.Using fluorescence 2-D difference gel electrophoresis to compare the proteomes of F2 genotypes of Schizaphis graminum segregating for virus transmission ability,we recently discovered a panel of protein biomarkers that predict vector competency.Here we used aphid and whitefly nucleotide and expressed sequence tag database mining to test whether these biomarkers are conserved in other homopteran insects.S.graminum gene homologs that shared a high degree of predicted amino acid identity were discovered in two other aphid species and in the whitefly Bemisia tabaci.Selected reaction monitoring mass spectrometry was used to validate the expression of these biomarkers proteins in multiple aphid vector species.The conservation of these proteins in multiple insect taxa that transmit plant viruses along the circulative transmission pathway creates the opportunity to use these biomarkers to rapidly identify insect populations that are the most efficient vectors and allow them to be targeted for control prior to the spread of virus within a crop.
基金the National Natural Science Foundation of China(projects30730061 and 31021003)the National Basic Research Programme of China(2009CB119203)for support to the International Symposium on Future Directions in Bemisia Research held in Hangzhou and thepublication of this special issue
文摘The whitefly Bemisia tabaci species complex and the begomoviruses they transmit are devastating agricultural pests worldwide.With the rapid and further inva-sions by some members of the whitefly species complex into new regions,their impacts on human society are likely to increase in the years to come.
文摘Whiteflies cause problems in vegetable production on a global scale. The primary worldwide whitefly pest is Bemisia tabaci (Gennadius). Insecticides are commonly used to mitigate the whitefly problem in vegetable crops. In limited-resource crop production, operator-carried spray applicators are commonly used for pesticide treatments. Three single-nozzle operator-carried spray applicators were assessed for their efficacies for whitefly (B. tabaci) control on summer squash (Cucurbita pepo L.) in Egypt. Each knapsack spray equipment was evaluated with five biorational and conventional insecticides. Counts of whitefly nymphs (first, second, third and fourth instars) on leaf samples were taken on 3, 9, 15 and 21 days after treatments with the insecticides. Nymphal mortality varied about 10% among the three spray equipment treatments. The Economy Micro Ulva sprayer resulted in significantly more nymphal mortality as compared with the Arimitsu sprayer and the CZP-3 sprayer, respectively. All insecticides greatly suppressed the whitefly populations;mean mortality ranged from 73% to 95% for all nymphs combined by day for a given treatment. These results provide pest management practitioners with performance assessment of the three operator-carried pesticide applicators for whitefly management with selected foliar insecticides.
文摘The whitefly is well-known as a serious pest on many economic vegetable crops. It feeds by absorbing plant sap which includes many important nutrients for plant,＇;. An experiment was carried out to investigate the effect of whitefly, B. tabaci （Gennadius）, infestation on the micronutrients; Manganese, Zinc, Copper and Molybdenum, in three plant varieties; cantaloupe （Cucumis melo L.）, cucumber （Cucumis sativus L.） and zucchini （Cucurbita pepo L.） that were planted in a greenhouse at the Agricultural Research Station in Hada AI Sham, north east of Jeddah in Saudi Arabia. Results of this investigation showed that, in general whitefly infestation reduced micronutrients content in plants. Mean content of total micronutrients in each of infested cucumber and zucchini were less than control plants significantly, but the infestation did not vary total micronutrients content in cantaloupe significantly. Feeding of the whitefly reduced mean content of each Zinc and Molybdenum in infested plants significantly, but did not vary Manganese and Copper content significantly.
基金funded by grants from the National Natural Science Foundation of China(30930062)the National Basic Research Program of China(2013CB127605)the CABI Special Fund for the Agricultural Industry(20130302404,201303019-02)
文摘The density seasonal dynamics of Bemisia tabaci MED were evaluated over two years in a cotton-growing area in Langfang, Hebei Province, northern China on cotton （Gossypium hirsutum L.） and six other co-occurring common plants, common ragweed （Ambrosia artemisiifolia L.）, piemarker （Abutilon theophrasti Medicus）, sunflower （Helianthus annuus L.）, sweet potato （Ipomoea batatas L.）, soybean （Glycine max L.）, and maize （Zea mays L.）. The whitefly species identity was repeatedly tested and confirmed; seasonal dynamics on the various host plants were standardized by the quartile method. B. tabaci MED appeared on weeds （the common ragweed and piemarker） about 10 days earlier than on cotton, or the other cultivated plants. The peak population densities were observed over a span of 2 to 3 weeks on cotton, starting in early （2010） or mid-August （2011）. The common ragweed growing adjacent to cotton supported the highest B. tabaci densities （no. on 100 cm2 leaf surface）, 12-22 fold higher than on cotton itself. Sunflower supported more B. tabaci than the other plants, and about 1.5-2 fold higher than cotton did, Our results indicate that weeds （esp. the common ragweed） around cotton fields could increase the population density of B. tabaci MED on cotton, while sunflower could act as a trap crop for decreasing pest pressure on cotton.
基金R.V.Chowda-Reddy(HEFCE fellowship)and Kiran Kumar,from the research projects funded by the University of Greenwich,together with the Department for International Development,UK(DFID project code R8247,Crop Protection Programme)
文摘Bemisia tabaci adults from various host-plant species were collected from 31 regions across India.266 B.tabaci samples were first screened by RAPD-PCR to examine molecular variability and to select individuals with different fingerprints.Host-plant and region of collection were then used to select 25 individuals for PCR amplification and sequencing of their partial mitochondrial cytochrome oxidase subunit one（mtCOI）genes.Pairwise comparisons with mtCOI consensus sequences showed that the majority of these samples had 〈3.5% sequence divergence from groups currently termed Asia I,Asia II-5,Asia II-7,and Asia II-8.The biotype-B B.tabaci from India clustered into the Middle East-Asia Minor 1 group.A new group of B.tabaci from Coimbatore,collected from pumpkin,was related most closely to the Asia I group（6.2% sequence divergence from the consensus Asia I sequence）.To increase our understanding of the epidemiology of tomato leaf curl disease（ToLCD）and the key B.tabaci genetic groups involved in virus spread,the indigenous Asia I and the exotic biotype-B population from South India were used to carry out transmission experiments using Tomato leaf curl Bangalore virus（ToLCBV）.The acquisition access periods（AAP）,inoculation access periods（IAP）,latent periods（LP）,and ToLCBV transmission efficiencies of the two populations were compared and the biotype-B had the more efficient transmission characteristics.These results are discussed in relation to recent changes in the epidemiology of tomato leaf curl disease in South India.
文摘In this study, the activities of phenylalanine ammonia lyase （PAL）, polyphenoloxidase （PPO）, and peroxidase （POD） were assayed in cucumber seedlings （Cucumis sativus L.） at 0, 6, 12, 24, 48, 72, and 96 h after they were infested by Bemisia tabaci （Gennadius） using spectrophotometric analysis. The results indicated that herbivore infestation increased the activities of PAL, PPO, and POD. The enzymes showed different activity levels at different times after the infestation. The PAL activity reached the first high peak by 23.1% at 6 h and the highest peak by 29.1% at 48 h compared to the control. The PPO activity reached the first high peak by 22.7% at 6 h and the highest peak by 52.6% at 24 h, and the POD activity reached the highest peak by 213.2% at 6 h and another higher peak value by 135.2% at 96 h. The results suggest that the enhanced activities of the enzymes may contribute to bioprotection of cucumber plants against B. tabaci infestation.
基金supported by the National Natural Science Foundation of China(30800131)the Fundamental Research Funds for the Central Universities, China(2012ZYTS043)
文摘The polyphagous B-biotype of Bemisia tabaci （Gennadius） has demonstrated a high capacity to adapt to numerous hosts from diverse plant families. To illustrate induced responses by the host plant, biochemical research on eight plant-insect interaction correlative enzymes, representing detoxifying, antioxidant and digestive pathways, were investigated. Transferring whitefly adults to Zhongmian 23 from the pre-adapted host Zhongmian 41 induced activities of carboxylesterase （by 1.80-fold）, glutathione S-transferase （by 3.79-fold）, proteinase （by 1.62-fold） and amylase （by 2.41-fold） activities, hut decreased polyphenol oxidase （by 1.89-fold） and peroxidase （by 1.88-fold）. However, transferring whitefly adults to the favorite host abutilon from Zhongmian 41 was associated with increased activities of cytochrome P450 monooxygenase （by 1.61-fold） and amylase （by 1.42-fold）, and decreased activities of polyphenol oxidase （by 2.96-fold） and peroxidase （by 2.07-fold）. Our results, together with previous studies, proved that multiple pathways are involved in coping with host shifts by polyphagous herbivores, and the taxonomic status and preference of the host transferred would affect which pathway would be induced. These results would represent a key challenge in developing long-term sustainable insect control strategies.
基金This work was funded by the National Basic Research and Development Program(2002CB111400).
文摘Bemisia tabaci(Gennadius) is a serious pest in many cropping systems worldwide and occurs in different biotypes. ThemtDNA COI gene of the 12 Bemisia tabaci (Gennadius) populations from different regions and countries were analyzed.Based on mtDNA COI sequences, their biotypes were characterized and phylogenetic relationships among thesepopulations were established with the method of UPGMA. The results indicated the genetic similarity between thosepopulations from Beijing, Zhengzhou, Zaozhuang, Nanjing, Shanghai, Haikou, and the B-biotype populations fromCalifornia, Texas, Arizona reached 99.8-100%, which meant the nation-wide infested populations of B.tabaci in China inrecent years were B-biotypes. Another population collected from Kunming of Yunnan Province showed very high similaritywith Q-biotype B.tabaci from Spain and Morocco, which meant the Kunming population was Q-biotype. This is the firstreport on the invasion of Q-biotype into China.
