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Topography and vegetation have a significant role in soil development in different ecosystems. Interactions between soil and landforms help to understand the pedogenic processes and soil variability. The present study assessed the impact of various landforms and vegetation on pedological variability along the toposequence of the eastern coastal plain. We characterized 46 soil profiles from five landforms, viz., foothills, upland, alluvial plains, coastal plains, and sandbars and performed factor analysis. The frequency distribution of the soil properties was significantly skewed with each other’s. Soils are classified into three orders: Alfisols, Inceptisols, and Entisols from hills to sandbars. The soils were characterized by clay (2.50–65.8%), AWC (4.0–28.0%), pH (5.40–9.40), EC (0.03–5.60 dSm−1), OC (0.01–1.13%), CEC (1.0-31.60 cmol (p+) kg−1), BS (57–95%) and ESP (0.54–27.8%). Whereas alluvial plain soils are rich in clay and organic carbon, foothill and upland soils experience severe to moderate soil erosion, leading to the leaching of basic cations. Coastal plains face regular seawater intrusion and flooding, causing excess deposition of salts, which alter the soil pedogenic process under different landforms and land use. Soil pH, EC, clay, CEC and ESP significantly influenced the paddy yield in alluvial and coastal plains landforms. Development of landform and soil relationships concerning land uses in coastal regions helps to identify factors involved in soil development, pedogenic processes and crop productivity. [ABSTRACT FROM AUTHOR]

Variations in the functional response of legume pod borer (Maruca vitrata) populations to sex pheromone blends were observed in Asia and Africa. Hence, this study was carried out to understand the differences in pheromone‐binding proteins (PBPs) among Maruca populations in Asia, Africa, Oceania, and South America. A de novo transcriptome assembly was adopted to sequence the entire transcribed mRNAs in M. vitrata from Taiwan. The raw‐sequence data were assembled using homologous genes from related organisms in GenBank to detect M. vitrata PBPs (MvitPBPs). Sections of the cDNA of MvitPBP of different length were used to design primers to amplify the full‐length cDNA of PBPs. All three PBP sequences comprised three exons interspersed by two introns. In total, 92 MvitPBP1 haplotypes, 77 MvitPBP2 haplotypes, and 64 MvitPBP3 haplotypes were identified in 105, 98, and 68 Maruca individuals, respectively. High pairwise FST values (0.41–0.73) and phylogenetic analyses distinguished the putative Maruca species in South America from those occurring in rest of the world, and possibly two putative subspecies in Asia and Africa. The haplotype networks and Automatic Barcode Gap Discovery analyses also confirmed these results. The negative Tajima's D and Fu's FS values showed the recent demographic expansion of Maruca populations. Thus, this study confirmed the presence of different Maruca species and/or subspecies in different continents based on the diversity within PBP genes. Additional sampling and studies are suggested for Oceania and South America. The genetic differences among Maruca populations should be carefully considered while using sex pheromone lures and bio‐control agents. [ABSTRACT FROM AUTHOR]

Abstract: The beet webworm, Spoladea recurvalis Fabricius, is a destructive pest on vegetable crops in tropics and subtropics; its main host plant is amaranth. It has become imperative to develop non‐chemical methods to control S. recurvalis on amaranth. However, the lack of molecular information about this species has hindered the development of novel pest management strategies. In this study, high‐throughput RNA sequencing covering de novo sequence assemblies, functional annotation of transcripts, gene function classification and enrichment was performed on S. recurvalis. Illumina sequencing generated a total of 120 435 transcript contigs ranging from 201 to 22 729 bases with a mean length of 688 bases. The assembled transcripts were subjected to Basic Local Alignment Search Tool‐X (BLASTX) to obtain the annotations against non‐redundant, Swiss‐Prot, Clusters of Orthologous Groups (COG) and Kyoto Encyclopedia of Genes and Genomes (KEGG) protein databases. A subset of 58 225 transcript sequences returned hits from known proteins in the National Center for Biotechnology Information database, and the majority of the transcript sequences had the highest number of hits for Danaus plexippus (50.43%). A total of 1217 Gene Ontology‐level 3 annotations were assigned to 51 805 transcripts, while 39 650 transcripts were predicted as functional protein‐coding genes in the COG database and 20 037 transcripts were enriched to KEGG pathways. We identified 40 putative genes related to pheromone production and reception in S. recurvalis, with the expression of one gene between 0.29 and 1141.79 fragments per kilo base per million (FPKM) reads. The transcriptome sequence of S. recurvalis is a first step toward offering a comprehensive genomic resource which would enable better understanding of molecular mechanisms to enable development of effective pest management practices for this species. [ABSTRACT FROM AUTHOR]

Neuropeptides play essential roles in a variety of physiological responses that contribute to the development and reproduction of insects. Both the diapause hormone (DH) and pheromone biosynthesis activating neuropeptide (PBAN) belong to the PBAN/pyrokinin neuropeptide family, which has a conserved pentapeptide motif FXPRL at the C-terminus. We identified the full-length cDNA encoding DH-PBAN in Maruca vitrata, a major lepidopteran pest of leguminous crops. The open reading frame of Marvi-DH-PBAN is 591 bp in length, encoding 197 amino acids, from which five putative neuropeptides [DH, PBAN, α-subesophageal ganglion neuropeptide (SGNP), β-SGNP and γ-SGNP] are derived. Marvi-DH-PBAN was highly similar (83%) to DH-PBAN of Omphisa fuscidentalis (Lepidoptera: Crambidae), but possesses a unique C-terminal FNPRL motif, where asparagine has replaced a serine residue present in other lepidopteran PBAN peptides. The genomic DNA sequence of Marvi-DH-PBAN is 6,231 bp in size and is composed of six exons. Phylogenetic analysis has revealed that the Marvi-DH-PBAN protein sequence is closest to its homolog in Crambidae, but distant from Diptera, Coleoptera and Hymenoptera DH-PBAN, which agrees with the current taxonomy. DH-PBAN transcripts were present in the head and thoracic complex, but absent in the abdomen of M. vitrata. Real-time quantitative PCR assays have demonstrated a relatively higher expression of Marvi-DH-PBAN mRNA in the latter half of the pupal stages and in adults. These findings represent a significant step forward in our understanding of the DH-PBAN gene architecture and phylogeny, and raise the possibility of using Marvi-DH-PBAN to manage M. vitrata populations through molecular techniques. [ABSTRACT FROM AUTHOR]

Whiteflies and spider mites are amongst the most harmful eggplant (Solanum melongena) pests. Considering the need for reduction of chemical applications for whitefly and spider mite control, the exploitation of wild relatives of eggplant as sources of pest resistances represents an important strategy in order to improve cultivated eggplant. The objectives of this study were to evaluate 15 accessions from 11 species of eggplant wild relatives together with seven S. melongena accessions for resistance to sweet potato whitefly (Bemisia tabaci) and to two-spotted spider mite (Tetranychus urticae). Resistance to whitefly was evaluated based on number of eggs, nymph, puparium and whitefly adults in a choice bioassay, while for two-spotted spider mite it was based on leaf damage scores in the choice and no-choice bioassays. The results revealed significantly (P < 0.05) different levels of resistance to the two pests among the accessions evaluated. Considering all screening parameters in the whitefly choice bioassay, the highest levels of resistance in wild eggplant relatives were detected in Solanum dasyphyllum (DAS1) and S. pyracanthos (PYR1), although one of the cultivated S. melongena (MEL2) accessions also displayed similar resistance levels. In addition, S. campylacanthum (CAM8) and S. tomentosum TOM1 were also resistant to whitefly based on numbers of puparium and adult whiteflies. Two accessions of S. sisymbriifolium (SIS1 and SIS2) exhibited strong resistance to two-spotted spider mite based on the choice and no-choice bioassays. High levels of spider mite resistance were also detected in the no-choice assay in S. dasyphyllum (DAS1) and S. torvum (TOR2) accessions. These resistant accessions can be used in pre-breeding program aiming to breed pest-resistant cultivars in cultivated eggplant. Moreover, to our knowledge, this study represents the first report on potential sources of resistance to whitefly and two-spotted spider mite in wild relatives of eggplant. [ABSTRACT FROM AUTHOR]

Spoladea recurvalis F. is a major pest moth of amaranth (Amaranthus spp.) flowers worldwide, with a potential of causing complete foliage loss under severe outbreaks. Chemical insecticides are uneconomical for resource-poor farmers and pose health and environmental risks. Host plant resistance (HPR) to insects is an effective, economical and environmentally friendly alternative that is poorly understood and largely unexploited among traditional leafy vegetables. A total of 35 amaranth accessions were evaluated for the expression of their antixenotic and antibiotic traits against S. recurvalis, focusing on their effects on the biology of the pest in comparison with a susceptible accession. The accession VI036227 was found to be highly resistant against the pest, exhibiting exemplary antibiosis by causing 100% larval mortality within the first 36 h, despite not being deterrent for oviposition. The accessions VI048076, VI056563 and VI047555-B demonstrated moderate resistance against the pest for specific parameters including low oviposition, moderate early stage larval mortality and reduced adult longevity. Total mortality and weight gain in these three accessions were, however, not significantly different from the susceptible control. Higher numbers of eggs were laid in no-choice compared to choice situations. The implications of these findings in the management of S. recurvalis on amaranths are discussed. [ABSTRACT FROM AUTHOR]

Tuta absoluta (Meyrick) is a destructive pest causing adverse environmental and economic effects globally. Management of T. absoluta by synthetic chemicals is of diminutive achievement due to resistance trick of the pest. Harnessing of biocontrols is currently fascinating and efficient for management of the tremendous pests. This study isolated an entomopathogenic fungus from dead larvae of T. absoluta on tomato leaves from farmer's field Tanzania. Two Aspergillus fungal isolates were isolated and tested against larvae and adults of T. absoluta under conditions of 19.5°C and 50%RH, 30.4°C and 70% RH, respectively, in the laboratory. Sequence analysis of Aspergillus isolates that we referred as A-Tz1 and A-Tz2 were analysed with the BLAST program available at the National Center for Biological Information (NCBI). The two isolates (A-Tz1 and A-Tz2) showed 100% similarity with Aspergillus oryzae of GeneBank accession numbers EF121337.1 and MG519722.1. Such similarity implied that both A-Tz1 and A-Tz2 isolates were A. oryzae. To confirm pathogenicity, bioassays were conducted against the larvae, pupa and adults of T. absoluta. Results showed that at 1.0 × 108 conidia/mL, fungal isolates caused up to 70% larval mortality 3 days post inoculation and consequently inhibited pupation by 84.5% and adult emergence by 74.4%. The identified A. oryzae reduced the life span of adult T. absoluta up to 5 days post inoculation at 1.0 × 108 conidia/mL whereas in control T. absoluta survived up to 25 days. This study found that isolates of Aspegillus species have the potential to be used as active ingrediennt for the formulation of a new bioinjections for application by farmers to control the pest in fields. [ABSTRACT FROM AUTHOR]

The two-spotted spider mite, Tetranychus urticae, is a serious global pest of eggplants and other vegetables in the tropics and subtropics. The scarlet (Solanum aethiopicum L.) and gboma (Solanum macrocarpon L.) are two cultivated eggplants indigenous to sub-Saharan Africa. In this study, 120 accessions of S. aethiopicum and five accessions of S. macrocarpon from the World Vegetable Center's genebank collection were evaluated for spider mite resistance based on leaf damage scores and trichome types and densities. The highest levels of resistance were detected in S. macrocarpon accessions VI050393 and VI050444. In addition, two accessions of S. aethiopicum, VI042749 and VI042753, were moderately resistant. All other S. aethiopicum accessions were susceptible or highly susceptible. Spider mite resistance was significantly associated with the presence of type VII glandular trichome, but nonglandular stellate trichomes were not associated with resistance. The resistant S. macrocarpon accessions can be directly used as resistant cultivars or in prebreeding programs aimed at breeding resistant lines of the most commonly cultivated eggplant (S. melogena). [ABSTRACT FROM AUTHOR]

Leucinodes orbonalisis the most detrimental South and Southeast Asian insect pest of eggplant. To help reduce the impact of this pest, population genetic diversity and structure ofL. orbonaliswere examined in eight populations from six countries using mitochondrialcytochrome c oxidase subunit IDNA sequences. No correlation between genetic diversity and geographic distance was detected among populations. Low levels of haplotype and nucleotide diversities were observed in the Philippines population, suggesting recent colonization. No significant gene flow was found among local populations in different countries. The Vietnam population is highly differentiated, indicated by significant pairwiseFSTvalues, and may be ascribed to a new subspecies or race. India was confirmed to be the source of genetic variation inL. orbonalispopulations. Our study showed thatL. orbonalisformed subpopulations for each local region, and the corresponding pest management technology should be developed at the country scale. [ABSTRACT FROM AUTHOR]

Despite accelerated developments in agricultural innovations, there has been a limited progress in their adoption by smallholder farmers, especially in the Global South. Innovations are not adequately reaching farmers, and new technologies are often unsuitable for farmers, or the overall innovation landscape is discouraging the deployment of innovations at scale. The methodological approaches to designing, testing and scaling of innovations play an important role. Involving farmers in the innovation process from the start increases the likelihood of them being more relevant and having a higher chance of adoption. Whereas there is much literature on participatory approaches, there is a limited guidance on choosing an appropriate level of farmer participation across the innovation process. This study aims to develop practical guidance for researchers, development agents and project managers on how to choose an appropriate methodological approach with a suitable level of farmer participation for designing, testing and scaling of agricultural innovations, according to levels of innovation readiness and innovation use. Relevant scientific literature on participatory design, research and scaling of agricultural innovations was reviewed, followed by compiling lessons learned from selected vegetable innovation projects implemented by the World Vegetable Center (WorldVeg) in Asia and Africa. A list of methodological approaches for participatory design, testing and scaling of innovations was generated, with various levels of farmer participation. A simple guiding framework was then developed for choosing an appropriate approach with a suitable level of farmer participation, according to the readiness and use of the innovations. Examples of selected approaches and application of the proposed guidance are given in project case studies. Based on the literature review and experience at WorldVeg, we believe it is critical to choose the right level of participation based on how ready are the innovations for application in the local setting. This dimension of how ready the innovations are has been largely overlooked in earlier frameworks on farmer participation. The developed guidance generally recommends increasing participation with higher levels of technology readiness and use. In addition, farmer consultation in early research design should also be strengthened, to co-design locally relevant innovations. The overall innovation systems' landscape must be considered when researching and scaling new innovations. The guidance, experiences and lessons provided in this paper will be useful to various scholars, researchers, development agents, funders and project managers who aim to design, test and scale agricultural innovations in a more inclusive and responsible way. [Display omitted] • Despite rapid developments in agricultural innovations, there has been limited adoption by smallholder farmers. • There is limited guidance on choosing an appropriate level of farmer participation in the innovation processes. • A list of participatory approaches for design, testing and scaling of innovations was created. • A guidance for choosing a suitable level of participation based on 'innovation readiness and use' was developed. [ABSTRACT FROM AUTHOR]

In a series of open field experiments, we studied the effects of two lepidopteran pests (Plutella xylostella and Crocidolomia pavonana) at equal population density on cabbage yield. Completely randomised plots were assigned to four treatments, replicated four times. Treatments were P. xylostella only, C. pavonana only, or P. xylostella and C. pavonana at 1:1 ratio at different phenological stages of cabbages and a control (without any caterpillars). The growth stages and applied densities were pre-heading, cupping and heading, with densities of 2, 4 and 6 larvae/plant, compared with control. The effects of the two species differed significantly in terms of both yield (P < 0.0001) and injury score (P < 0.0001) compared to the control, which produced 67.4 ± 5.79 t/ha of clean, marketable cabbage. Crocidolomia pavonana reduced yield by 68% (21.8 ± 0.82 t/ha) with no market value at a cumulative injury score of 5, while P. xylostella reduced the yield by 40% (40.4 ± 2.38 t/ha at a cumulative injury score of 3.5). The sequential infestation of cabbage by P. xylostella and C. pavonana reduced yield by 41%, with 39.4 ± 3.48 t/ha of marketable yield at a cumulative injury score of 4.4. Thus, C. pavonana is more damaging than P. xylostella under the same growing conditions. Hence, zero infestation is recommended during the seedling and transplanting stages of the cabbages. The findings can serve as a basis to establish an economic threshold for C. pavonana and modify a two-decade-old economic threshold for P. xylostella in Tanzania. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acorus calamus rhizome is a good source of zinc oxide nanoparticles (AC-ZnONPs). • The synthesized AC-ZnONPs showed good antimicrobial activity. • AC-ZnONPs coated fabrics could be used for wound healing and antimicrobial purposes. Microbial infections are a general public health problem worldwide, and their resistance to antibiotics has increased rapidly. The prevention of microbial growth on the surface of cotton fabric is essential to control skin-related infections. In this work, we evaluated A.calamus - zinc oxide nanoparticle (AC-ZnONPs) coated cotton fabrics for antibacterial and cytotoxic activities. The formulated AC-ZnONPs were characterized by UV-spectrophotometer, SEM, EDX, FT-IR, and TEM studies. The AC-ZnONPs amalgamation into the cotton fabrics was done by the dipping technique. The antimicrobial activity and cytotoxic activity were executed by standard approaches. The results of UV-spectrophotometer, TEM, and SEM, and EDX proved the formation and existence of AC-ZnONPs on the fabrics' surface. FT-IR results demonstrated the existence of numerous functional groups. AC-ZnONPs efficiently suppressed the growth of the pathogenic microbes with a maximum inhibition at 60 μg of AC-ZnONPs against E.coli and S.aureus. The AC-ZnONPs coated fabrics also prevented microbial growth with maximum inhibition against P.aeruginosa , K.oxytoca , and A.baumanii. In addition, AC-ZnONPs efficiently suppressed the viability of SK-MEL-3 cells. Altogether, our findings disclosed that the AC-ZnONPs coated fabrics displayed excellent antimicrobial activity against the pathogenic microbes and could be utilized in the medical fields in the future. [ABSTRACT FROM AUTHOR]

Given the new spread and potential damage of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in Asia, it has become imperative to understand the development biology of this invasive species on selected vegetable crops in newer geographical regions. In this study, we investigated the ovipositional preference of FAW females on different host plants, under choice- and non-choice tests. In addition, using the age-stage, two-sex life table theory, we assessed the performance of immature FAW individuals fed and reared on selected vegetable crops to get information related to development time, survival, reproduction and longevity. Fall armyworm females had an oviposition preference on maize compared to other vegetable crops, including cabbage and soybean, and reluctance for tomato, which was confirmed during the choice and non-choice tests. In contrast to the oviposition preference, our results also suggest that despite low preference for cabbage, soybean, and tomato, these crops seemed to provide a high benefit for an appropriate offspring performance, exceeding in some cases the benefits from a maize-based diet. Information from this study was discussed in terms of FAW ecology and how female's decision affects their reproductive fitness, and the survival and performance of its offspring. [ABSTRACT FROM AUTHOR]

Given the new spread and potential damage of the fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in Asia, it has become imperative to understand the development biology of this invasive species on selected vegetable crops in newer geographical regions. In this study, we investigated the ovipositional preference of FAW females on different host plants, under choice- and non-choice tests. In addition, using the age-stage, two-sex life table theory, we assessed the performance of immature FAW individuals fed and reared on selected vegetable crops to get information related to development time, survival, reproduction and longevity. Fall armyworm females had an oviposition preference on maize compared to other vegetable crops, including cabbage and soybean, and reluctance for tomato, which was confirmed during the choice and non-choice tests. In contrast to the oviposition preference, our results also suggest that despite low preference for cabbage, soybean, and tomato, these crops seemed to provide a high benefit for an appropriate offspring performance, exceeding in some cases the benefits from a maize-based diet. Information from this study was discussed in terms of FAW ecology and how female's decision affects their reproductive fitness, and the survival and performance of its offspring. [ABSTRACT FROM AUTHOR]

Mungbean has potential for expansion as an opportunity crop planted on residual soil water after flood on active floodplains in Cambodia. However, mungbean production is severely affected by insect pests and excessive application of chemical insecticides has led to increased losses from secondary pests such as bean flower thrips (Megalurothrips usitatus Bagnall). In an exploratory study, we evaluated the effectiveness of blue and yellow sticky traps as part of an integrated management strategy to control bean flower thrips in mungbean at three locations in Battambang province in the early dry season 2021. The sites were situated in three different agro-ecological systems: semi-urban (Sala Balat); lowland rice (Os Tuk); and intensive mungbean (Preaek Trab). Blue sticky traps, impregnated with thrip pheromone, were six-times more effective than yellow traps for capturing thrips. Thrip numbers varied between sites but increased in a linear fashion between 15 and 35 days after sowing at Preak Trab which has a history of intensive insecticide use in mungbean. A concern with blue traps was that they were more effective than yellow traps for capturing beneficial ground beetles, rove beetles and hoverflies. Therefore, further study is required to determine potential adverse impacts of deployment of blue sticky traps. This study confirmed the potential value for blue sticky traps to monitor and potentially control bean flower thrips in mungbean in North-West Cambodia. We also put forward a range of Integrated Pest Management (IPM) options to manage bean flower thrips in mungbean and the challenge is to find a way to have them adopted. Transfer of technical information in this community is primarily through the village network, especially for information on fertilisers and pesticides. The key to an effective strategy is to engage the key influencers on insect pest management to facilitate adoption of IPM in mungbean. [ABSTRACT FROM AUTHOR]

Since 2007, diamide insecticides have been widely used in Korea to control various types of lepidopteran pests including Spodoptera exigua. For nearly a decade, diamide resistance in field populations of S. exigua across 18 localities has been monitored using bioassays. Despite their short history of use, resistance to diamide insecticides has emerged. Based on the LC 50 values, some field populations showed a higher level of resistance to chlorantraniliprole, a diamide insecticide, compared to that of the susceptible strain, although regional and temporal variations were observed. To investigate resistance at a molecular level, we examined three mutations (Y4701C, I4790M, and G4946E) in the ryanodine receptor (RyR), which is the primary mechanism underlying diamide insecticide resistance. DNA sequencing showed that only the I4790M mutation was found in most field populations. As resistance levels varied significantly despite the uniform presence of the I4790M mutation, we considered the presence of another resistance factor. Further, the I4790M mutation was also found in S. exigua specimens collected prior to the commercialization of diamide insecticides in Korea as well as in other countries, such as the USA. This finding led us to hypothesize that the I4790M mutation were predisposed in field populations owing to selection factors other than diamide use. For further clarification, we conducted whole-genome sequencing of S. exigua (449.83 Mb) and re-sequencing of 18 individual whole genomes. However, no additional non-synonymous mutations were detected in the RyR-coding region. Therefore, we concluded that the high level of diamide insecticide resistance in Korean S. exigua is not caused by mutations at the target site, RyR, but is attributed to other factors that need to be investigated in future studies. [Display omitted] • The I4790M mutation in the RyR gene was identified in field populations of S. exigua before the introduction of commercial diamide insecticides. • No other non-synonymous mutations were detected in the RyR coding sequences obtained from whole genome re-sequencing. • It is possible that alternative mechanisms, rather than the I4790M mutation, are primarily responsible for diamide resistance in S. exigua. [ABSTRACT FROM AUTHOR]

Abstract: Nemorilla maculosa Meigen (Diptera: Tachinidae) is a solitary endoparasitoid of the legume pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae), a key pest of cowpea, Vigna unguiculata (L.) Walp. (Fabaceae) in Africa. A colony of N. maculosa, introduced for experimental purposes from Taiwan to the laboratories of the International Institute of Tropical Agriculture (IITA) in Benin, was used for our studies. Olfactory reponses of N. maculosa to leaves of infested or uninfested cowpea and yellow peabush, Sesbania cannabina (Retz.) Pers. (Fabaceae), and to M. vitrata larvae were evaluated in a four‐arm olfactometer. For all combinations of odor sources, responses between naïve and oviposition‐experienced female flies did not differ. Nemorilla maculosa females were attracted by odors from uninfested leaves of yellow peabush and flowers of cowpea when compared with clean air, and they were attracted to plants damaged by M. vitrata with larvae removed. However, the female fly did not discriminate between odors from infested and uninfested plants. The parasitic fly N. maculosa proved well able to use volatile compounds from various host plants (peabush and cowpea) to locate its host, with a more pronounced attraction by the combination of host larvae and infested host plant parts. These findings are discussed in light of the prospective use of N. maculosa as a biological control agent against the legume pod borer. [ABSTRACT FROM AUTHOR]

South and Southeast Asia endure high vegetable production losses due to begomovirus diseases mainly transmitted by the insect vector, whitefly (Bemisia tabaci). Control over the spread of virus infection can be achieved through a better understanding of genetic diversity among B. tabaci. A total of 64 populations of B. tabaci collected from Tamil Nadu (India), Vietnam, Thailand, and Indonesia were investigated based on mitochondrial cytochrome c oxidase I (coxI) sequences. Populations from Tamil Nadu are distributed into three clades (Asia I, Asia II 7, and Asia II 8), whereas Indonesian populations settle along with Asia I population of India in the phylogenetic tree. Vietnam populations align with the Middle East-Asia Minor 1 (MEAM1) clade, and interestingly MEAM1 invades northern Vietnam quite recently. Samples from Thailand made a unique clade between the outgroup and the remaining B. tabaci, representing the possibility of a new subspecies. AMOVA analysis among populations from various districts in Tamil Nadu exhibits significant differences, which represent each district's individuality. This study proves that the use of coxI as a marker for molecular identification of B. tabaci can provide a better estimate of diversity. We provide important clues for developing insight into the genetic structure of B. tabaci, and suggest strategies for control. [ABSTRACT FROM AUTHOR]

The tomato leaf miner ( Tuta absoluta) is a serious pest of tomato ( Solanum lycopersicum) in the tropics and subtropics. Previous World Vegetable Center studies identified selected accessions of S. galapagense, S. cheesmaniae and S. pimpinellifolium that were resistant to whitefly ( Bemisia tabaci Genn.) and spider mite ( Tetranychus urticae Koch). Here, we evaluated these accessions for resistance to T. absoluta based on the number of eggs from choice bioassays, and larval mortality and adults emerged percentages in no-choice feeding bioassays at WorldVeg Eastern and Southern Africa (WorldVeg) and the International Centre for Insect Physiology and Ecology ( icipe). At WorldVeg, S. galapagense exhibited high resistance in both choice and no-choice bioassays. There was strong negative correlation between larval mortality and adults emerged percentages in the no-choice feeding bioassays. Results from the icipe experiments were consistent with those of the WorldVeg screening, except for S. pimpinellifolium accession , which was susceptible at icipe. Tuta absoluta is rapidly spreading and the resistance sources reported here will be valuable in breeding tomato varieties resistant to this insect and others. [ABSTRACT FROM AUTHOR]

Background: Bruchid beetles are an important storage pest of grain legumes. Callosobruchus sp. infect mungbean (Vigna radiata) at low levels in the field, multiply during grain storage and can destroy seed stocks in a few months. Resistance against bruchid beetles has been found in wild mungbean V. radiata var. sublobata TC1966 and in cultivated mungbean line V2802. Results: Bruchid resistance data were obtained from recombinant inbred line populations TC1966 (V. radiata var. sublobata) x NM92 (F12) and V2802 (V. radiata) x NM94 (F7). More than 6,000 single nucleotide polymorphic markers were generated through genotyping by sequencing (GBS) for each of these populations and were used to map bruchid resistance genes. One highly significant quantitative trait locus (QTL) associated with bruchid resistance was mapped to chromosome 5 on genetic maps of both populations, suggesting that TC1966 and V2802 contain the same resistance locus. Co-segregation of all markers associated with resistance indicated the presence of only one major resistance QTL on chromosome 5, while QTL analysis based on physical map positions of the markers suggested the presence of multiple QTLs on different chromosomes. The diagnostic capacity of the identified molecular markers located in the QTL to correctly predict resistance was up to 100 %. Conclusions: Molecular markers tightly linked to bruchid resistance loci of two different mungbean resistance sources were developed and validated. These markers are highly useful for developing resistant lines. [ABSTRACT FROM AUTHOR]

Sesquiterpenes play important roles in insect communication, for example as pheromones. However, no sesquiterpene synthases, the enzymes involved in construction of the basic carbon skeleton, have been identified in insects to date. We investigated the biosynthesis of the sesquiterpene (6R,7S)-himachala-9,11-diene in the crucifer flea beetle Phyllotreta striolata, a compound previously identified as a male-produced aggregation pheromone in several Phyllotreta species. A (6R,7S)-himachala-9,11-diene-producing sesquiterpene synthase activity was detected in crude beetle protein extracts, but only when (Z,E)-farnesyl diphosphate [(Z,E)-FPP] was offered as a substrate. No sequences resembling sesquiterpene synthases from plants, fungi, or bacteria were found in the P. striolata transcriptome, but we identified nine divergent putative trans-isoprenyl diphosphate synthase (trans-IDS) transcripts. Four of these putative trans-IDSs exhibited terpene synthase (TPS) activity when heterologously expressed. Recombinant PsTPS1 converted (Z,E)-FPP to (6R,7S)-himachala-9,11-diene and other sesquiterpenes observed in beetle extracts. RNAi-mediated knockdown of PsTPS1 mRNA in P. striolata males led to reduced emission of aggregation pheromone, confirming a significant role of PsTPS1 in pheromone biosynthesis. Two expressed enzymes showed genuine IDS activity, with PsIDS1 synthesizing (E,E)-FPP, whereas PsIDS3 produced neryl diphosphate, (Z,Z)-FPP, and (Z,E)-FPP. In a phylogenetic analysis, the PsTPS enzymes and PsIDS3 were clearly separated from a clade of known coleopteran trans-IDS enzymes including PsIDS1 and PsIDS2. However, the exon-intron structures of IDS and TPS genes in P. striolata are conserved, suggesting that this TPS gene family evolved from trans-IDS ancestors. [ABSTRACT FROM AUTHOR]

This study was undertaken to assess the genetic diversity and host plant races of M. vitrata population in South and Southeast Asia and sub-Saharan Africa. The cytochrome c oxidase subunit 1 (cox1) gene was used to understand the phylogenetic relationship of geographically different M. vitrata population, but previous studies did not include population from Southeast Asia, the probable center of origin for Maruca, and from east Africa. Extensive sampling was done from different host plant species in target countries. Reference populations from Oceania and Latin America were used. An amplicon of 658 bp was produced by polymerase chain reaction, and 64 haplotypes were identified in 686 M. vitrata individuals. Phylogenetic analysis showed no difference among the M. vitrata population from different host plants. However, the results suggested that M. vitrata has formed two putative subspecies (which cannot be differentiated based on morphological characters) in Asia and sub-Saharan Africa, as indicated by the high pairwise FST values (0.44–0.85). The extremely high FST values (≥0.93) of Maruca population in Latin America and Oceania compared to Asian and African population seem to indicate a different species. On the continental or larger geographical region basis, the genetic differentiation is significantly correlated with the geographical distance. In addition, two putative species of Maruca, including M. vitrata occur in Australia, Indonesia and Papua New Guinea. The negative Tajima’s D and Fu’s FS values showed the recent demographic expansion of Maruca population. The haplotype network and Automatic Barcode Gap Discovery analyses confirmed the results of phylogenetic analysis. Thus, this study confirmed the presence of three putative Maruca species, including one in Latin America, one in Oceania (including Indonesia) and M. vitrata in Asia, Africa and Oceania. Hence, the genetic differences in Maruca population should be carefully considered while designing the pest management strategies in different regions. [ABSTRACT FROM AUTHOR]

The ability of a specialized herbivore to overcome the chemical defense of a particular plant taxon not only makes it accessible as a food source but may also provide metabolites to be exploited for communication or chemical defense. Phyllotreta flea beetles are adapted to crucifer plants (Brassicales) that are defended by the glucosinolate-myrosinase system, the so-called "mustard-oil bomb." Tissue damage caused by insect feeding brings glucosinolates into contact with the plant enzyme myrosinase, which hydrolyzes them to form toxic compounds, such as isothiocyanates. However, we previously observed that Phyllotreta striolata beetles themselves produce volatile glucosinolate hydrolysis products. Here, we show that P. striolata adults selectively accumulate glucosinolates from their food plants to up to 1.75% of their body weight and express their own myrosinase. By combining proteomics and transcriptomics, a gene responsible for myrosinase activity in P. striolata was identified. The major substrates of the heterologously expressed myrosinase were aliphatic glucosinolates, which were hydrolyzed with at least fourfold higher efficiency than aromatic and indolic glucosinolates, and β-O-glucosides. The identified beetle myrosinase belongs to the glycoside hydrolase family 1 and has up to 76% sequence similarity to other β-glucosidases. Phylogenetic analyses suggest species-specific diversification of this gene family in insects and an independent evolution of the beetle myrosinase from other insect β-glucosidases. [ABSTRACT FROM AUTHOR]