Transcriptome Analysis of Host-Associated Differentiation in \u3cem\u3eBemisia tabaci\u3c/em\u3e (Hemiptera: Aleyrodidae)

Host-associated differentiation is one of the driving forces behind the diversification of phytophagous insects. In this study, host induced transcriptomic differences were investigated in the sweetpotato whitefly Bemisia tabaci, an invasive agricultural pest worldwide. Comparative transcriptomic analyses using coding sequence (CDS), 5′ and 3′ untranslated regions (UTR) showed that sequence divergences between the original host plant, cabbage, and the derived hosts, including cotton, cucumber and tomato, were 0.11–0.14%, 0.19–0.26%, and 0.15–0.21%, respectively. In comparison to the derived hosts, 418 female and 303 male transcripts, respectively, were up-regulated in the original cabbage strain. Among them, 17 transcripts were consistently up-regulated in both female and male whiteflies originated from the cabbage host. Specifically, two ESTs annotated as Cathepsin B or Cathepsin B-like genes were significantly up-regulated in the original cabbage strain, representing a transcriptomic response to the dietary challenges imposed by the host shifting. Results from our transcriptome analysis, in conjunction with previous reports documenting the minor changes in their reproductive capacity, insecticide susceptibility, symbiotic composition and feeding behavior, suggest that the impact of host-associated differentiation in whiteflies is limited. Furthermore, it is unlikely the major factor contributing to their rapid range expansion/invasiveness

Effects of Plant Virus and Its Insect Vector on Encarsia Formosa, a Biocontrol Agent of Whiteflies

In this study, we investigated the tritrophic interactions among a persistently transmitted plant virus, Tomato yellow leaf curl virus (TYLCV), its insect vector, the sweetpotato whitefly Bemisia tabaci, and a parasitoid, Encarsia formosa Gahan, one of the most extensively used biological control agents. As an emerging invasive pest worldwide, the two most damaging whiteflies are B. tabaci B and Q cryptic species. On healthy tomato plants, parasitoid-induced mortality was significantly higher in B. tabaci B than in Q. In contrast, similar mortality levels of B and Q were observed on TYLCV-infected plants. A higher rate of parasitism was consistently observed in B, independent of the TYLCV infection. Similarly, the life history traits of E. formosa were influenced by both TYLCV and the two cryptic species of B. tabaci. Specifically, E. formosa parasitizing B had a greater adult longevity and shorter developmental time on healthy plants, whereas the parasitoids developing from Q has a greater adult longevity on TYLCV-infected plants. The emergence rate of E. formosa was unaffected by either B. tabaci cryptic species or the virus. These results suggest that the vector-borne pathogen can manipulate the host suitability of a parasitoid and hence the parasitoid-host interactions

Natal Host Plants Can Alter Herbivore Competition

Interspecific competition between herbivores is widely recognized as an important determinant of community structure. Although researchers have identified a number of factors capable of altering competitive interactions, few studies have addressed the influence of neighboring plant species. If adaptation to/ epigenetic effects of an herbivore\u27s natal host plant alter its performance on other host plants, then interspecific herbivore interactions may play out differently in heterogeneous and homogenous plant communities. We tested wether the natal host plant of a whitefly population affected interactions between the Middleeast Asia Minor 1 (MEAM1) and Mediterranean (MED) cryptic species of the whitefly Bemisia tabaci by rearing the offspring of a cabbage-derived MEAM1 population and a poinsettia- derived MED population together on three different host plants: cotton, poinsettia, and cabbage. We found that MED dominated on poinsettia and that MEAM1 dominated on cabbage, results consistent with previous research. MED also dominated when reared with MEAM1 on cotton, however, a result at odds with multiple otherwise-similar studies that reared both species on the same natal plant. Our work provides evidence that natal plants affect competitive interactions on another plant species, and highlights the potential importance of neighboring plant species on herbivore community composition in agricultral systems

Transcriptomic Dissection of Sexual Differences in \u3cem\u3eBemisia tabaci\u3c/em\u3e, an Invasive Agricultural Pest Worldwide

Sex difference involving chromosomes and gene expression has been extensively documented. In this study, the gender difference in the sweetpotato whitefly Bemisia tabaci was investigated using Illumina-based transcriptomic analysis. Gender-based RNAseq data produced 27 Gb reads, and subsequent de novo assembly generated 93,948 transcripts with a N50 of 1,853 bp. A total of 1,351 differentially expressed genes were identified between male and female B. tabaci, and majority of them were female-biased. Pathway and GO enrichment experiments exhibited a gender-specific expression, including enriched translation in females, and enhanced structural constituent of cuticle in male whiteflies. In addition, a putative transformer2 gene (tra2) was cloned, and the structural feature and expression profile of tra2 were investigated. Sexually dimorphic transcriptome is an uncharted territory for the agricultural insect pests. Molecular understanding of sex determination in B. tabaci, an emerging invasive insect pest worldwide, will provide potential molecular target(s) for genetic pest control alternatives

Spatial and temporal variations of organochlorine pesticides (OCPs) in water and sediments from Honghu Lake, China

Honghu Lake in Jianghan Plain, central China is an important habitat for many migratory birds and an important site for freshwater fishery, and Honghu Lake region is also a main area for rice and cotton production in China. To understand the status and changes of organochlorine pesticide (OCP) contamination, and to assess the OCPs' risks for the ecosystem in Honghu Lake, thirty surface water samples, fifteen surface sediments, and a sediment core were collected in January and July, 2005. OCPs, such as DDTs, HCHs and chlordanes, were determined by GC-ECD in all samples. Concentrations of OCPs in surface water collected during the wet season (July 2005) were relatively higher than those collected during the dry season (January 2005), indicating that the increasing land runoff during the summer might bring the chemical residues from soils to Honghu Lake. The relatively low alpha-HCH/gamma-HCH ratio and the relatively high o,p'-DDT/p,p'-DDT ratio indicated the application of lindane on regional agricultural lands in late spring and summer (April-August), which increased the increasing contribution of dicofol to DDT in Honghu Lake, respectively. The levels of Sigma HCHs and Sigma DDTs in the surface sediments were relatively lower than those from the Yangtze River Delta, but comparable to those from other lakes and rivers in China. The composition of HCHs and DDTs in the surface sediments showed that there was fresh input of lindane (gamma-HCH), and DDT residues in Honghu Lake were aged and probably mainly originated from weathered agricultural soils of surrounding Jianghan Plain. Wash out of HCHs and DDTs from soil was the possible process which caused the increasing concentrations of these chemicals in recent years. (C) 2013 Elsevier B.V. All rights reserved.Honghu Lake in Jianghan Plain, central China is an important habitat for many migratory birds and an important site for freshwater fishery, and Honghu Lake region is also a main area for rice and cotton production in China. To understand the status and changes of organochlorine pesticide (OCP) contamination, and to assess the OCPs' risks for the ecosystem in Honghu Lake, thirty surface water samples, fifteen surface sediments, and a sediment core were collected in January and July, 2005. OCPs, such as DDTs, HCHs and chlordanes, were determined by GC-ECD in all samples. Concentrations of OCPs in surface water collected during the wet season (July 2005) were relatively higher than those collected during the dry season (January 2005), indicating that the increasing land runoff during the summer might bring the chemical residues from soils to Honghu Lake. The relatively low alpha-HCH/gamma-HCH ratio and the relatively high o,p'-DDT/p,p'-DDT ratio indicated the application of lindane on regional agricultural lands in late spring and summer (April-August), which increased the increasing contribution of dicofol to DDT in Honghu Lake, respectively. The levels of Sigma HCHs and Sigma DDTs in the surface sediments were relatively lower than those from the Yangtze River Delta, but comparable to those from other lakes and rivers in China. The composition of HCHs and DDTs in the surface sediments showed that there was fresh input of lindane (gamma-HCH), and DDT residues in Honghu Lake were aged and probably mainly originated from weathered agricultural soils of surrounding Jianghan Plain. Wash out of HCHs and DDTs from soil was the possible process which caused the increasing concentrations of these chemicals in recent years. (C) 2013 Elsevier B.V. All rights reserved

Bemisia Tabaci Q Carrying Tomato Yellow Leaf Curl Virus Strongly Suppresses Host Plant Defenses

The concurrence of tomato yellow leaf curl virus (TYLCV) with the spread of its vector Bemisia tabaci Q rather than B in China suggests a more mutualistic relationship between TYLCV and Q. Here, we investigated the hypothesis that viruliferous B and Q have different effects on plant defenses. We found the fecundity of nonviruliferous B, nonviruliferous Q, viruliferous Q and viruliferous B was 11.080, 12.060, 10.760, and 11.220 respectively on plants previously attacked by the other biotype, however, on their respective noninfested control leaves fecundity was 12.000, 10.880, 9.760, and 8.020 respectively. Only viruliferous B had higher fecundity on viruliferous Q-infested plants than on control plants. The longevity of viruliferous B showed the same phenomenon. At 1 d infestion, the jasmonic acid content in leaves noninfested and in leaves infested with nonviruliferous B, nonviruliferous Q, viruliferous B and viruliferous Q was 407.000, 281.333, 301.333, 266.667 and 134.000 ng/g FW, respectively. The JA content was lowest in viruliferous Q-infested leaves. The proteinase inhibitor activity and expression of JA-related upstream gene LOX and downstream gene PI II showed the same trend. The substantial suppression of host defenses by Q carrying TYLCV probably enhances the spread of Q and TYLCV in China

Difference in Feeding Behaviors of Two Invasive Whiteflies on Host Plants with Different Suitability: Implication for Competitive Displacement

In China, Bemisia tabaci Q (commonly known as biotype Q) has rapidly displaced B (commonly known as biotype B) in the past 6 years. The mechanisms underlying such phenomenon have been studied extensively in recent years; however, we have not come to a definitive conclusion yet. In the present study, the differences in host suitability between B and Q whitefly adults to five host plants (cabbage, cotton, cucumber, poinsettia, and tomato) were evaluated based on their respective feeding behaviors using a direct-current electrical penetration graph (DC-EPG) system. Pair-wise comparisons of B. tabaci B and Q feeding on each of the five host plants clearly indicate that Q feeds better than B on tomato, cotton and poinsettia, while B feeds better than Q on cabbage and cucumber. The EPG parameters related to both phloem and non-phloem phases confirm that cabbage and cucumber are best suited to B, while tomato, cotton, and poinsettia are best suited to Q. Our present results support the contention that host suitability and adult feeding behavior contribute to the competitive displacement of biotype B by biotype Q. The discrepancy between field (previous studies) and laboratory results (this study), however, suggests that 1) whitefly displacement is apparently contributed by multiple factors; and 2) factor(s) other than the host plant suitability may play a vital role in dictating the whitefly biotypes in the field

Atmospheric polychlorinated biphenyls measured during the 2008 Chinese National Arctic Research Expedition

From July to September 2008, air samples were collected aboard the R/V XUE LONG icebreaker (Snow Dragon) as part of the 2008 Chinese National Arctic Research Expedition program. Σ20PCBs in the atmosphere ranged from 6.20 to 365 pg∙m−3 with average concentration 117±107 pg∙m−3. Congener profiles in all samples showed a prevalence of tri- and tetrachlorobiphenyls, dominated by PCB-18, PCB-28, PCB-44 and PCB-52. Along the cruise, the highest concentration was observed over the Sea of Japan and the lowest over the high-latitude Arctic Ocean. Air mass backward trajectories indicated that samples with relatively high levels of PCBs might have been influenced by atmospheric transport of these chemicals from primary and/ or secondary sources. PCB-18 displayed a significant correlation between vapor pressure and ambient temperature along the cruise, but there was no such correlation between gas-phase concentration and latitude. This suggests that atmospheric PCB-18 was related to volatilization from the earth surface during summer 2008, during which temperatures were relatively high. PCB-52 presented a significant correlation between gas-phase concentration and latitude, but no such correlation was found between vapor pressure and ambient temperature, indicating that atmospheric PCB-52 detected during the cruise might be attributed directly to atmospheric transport from source regions. In the Arctic, levels of PCB-52 in the floating sea ice region were higher than those measured in the open sea area and pack ice region. Intense ice retreat during summer 2008 might have enhanced the volatilization of previously accumulated PCBs from sea ice, especially those with heavier molecular weight and lower vapor pressure such as PCB-52

Quantification of patient-specific coronary material properties and their correlations with plaque morphological characteristics: An in vivo IVUS study

BACKGROUND: A method using in vivo Cine IVUS and VH-IVUS data has been proposed to quantify material properties of coronary plaques. However, correlations between plaque morphological characteristics and mechanical properties have not been studied in vivo. METHOD: In vivo Cine IVUS and VH-IVUS data were acquired at 32 plaque cross-sections from 19 patients. Six morphological factors were extracted for each plaque. These samples were categorized into healthy vessel, fibrous plaque, lipid-rich plaque and calcified plaque for comparisons. Three-dimensional thin-slice models were constructed using VH-IVUS data to quantify in vivo plaque material properties following a finite element updating approach by matching Cine IVUS data. Effective Young\u27s moduli were calculated to represent plaque stiffness for easy comparison. Spearman\u27s rank correlation analysis was performed to identify correlations between plaque stiffness and morphological factor. Kruskal-Wallis test with Bonferroni correction was used to determine whether significant differences in plaque stiffness exist among four plaque groups. RESULT: Our results show that lumen circumference change has a significantly negative correlation with plaque stiffness (r = -0.7807, p = 0.0001). Plaque burden and calcification percent also had significant positive correlations with plaque stiffness (r = 0.5105, p \u3c 0.0272 and r = 0.5312, p \u3c 0.0193) respectively. Among the four categorized groups, calcified plaques had highest stiffness while healthy segments had the lowest. CONCLUSION: There is a close link between plaque morphological characteristics and mechanical properties in vivo. Plaque stiffness tends to be higher as coronary atherosclerosis advances, indicating the potential to assess plaque mechanical properties in vivo based on plaque compositions

Rapid spread of tomato yellow leaf curl virus in China is aided differentially by two invasive whiteflies

BACKGROUND: Tomato yellow leaf curl virus (TYLCV) was introduced into China in 2006, approximately 10 years after the introduction of an invasive whitefly, Bemisia tabaci (Genn.) B biotype. Even so the distribution and prevalence of TYLCV remained limited, and the economic damage was minimal. Following the introduction of Q biotype into China in 2003, the prevalence and spread of TYLCV started to accelerate. This has lead to the hypothesis that the two biotypes might not be equally competent vectors of TYLCV. METHODOLOGY/PRINCIPAL FINDINGS: The infection frequency of TYLCV in the field-collected B. tabaci populations was investigated, the acquisition and transmission capability of TYLCV by B and Q biotypes were compared under the laboratory conditions. Analysis of B. tabaci populations from 55 field sites revealed the existence of 12 B and 43 Q biotypes across 18 provinces in China. The acquisition and transmission experiments showed that both B and Q biotypes can acquire and transmit the virus, however, Q biotype demonstrated superior acquisition and transmission capability than its B counterparts. Specifically, Q biotype acquired significantly more viral DNA than the B biotype, and reached the maximum viral load in a substantially shorter period of time. Although TYLCV was shown to be transmitted horizontally by both biotypes, Q biotype exhibited significantly higher viral transmission frequency than B biotype. Vertical transmission result, on the other hand, indicated that TYLCV DNA can be detected in eggs and nymphs, but not in pupae and adults of the first generation progeny. CONCLUSIONS/SIGNIFICANCE: These combined results suggested that the epidemiology of TYLCV was aided differentially by the two invasive whiteflies (B and Q biotypes) through horizontal but not vertical transmission of the virus. This is consistent with the concomitant eruption of TYLCV in tomato fields following the recent rapid invasion of Q biotype whitefly in China