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A description of a new species of plant parasitic nematodes of the genus Rotylenchus from the family Hoplolaimidae is given and a recognition of Rotylenchus jaeni comb. n., previously known as subspecies R. magnus jaeni, as separate species is proposed. Rotylenchus montanus sp. n. is characterized by a hemispherical lip region with six rarely seven annuli, stylet 33–37 µm, female tail rounded, regularly annulated tip with 12–18 annuli and phasmid located 2–9 annuli anterior to anus. Rotylenchus montanus sp. n. is close to species of the monosexual group R. arsenjevi, R. corsicus, R. fragaricus, R. helicus, R. indorobustus and R. neorobustus, by a number of specific characteristics resulting from its specific matrix code: A5, B1, C1, D4, E2, F2, G3, H2, I2, J2, K2. Molecular characterization of R. montanus sp. n. and other Rotylenchus species are provided using D2–D3 expansion segments of 28S and the ITS1 of rRNA genes. The D2–D3 of 28S rRNA and the ITS1–rRNA sequences of R. montanus sp. n. differed in one nucleotide and in 16–20 nucleotides from those of an unidentified Rotylenchus species from Russia, respectively. Molecular analysis of populations of R. magnus and R. jaeni comb. n. demonstrated differences in the D2–D3 and the ITS1–rRNA sequences. These genetic differences together with some minor morphological characters support that both subspecies should be considered as two cryptic sibling species and warranted their elevation to species rank. The result of phylogenetic analysis of Hoplolaimidae for 45 sequences of the D2 and D3 expansion regions of 28S rRNA gene using Bayesian inference analysis under the complex model is presented. Phylogenetic tree of Rotylenchus species represents seven moderate to highly supported lineages. Grouping of Rotylenchus species within other hoplolaimids and analysis of phylogenetic relationships within the genus Rotylenchus using the ITS1 of rRNA gene sequences are also discussed. [ABSTRACT FROM AUTHOR]

A survey of nematodes associated with the red palm weevil Rhynchophorus ferrugineus was conducted in southern Italy in 2015 and 2016 in order to create a species inventory and obtain data about nematode biodiversity. A total of 70 insect samples (pupae and adults) were collected from infested Phoenix canariensis, Phoenix dactylifera, and Chamaerops humilis palms in three Italian Regions: sampling took place at 11 locations in Apulia, 1 in Basilicata, and 1 in Sardinia regions. Individual insects were dissected to determine nematode presence, and different nematode species were also recovered from red palm weevil cocoons collected at the sites in Apulia. Individual nematodes were molecularly identified by sequencing the ITS, D2‐D3 expansion domains of the 28SrRNA gene and the mitochondrial COI and inferring the phylogenetic relationships. The insect‐associated nematofauna identified belonged to the families Rhabditidae, Cephalobidae, and Diplogastridae. Just two nematode species, Teratorhabditis synpapillata and Mononchoides macrospiculum, were always found in association with adult insects and cocoons taken from all sampling sites. This paper reports on the biodiversity of the nematodes associated with R. ferrugineus and on current knowledge of the specific habitat of specialized and divergent entomophilic nematodes. [ABSTRACT FROM AUTHOR]

Ditylenchus gigas Vovlas is the dominant species of Ditylenchus nematode on faba bean in the UK. It is normally reported with Botrytis fabae Sardiña, which causes chocolate spot of faba bean. The aim of the work reported here was to estimate how fast isolated infections of D. gigas may spread spatially and how background infection of the host with B. fabae alters multiplication of D. gigas. Spatial spread in field conditions was measured in plants growing in square grids. After establishment, single plants at the centre of each grid were spray inoculated with D. gigas. In summer 2017, D. gigas spread to a distance of at least 1 m, the edge of each 2 m × 2 m plot. Incidence on shoots decreased very slowly with distance beyond 0.4 m. In a repeat experiment harvested in autumn 2018, D. gigas was detected at distances of up to 160 cm in 4 m × 4 m plots. The yield effect and reproduction rate of D. gigas were measured in glasshouse experiments, alone and following brush inoculation with low (103) or high (106 conidia/mL) doses of B. fabae. At low doses of D. gigas inoculum multiplied by approximately 75‐fold, with lower rates of multiplication as the inoculum dose increased. The reproduction rate of D. gigas was reduced in plants inoculated with B. fabae, especially at high doses of D. gigas. The reduction was approximately proportional to log (B. fabae dose). Seed yield from inoculated plants decreased approximately in proportion to the logarithms of the initial dose of D. gigas and of B. fabae. [ABSTRACT FROM AUTHOR]

Morphologial, biochemical, molecular and karyological analyses of different populations and races of the stem and bulb nematode Ditylenchus dipsaci have suggested that it represents a species complex, of which only D. dipsaci sensu stricto and its morphologically larger variant, known as the giant race of the stem and bulb nematode, are plant parasites of economic importance. The present study singles out the giant race from this complex, herein described as a new species named Ditylenchus gigas n. sp., on the basis of morphological and molecular data obtained from several populations collected from broad beans in southern Italy, southern Spain and Lebanon. The new species epithet, which refers to the large body size of the nematode with respect to the normal races, must be considered to be conspecific with the D. dipsaci ‘giant race’ from Fabaceae in recent literature. Morphologically, the new species is characterized by a body size 1Æ5–2 times longer than the ‘normal race’, stylet delicate (11Æ5–13Æ0 lm long) with knobs distinctly sloping backwards, and long post-vulval uterine sac (81–150 lm long). Results of molecular analysis of rDNA sequences including the ITS1-5.8S-ITS2 region, the D2–D3 fragment of the 28S gene, the small 18S subunit, the partial mitochondrial gene for cytochrome c oxidase I (mtCOI), and hsp90 gene sequences, support the new taxonomic species status for the former D. dipsaci giant race from Vicia faba, and clearly distinguish D. gigas n. sp. from D. dipsaci sensu stricto. [ABSTRACT FROM AUTHOR]

Host–parasite relationships and pathogenicity of Meloidogyne javanica on potatoes (newly recorded from Malta) were studied under glasshouse and natural conditions. Potato cvs Cara and Spunta showed a typical susceptible reaction to M. javanica under natural and artificial infections, respectively. In potato tubers, M. javanica induced feeding sites that consisted of three to four hypertrophied giant cells per adult female. Infection of feeder roots by the nematode resulted in mature large galls which usually contained at least one mature female and egg mass. In both tubers and roots, feeding sites were characterized by giant cells containing granular cytoplasm and many hypertrophied nuclei. Cytoplasm in giant cells was aggregated alongside the thickened cell walls. Stelar tissues within galls appeared disorganized. The relationship between initial nematode population density ( P) [0–64 eggs + second-stage juveniles (J2s) per cm3 soil] and growth of cv. Spunta potato seedlings was tested under glasshouse conditions. A Seinhorst model [ y = m + (1 −  m) z( P− T)] was fitted to fresh shoot weight and shoot height data of nematode-inoculated and control plants. Tolerance limits ( T) for fresh shoot weight and shoot height of cv. Spunta plants infected with M. javanica were 0·50 and 0·64 eggs + J2s per cm3 soil, respectively. The m parameter in that model (i.e. the minimum possible y-values) for fresh shoot weight and shoot height were 0·60 and 0·20, respectively, at P = 64 eggs + J2s per cm3 soil. Root galling was proportional to the initial nematode population density. Maximum nematode reproduction rate was 51·2 at a moderate initial population density ( P = 4 eggs + J2s per cm3 soil). [ABSTRACT FROM AUTHOR]

Fifteen populations of cyst-forming nematodes belonging to 11 known and one unidentified species collected in countries bordering the Mediterranean Sea were studied using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and internal transcribed spacer (ITS)-rDNA sequences. RFLP profiles generated by the restriction enzymes AluI, AvaI, Bsh1236I, HaeIII, Hin6I, MvaI, PstI and RsaI are presented for Heterodera carotae, H. ciceri, H. fici, H. filipjevi, H. goettingiana, H. hordecalis, H. humuli, H. mediterranea, H. ripae and H. schachtii. Molecular data support the first detection of H. filipjevi from wheat in Italy and H. ripae from nettle in Greece. A relative high level of sequence divergence between populations of H. hordecalis was observed. This suggests that two species might presently be grouped under this taxon. The phylogenetic relationship between the Mediterranean cyst-forming nematode species is analysed based on the ITS-rDNA sequences. [ABSTRACT FROM AUTHOR]

A virus with filamentous particles 697 nin in length was isolated from artichoke plants in Southern Italy and identified as a new possible member of Carlavirus group, for which the name artichoke virus M (AVM) is suggested. AVM could not be transmitted by sap inoculation to herbaceous hosts and was always present in artichoke in mixed infections with other viruses. Virus particles had a buoyant density in CsCl of 1.31 g x cm-3 and contained a single species of nucleic acid with an apparent size of 7.5 Kb and a single coat protein species with a mol. wt of 31,000. The virus was distantly related serologically to carnation latent and poplar mosaic carlaviruses but not to other members of the group including the recently described artichoke latent S carlavirus. Cytological alterations consisted of complex cytoplasmic inclusions composed of deranged organelles, lipid droplets and accumulations of membranes. [ABSTRACT FROM AUTHOR]

High infection rates of European holly ( Ilex aquifolium) feeder roots by an unknown root-knot nematode were found in a holly forest at Arévalo de la Sierra (Soria province) in northern Spain. Holly trees infected by the root-knot nematode showed some decline and low growth. Infected feeder roots were distorted and showed numerous root galls of large (8–10 mm) to moderate (2–3 mm) size. Morphometry, esterase and malate dehydrogenase electrophoretic phenotypes and phylogenetic trees of sequences within the ribosomal DNA (rDNA) demonstrated that this nematode species differs clearly from other previously described root-knot nematodes. Studies of host-parasite relationships showed a typical susceptible reaction in naturally infected European holly plants, but did not reproduce on a number of cultivated plants, including tomato, grapevine, princess-tree and olive. The species is described here, illustrated and named as Meloidogyne silvestris n. sp. The new root-knot nematode can be morphologically distinguished from other Meloidogyne spp. by: (i) roundish perineal pattern, dorsal arch low, with fine, sinuous cuticle striae, lateral fields faintly visible; (ii) female excretory pore level with stylet knobs, or just anterior to them, EP/ST ratio about 0·8; (iii) second-stage juveniles with hemizonid located 1 to 2 annuli anterior to excretory pore and short, sub-digitate tail; and (iv) males with lateral fields composed of four incisures, with areolated outer bands. Phylogenetic trees derived from maximum parsimony analysis based on 18S, ITS1-5·8S-ITS2 and D2–D3 of 28S rDNA showed that M. silvestris n. sp. can be differentiated from all described root-knot nematode species, and it is clearly separated from other species with resemblance in morphology, such as M. ardenensis, M. dunensis and M. lusitanica. [ABSTRACT FROM AUTHOR]

Pathogenicity and host-parasite relationships in root-knot disease of celery ( Apium graveolens ) caused by Meloidogyne incognita race 1 were studied under glasshouse conditions. Naturally and artificially infected celery cv. D’elne plants showed severe yellowing and stunting, with heavily deformed and damaged root systems. Nematode-induced mature galls were spherical and/or ellipsoidal and commonly contained more than one female, males and egg masses with eggs. Feeding sites were characterized by the development of giant cells that contained granular cytoplasm and many hypertrophied nuclei. The cytoplasm of giant cells was aggregated along their thickened cell walls and consequently the vascular tissues within galls appeared disrupted and disorganized. The relationship between initial nematode population density ( Pi) and growth of celery plants was tested in glasshouse experiments with inoculum levels that varied from 0 to 512 eggs and second-stage juveniles (J2) mL−1 soil. Seinhorst's model y =  m + (1 –  m) zP–T was fitted to height and top fresh weight data of the inoculated and control plants. The tolerance limit with respect to plant height and fresh top weight of celery to M. incognita race 1 was estimated as 0·15 eggs and J2 mL−1 soil. The minimum relative values ( m) for plant height and top fresh weight were 0·37 and 0·35, respectively, at Pi ≥ 16 eggs and J2 mL−1 soil. The maximum nematode reproduction rate ( Pf/Pi) was 407·6 at an initial population density ( Pi) of 4 eggs and J2 mL−1 soil. [ABSTRACT FROM AUTHOR]

Host–parasite relationships in root-knot disease of spinach caused by Meloidogyne incognita race 1 were studied under glasshouse conditions. Nematode-induced mature galls were large and usually contained one or more females and egg masses with eggs. Feeding sites were characterized by the development of giant cells containing granular cytoplasm and many hypertrophied nuclei. The cytoplasm in these giant cells was aggregated alongside the thickened cell walls. Stelar tissues within galls appeared disorganized. The relationship between initial nematode population density ( Pi) in a series from 0–128 eggs and second-stage juveniles per cm3 soil and growth of spinach cv. Symphony F1 seedlings was tested under glasshouse conditions. A Seinhorst model [ y = m + (1 −  m) z P–T] was fitted to fresh top- and total plant-weight data for inoculated and control plants. Tolerance limits ( T) of spinach cv. Symphony F1 to M. incognita race 1 for fresh top and total plant weights were 0·25 and 0·5 eggs and second-stage juveniles per cm3 soil, respectively. The minimum relative values for fresh top and total plant weights were zero in both cases at Pi ≥ 32 eggs and second-stage juveniles per cm3 soil. Root galling was least at low initial population densities and greatest at 16 eggs and second-stage juveniles per cm3 soil. Maximum nematode reproduction rate was 33·1-fold at the lowest Pi. [ABSTRACT FROM AUTHOR]

Investigates the strain-specific diagnostic methods used to detect alfalfa mosaic alfamovirus, cucumber mosaic cucumovirus and tomato spotted wilt tospovirus infecting tomato in Italy. Biodiversity of viruses; Change in population structure of resident viruses; Reverse-transcription polymerase chain reaction; Restriction analysis of amplicons; Single-stranded conformational polymorphism.

Four populations of Pratylenchus thornei from different locations were tested for reproductive fitness in axenic carrot disc cultures and for pathogenicity to chickpea cultivars JG 62 and UC 27 and lines K 850 and ILC 1929. Parasitism and histopathology on selected chickpea genotypes (JG 62, UC 27 and lines ILC 482, ICC 11324 and ICC 12237) were also investigated. Reproductive fitness, assessed as the ratio of the final number of nematodes per carrot disc to the number of nematodes inoculated, was similar among the populations tested and the four populations reproduced to a similar extent in a given chickpea genotype. However, the extent of reproduction was significantly affected by the chickpea genotype, JG 62 and UC 27 being the best and poorest hosts, respectively. Pathogenicity to chickpea genotypes was assessed by the difference in fresh root and dry shoot weights between infected and uninfected plants 90 days after inoculation. Plant growth was significantly reduced by the four nematode populations in all chickpea genotypes, with the exception of cv. JG 62, which was tolerant of P. thornei. Severity of root necrosis caused by nematode infection was similar for all populations. Histopathological studies of chickpea genotypes infected by P. thornei showed that all were suitable hosts according to nematode reproduction and host reaction. P. thornei always migrated through epidermal and cortical cells by breaking down cell walls along the nematode pathway. In the most susceptible lines (ILC 482 and JG 62), damage to endodermal cells adjacent to nematode feeding sites was occasionally observed. [ABSTRACT FROM AUTHOR]

The potato cyst nematodes ( PCNs) Globodera pallida and Globodera rostochiensis are important parasites of potato. PCNs undergo complex biotrophic interactions with their hosts that involve gene expression changes in both the nematode and the host plant. The aim of this study was to determine key genes that are differentially expressed in Globodera pallida life cycle stages and during the initiation of the feeding site in susceptible and partially resistant potato genotypes. For this purpose, two microarray experiments were designed: (i) a comparison of eggs, infective second-stage juveniles ( J2s) and sedentary parasitic-stage J2s ( SJ2); (ii) a comparison of SJ2s at 8 days after inoculation ( DAI) in the susceptible cultivar ( Desirée) and two partially resistant lines. The results showed differential expression of G. pallida genes during the stages studied, including previously characterized effectors. In addition, a large number of genes changed their expression between SJ2s in the susceptible cultivar and those infecting partially resistant lines; the number of genes with modified expression was lower when the two partially resistant lines were compared. Moreover, a histopathological study was performed at several time points (7, 14 and 30 DAI) and showed the similarities between both partially resistant lines with a delay and degeneration in the formation of the syncytia in comparison with the susceptible cultivar. Females at 30 DAI in partially resistant lines showed a delay in their development in comparison with those in the susceptible cultivar. [ABSTRACT FROM AUTHOR]

The witches' broom disease of sweet potato has so far been reported only from Asia and the South Pacific. To insure safe distribution of germplasm it is important that vegetative material introduced from regions in which this disease is present has to be free of this pathogen. Meristem tip culture was found to be effective in eliminating MLO from infected sweet potato tissue. On the other hand, all plantlets originating from 1 cm long stem tips immediately below the meristems developed typical witches' broom symptoms as early as 5 weeks after excision of the stem tips. A high percentage of stem tips originating from cuttings previously treated with 25, 50 and 100 mg tetracycline for 3 days developed into healthy plants. Similarly, more than 9% of plants derived from stem tips excised from cuttings which had received a one-month heat treatment at 37°C remained without symptoms for 9 months. [ABSTRACT FROM AUTHOR]

Pratylenchus thornei-chickpea interactions were investigated under controlled and fluctuating environmental conditions in the growth chamber, greenhouse and shadehouse. Under controlled conditions. P. thornei infected chickpea tines 12071/10054 and P 2245 and cukivars Andoum 1, JG 62 and UC27. Line P2245 and cv. JG 62 were the most susceptible genotypes on the basis of root damage and nematode reproduction, but nematode infection did not significantly reduce root and shoot weights. Cultivars Andoum 1 and UC 27 and line 12071/10054 showed the least root damage and nematode reproduction. Inoculation of cv. Andoum 1 with 2500,5000 or 10000 nematodes per plant in pots did not affect shoot weight. regardless of the conditions of water stress of the plants. However, root weight was significantly reduced by nematode infection in plants grown under water stress and fluctuating temperature conditions in the greenhouse. but was not affected by any other treatment. The nematode reproduction index was not affected by soil water content under shadehouse conditions, but was greater on plants watered to soil water-holding capacity than in water-stressed plants under greenhouse conditions. For both environments, the nematode reproduction index decreased when inoculum density was greater than 5000 nematodes per plant. [ABSTRACT FROM AUTHOR]

The article discusses on olive latent virus 2 observed in wild castor bean (Ricinus communis) in Vibo Valentio, Calabria in southern Italy. The plants, which were collected during spring and summer of 2005 and 2006, showed bright yellow mosaic leaf symptoms that consisted of yellow speckled leaves with significant mottled areas. Some of the leaves manifested an arabesque line pattern. Through electron microscopy, the sap of extracts were observed showing semi-spherical to bacilliform particles consistent with Alfamovirus and Oleavirus. Comparable symptoms of the OLV2 virus were observed by using a range of herbaceous plants and mechanical inoculation. Serological tests through particle decoration with an OLV2 antiserum raised against an italian OLV2 isolate identified the virus.

The abandonment of agricultural land and the afforestation of grassland habitats represent major threats for butterflies in European and Mediterranean areas. A crucial goal for Lepidoptera conservation is to maintain and/or restore habitat quality by targeted management. Nevertheless, there are few experimental studies allowing to derive data‐driven strategies to protect butterflies of open grasslands in the Mediterranean region.We developed a habitat management strategy for the conservation of the Italian endemic butterfly Zerynthia cassandra by adopting a three‐step procedure: (i) characterising which environmental and host plant features influence oviposition on plants; (ii) identifying and testing the effect of a data‐driven habitat management intervention; (iii) understanding which micro‐habitat features promote Z. cassandra oviposition in restored places to optimise the intervention.Both patch (areas of 1 m radius hosting Aristolochia shoots) and plant features affect oviposition, with the strongest positive effects showed by high irradiation of the patch and plant quality (high number of flowers and leaves). Accordingly, the management consisted in vegetation cuts to increase irradiation, and 2 years of monitoring demonstrated that this procedure significantly increased oviposition (average increase of about 2 eggs per plant) and larval presence. Micro‐habitat sampling demonstrated that the maximum oviposition differed between vegetation structures, highlighting the importance of a local fine‐tuning before the intervention.We provided a data‐driven, effective, and sustainable management strategy to increase habitat suitability and oviposition for an endemic and endangered Mediterranean butterfly. Our framework can drive management strategies for other species with similar ecological requirements and subjected to similar threats. [ABSTRACT FROM AUTHOR]

Arabidopsis thaliana is a suitable host for phytoparasitic nematodes of the genus Meloidogyne. Successful nematode infection leads to the formation of root galls. We tested for natural genetic variation and inoculation density effects on nematode reproductive success in the interaction between A. thaliana and Meloidogyne javanica. We inoculated different Arabidopsis genotypes with two sources of nematodes at two different doses, using a mild protocol for inoculum preparation. We counted root galls and egg masses 2 months after inoculation. We obtained a high number of successful nematode infections. Infection success differed among Arabidopsis genotypes in interaction with the nematode source. Overall, infection success and reproductive success of nematodes were lower at a higher inoculum dose of nematodes. Our results indicate that natural genetic variation in both host plants and nematodes, as well as short‐ and long‐term negative density effects, shape nematode reproductive success. [ABSTRACT FROM AUTHOR]

A new tombusvirus clearly distinguishable from other members of the group was isolated in Apulia from river Lato and therefore referred to as Lato River Tombusvirus (LRV). Purified virus preparations after storage for 5 months at 4°C in 20 mM phosphate buffer, pH 7.2, contained variable amounts of small particles (c. 17 nm in diameter) in addition to typical virus particles (c. 30 nm in diameter). LRV small particles were constituted by a single protein species with a mol. wt of 29,000, did not contain nucleic acid and were not infective but proved to be serologically undistinguishable from ordinary virus particles. Attempts to artificially produce small particles by chemical or enzymatic treatments of full size LRV virions failed but their spontaneous production under particular storage conditions seems to be a remarkable feature of this virus as it does not occur with other definitive tombusviruses. [ABSTRACT FROM AUTHOR]

The root‐knot nematode Meloidogyne incognita is one of the most damaging plant parasitic nematodes in the world. In this study, the effect of cystatin from Amaranthus hypochondriacus (AhCPI) as a potential control agent for M. incognita was explored. In vitro bioassays demonstrated that AhCPI affects the growth and development of eggs and the infectivity of juveniles (J2) of M. incognita, such as mortality and slower development, showing characteristic tissue damage. Mortality levels were quantified by Probit analysis, estimating LC50s of 1.4 mg/mL for eggs and 0.028 mg/mL for J2. In planta bioassays showed that infected tomato seedlings treated with 0.056 mg/mL of AhCPI showed a 60% reduction in the number of galls, as compared with untreated J2‐inoculated seedlings. Under greenhouse conditions, three applications of 10 mL of AhCPI (1.4 mg/mL) in the soil around the stem of M. incognita‐infected tomato plants, reduced the number of galls by 93 ± 8%, as compared to the control M. incognita‐infected plants. The application of AhCPI to the infected plants increased the yield (10.7%) of harvested tomato fruits, as compared to infected plants. These results show the potential of AhCPI for the control of M. incognita in tomato plants. [ABSTRACT FROM AUTHOR]

Citrus plants are host to several plant parasitic nematodes (PPNs), which are microscopic organisms. Among PPNs, the citrus root nematode, T. semipenetrans (Cobb 1913) (Tylenchida: Tylenchulidae), causes significant damage to citrus plantations worldwide. Understanding citrus nematode populations, precise identification, host preference among citrus species, and damage threshold are crucial to control T. semipenetrans. The minutiae of citrus plant–nematode interactions, nematode density and molecular nematode identification are not well understood. In this study, nematode species and density in citrus orchards, host specialization, molecular and morphological characteristics of nematodes were assessed.Molecular and morphological methods, host–nematode interactions, host (citrus species) preference, damage economic threshold (ET), and economic injury level (EIL) were determined using laboratory methods and field sampling. Citrus plantations in different provinces in the Mediterranean region of Turkey were investigated.Nematode species were identified molecularly and morphologically. ITS sequences revealed that samples were infected by citrus root nematode T. semipenetrans. The lowest nematode density was in C. reticulata in Mersin (53 2nd stage juveniles (J2s) 100 g−1 soil), while the highest density was from Hatay in C. sinensis (12173 J2s 100 g−1 soil). Highest citrus nematode population density was on roots of C. reticulata, followed by C. sinensis, C. limon, and C. paradisi.The citrus nematode is more common than was thought and population fluctuations change according to specific citrus species. Environmental conditions, host and ecological factors, such as temperature, soil pH, and soil nutrients, might influence nematode populations in citrus orchards. Investigating nematode density in diverse soil ecologies and the responses of different resistant/tolerant citrus species and cultivars to nematode populations is essential in future studies. [ABSTRACT FROM AUTHOR]

Rotylenchulus reniformis Linford and Oliveira (reniform nematode) infestation has been a concerning issue in the Cotton Belt region of the United States for the past decade. Reniform nematode damage is more evident on cotton compared to other row crops in US Mid‐South because they share common edaphic conditions to sustain and develop. Annual cotton (Gossypium spp.) yield loss over the United States due to reniform nematode ranged from 1.14% to 2.37% in the past decade but exceeded 8% in the US Mid‐South States such as Mississippi. Yield losses due to nematode damage are mainly due to inconsistent control by cultural and chemical practices. In addition, there are location‐specific responses due to agronomic practices that result in its wide adaption. This review summarizes factors that influence reniform nematode infestations and the process of a plant infection, as well as management practices to mitigate nematode cotton production losses in the United States. The recent development of resistant cotton germplasm is a promising tool for reniform nematode management, although limited research has been conducted on the physiological mechanisms of resistance. In addition, understanding the role of host plant resistance and the interaction with other soilborne pathogens or abiotic stresses to control the nematode also is lacking. Future research must investigate best suited production practices specific to a region that could exploit the full potential of host plant resistance to minimize the risk of reniform nematode damage in cotton while protecting the environment. Core Ideas: Reniform nematode caused up to 8% annual loss to cotton production in the US Mid‐South over the last decade.Chemical and cultural practices showed inconsistent control of reniform nematode damage.The recently released reniform nematode‐resistant varieties are invaluable for cotton producers, industry, and researchers. [ABSTRACT FROM AUTHOR]

Genomic data are not yet widely used in insect conservation practice. Here, with a focus on butterflies, we aim to identify the strengths, limitations and remaining gaps between the fields of population genomics and insect conservation management. Based on a literature search complemented with expert opinion, we discuss avenues for translating research into practice.We found that current genomic methodologies available for insect management enhance the assessment of cryptic diversity and facilitate the inference of historical population trends (temporal monitoring) by using even degraded material from historical collections.Discovering and tracking adaptive genetic variation linked to increased survival and fitness is a relatively young research field, but we highlight it as a promising tool in future insect management actions.We highlight recent case studies where population genomics have guided butterfly conservation. One conclusion from our advice from our non‐exhaustive survey of expert opinion is to establish meaningful partnerships between researchers and practitioners, starting at the stage of project planning. Genomics is an informative tool for securing legal protection of unique populations and may offer guidance in future conservation translocations and captive breeding programmes.Although insect conservation usually targets habitats, genomic guidance focusing on populations of flagship and umbrella taxa is a straightforward path to connect species‐specific and habitat conservation initiatives. We conclude that there is urgency in reporting insect conservation actions guided by genomic data, both successful and unsuccessful. This will lead to constructive feedback between fields and the establishment of standardised methodologies. [ABSTRACT FROM AUTHOR]

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Potato (Solanum tuberosum L.) is one of the major crops for human nutrition. Columbia root‐knot nematode, Meloidogyne chitwoodi Golden et al. (1980), can cause significant decrease in potato yields in the world. The aim of the study was to develop a novel molecular method for the rapid and accurate detection of M. chitwoodi on infested potato tubers. Total DNA from peel and tissues of potato were directly isolated from M. chitwoodi‐infested potato tubers without using any nematode extraction method. Meloidogyne chitwoodi was successfully detected and identified in total DNA isolated using species‐specific primers. Meloidogyne chitwoodi was also successfully identified in DNA isolated from only one necrotic spot in potato. Our results show that this molecular method is quite useful for fast and accurate identification of M. chitwoodi on potato. Based on these results, it seems that useful practical and applicable aspects for direct detection of M. chitwoodi from potato tubers without nematode extraction. The novel technique can be used in quarantine laboratories and potato seed producer companies. To the best of the authors' knowledge, this is the first report to identify M. chitwoodi using a novel molecular method from potato tubers without nematode extraction. [ABSTRACT FROM AUTHOR]

Root‐lesion nematodes (RLNs) Pratylenchus thornei and P. neglectus are globally important pathogens of cereal and pulse crops. These RLNs can occur together in farming systems and must be managed concurrently to minimize substantial yield losses in intolerant crop cultivars. Australian wheat cultivars with resistance to P. neglectus, have either the Rlnn1 resistance gene, which provides a high level of resistance but is linked with yellow flour colour that reduces cultivar marketability for bread production, or QRlnn.lrc‐2B, which provides moderate resistance. We evaluated a collection of 91 P. thornei‐resistant Iranian landrace wheats (ILWs) for their resistance to P. neglectus in four glasshouse experiments to (a) identify genotypes with resistance to both RLNs, (b) determine if any genotypes carried Rlnn1 and/or QRlnn.lrc‐2B and (c) develop ILW‐derived advanced breeding lines (ABLs) with resistance to both RLNs. A factor analytic linear mixed model (FA‐1) that explained 70% of the genetic variation, where the genetic correlations between the experiments ranged from 0.54 to 0.77, was used for the combined analysis of all experiments. Seven P. neglectus‐resistant genotypes were identified, with five that had potentially novel resistance. Subsequently, six breeding lines that were resistant to both RLNs were developed by crossing six ILWs with Australian cultivars and selecting for resistance in each generation. Both the ILWs and ABLs will be valuable genetic resources for wheat breeders to develop cultivars with dual resistance, enabling better management of mixed RLN populations with novel P. neglectus resistance that potentially is not linked with yellow flour colour. [ABSTRACT FROM AUTHOR]

Motivation: Butterflies represent a model in biology and a flagship group for invertebrate conservation. We provide four new resources for the Western Palaearctic butterflies: (1) an updated checklist comprising 552 species; (2) a curated dataset of 32,126 mitochondrial cytochrome c oxidase subunit I (COI) sequences for 532 species, including a de novo reference library for the Maghreb (Morocco, northern Algeria and Tunisia) and Macaronesia (Azores, Madeira and Canary Islands); (3) seven indexes of intraspecific genetic variation (IGV): observed and expected number of haplotypes, haplotype and nucleotide diversity, two fixation indexes and maximum p‐distance; and (4) species‐level maps illustrating the distribution of COI variability and haplotype networks. The updated checklist will be fundamental for any application dealing with butterfly diversity in the Western Palaearctic. The IGV indexes provide measures for genetic polymorphism and spatial structure and represent proxies for dispersal capacity. These resources will facilitate comparative studies of macrogenetics, foster integrative taxonomy and aid conservation strategies. Main types of variables contained: A complete species checklist in table format, 32,126 mitochondrial DNA barcodes provided with metadata (species membership, WGS84 coordinates and sequence length) and a book in PDF format, including the IGV atlas and indexes, are provided. Spatial location and grain: The checklist encompasses Europe up to the Urals in the east, north Macaronesia (the Azores, Madeira and the Canary Islands) and the Maghreb (Morocco, northern Algeria and Tunisia). COI sequences have been retained in the geographical interval of −31.3 to 67.5° of longitude and 27.5–71.2° of latitude. Time period and grain: COI sequences originate from studies published between 1998 and 2022 and from de novo sequencing of 2541 specimens done between 2007 and 2022. Major taxa and level of measurement: Butterflies (Lepidoptera: Papilionoidea), analysed from individual to species level. Software format: Data and functions to manage the dataset are provided in the iodatabase R package (https://github.com/leondap/iodatabase) and in Dryad (https://doi.org/10.5061/dryad.9w0vt4bjj). [ABSTRACT FROM AUTHOR]

The resource‐use hypothesis, proposed by E.S. Vrba, states that habitat fragmentation caused by climatic oscillations would affect particularly biome specialists (species inhabiting only one biome), which might show higher speciation and extinction rates than biome generalists. If true, lineages would accumulate biome‐specialist species. This effect would be particularly exacerbated for biomes located at the periphery of the global climatic conditions, namely, biomes that have high/low precipitation and high/low temperature such as rainforest (warm‐humid), desert (warm‐dry), steppe (cold‐dry) and tundra (cold‐humid). Here, we test these hypotheses in swallowtail butterflies, a clade with more than 570 species, covering all the continents but Antarctica, and all climatic conditions. Swallowtail butterflies are among the most studied insects, and they are a model group for evolutionary biology and ecology studies. Continental macroecological rules are normally tested using vertebrates, this means that there are fewer examples exploring terrestrial invertebrate patterns at global scale. Here, we compiled a large Geographic Information System database on swallowtail butterflies' distribution maps and used the most complete time‐calibrated phylogeny to quantify diversification rates (DRs). In this paper, we aim to answer the following questions: (1) Are there more biome‐specialist swallowtail butterflies than biome generalists? (2) Is DR related to biome specialization? (3) If so, do swallowtail butterflies inhabiting extreme biomes show higher DRs? (4) What is the effect of species distribution area? Our results showed that swallowtail family presents a great number of biome specialists which showed substantially higher DRs compared to generalists. We also found that biome specialists are unevenly distributed across biomes. Overall, our results are consistent with the resource‐use hypothesis, species climatic niche and biome fragmentation as key factors promoting isolation. [ABSTRACT FROM AUTHOR]

The plant-parasitic nematode Nacobbus aberrans sensu lato is an agricultural pest of quarantine importance. Due to the morphometric, physiological and genetic variability observed within the species, there is no agreement on the taxonomy of this nematode. The objective of this study was to analyse the ITS r DNA region and the D2- D3 expansion segments of 28 S r DNA in 10 Argentine populations and one from Ecuador and to establish their phylogenetic relationship with other known sequences from South and North America. Phylogenetic trees of the ITS gene showed seven statistically well-supported clades; the high and significant Fst values obtained among these groups confirmed this partitioning. The Argentine populations here considered were separated into three clades: one comprising a population from the Andean region and two grouping nematodes from lower altitudes. Three other clades were distinguished for South American populations, which included known sequences of individuals from Peru, Bolivia and north of Argentina. The other clade included sequences from Mexico, Ecuador and two Argentine populations of unknown origin. The important degree of genetic divergence observed among Andean populations suggests that the Andes may have played a crucial role in speciation of Nacobbus, which would have originated in this region. Although D2- D3 segments exhibited lower variation, they were useful for establishing phylogenetic relationships among the Argentine populations considered in this work. As there are no other Gen Bank sequences available for these segments, it was not possible to make comparisons with other populations from South and North America. The considerable genetic differentiation observed in ITS r DNA region among Nacobbus populations showed evidence of cryptic species within the N. aberrans s.l. complex. Integration of morphological and morphometric studies and molecular analyses considering other genes may aid in the identification of species and their phylogenetic relationships within this genus. [ABSTRACT FROM AUTHOR]

Factors shaping the distribution and abundance of species include life‐history traits, population structure, and stochastic colonization–extinction dynamics. Field studies of model species groups help reveal the roles of these factors. Species of Caenorhabditis nematodes are highly divergent at the sequence level but exhibit highly conserved morphology, and many of these species live in sympatry on microbe‐rich patches of rotten material. Here, we use field experiments and large‐scale opportunistic collections to investigate species composition, abundance, and colonization efficiency of Caenorhabditis species in two of the world's best‐studied lowland tropical field sites: Barro Colorado Island in Panamá and La Selva in Sarapiquí, Costa Rica. We observed seven species of Caenorhabditis, four of them known only from these collections. We formally describe two species and place them within the Caenorhabditis phylogeny. While these localities contain species from many parts of the phylogeny, both localities were dominated by globally distributed androdiecious species. We found that Caenorhabditis individuals were able to colonize baits accessible only through phoresy and preferentially colonized baits that were in direct contact with the ground. We estimate the number of colonization events per patch to be low. [ABSTRACT FROM AUTHOR]

Chickpea (Cicer arietinum) is a major legume crop, with Australia being the second largest producer worldwide. Pratylenchus neglectus is a root‐lesion nematode that invades, feeds and reproduces in roots of pulse and cereal crops. In Australia, chickpea and wheat (Triticum aestivum) are commonly grown in rotation and annual damage by P. neglectus accounts for large economic losses to both crops. Cultivated chickpea has narrow genetic diversity that limits the potential for improvement in resistance breeding. New collections of wild chickpea species, C. reticulatum and C. echinospermum, have substantially increased the previously limited world collection of wild Cicer germplasm and offer potential to widen the genetic diversity of cultivated chickpea through the identification of accessions with good resistance. This research assessed 243 C. reticulatum and 86 C. echinospermum accessions for response to P. neglectus in replicated experiments under controlled glasshouse conditions from 2013 and 2014 collection missions that were received, tested and analysed in two experimental sets. Multi‐experiment analyses showed lower P. neglectus population densities in both sets of wild Cicer accessions tested than Australia's elite breeding cultivar PBA HatTrick at the significance level p < 0.05. Provisional resistance ratings were given to all genotypes tested in both experimental sets, with C. reticulatum accessions CudiB_008B and Kayat_066 rated as resistant in both Set 1 and Set 2. New sources of resistance to P. neglectus observed in this study can be introgressed into commercial chickpea cultivars to improve their resistance to this nematode. [ABSTRACT FROM AUTHOR]

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1. Organisms with low mobility, living within ephemeral environments, need to find vehicles that can disperse them reliably to new environments. The requirement for specificity in this passenger–vehicle relationship is enhanced within a tritrophic interaction when the environment of passenger and vehicle is provided by a third organism. Such relationships pose many interesting questions about specificity within a tritrophic framework. 2. Central to understanding how these tritrophic systems have evolved, is knowing how they function now. Determining the proximal cues and sensory modalities used by passengers to find vehicles and to discriminate between reliable and non-reliable vehicles is, therefore, essential to this investigation. 3. The ancient, co-evolved and highly species-specific nursery pollination mutualism between figs and fig wasps is host to species-specific plant-parasitic nematodes which use fig wasps to travel between figs. Since individual globular fig inflorescences, i.e. syconia, serve as incubators for hundreds of developing pollinating and parasitic wasps, a dispersal-stage nematode within such a chemically complex and physically crowded environment is faced with the dilemma of choosing the right vehicle for dispersal into a new fig. Such a system therefore affords excellent opportunities to investigate mechanisms that contribute to the evolution of specificity between the passenger and the vehicle. 4. In this study of fig–wasp–nematode tritrophic interactions in Ficus racemosa within which seven wasp species can breed, we demonstrate using two-choice as well as cafeteria assays that plant-parasitic nematodes ( Schistonchus racemosa) do not hitch rides randomly on available eclosing wasps within the fig syconium, but are specifically attracted, at close range, i.e. 3 mm distance, to only that vehicle which can quickly, within a few hours, reliably transfer it to another fig. This vehicle is the female pollinating wasp. Male wasps and female parasitic wasps are inappropriate vehicles since the former are wingless and die within the fig, while the latter never enter another fig. Nematodes distinguished between female pollinating wasps and other female parasitic wasps using volatiles and cuticular hydrocarbons. Nematodes could not distinguish between cuticular hydrocarbons of male and female pollinators but used other cues, such as volatiles, at close range, to find female pollinating wasps with which they have probably had a long history of chemical adaptation. 5. This study opens up new questions and hypotheses about the evolution and maintenance of specificity in fig–wasp–nematode tritrophic interactions. [ABSTRACT FROM AUTHOR]

In mountain ecosystems, it is crucial to identify conservation strategies to avoid local extinctions mainly due to agropastoral abandonment. For this purpose, identifying appropriate system indicators is required, for example, butterflies, which respond precisely and quickly to environmental changes. Zerynthia polyxena is an ecotonal species of butterfly, and thus, through its conservation it could be possible to protect clearing and ecotonal species. To develop conservation measures, we set up a hierarchical investigation that characterizes the ecological preferences of the adult and larval Z. polyxena, and host plant—Aristolochia pallida—by collecting data on the butterfly abundance (adult and larvae), tree cover, and litter plant features and by phytosociological surveys. Adult preferences change along an altitudinal gradient; the highest butterfly presence is at sites with medium elevation (1100 m above sea level [asl]) with high presence of forest, but even sites at low elevation (975 m asl), a high presence of forest favors butterfly abundance. Larvae prefer partially shaded ecotone plots with abundant host plants and low management intensity (corresponding to abundant litter) and with heterogeneous tree cover. High tree cover (70%) at low altitude and low tree cover (<20%) at high altitude favor larval presence. Larvae prefer plants with large leaves. Host plants were more abundant at low elevation where tree cover was low (<20%). We found that the optimal ecological niches of host plant and larvae have a spatial mismatch. By analyzing vegetation dynamics and butterfly monitoring during one field season, we are able to describe current and past (about 10–50 years ago) management pressures, in order to identify butterfly ecological preferences in relation to local features and therefore to suggest local conservation actions that might support Z. polyxena, as well as other butterflies and insects. Specifically, management measures should prevent afforestation (e.g., through irregular mowing) and favor the presence of small clearings and of ecotonal habitats in relation to elevation. Our study suggests that a new multifunctional approach that combines local entomological and vegetational surveys could be applied to define species optimal habitat features and, thus, to address appropriate conservation measures. [ABSTRACT FROM AUTHOR]

To identify host factors for tomato spotted wilt orthotospovirus (TSWV), a virus‐induced gene silencing (VIGS) screen using tobacco rattle virus (TRV) was performed on Nicotiana benthamiana for TSWV susceptibility. To rule out any negative effect on the plants' performance due to a double viral infection, the method was optimized to allow screening of hundreds of clones in a standardized fashion. To normalize the results obtained in and between experiments, a set of controls was developed to evaluate in a consist manner both VIGS efficacy and the level of TSWV resistance. Using this method, 4532 random clones of an N. benthamiana cDNA library were tested, resulting in five TRV clones that provided nearly complete resistance against TSWV. Here we report on one of these clones, of which the insert targets a small gene family coding for the ribosomal protein S6 (RPS6) that is part of the 40S ribosomal subunit. This RPS6 family is represented by three gene clades in the genome of Solanaceae family members, which were jointly important for TSWV susceptibility. Interestingly, RPS6 is a known host factor implicated in the replication of different plant RNA viruses, including the negative‐stranded TSWV and the positive‐stranded potato virus X. [ABSTRACT FROM AUTHOR]

Rhynchophorus ferrugineus Olivier (Coleoptera: Curculionidae) red palm weevils are often reported in association with different organisms including nematodes. The significance of this interaction and whether nematodes can influence their life‐history traits is unclear. We collected Rhynchophorus ferrugineus red palm weevils at different developmental stages and locations in Tunisia, observed and dissected them in search for nematodes and other interacting organisms, established laboratory colonies and identified the nematodes associated with them, and conducted nematode–insect interaction assays to determine the capacity of the nematodes to influence their life‐history traits. We observed Beauveria bassiana fungi in larvae, nymph, and adults; Centrouropoda and Uroobovella acari associated with the adults, and Teratorhabditis synpapillata nematodes associated with larvae and adults. Nematode–insect interaction bioassays revealed that T. synpapillata nematodes reduce the lifespan of the insect larvae in a population‐dependent manner, but do not influence the lifespan of adults. Our study uncovers an important factor that may determine population dynamics of this important palm pests and provides evidence to conclude that these organisms establish a parasitic relationship, rather than a phoretic relationship. [ABSTRACT FROM AUTHOR]

Cultivated peanut (Arachis hypogaea L.) has a narrow genetic base and is isolated from its wild relatives. This genetic bottleneck results in a lack of strong resistance to biotic and abiotic stress. However, high levels of genetic variation and resistance exist among the wild relatives. In order to enlarge the genetic base of cultivated peanut and introgress beneficial alleles from the wild relatives, interspecific hybrids were produced among a set of selected diploid species. Upon colchicine treatment, fertile allotetraploids were recovered from three combinations including (A. ipaënsis KG 30076 × A. correntina GKP 9530)4x (Reg. no. GP‐241, PI 695391), (A. ipaënsis KG 30076 × A. duranensis KGBSPSc 30060)4x (Reg. no. GP‐242, PI 695392), and (A. valida KG30011 × A. stenosperma V 10309)4x (Reg. no. GP‐243, PI 695393). All of them demonstrated high levels of resistance to leaf spot diseases in the field. Tolerance to Tomato spotted wilt virus was found in (A. valida KG 30011 × A. stenosperma V 10309)4x. These newly created allotetraploids are cross‐compatible with cultivated peanut. These genetic resources will provide peanut breeding researchers with new sources of disease resistances to improve the agronomic performance of cultivated peanut. Core Ideas: These hybrids can broaden the genetic base of cultivated peanut by introgression.New synthetic allotetraploids from peanut wild relatives carry disease resistance.Synthetic allotetraploids are cross‐compatible with cultivated peanut. [ABSTRACT FROM AUTHOR]

Plant‐parasitic nematodes pose a major threat to crop production in Nigeria. Comprehensive data on yield losses for most cereal crops are not readily available. Research on maize (Zea mays), rice (Oryza sativa), and sorghum (Sorghum bicolor) has shown an 18%–67% reduction in yield linked to the destructiveness of parasitic nematodes, particularly root‐knot and root‐lesion nematodes. Continuous monoculture and a conservative approach to agriculture increase the incidence and population density of nematodes, leading to higher levels of damage and losses in most cultivated cereal crops. These losses affect the food security of the growing population of Nigeria and many African countries that are heavily dependent on cereals. The accurate identification of nematodes is fundamental for effective management strategies. Nematode taxonomy based on morphology has been difficult due to intraspecific character variations coupled with the limited expertise of indigenous nematologists. Biochemical and molecular marker‐based tools and approaches have allowed efficient diagnosis of most nematode species affecting cereal production globally. These approaches have proved useful due to their practicality, rapidness, accuracy, and cost‐effectiveness. This review describes the important economic effects of these parasitic nematodes on cereal production and highlights the need for integrative approaches to taxonomy for accurate species identification that will improve nematode diagnosis, thereby contributing to the increase of food production in Nigeria. [ABSTRACT FROM AUTHOR]

The plant‐parasitic nematode Nacobbus aberranss.l. is a major agricultural pest of quarantine importance worldwide and is one of the top 10 nematodes in plant pathology because it causes significant losses in several crops. There are evidences of the existence of a species complex, with species being difficult to discriminate using only morphological characters. In this study, we aimed at resolving the taxonomic situation from a multi‐disciplinary approach, based on morphometric data and molecular analyses. The results supported the identification of three nominal species in the complex: N. aberranss.s., N. bolivianus and a new taxon, Nacobbus celatus sp. n. This new species, described based on the revision of published and new data, is widely distributed in the lowlands of Argentina. Our results also evidence the possible existence of a new taxon native to the Andean region of the same country. For the first time, the utility of cytochrome oxidase c subunit 1 barcoding for Nacobbus species identification is corroborated. This study also includes the estimation of divergence time among Nacobbus spp.; the possible geographical origin of the genus and colonization pattern are discussed. The present work shows the usefulness of an integrated approach to the resolution of systematic problems. [ABSTRACT FROM AUTHOR]