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Guidance: Effective Management of Bemisia tabaci Relies on Fundamental Research     YAN Feng-ming Scientia Agricultura Sinica   2016,49(13 ):2511 -2513. DOI:10.3864/j.issn.0578-1752.2016.13.006 Abstract  （346） HTML （6） PDF（pc） （242KB）（345） Save Reference丨 Related Articles丨 Metrics

Differential Physiological and Biochemical Responses of Cucumber to the Feeding by Bemisia tabaci B and Q Biotypes     LIU Ming-yang, LEI Cai-yan, LI Jing-jing, LU Shao-hua, BAI Run-e, TANG Qing-bo, YAN Feng-ming Scientia Agricultura Sinica   2016,49(13 ):2514 -2523. DOI:10.3864/j.issn.0578-1752.2016.13.007 Abstract  （406） HTML （1） PDF（pc） （455KB）（417） Save 【Objective】B (Middle East-Asia Minor 1) and Q (Mediterranean) biotypes, two cryptic species of Bemisia tabaci species complex, are important agricultural pests. Extensive applications of insecticides for control of the pests have resulted in pesticide resistance in the whiteflies, have endangered ecological safety and human health. Implementation of safe pest management strategy is therefore becoming very important and urgent. Utilization of plant defense is one of the important components in integrated pest management. The objective of this study is to investigate the differential responses of nutrients and defensive enzymes in cucumber induced by the feeding of B. tabaci B and Q biotypes and thereby to elucidate the physiological and biochemical mechanism underlying defence responses of cucumber to B. tabaci.【Method】Adults of B. tabaci B and Q biotypes and cucumber plants (var. Bojie-I) from the laboratory cultures were used for the experiments. The cucumber plants at four-leaf stage were respectively used to feed 200 adults of B. tabaci B and Q biotypes, with healthy plants as controls, and the contents of nutrients (soluble sugar and soluble protein) and polyphenolic contents, activity of phenylalanine ammonialyase (PAL), the enzyme of defensive substance biosynthesis, and activity of protective enzymes in cucumber were determined after continuously feeding for 1, 3, 5, 7 and 9 days by B and Q biotypes of B. tabaci. 【Result】Within the experimental period, the contents of soluble sugar and protein in cucumber increased after 3 d by B. tabaci B biotype, but decreased after 1 d by B. tabaci Q biotype, compared to those in controls. The contents of polyphenols and activity of PAL, the key enzyme in its biosynthesis pathway, increased after infested both by B and Q biotypes, with higher activities to Q biotype feeding. The activity of superoxide dismutase (SOD) and catalase (CAT) increased and the activity of peroxidase (POD) decreased after feeding by B biotype, while the activities of SOD increased and the activity of POD and CAT decreased after feeding by Q biotype. 【Conclusion】Differential changes of nutrients and defensive enzymes in cucumber after the feeding of B. tabaci B and Q biotypes were found in the present study. Both B and Q biotypes of B. tabaci were able to induce the synthesis of defensive substance polyphenols, and increased the content of polyphenols in cucumber; but there were differences in inducing the contents of nutrients and the activities of protective enzymes, i.e., more nutrients in cucumber by B biotype feeding, while higher activities of defensive enzymes by Q biotype feeding. Those different changes in induced physiological and biochemical responses in plants to the herbivore may result from the difference in host plant adaptability between B and Q biotypes of B. tabaci. These results provide a basis for pest management strategies, especially for utilization of plant defense as the main control tactic, so as to target different biotypes of B. tabaci on different host plants. Reference丨 Related Articles丨 Metrics

Analysis of Physiological Characteristics with Response to Bemisia tabaci B Biotype in Different Resistant Varieties of Tomato     CAI Chong, XU Ying-ying, CUI Xu-hong Scientia Agricultura Sinica   2016,49(13 ):2524 -2533. DOI:10.3864/j.issn.0578-1752.2016.13.008 Abstract  （323） HTML （1） PDF（pc） （451KB）（682） Save 【Objective】The objective of this study is to clarify the physiological characteristic changes inside the leaves of tomato between the resistance and the susceptible cultivars under the stresses of Bemisia tabaci B biotype, and to provide a reference for the breeding and popularization of tomato varieties resistant to B. tabaci.【Method】 An experiment was carried out under artificial climate conditions. The resistant variety (Hongshengnv, HSN) and the susceptible variety (Huangshengguo, HSG) were infested by B. tabaci B biotype in a no-choice way. The contents variation of the secondary metabolic materials (i.e., sucrose esters, gallic acid, caffeic acid, ferulic acid, benzoic acid, salicylic acid, lignin), the changes of some protective enzymes activities (i.e., POD, CAT, PPO, LOX) and trypsin proteinase inhibitor activity (TI), the value variation of two photosynthetic parameters (i.e., Fv/Fm, Fv/Fo), the changes of cell membrane lipid peroxidation (i.e. H2O2 content, production rate, MDA content and electric conductivity (EC)), were determined all together at the same time.【Result】There were marked differences in the contents of the SE, phenolic acids, lignin, H2O2, and MDA between the HSN and the HSG. Meanwhile, the differences of the activities of TI and protective enzymes, the values of Fv/Fo, were also significant between these two varieties. However, the value differences of these parameters, such as Fv/Fm, production rate, and EC, were not obvious. The two varieties showed different responses to the infestation of B. tabaci B biotype. For example, after 9 h, the contents of sucrose esters, phenolic acids, and lignin as well as the activities of protective enzymes increased all together. However, there were considerable raises as to its extent with comparing HSN to the HSG. Photosynthesis was inhibited in the leaves, confirmed by the observation of reducing of the activities of TI and photosynthetic parameter values. There were reducing to lower intensities with comparing the HSN to the HSG. More active oxygen, MDA and EC found in the latter indicated that HSG cell had been damaged greatly.【Conclusion】There were different responses to the stresses of B. tabaci B biotype as to tomato of different resistant varieties. Higher variation of secondary metabolic materials contents and protective enzymes activities were observed in the resistant variety. Meanwhile, the photosynthetic parameter values, active oxygen content, cell membrane lipid peroxidation, as well as the TI activities changed more dramatically in the susceptible variety. Reference丨 Related Articles丨 Metrics

Identification and Expression Analysis on Lysozyme Gene of Bemisia tabaci     YU Jie, WANG Deng-jie, LEI Zhong-ren, WANG Hai-hong Scientia Agricultura Sinica   2016,49(13 ):2534 -2543. DOI:10.3864/j.issn.0578-1752.2016.13.009 Abstract  （311） HTML （2） PDF（pc） （2891KB）（369） Save 【Objective】The objective of this study is to provide a basis for understanding the important role of lysozyme genes in Bemisia tabaci infected by the fungus Beauveria bassiana , identify lysozyme genes and analyze their sequence features, evolutionary relationships and expression pattern, and to provide a theoretical foundation for charifying innate immunity in B. tabaci. 【Method】Target genes were screened from the results of the second-generation high-throughput sequencing against the redundancy nucleotide databases when the E value ＜10-5. The open reading frame and amino acid sequence of BtLyzs were found using the ORF Finder software; the protein domains of BtLyzs were predicted using Pfam and SMART software; the signal peptide sequence of BtLyzs was predicted using SignalP 4.1 Server; the amino acid sequence alignment of BtLyzs was performed using the MEGA6.0 software; BtLyzs were characterized by using phylogenetic analysis with homologous genes of 31 other insects, a neighbor-joining of phylogenetic tree was constructed using the MEGA 6.0 software for further analysis and identification of the genes. The expression pattern of screened genes were determined at egg, nymph and adult stages of B. tabaci which were infected by the fungus Be. bassiana after 12, 24, 36, 48, 60 h using the quantitative real-time PCR (qRT-PCR). 【Result】 Four lysozyme genes were identified and designated as BtLyz1, BtLyz2, BtLyz3 and BtLyz4, which were 1 819, 1 149, 829, 928 nt, respectively. They were predicted to encode proteins of 159, 160, 148, 160 amino acids, respectively. Amino acid sequence alignment, phylogenetic analysis and protein tertiary structure prediction showed that BtLyz1 and BtLyz4 belong to i-type lysozymes, BtLyz2 and BtLyz3 belong to c-type lysozymes. BtLyz-1 formed a clade specific with Acyrthosiphon pisum of ApLyz-i1, BtLyz4 formed a clade specific with Diaphorina citri of DcLyz-i3 and Acyrthosiphon pisum of ApLyz-i2; BtLyz2 and BtLyz3 formed a clade specific with Nilaparvata lugens of NlLyz-c1 and Harmonia axyridis of HaLyz-c3. Compared to the control, the relative expression of all four genes in egg and BtLyz4 in nymph were not induced significantly by fungi-infected; the transcription of BtLyz1 nymph stage underwent the fluctuation of up-regulation, down-regulation, and second up-regulation and peaked at 24 h, it was increased 4.55 folds compared to the control; the transcription of BtLyz1 and BtLyz4 adult stage underwent the fluctuation of up-regulation, down-regulation, and second up-regulation and peaked at 60 h, they were increased 11.31 and 4.21 folds compared to the control. The transcription of BtLyz2 and BtLyz3 nymph stage underwent the fluctuation of up-regulation and down-regulation and peaked at 24 h, they were increased 5.09 and 8.31 folds compared to the control, then down-regulated obviously at 60 h, they were reduced 0.19 and 0.13 folds compared to the control. The transcription of BtLyz2 and BtLyz3 adult stage underwent the fluctuation of up-regulation and down-regulation and peaked at 24 h, they were increased 5.56 and 8.84 folds compared to the control. 【Conclusion】 Four BtLyz genes were identified in B. tabaci. Among them, two are c-type and two are i-type lysozymes. Transcriptional levels of four BtLyzs genes in B. tabaci were induced through different developmental stages and different time points in fungi-treated individuals compared to the control, they were not induced significantly in eggs, and showed different expression trends in nymphs and adults. The four BtLyzs genes probably might participated in the innate immune responses to fungus infection, and could be a new potential target for biocontrol of B. tabaci. Reference丨 Related Articles丨 Metrics

Comparison of Feeding Behavior Between Two Bemisia tabaci Strains Using EPG Technique     ZHANG Wen-ping, LIU Bai-ming, ZHANG Shan, WAN Fang-hao, CHU Dong Scientia Agricultura Sinica   2016,49(13 ):2544 -2552. DOI:10.3864/j.issn.0578-1752.2016.13.010 Abstract  （448） HTML （3） PDF（pc） （415KB）（369） Save 【Objective】Cardinium is one of the endosymbiont species infects in sweetpotato whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae). Previous studies have shown that there was a significant difference in the fitness between Cardinium- infected (C+) and -uninfected (C-) strains of B. tabaci Q biotype. However, the behavioral mechanism causing the difference in fitness between the two strains is not clear. This study investigated the difference in the feeding behavior of these two strains to reveal the underlying mechanism responsible for the difference in fitness. 【Method】The feeding behavior of C+ strain and C- strain on cotton and tomato during 6 h was recorded using an electrical penetration graph (EPG). The waveform types of feeding behavior were then identified and analyzed. A total of 19 parameters (11 parameters associated with non-phloem phase and 8 parameters associated with phloem phase) were calculated and analyzed to compare the two strains’ feeding behavior at phloem stage and non-phloem stage.【Result】Of the 118 successful recordings obtained in this experiment, 58 recordings (C- strain=28 replicates and C+ strain=30 replicates) were on cottons and 60 recordings (C- strain=31 replicates and C+ strain=29 replicates) were on tomatoes. The results showed that at the non-phloem phase on cotton C+ strain had a significantly longer total duration of probes than C- strain. C+ strain had a significantly shorter time than C- strain in terms of in duration of np after the first E. The parameters associated with salivation into a sieve element and ingestion of a sieve element sap had no significant difference between the two strains on cotton at phloem phase, and the percentage of whiteflies reaching phloem phase within 6 hours had no significant difference. Meanwhile, at the non-phloem phase, C+ strain had a greater number of total probes and probes before the 1st E than C- strain on tomato. C+ strain also had a longer time from the 1st probe to the 1st sustained E2 and a shorter average probe time than C- strain. The parameters regarding salivation into a sieve element and ingestion of sieve element sap also had no significant difference between the two strains on tomato at phloem phase. Also, the percentage of whiteflies reaching phloem phase within 6 hours had no significant difference. On the whole, the parameters associated phloem phase had no significant difference between the two strains. Compared with C- strain, C+ strain has a longer probing time and requires more probes at non-phloem phase.【Conclusion】The feeding behavior of C+ strain and C- strain has no significant difference at phloem phase, but does have a significant difference at non-phloem phase. The results indicate that the feeding behavior difference of the two strains at non-phloem phase is most likely related to the difference in fitness. Reference丨 Related Articles丨 Metrics

Integration of Emulsifiable Formulation Metarhizium flavoviride with Low-Rate Abamectin for Control of Bemisia tabaci Q Biotype     LI Mao-ye, CHEN De-xin, LIN Hua-feng, LI Shi-guang, PAN Jing, WU Sheng-yong Scientia Agricultura Sinica   2016,49(13 ):2553 -2560. DOI:10.3864/j.issn.0578-1752.2016.13.011 Abstract  （403） HTML （1） PDF（pc） （395KB）（382） Save 【Objective】 Bemisia tabaci, an important invasion insect pest in agriculture, has displayed a high resistance to many conventional pesticides. The objective of this study is to evaluate the synergistic effect of joint application of entomopathogenic fungi and chemical pesticides against B. tabaci in laboratory and field, and to provide a new approach for effective control of B. tabaci. 【Method】 Based on the previous study that a highly virulent of Metarhizium flavoviride strain (Mf96) was screened for control of B. tabaci Q biotype, three gradient emulsifiable formulation of Mf96 (1.0×108, 1.0×107, 1.0×106 conidia/mL), which were combined with five low doses of abamectin EC (0, 15, 30, 45 and 60 µg·mL-1) were separately sprayed to the body surface of 2nd instar nymphs of B. tabaci Q biotype in laboratory, and the mortalities were tested. The number of conidia deposited on the unit surface was counted under stereomicroscope. Single agent and their equal volume mixture of the suspension emulsion of Mf96 strain (1.0×108 conidia/mL) and 1.8% abamectin WP (60 µg·mL-1) were separately sprayed to control B. tabaci Q biotype on tobacco in the field, and the control efficacies were evaluated. 【Result】 LC50 of Mf96 against 2nd instar nymphs of B. tabaci Q biotype decreased from 1 376 to 183 conidia/mm2 during 4th to 8th day. After 7 days, LC50 of the fungus combined with abamectin (60 µg·mL-1) decreased from 378 to 46 conidia/mm2. Abamectin had no significant effect on the fungal outgrowths and infection to 2nd instar nymphs of B. tabaci Q biotype at the low spray rates. The mixture suspension of different concentrations of fungus (low, medial and high) with abamectin (15, 30, 45 and 60 µg·mL-1) resulted in different rates of mycotized cadavers, and high concentration of fungal mixture suspension with 30 µg·mL-1 of abamectin caused 86.8% mortality of B. tabaci. No cadavers were observed in untreated control and single abamectin spray. Fungal conidia suspension emulsion, abamectin and their mixture were separately sprayed in the field, and the decline rates in nymphae of B. tabaci Q biotype population was the highest (53.6% and 85.7%) when the mixture was sprayed after 5 d and 10 d. Meanwhile, the changing trends of corrected control efficacies and population decline rate of B. tabaci Q biotype were similar at 5 random checks, the corrected control efficacy of the mixture was the highest (88.9%) after 25 d. The population decline rate of B. tabaci Q biotype in untreated control was negative value.【Conclusion】The combined of M. flavoviride with abamectin showed synergistic interaction, with additive effects on Q biotype B. tabaci. Therefore, it is an effective approach to control B. tabaci by combining M. flavoviride with abamectin at low spray rate. Reference丨 Related Articles丨 Metrics