Trace Metals in Soot and PM2.5 from Heavy-Fuel-Oil Combustion in a Marine Engine.

Heavy fuel oil (HFO) particulate matter (PM) emitted by marine engines is known to contain toxic heavy metals, including vanadium (V) and nickel (Ni). The toxicity of such metals will depend on the their chemical state, size distribution, and mixing state. Using online soot-particle aerosol mass spectrometry (SP-AMS), we quantified the mass of five metals (V, Ni, Fe, Na, and Ba) in HFO-PM soot particles produced by a marine diesel research engine. The in-soot metal concentrations were compared to in-PM2.5 measurements by inductively coupled plasma-optical emission spectroscopy (ICP-OES). We found that <3% of total PM2.5 metals was associated with soot particles, which may still be sufficient to influence in-cylinder soot burnout rates. Since these metals were most likely present as oxides, whereas studies on lower-temperature boilers report a predominance of sulfates, this result implies that the toxicity of HFO PM depends on its combustion conditions. Finally, we observed a 4-to-25-fold enhancement in the ratio V:Ni in soot particles versus PM2.5, indicating an enrichment of V in soot due to its lower nucleation/condensation temperature. As this enrichment mechanism is not dependent on soot formation, V is expected to be generally enriched within smaller HFO-PM particles from marine engines, enhancing its toxicity.

Association between vascular supply, stage and tumour size of juvenile nasopharyngeal angiofibroma.

Juvenile nasopharyngeal angiofibroma (JNA) is a highly vascular tumour seen in adolescent males. To study the vascular pattern of these tumours, we retrospectively reviewed the records of patients with JNA who underwent preoperative angiography. Most (82.2 %) of the 45 patients assessed were Radkowski stage III with a mean size of 5.29 cm. There was a significant association between tumour stage and size (p = 0.029). Ten different vessels were seen to supply these tumours. All tumours had primary supply from the distal third of the ipsilateral internal maxillary artery (IMA). Accessory vessel supply was chiefly from the Vidian branch of internal carotid artery (ICA) (55.6 %). Stage III tumours were supplied by a greater number of feeding vessels than earlier stage tumours (p < 0.01). Larger tumours were more likely to have ICA supply (p = 0.04). Bilateral supply was seen in 48.7 %. However, there was no predominance of bilateral over ipsilateral IMA supply even in advanced stage tumours. One patient in our series was found to have a caroticocavernous fistula. Residual or recurrent tumours were characterized by new vasculature (100 %) and greater accessory supply from the ipsilateral ICA (85.7 %). Our study highlights the fact that surgical planning cannot be dependent on staging alone and should include preoperative assessment of tumour vasculature by angiography.

Multiple Mutations on the Second Acetylcholinesterase Gene Associated With Dimethoate Resistance in the Melon Aphid, Aphis gossypii (Hemiptera: Aphididae).

The melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is an important cosmopolitan and extremely polyphagous species capable of causing direct and indirect damage to various crops. Insecticide resistance in melon aphids is of particular concern. To determine the basis of resistance, organophosphate (OP)-resistant strains of A. gossypii were obtained by continuous selection with dimethoate in the laboratory, and resistance mechanisms were investigated along with susceptible strains. Three resistant strains LKR-1, LKR-2, and LKR-3 exhibiting 270-, 243-, and 210-fold resistance obtained after 30 generations of selection with dimethoate, respectively, were utilized in this study. The role of acetylcholinesterase (AChE), a target enzyme for OPs and carbamates (CMs), was investigated. AChE enzyme assay revealed that there was no significant change in the activities of AChE in resistant and susceptible strains. However, AChE inhibitory assay showed that 50% of the enzyme activity in resistant strains was inhibited at significantly higher concentration of dimethoate (131.87, 158.65, and 99.29 µmolL(−1)) as compared with susceptible strains (1.75 and 2.01 µmolL(−1)), indicating AChE insensitivity owing to altered AChE. Molecular diagnostic tool polymerase chain reaction-restriction fragment length polymorphism revealed the existence of two consistent non-synonymous point mutations, single-nucleotide polymorphism, viz., A302S (equivalent to A201 in Torpedo californica Ayres) and S431F (equivalent to F331 in T. californica), in the AChE gene Ace2 of resistant strains. Further, cloning and sequencing of a partial fragment of Ace2 (897 bp) gene from susceptible and resistant strains revealed an additional novel mutation G221A in resistant strains, LKR-1 and LKR-2. Susceptible Ace2 genes shared 99.6 and 98.9% identity at the nucleic acid and amino acid levels with resistant ones, respectively. Functional analysis of these point mutations was assessed by in silico docking studies using the modeled wild-type and naturally mutated AChE2. Computational analysis showed that the conformational changes in AChE2 active site due to structural gene substitutions (A302S, S431F, and G221A) significantly reduced the level of ligand (OP-dimethoate, omethoate, and CM-pirimicarb) binding, suggesting that they are potentially associated with resistance development. These results unambiguously suggested that multiple mutations located in the enzyme active site are responsible for AChE insensitivity to dimethoate and are likely the molecular basis for dimethoate resistance in these selected field populations of A. gossypii.

Comparative virulence of strains of entomopathogenic nematodes for management of eggplant Grey Weevil, Myllocerus subfasciatus Guerin (Coleoptera: Curculionidae).

The Grey Weevil, Myllocerus subfasciatus Guerin, is an important emerging pest of quarantine significance in Solanaceae crops including the eggplant, Solanum melongena. Entomopathogenic nematodes (EPNs) have been shown to be a potential source of safe and effective control of M. subfasciatus. In this study, we determined the virulence of seven strains of EPNs (Nematoda: Rhabditida) viz. Heterorhabditis bacteriophora NBAIIHb105, H. indica NBAIIHi101, H. indica NBAIIHiMah, Steinernema abbasi NBAIISa01, Steinernema abbasi NBAIISa04, S. carpocapsae NBAIISc04 and S. glaseri NBAIISg01, with different foraging behaviour, against larvae of eggplant grey weevil, M. subfasciatus (Coleoptera: Curculionidae), and their suitability in five representative soils from the eggplant grown areas under laboratory conditions. All seven nematode strains caused >80% mortality of M. subfasciatus larvae at 40 IJs/cm2. LC90 values ranged between 21.18 and 46.41 IJs/cm2 at 96 h post-application, which corresponded to field concentrations between 2.1-4.6×109 IJs/ha. H. indica NBAIIHi101, S. glaseri NBAIISg01, S. abbasi NBAIISa01 and S. carpocapsae NBAIISc04 recorded higher grub mortality, compared to H. indica NBAIIHiMah, H. bacteriophora NBAIIHb05 and S. abbasi NBAIISa04 indicating existence of inter- and intra-specific variation in virulence. Response Surface Modelling (RSM) optimized LC and LT values for maximised larval mortality. RSM predicted a concentration of 58.05-62.54 IJs/cm2 of these EPN (corresponding to a field dose of 5.8-6.2×109 IJs/ha) required for effecting 97.10-99.67% grub mortality, at 90-97 h of exposure. EPN strains performed better in terms of larval mortality in loamy sand, alluvial, mountain soil, red laterite compared to black cotton soils. Efficacy of EPN was positively correlated with the content of sand, and negatively with the clay content. It is possibly the first report that established the potential of local strains of EPNs with different foraging ability and their dosages for suppression of subterranean root feeding larvae of M. subfasciatus in five broad soil types of eggplant grown areas. Validation of this baseline data in real-time eggplant crop situations may help in evolving EPN-based viable management schedules for M. subfasciatus.

Magneto-optics of massive dirac fermions in bulk Bi2Se3.

We report on magneto-optical studies of Bi2Se3, a representative member of the 3D topological insulator family. Its electronic states in bulk are shown to be well described by a simple Dirac-type Hamiltonian for massive particles with only two parameters: the fundamental band gap and the band velocity. In a magnetic field, this model implies a unique property-spin splitting equal to twice the cyclotron energy: Es=2Ec. This explains the extensive magnetotransport studies concluding a fortuitous degeneracy of the spin and orbital split Landau levels in this material. The Es=2Ec match differentiates the massive Dirac electrons in bulk Bi2Se3 from those in quantum electrodynamics, for which Es=Ec always holds.

[Evaluation of reference genes for quantitative real-time PCR normalization in cotton bollworm, Helicoverna armigera].

Reverse-transcription quantitative real-time PCR (RT-qPCR), a sensitive technique is being extensively employed in quantification of gene expression. However this requires normalization with suitable reference gene (RG) which is crucial in minimizing inter sample variations. Information regarding suitable RG is scarce in general and more so in insects, including the cotton bollworm, Helicoverpa armigera, an economically important pest. In management of this pest RNA interference (RNAi), is perceived as a potential tool, which is achieved by double-stranded RNA (dsRNA) delivery. These studies demand accurate quantification of gene silencing. In this study we assessed the suitability of five RGs viz. ß-actin (ACTB), 18S rRNA (18S), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ß-tubulin (TUB) and elongation fator-1-alfa (EF1-α) for gene expression studies in dsRNA treatment and across different developmental stages of H. armigera and ranked using geNorm, NormFinder and BestKeeper software programs. Data analysis revealed that best ranked RGs were varied in dsRNA treatment and in developmental stages. Under dsRNA treatment, 18S and GAPDH were more stable whereas, TUB and GAPDH were more stable across developmental stages. We also demonstrate that inappropriate selection of RG led to erroneous estimation of the target gene, chymotrypsin, expression. These results facilitate accurate quantification of gene expression in H. armigera.

One-step DNA fragment assembly for expressing intron-containing hairpin RNA in plants for gene silencing.

Double-stranded RNA-mediated RNA interference in plants involves generating a construct expressing intron-containing hairpin RNA (ihpRNA), which usually is a cumbersome, multistep process. Here, we describe a simplified method involving single steps of PCR, restriction, ligation, and transformation for assembling an ihpRNA construct for plant transformation. Our method has several advantages over the currently available ones, viz., wider choice of restriction sites and facility for rapid screening of positive clones, among others. We demonstrate the utility of this approach in assembling the tomato phytoene desaturase gene. This simplified DNA fragment assembly strategy for ihpRNA construction facilitates high-throughput gene silencing in plants.

Effect of diet delivered various concentrations of double-stranded RNA in silencing a midgut and a non-midgut gene of Helicoverpa armigera.

Ribonucleic acid interference (RNAi) is a sequence-specific gene silencing mechanism induced by double-stranded RNA (dsRNA). Recently, RNAi has gained popularity as a reverse genetics tool owing to its tremendous potential in insect pest management, which includes Helicoverpa armigera. However, its efficiency is mainly governed by dsRNA concentration, frequency of application, target gene, etc. Therefore, to obtain a robust RNAi response in H. armigera, we evaluated various concentrations of dsRNA and its frequency of applications delivered through diet in silencing a midgut gene, chymotrypsin and a non-midgut gene, juvenile hormone acid methyl transferase (jhamt) of H. armigera. The extent of target gene silencing was determined by employing reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Our study revealed four significant findings: (i) single application of dsRNA elicited a delayed and transient silencing, while multiple applications resulted in early and persistent silencing of the above genes; (ii) silencing of the non-midgut gene (jhamt) through diet delivered dsRNA revealed prevalence of systemic silencing probably due to communication of silencing signals in this pest; (iii) the extent of silencing of chymotrypsin was positively correlated with dsRNA concentration and was negatively correlated with jhamt; (iv) interestingly, over-expression (15­18 folds) of an upstream gene, farnesyl diphosphate synthase (fpps), in juvenile hormone (JH) biosynthetic pathway at higher concentrations of jhamt dsRNA was the plausible reason for lesser silencing of jhamt. This study provides an insight into RNAi response of target genes, which is essential for RNAi design and implementation as a pest management strategy.

DNA barcoding and elucidation of cryptic aphid species (Hemiptera: Aphididae) in India.

Rapid, precise and timely identification of invasive pest insects such as aphids is important and a challenge worldwide due to their complex life cycles, parthenogenetic reproduction, sex and colour morphs. In this respect, DNA barcoding employing a 658 bp fragment of 5' region of the mitochondrial cytochrome oxidase I (CO-I) gene is an effective tool in addressing the above. In the present study, we employed CO-I for discriminating 142 individuals representing 32 species of aphids from India. Sequence analyses revealed that the intraspecific and interspecific distances ranged from zero to 3.8% and 2.31 to 18.9%, respectively. In addition, the study also showed for the first time the prevalence of three cryptic species, namely Brevicoryne brassicae (Linnaeus), Hyperomyzus carduellinus (Theobald) and Brachycaudus helichrysi (Kaltenbach) from India. Our work has clearly demonstrated that DNA barcoding is an efficient and accurate method for identification of aphid species (including cryptic species), an approach that potentially could play an important role in formulating viable pest management strategies, more especially biocontrol.

Stakeholders' perspective on the daily regimen of tuberculosis treatment- A qualitative approach.

INTRODUCTION: In the context of changing over from an intermittent treatment regimen to a daily regimen, it becomes crucial to understand the impact of a daily regimen on the treatment process and outcome. It enables health professionals to strengthen strategies, to enhance the quality of treatment as well as the quality of life of TB patients. The perspective of each stakeholder involved in the process is important in assessing the impact of the daily regimen. OBJECTIVES: To understand patients' and providers' perspectives on the daily regimen of Tuberculosis treatment. METHODOLOGY: A qualitative study was conducted between March 2020 to June 2020, including in-depth interviews with TB patients on treatment and DOT providers, and Key Informant Interview(KII) with TB Health Visitors(TBHV) and family members of TB patients. A thematic-network analysis approach was utilized to get the results. RESULTS: Two sub-themes emerged: (i) Acceptance of the daily regimen of treatment; (ii) operational difficulties of the daily regimen. No injections in the regimen, fewer side effects of drugs as dose depends on weight band, family members can be treatment supporter, awareness about disease and treatment, the drugs are as same as private drugs available, adherence has improved, monthly DBT were found to some of the enablers in the study. The Barriers found in the study were traveling daily to get drugs, loss of daily wages, accompanying patients daily, tracing private patients, pyridoxine is not given free in this regimen, increased workload for treatment providers, etc. CONCLUSION: The study points out that acceptance of the patient to the daily regimen is better as they have lesser side effects. The operational difficulties in the implementation of the daily regimen can be addressed by providing family members as treatment supporters.

Pre-treatment delay and out of pocket expenses by notified new tuberculosis patients in an Indian mega city.

BACKGROUND: Study was carried out to find out delay from onset of symptoms and out of pocket expenditure (OOPE) until initiation of anti-TB treatment (ATT) by new Tuberculosis (TB) patients registered in public health facilities in Bengaluru. METHODS: Notified patients (N = 228) selected purposively were interviewed at initiation of ATT regarding number and type of facilities visited and delay in initiating ATT. OOPE was elicited separately for in- and out-patient visits, towards consultation, purchase of medicines, diagnostic tests, transportation, hospitalization and food. Dissaving or money borrowed was ascertained. RESULTS: Two-thirds of participants were 15-44 years of age and 56% were males, mean annual household income was $4357. About 75% first visited a private health facility; 68% and 87% respectively were diagnosed and started on ATT in public sector after visiting an average of three facilities and after a mean delay of 68 days; the median delay was 44 days. Of mean OOPE of $402, 54% was direct medical expenditure, 5% non-medical direct and 41% indirect. OOPE was higher for Extra-pulmonary TB compared to PTB and when number of health facilities visited before initiating treatment was >3 compared to those who visited ≤3 and when the time interval between onset of symptoms and treatment initiation (total delay) was >28 days compared to when this interval was ≤28 days. About 20% suffered catastrophic expenditure; 34% borrowed money and 37% sold assets. CONCLUSION: Concerted efforts are needed to reduce delay and OOPE in pre-treatment period and social protection to account for indirect expenditure.

Transmission efficiency of Papaya ringspot virus by three aphid species.

The transmission efficiency of Papaya ringspot virus (PRSV) by three aphid vectors (i.e., Aphis gossypii, A. craccivora, and Myzus persicae) was studied. Efficiency was measured by single-aphid inoculation, group inoculation (using five aphids), duration of virus retention, and the number of plants following a single acquisition access period (AAP) to which the aphids could successfully transmit the virus. Single-aphid inoculation studies indicated that M. persicae (56%) and A. gossypii (53%) were significantly more efficient in transmitting PRSV than A. craccivora (38%). Further, in the former two species, the time required for initiation of the first probe on the inoculation test plant was significantly shorter compared to A. craccivora. PRSV transmission efficiency was 100% in all three species when a group of five aphids were used per plant. There was a perceptible decline in transmission efficiency as the sequestration period increased, although M. persicae successfully transmitted PRSV after 30 min of sequestration. A simple leaf-disk assay technique was employed for evaluating the transmission efficiency of three species of aphids. The results of leaf-disk assays also indicated that A. gossypii (48%) and M. persicae (56%) were more efficient PRSV vectors than A. craccivora. Using leaf-disk assays, the ability of individual aphids to inoculate PRSV serially to a number of plants was studied. Following a single AAP on an infected leaf, M. persicae was more efficient than the other two species with 52.5% transmission after the first inoculation access period (IAP). However, its inoculation efficiency significantly decreased with the second and subsequent IAPs. A. gossypii was able to transmit PRSV sequentially up to four successive leaf disks, but with significantly declining efficiency. Since A. gossypii is reported to be the numerically dominant vector in south India in addition to being a more efficient vector capable of inoculating PRSV to multiple plants, it should be the target vector for control strategies.

A soluble form of the Tomato spotted wilt virus (TSWV) glycoprotein G(N) (G(N)-S) inhibits transmission of TSWV by Frankliniella occidentalis.

Tomato spotted wilt virus (TSWV) is an economically important virus that is transmitted in a persistent propagative manner by its thrips vector, Frankliniella occidentalis. Previously, we found that a soluble form of the envelope glycoprotein G(N) (G(N)-S) specifically bound thrips midguts and reduced the amount of detectable virus inside midgut tissues. The aim of this research was to (i) determine if G(N)-S alters TSWV transmission by thrips and, if so, (ii) determine the duration of this effect. In one study, insects were given an acquisition access period (AAP) with G(N)-S mixed with purified virus and individual insects were assayed for transmission. We found that G(N)-S reduced the percent of transmitting adults by eightfold. In a second study, thrips were given an AAP on G(N)-S protein and then placed on TSWV-infected plant material. Individual insects were assayed for transmission over three time intervals of 2 to 3, 4 to 5, and 6 to 7 days post-adult eclosion. We observed a significant reduction in virus transmission that persisted to the same degree throughout the time course. Real-time reverse transcription polymerase chain reaction analysis of virus titer in individual insects revealed that the proportion of thrips infected with virus was reduced threefold when insects were preexposed to the G(N)-S protein as compared to no exposure to protein, and nontransmitters were not infected with virus. These results demonstrate that thrips transmission of a tospovirus can be reduced by exogenous viral glycoprotein.

Double-Stranded RNA-Mediated Suppression of Trypsin-Like Serine Protease (t-SP) Triggers Over-Expression of Another t-SP Isoform in Helicoverpa armigera.

High diversity of digestive proteases is considered to be the key factor in the evolution of polyphagy in Helicoverpa armigera. Serine proteases (SPs) contribute ~85% of the dietary protein digestion in H. armigera. We investigated the dynamics of SP regulation in the polyphagous pest, H. armigera using RNA interference (RNAi). HaTry1, an isoform of SP, expressed irrespective of the composition of the diet, and its expression levels were directly proportional to the larval growth rate. Therefore, HaTry1 was silenced by delivering 10 and 20 µg concentrations of double-stranded RNA through semi-synthetic diet. This led to a drastic reduction in the target gene transcript levels that manifested in a significant reduction in the larval weight initially, but the larvae recovered in later stages despite continuous dsRNA treatment. This was probably due to the compensatory effect by over-expression of HaTry13 (31-folds), another isoform of SP. Phylogenetic analysis of H. armigera SPs revealed that the over-expressed isoform was closely related to the target gene as compared to the other tested isoforms. Further, silencing of both the isoforms (HaTry1 and HaTry13) caused the highest reduction in the larval weight and there was no larval growth recovery. These findings provide a new evidence of the existence of compensatory effect to overcome the effect of silencing individual gene with RNAi. Hence, the study emphasizes the need for simultaneous silencing of multiple isoforms.

Future Research Priorities for Morbidity Control of Lymphedema.

BACKGROUND: Innovation in the treatment of lower extremity lymphedema has received low priority from the governments and pharmaceutical industry. Advancing lymphedema is irreversible and initiates fibrosis in the dermis, reactive changes in the epidermis and subcutis. Most medical treatments offered for lymphedema are either too demanding with a less than satisfactory response or patients have low concordance due to complex schedules. A priority setting partnership (PSP) was established to decide on the future priorities in lymphedema research. METHODS: A table of abstracts following a literature search was published in workshop website. Stake holders were requested to upload their priorities. Their questions were listed, randomized, and sent to lymphologists for ranking. High ranked ten research priorities, obtained through median score, were presented in final prioritization work shop attended by invited stake holders. A free medical camp was organized during workshop to understand patients' priorities. RESULTS: One hundred research priorities were selected from priorities uploaded to website. Ten priorities were short listed through a peer review process involving 12 lymphologists, for final discussion. They were related to simplification of integrative treatment for lymphedema, cellular changes in lymphedema and mechanisms of its reversal, eliminating bacterial entry lesions to reduce cellulitis episodes, exploring evidence for therapies in traditional medicine, improving patient concordance to compression therapy, epidemiology of lymphatic filariasis (LF), and economic benefit of integrative treatments of lymphedema. CONCLUSION: A robust research priority setting process, organized as described in James Lind Alliance guidebook, identified seven priority areas to achieve effective morbidity control of lymphedema including LF. All stake holders including Department of Health Research, Government of India, participated in the PSP.

The First Report of miRNAs from a Thysanopteran Insect, Thrips palmi Karny Using High-Throughput Sequencing.

Thrips palmi Karny (Thysanoptera: Thripidae) is the sole vector of Watermelon bud necrosis tospovirus, where the crop loss has been estimated to be around USD 50 million annually. Chemical insecticides are of limited use in the management of T. palmi due to the thigmokinetic behaviour and development of high levels of resistance to insecticides. There is an urgent need to find out an effective futuristic management strategy, where the small RNAs especially microRNAs hold great promise as a key player in the growth and development. miRNAs are a class of short non-coding RNAs involved in regulation of gene expression either by mRNA cleavage or by translational repression. We identified and characterized a total of 77 miRNAs from T. palmi using high-throughput deep sequencing. Functional classifications of the targets for these miRNAs revealed that majority of them are involved in the regulation of transcription and translation, nucleotide binding and signal transduction. We have also validated few of these miRNAs employing stem-loop RT-PCR, qRT-PCR and Northern blot. The present study not only provides an in-depth understanding of the biological and physiological roles of miRNAs in governing gene expression but may also lead as an invaluable tool for the management of thysanopteran insects in the future.

RNA Interference of Odorant-Binding Protein 2 (OBP2) of the Cotton Aphid, Aphis gossypii (Glover), Resulted in Altered Electrophysiological Responses.

Aphis gossypii (Glover) (Hemiptera: Aphididae) is a highly invasive pest that feeds primarily on phloem resulting in severe economic loss to growers. A. gossypii has cosmopolitan distribution with broad host range, polyphenism, parthenogenetic mode of reproduction, vectoring abilities, and host alteration which has profound influence on its management. Odorant-binding proteins (OBPs) in insects are involved in olfaction, playing a key role in orienting the insect for feeding or oviposition. Recent studies revealed that OBP2 is found in both sensilla trichodea and sensilla basiconica and is preferentially binds to plant volatiles, thus playing crucial roles in host-seeking, detection of oviposition attractants, etc., However, information about the role of OBP2 in A. gossypii (AgOBP2) is still unavailable. In this study, we cloned and characterized OBP2, ortholog from A. gossypii, and the full-length AgOBP2 complementary DNA (cDNA) consisted of 859 bp with an open reading frame of 732 bp. Phylogenetic analysis resulted in grouping of AgOBP2 protein with members of the tribe Aphidini. Further, diet-mediated delivery of double-stranded RNA for AgOBP2 induced silencing, which was evaluated at 48 and 96 h. The reverse transcriptase real-time quantitative polymerase chain reaction (RTq-PCR) results revealed that the level of AgOBP2 messenger RNA (mRNA) was significantly reduced (55-77 %) in dsAgOBP2 treatment after 96 h as compared to the untreated control. The same was reiterated by the electrophysiological responses in the aphids which was reduced (>50 % at 0.25 µg/µl concentration) as compared to the untreated control. Thus, our results showed the potential of gene silencing, possibly to interfere with the odorant perception of A. gossypii for RNAi-mediated pest management. The results from our study provided the first evidence that AgOBP2 play crucial roles in host-seeking, detection of oviposition attractants, etc.; as a result, we suggests that OBP2 could potentially serve as a practicable target for RNAi-mediated gene silencing in hemipteran insect pest control.

Diet-Delivered dsRNAs for Juvenile Hormone-Binding Protein and Vacuolar ATPase-H Implied Their Potential in the Management of the Melon Aphid (Hemiptera: Aphididae).

RNA interference is a sequence-specific gene silencing mechanism mediated by double-stranded RNA (dsRNA), which has been harnessed as a useful tool in devising novel insect pest management strategies for various pests such as melon aphid, Aphis gossypii (Glover). In the current study, we cloned and sequenced juvenile hormone-binding protein (JHBP) and vacuolar ATPase subunit H (V-ATPase-H) from A. gossypii. We also showed the effectiveness of diet-mediated delivery of dsRNA for JHBP and V-ATPase-H, which silenced the above genes and resulted in mortality. The extent of silencing and mortality were similar for both genes up until 96 h. Bioassay results revealed that the target genes were silenced variably, 1.0 µg/µl concentration having a more profound effect than 0.5 and 0.25 µg/µl concentration in reducing the cognate mRNA transcript level. Results indicated a 9.56­73.21% down regulation (across time and concentrations for both the genes) that resulted in the mortality of A. gossypii. Mortality was in the range of 10­63% for both these genes. Thus, the current study demonstrated the potentiality of both JHBP and V-ATPase-H as excellent targets for the management of A. gossypii.

Non-invasive delivery of dsGST is lethal to the sweet potato whitefly, Bemisia tabaci (G.) (Hemiptera: Aleyrodidae).

The sweet potato whitefly, Bemisia tabaci (G.) biotype B (Hemiptera: Aleyrodidae), is one of the most economically important pest, by being a dreaded vector of Geminiviruses, and also causes direct damage to the crops by sucking phloem sap. Glutathione S-transferase (GST) is a large family of multifunctional enzymes that play pivotal roles in the detoxification of secondary allelochemical produced by the host plants and in insecticide resistance, thus regulates insect growth and development. The objective of this study is to show the potential of RNA interference (RNAi) in the management of B. tabaci. RNAi is a sequence-specific gene silencing mechanism induced by double-stranded RNA (dsRNA) which holds tremendous potential in pest management. In this regard, we sequenced the GST from B. tabaci and synthesized approximately 500-bp dsRNA from the above and delivered through diet to B. tabaci. Real-time quantitative PCR (RT-qPCR) showed that continuous application of dsGST at 1.0, 0.5, and 0.25 µg/µl reduced mRNA expression levels for BtGST by 77.43, 64.86, and 52.95 % which resulted in mortality by 77, 59, and 40 %, respectively, after 72 h of application. Disruption of BtGST expression will enable the development of novel strategies in pest management and functional analysis of vital genes in B. tabaci.