<Emphasis Type="Italic">Dittrichia viscosa</Emphasis> and<Emphasis Type="Italic">Rubus ulmifolius</Emphasis> as reservoirs of aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) and the role of certain Coccinellid species

The role of the self-sown shrubsDittrichia viscosa (L.) W. Greuter andRubus ulmifolius Schott as reservoirs of aphid parasitoids was investigated. In the field studies conducted,D. viscosa grew adjacent to crops of durum wheat and barley andR. ulmifolius grew adjacent to cotton. The relative abundance of the parasitoids of(a) Capitophorus inulae (Passerini) onD. viscosa, (b) Rhopalosiphum padi (Linnaeus) on durum wheat and barley,(c) Aphis ruborum (Börner) onR. ulmifolius, and(d) Aphis gossypii Glover on cotton in various parts of Greece, was assessed during the years 1996–2000. In 2000, the fluctuation of parasitization of the above four aphid species was recorded and the action of the aphidophagous predators of the family Coccinellidae was studied. It was observed thatAphidius matricariae Haliday predominated onC. inulae andR. padi in all sampling cases. In contrast,Lysiphlebus fabarum (Marshall) was the dominant species parasitizingA. ruborum onR. ulmifolius andA. gossypii on cotton in Thessaly (central Greece) and Macedonia (northern Greece), whereasLysiphlebus confusus Tremblay et Eady andBinodoxys acalephae (Marshall) were the dominant parasitoid species in Thrace (northern Greece).Coccinella septempunctata Linnaeus was the most abundant coccinellid species on durum wheat, whereasAdonia variegata (Goeze) predominated on cotton. However, coccinellid individuals were scarce on bothD. viscosa andR. ulmifolius. The present study indicated that these two shrubs can be regarded as useful reservoirs of aphid parasitoids.     

Toxicity of soybean-registered agrochemicals to <Emphasis Type="Italic">Telenomus podisi</Emphasis> and <Emphasis Type="Italic">Trissolcus basalis</Emphasis> immature stages

Biological control of phytophagous bugs in soybean crops is efficiently performed by egg parasitoids, such as Telenomus podisi and Trissolcus basalis. Based on this, the use of agrochemicals in these crops must be managed consciously, making use of pesticides that are selective to the egg of these parasitoids, in order to ensure a balanced ecosystem. The aim of this study was to assess the selectivity of 15 registered pesticides to the immature stages (pre and post-parasitism) of T. podisi and T. basalis, following the method proposed by the “International Organization for Biological and Integrated Control” (IOBC). Pesticides were classified as class 1 – harmless (RP?<?30%); class 2 – slightly harmful (30%?≤?RP?≤?79%); class 3 – moderately harmful (80%?≤?RP?≤?99%); and class 4 – harmful (RP?>?99%). During pre-parasitism, the insecticides imidacloprid+beta-cyfluthrin, deltamethrin, lambda-cyhalothrin+thiamethoxam, acephate, and fenitrothion reduced parasitism of both parasitoids. The others: flubendiamide, diflubenzuron, Bacillus thuringiensis, lufenuron, and the herbicide isopropylamine were selective, i.e. harmless (class 1), to both parasitoids, except for pyraclostrobin+metconazole, which significantly reduced T. basalis parasitism, being considered slightly harmful (class 2). In post parasitism, all the aforementioned pesticides were harmless to T. podisi and T. basalis. Moreover, in pre-parasitism, T. basalis was found to be more sensitive to the tested pesticides when compared to T. podisi. Still, more studies must be conducted to provide a better understanding of the impact of agrochemicals on these parasitoid species in semi-field conditions.     

Natural enemies of <Emphasis Type="Italic">Diaspis echinocacti</Emphasis> in Greece and first records of <Emphasis Type="Italic">Aphytis debachi</Emphasis> and <Emphasis Type="Italic">Plagiomerus diaspidis</Emphasis>

Two hymenopteran parasitoids of the cactus scale Diaspis echinocacti (Bouché) (Hemiptera: Diaspididae) on Opuntia ficus-indica (L.) Mill. (Cactaceae) are recorded in Greece. Aphytis debachi Azim, 1963 (Aphelinidae) is first recorded for Europe and Plagiomerus diaspidis Crawford, 1910 (Encyrtidae) is first recorded for Greece. Preliminary data on phenology and natural enemies of the scale D. echinocacti on O. ficus-indica are presented. Parasitism of D. echinocacti by P. diaspidis reached 86% in southern Greece (Kalamata) and parasitism by A. debachi reached 9.3% and 12% in Kalamata and Athens, respectively. Two predators, Cybocephalus fodori Endrödy-Youga (Coleoptera: Nitidulidae) and a mite species (Prostigmata: Bdellidae), were found to be associated with D. echinocacti.     

Parasitism of <Emphasis Type="Italic">Psytallia concolor</Emphasis> (Hymenoptera: Braconidae) on <Emphasis Type="Italic">Bactrocera oleae</Emphasis> (Diptera: Tephritidae) infesting different olive varieties

Psytallia concolor (Szépligeti) is a koinobiont endoparasitoid of many Tephritidae larvae, including Bactrocera oleae (Rossi), and has been used in Mediterranean areas for biological control of olive fruit fly by inundative release. The present study evaluates the influence of olive fruit variety (Amfissis, Arbequina, Branquita de Elvas, Carolea, Kalamon, Koroneiki, Leccino, Manzanilla, Mastoidis, Moroccan Picholine and Picholine) on P. concolor parasitism efficiency and performance in the field during two successive years. The results showed that the percentage of parasitism was significantly higher (>30%) in Mastoidis and Koroneiki (light-weight varieties <1.5 g) than Leccino which has a medium fruit weight, followed by Amfissis, Moroccan Picholine, Picholine and Branquita de Elvas. Only Manzanilla among large weight varieties, exhibited high percentage of parasitization (42.72%) during 2013. The mean weight of the pupae (>4.21 mg) as well as the length of the developed adult parasitoids (>3.5 cm) in Mastoidis and Manzanilla were significantly higher than these individuals developed from other varieties such as Koroneiki and Kalamon. Finally, the optimal host fruit for P. concolor development seems to be Mastoidis variety with great biological parameters and percentage of parasitism.     

Egg and larval parasitoids of the beet armyworm<Emphasis Type="Italic">Spodoptera exigua</Emphasis> on maize in Turkey

The present study was conducted to determine egg and larval parasitoids of the beet armywormSpodoptera exigua Hübner (Lepidoptera: Noctuidae), which is an important but sporadic pest in Turkey. High beet armyworm population levels were recently observed in fields of first and second crop maize in the southeast Mediterranean region of Turkey. The parasitoid species complex and its impact on the pest were analyzed in a 4-year study in first and second crop maize. The braconid larval parasitoidsMicroplitis rufiventris Kokujev,M. tuberculifer Wesmael,Meteorus ictericus Nees,Chelonus obscuratus (Herrich Schäffer) (an egg-larval parasitoid),Apanteles ruficrus (Haliday); the ichneumonid larval parasitoidsHyposoter didymator (Thunberg) andSinophorus xanthostomus Gravenhorst; and the egg parasitoidTrichogramma evanescens (Westwood) were found to be the natural enemies attacking the pest. Among the parasitoid species the solitary endoparasitoidH. didymator was the most prevalent species, being reared from 40.5% of the parasitized larvae found. Higher parasitism rates were recorded on first crop than on second crop maize in every year. Possible reasons for this difference in larval parasitism between two growing seasons include lower population of the pest and reduced insecticide applications in first crop maize fields which permitted higher parasitism. However, parasitoid activity was insufficient to counterbalance the population growth of the pest on subsequent second crop maize.     

The effects of <Emphasis Type="Italic">Gibberella zeae</Emphasis>, <Emphasis Type="Italic">Barley Yellow Dwarf Virus</Emphasis>, and co-infection on <Emphasis Type="Italic">Rhopalosiphum padi</Emphasis> olfactory preference and performance

Insect-borne viruses promote several changes in plant phenotype, which can modify plant-vector interactions in favor of virus survival and dissemination. Although co-infections commonly occur in the field, little is known about their effects on interactions with the vector. The ecological interactions between Barley Yellow Dwarf Virus (BYDV) and its aphid vector, Rhopalosiphum padi, have been investigated extensively, but the vector’s behavior in more complex scenarios has yet to be examined. We assessed olfactory response and performance of R. padi to wheat singly and doubly infected by the pathogenic fungus Giberella zeae and BYDV. Non-viruliferous aphids preferred odors of BYDV-infected wheat over healthy wheat, as previously reported in the literature, and they were still preferentially attracted to BYDV-infected plant during co-infection. However, around 35% more non-viruliferous aphids chose healthy wheat over G. zeae-infected wheat. Viruliferous aphids did not show any preference to the treatments. BYDV-infected wheat was a superior host than healthy wheat for the aphids whose population increased in 25%. We observed a synergistic effect of the co-infected wheat, which was the best host for aphids, and promoted an elevation of 42% on population growth. Our results indicate that co-infection might be beneficial for virus spread as does not interfere with aphid olfactory preference and provides greater colony growth than in singly infected plants.     

Pathogenicity,Morpho-Species and Mating Types of <Emphasis Type="Italic">Alternaria</Emphasis> spp. causing Alternaria blight in <Emphasis Type="Italic">Pistacia</Emphasis> spp. in Turkey

Alternaria genus includes many plant pathogens on numerous hosts, causing leaf spots, rots and blights. Alternaria blight has been observed as one of the important fungal diseases of pistachio (Pistacia vera L.) as well as its wild relatives (P. terebinthus, P. lentiscus, P. khinjuk, P. atlantica, P. mutica) in Turkey. Alternaria species were sampled from Pistacia spp. hosts from different geographic regions in Turkey during field trips in late spring to early fall of 2013. Alternaria blight symptoms were observed mainly on fruits and rarely on leaves. Four hundred and twenty two of the isolates were morphologically defined as A. alternata, A. tenuissima, A. arborescens and also intermediate morpho-species between A. alternata/A. arborescens. Pathogenicity of the isolates was confirmed with host inoculations on detached fruits. Mating types of 270 isolates of Alternaria spp. from the collection were identified using a PCR-based mating type assay that amplifies either a MAT1-1 or a MAT1-2 fragment from the mating locus. Although a strongly clonal population structure was expected due to the putative asexual reproduction of these fungi, both idiomorphs were detected at equal frequencies at several different spatial scales. The distribution of mating types within each geographic region, within host species as well as in overall collection was not significantly different from 1:1. Amplified fragments of partial idiomorph sequences were obtained for representative isolates. Parsimony trees were depicted based on sequence data of mating type genes for these representative isolates as well as some other Alternaria species obtained by Genebank. Several point mutations presented a few clusters which are supported by high bootsrapped values. The Alternaria blight disease agents both from cultivated and wild hosts were pathogenic on pistachio which may cause difficulties to control the disease because of extensity of pathogen sources. Besides, equal mating type distribution of the pathogen at both geographic and host species levels suggests a potential for sexual reproduction of Alternaria spp. in Turkey.     

Parasitoids of European species of the genus <Emphasis Type="Italic">Yponomeuta</Emphasis> Latreille 1796 (Lepidoptera: Yponomeutidae): new findings with an updated checklist

The species of the genus Yponomeuta Latreille (Lepidoptera: Yponomeutidae) are known as ermine moths and can be found on various host plant species, sometimes appearing as pests. They are attacked by a wide range of parasitoids. We studied parasitoid complexes of several communities in Austria, Poland, Serbia, Slovenia and Sweden during 2014–2018. From four species, Yponomeuta cagnagella (Hübner), Yponomeuta evonymella (Linnaeus), Yponomeuta malinellus Zeller and Yponomeuta padella (Linnaeus), we reared 15 parasitoid species of seven hymenopteran and one dipteran family. In this study, the family Ichneumonidae is the most numerous, while Ageniaspis fuscicollis (Dalman) (Hymenoptera: Encyrtidae) was found in all four Yponomeuta species. Within reared parasitoids, A. fuscicollis is new record for Slovenia and Austria, Baryscapus evonymellae (Bouché) (Hymenoptera: Eulophidae) and Diadegma armillatum (Gravenhorst) (Hymenoptera: Ichneumonidae) are new records for Slovenia and Agrypon canaliculatum (Ratzeburg) (Hymenoptera: Ichneumonidae), Dolichogenidea dilecta (Haliday) (Hymenoptera: Braconidae), Elasmus steffani Viggiani (Hymenoptera: Eulophidae), Herpestomus brunnicornis (Gravenhorst) (Hymenoptera: Ichneumonidae), Trieces tricarinatus (Holmgren) (Hymenoptera: Ichneumonidae) and Mesochorus nuncupator (Panzer) (Hymenoptera: Ichneumonidae) are new records for Serbia. Also, Yponomeuta cagnagella is a new host record for Pteromalus semotus (Walker) (Hymenoptera: Pteromalidae) and Y. padella for E. steffani. Finally, we reviewed parasitoids of European Yponomeuta species and their associated host plants. In total 154 species are recorded from nine hymenopteran and one dipteran family.     

<Emphasis Type="Italic">Fusarium ershadii</Emphasis> sp. nov., a Pathogen on <Emphasis Type="Italic">Asparagus officinalis</Emphasis> and <Emphasis Type="Italic">Musa acuminata</Emphasis>

Two Fusarium strains, isolated from Asparagus in Italy and Musa in Vietnam respectively, proved to be members of an undescribed clade within the Fusarium solani species complex based on phylogenetic species recognition on ITS, partial RPB2 and EF-1α gene fragments. Macro- and micro-morphological investigations followed with physiological studies done on this new species: Fusarium ershadii sp. nov can be distinguished by its conidial morphology. Both isolates of Fusarium ershadii were shown to be pathogenic to the monocot Asparagus officinalis when inoculated on roots and induced hollow root symptoms within two weeks in Asparagus officinalis seedlings. In comparison mild disease symptoms were observed by the same strains on Musa acuminata seedlings.     

Random pattern of parasitism and female-biased sex ratio in the egg parasitoid <Emphasis Type="Italic">Neochrysocharis formosa</Emphasis> attacking the pine sawfly <Emphasis Type="Italic">Diprion pini</Emphasis> in mountain forests of Spain

The most harmful hymenopteran pests of Pinus sylvestris L. are conifer sawflies from the family Diprionidae, including the widespread Diprion pini (L.). Natural enemies of this pest are still poorly known in many European areas where attacks occur. We studied the egg parasitoids of D. pini at four sites in two mountainous areas of Spain: the Sierra de Francia (western Spain) and the Sierra de Albarracín (eastern Spain). At all sites, the dominant egg parasitoid was Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae), whereas other three chalcidoid species were rare. All these species were previously recorded in association with D. pini, but we report here their first record in Spain. Neochrysocharis formosa attacked up to 32.3% of egg clusters of D. pini in the Sierra de Albarracín and 18.5% in the Sierra de Francia. In the attacked egg clusters, this species parasitized up to 35% of eggs in the Sierra de Albarracín and 23.7% in the Sierra de Francia, with a marked female-biased sex ratio. Contrary to the clustered pattern of parasitism observed for N. formosa while attacking other gregarious diprionids, the oviposition in egg clusters of D. pini followed a random pattern, probably due to the froth roof (spumous coating) that covers its eggs and interferes with the egg-searching behavior of females. Indeed, other parasitoid species of D. pini have been reported to behave similarly.     

Efficacy of a bacterial preparation of <Emphasis Type="Italic">Aneurinibacillus migulanus</Emphasis> against downy mildew of cucumber (<Emphasis Type="Italic">Pseudoperonospora cubensis</Emphasis>)

The reniform nematodes of the genus Rotylenchulus are semi-endoparasites of numerous herbaceous and woody plant roots and distributed in regions with Mediterranean, subtropical and tropical climates. In this study, we provide morphological and molecular characterisation of three out of 11 valid species of the genus Rotylenchulus: R. macrodoratus, R. macrosoma, and R. reniformis from Greece (Crete), Italy and Spain. The overall prevalence of reniform nematodes in wild and cultivated olives in Greece, Italy, and Spain was 11.5%, 19.0% and 0.6%, respectively. In Greece, R. macrodoratus and R. macrosoma were detected in cultivated olive with a prevalence of 8.2% and 6.2%, respectively, but none of them were found in wild olive. This is the first report of R. macrosoma in Greece. Only one reniform nematode species was detected in olive from Italy and Spain, viz. R. macrodoratus and R. macrosoma, respectively. The parasitism of R. macrosoma on hazelnut in northern Spain was also confirmed for the first time. This study demonstrates that R. macrodoratus and R. macrosoma have two distinct rRNA gene types in their genomes, specifically the two types of D2-D3 for R. macrosoma and R. macrodoratus, the two types of ITS for R. macrodoratus and the testing of the ITS variability in other R. macrosoma populations in different countries. Rotylenchulus macrosoma from Greece and Spain showed differences in nucleotide sequences in the ITS region and D2-D3 of 28S rRNA gene.     

Vertical distribution of resting spores of <Emphasis Type="Italic">Plasmodiophora brassicae</Emphasis> in soil

Pratylenchus zeae parasitizes various crops and damages the host roots, resulting in decreased yield and quality of the host plants. Alignments of mitochondrial DNA (mtDNA) Cytochrome Oxidase I (COΙ) sequences revealed the genetic variation among Pratylenchus species. The results indicated 0.2–2.4% intraspecific variations for mtDNA COI sequences among eight P. zeae populations, and 25.4–35.1% interspecific variations between P. zeae and other Pratylenchus species. Based on the mtDNA COΙ region, a loop-mediated isothermal amplification (LAMP) assay was developed for the rapid and specific detection of P. zeae. The optimal conditions for the LAMP assay were 64 °C for 40 min. The LAMP products were confirmed using conventional polymerase chain reaction (PCR), analysis with the restriction enzyme Bam HI and visual inspection by adding SYBR Green I to the products. The LAMP assay could detect P. zeae populations from different hosts and different geographical origins specifically. The LAMP assay was also sensitive, detecting 0.1 individual P. zeae, which was 10 times more sensitive than conventional PCR. This is the first report of the detection of Pratylenchus spp. using LAMP. In addition, the results also suggested that use of the COI gene might allow for good resolution at the Pratylenchus species level.     

Comparative colonisation by virulent versus avirulent <Emphasis Type="Italic">Pyricularia oryzae</Emphasis> on wild <Emphasis Type="Italic">Oryza australiensis</Emphasis>

Pyricularia oryzae (rice blast) conidial development at pre-penetration stage determines success or otherwise of infection inside the rice host plants. Studies on conidial germination and growth on the leaf surface in commercial rice (Oryza sativa) report differently, dependent upon host type and level of blast resistance. Although wild rice (O. australiensis) is known to be an alternative host of blast, the interaction between P. oryzae conidia and wild O. australiensis on its leaf surface has not been previously studied. We found significant (P?<?0.001) differences in conidial development between two blast isolates with different virulence in terms of conidial germination, germ tube growth and appressoria formation on both wild and cultivated rice. Conidial germination at 6 h post-inoculation (hpi) for the virulent isolate was significantly (P?<?0.001) delayed. Germ tubes of the avirulent isolate conidia grew significantly (P?<?0.001) faster and with significantly (P?<?0.001) longer germ tubes than from virulent conidia. Appressoria development for the virulent isolate was significantly (P?<?0.001) faster at its later growth stages of 12 and 18 hpi when approximately 100% of germ tubes formed appressoria. In contrast, formation rate of appressoria for the avirulent isolate was significantly (P?<?0.001) slower and only reached 76% of germ tubes forming appressoria. Appressoria formation on O. australiensis was significantly (P?<?0.001) greater than the formation on O. sativa for both virulent and avirulent P. oryzae at 12 hpi, a clear indication that host type influences the extent of appressoria formation.     

Genetic structure of <Emphasis Type="Italic">Pyrenophora teres</Emphasis> f. <Emphasis Type="Italic">teres</Emphasis> and <Emphasis Type="Italic">P. teres</Emphasis> f. <Emphasis Type="Italic">maculata</Emphasis> populations from western Canada

Infection by Pyrenophora teres f. teres (Ptt) or P. teres f. maculata (Ptm), the causal agents of the net and spot forms of net blotch of barley, respectively, can result in significant yield losses. The genetic structure of a collection of 128 Ptt and 92 Ptm isolates from the western Canadian provinces of Alberta (55 Ptt, 27 Ptm), Saskatchewan (58 Ptt, 46 Ptm) and Manitoba (15 Ptt, 19 Ptm) were analyzed by simple sequence repeat (SSR) marker analysis. Thirteen SSR loci were examined and found to be polymorphic within both Ptt and Ptm populations. In total, 110 distinct alleles were identified, with 19 of these shared between Ptt and Ptm, 75 specific to Ptt, and 16 specific to Ptm. Genotypic diversity was relatively high, with a clonal fraction of approximately 10 % within Ptt and Ptm populations. Significant genetic differentiation (PhiPT = 0.230, P = 0.001) was found among all populations; 77 % of genetic variation occurred within populations and 23 % between populations. Lower, but still significant genetic differentiation (PhiPT = 0.038, P = 0.001) was detected in Ptt, with 96 % of genetic variation occurring within populations. No significant genetic differentiation (PhiPT = 0.010, P = 0.177) was observed among Ptm populations. Isolates clustered in two distinct groups conforming to Ptt or Ptm, with no intermediate cluster. The high number of haplotypes observed, combined with an equal mating type ratio for both forms of the fungus, suggests that P. teres goes through regular cycles of sexual recombination in western Canada.     

Overexpression of <Emphasis Type="Italic">SlARG2</Emphasis> or <Emphasis Type="Italic">SlTD2</Emphasis> in Arabidopsis enhances resistance against <Emphasis Type="Italic">Plutella xylostella</Emphasis> L.

Tomato (Solanum lycopersicum L.) ARGINASE2 (ARG2) and THREONINE DEAMINASE2 (TD2) are involved in plant defense. These enzymes act in the midgut of herbivores fed on tomato plants to degrade the essential amino acids Arg and Thr, respectively. Although it has been demonstrated that overexpression of the SlARG2 gene in tomato enhanced its resistance against M. sexta larvae, knock-down the expression of SlTD2 reduced the resistance of tomato to lepidopteran herbivores; it remains unclear whether overexpression of SlTD2 could enhance the resistance of the host plants to herbivores, or whether combined overexpression of SlARG2 and SlTD2 could lead to synergistically enhanced resistance to insects. Here, we generated transgenic Arabidopsis plants overexpressing SlARG2 (SlARG2 OE) and SlTD2 (SlTD2 OE) individually as well as in combination (SlARG2-SlTD2 OE). Overexpression of these genes did not affect Arabidopsis development, seed yield, or Arg and Thr content. Insect-feeding bioassay was performed by feeding diamondback moth (Plutella xylostella L.) larvae on detached leaves of wild-type, SlARG2 OE, SlTD2 OE, and SlARG2-SlTD2 OE plants. Larvae fed on SlARG2 OE leaves showed approximately 31% to 35% reduction in weight and 6% to 10% reduction in survival rate compared to those fed on wild-type leaves. Although larvae fed on SlTD2 OE leaves showed no reduction in survival rate, they gained less weight. Whereas larvae fed on SlARG2-SlTD2 OE leaves showed neither reduction in weight nor reduction in survival rate. We further investigated the arginase enzymatic activity of the SlARG2 OE and SlARG2-SlTD2 OE transgenic plants. The SlARG2 OE line most resistant to diamondback moth larvae displayed the highest arginase activity. Our data indicate that overexpression of SlARG2 or SlTD2 in Arabidopsis can enhance its resistance against diamondback moth, whereas combined overexpression of SlARG2 and SlTD2 did not generate synergistically increased resistance to diamondback moth.     

Host-suitability of black medick (<Emphasis Type="Italic">Medicago lupulina</Emphasis> L.) and additional molecular markers for identification of the pea cyst nematode <Emphasis Type="Italic">Heterodera goettingiana</Emphasis>

A survey was conducted in 16 fields cultivated with broad bean (Vicia faba L.) and garden pea (Pisum sativum L.) in nine localities of Apulia, southern Italy, to determine whether annual weeds were susceptible to the pea cyst nematode (PEACN), Heterodera goettingiana, and could therefore serve as alternate host for the nematode. The results of this study showed that black medick (Medicago lupulina L.) is a good host for the nematode increasing its population levels in the soil in the absence of the primary hosts. The identity of the PEACN was confirmed by integrative taxonomic approaches (classical, and molecular), resulting identical in all cases (broad bean and garden pea, as well as the spontaneous black medick infections). The phylogenetic analyses using ITS and coxI gene regions strongly support the identification of the populations of H. goettingiana from Italy. Also, ITS and coxI gene sequences were obtained from the same cyst, confirming the species identity in comparison to other nematodes and populations in the Goettingiana group, demonstrating that ITS and coxI gene regions of the PEACN are suitable molecular markers for accurate and unequivocal identification of the PEACN. Reproduction and histopathological analyses demonstrated a good host-suitability of black medick to the PEACN. This record enlarges the relatively narrow host-range of the pea cyst nematode and indicates the need to control M. lupulina to avoid the increase of the nematode population in the absence of the main host crop.     

The chemotaxis regulator <Emphasis Type="Italic">pilG</Emphasis> of <Emphasis Type="Italic">Xylella fastidiosa</Emphasis> is required for virulence in <Emphasis Type="Italic">Vitis vinifera</Emphasis> grapevines

Type IV pili of X. fastidiosa are regulated by pilG, a response regulator protein putatively involved in chemotaxis-like operon sensing stimuli through signal transduction pathways. To elucidate the roles of pilG in pathogenicity of X. fastidiosa, the pilG-deletion mutant XfΔpilG and complemented strain XfΔpilG-C were generated. While all strains had similar growth curves in vitro, XfΔpliG showed significant reduction in cell-matrix adherence and biofilm production compared with wild-type X. fastidiosa and XfΔpilG-C. The genes pilE, pilU, pilT, and pilS were down-regulated in XfΔpliG when compared with its complemented strain and wild-type X. fastidiosa. Finally, no Pierce’s disease symptoms were observed in grapevines inoculated with XfΔpilG, whereas grapevines inoculated with the wild-type X. fastidiosa and complemented strain of XfΔpilG-C developed typical Pierce’s Disease (PD) symptoms. The results indicate that pilG has a role in X. fastidiosa virulence in grapevines.     

Diversity of the cultivable gut bacterial communities associated with the fruit flies <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis> and <Emphasis Type="Italic">Bactrocera cucurbitae</Emphasis> (Diptera: Tephritidae)

Gut microbes play an important role in insect morphogenesis, nutrition, development of resistance against parasitoids and detoxification of toxic compounds. A culture-based approach is therefore an useful tool for the characterization of cultivable microbial communities associated with the insect gut. In the present study an attempt was made to decipher the gender specificity of gut bacterial communities of two major fruit fly species of India viz., Bactrocera dorsalis (Hendel) and Bactrocera cucurbitae (Conquillett) (Diptera: Tephritidae). Based on molecular identification, B. dorsalis females were found to predominantly harbor the bacterial species Enterobacter cloacae, Enterobacter asburiae and Citrobacter freundii, while B. dorsalis males were found to harbor Providencia rettgerii, Klebsiella oxytoca, Enterococcus faecalis and Pseudomonas aeruginosa The cultivable diversity from females of B. cucurbitae comprised mainly of Morganella morganii and Bacillus pumilis while B.cucurbitae males were predominantly colonized by aerobic endospore formers viz., Bacillus cereus, B. licheniformis and B. subtilis. The above findings have thrown light on a distinct pattern of gender specific gut bacterial colonization in fruit flies, which have to be factored in for the formulation of fruit fly management strategies.     

Competence of <Emphasis Type="Italic">Frankliniella occidentalis</Emphasis> and <Emphasis Type="Italic">Frankliniella intonsa</Emphasis> strains as vectors for <Emphasis Type="Italic">Chrysanthemum stem necrosis virus</Emphasis>

The vector competence of Frankliniella occidentalis for Chrysanthemum stem necrosis virus (CSNV) was evaluated. Three vector strains with distinct competences for Tomato spotted wilt virus (TSWV) transmission were investigated, including an artificially selected strain (TsH) that has a particularly high competence (>90 %). Newly hatched larvae of F. occidentalis were given an acquisition access period of 5 days on CSNV-infected D. stramonium leaves, and reared to maturity. Their transmission efficiencies were examined using a leaf disk assay using Petunia x hybrida leaves. Following the leaf disk assay, the virus accumulation in the vectors was examined via a double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) of their bodies. The results showed that the CSNV acquisition and transmission efficiency of the TsH strain did not differ from those of the others, indicating that the competence of F. occidentalis as a vector for CSNV is not related to that for TSWV. The CSNV transmission and acquisition efficiencies of two F. intonsa strains (Hiroshima and Fukuoka) were also evaluated. In Hiroshima strain, 35 % of adults were viruliferous, but only two transmitters (3 %) were observed. In Fukuoka strain, 6 % were viruliferous, and no transmitters were observed. These results indicate that F. intonsa cannot be a major vector for CSNV. The accumulation of CSNV in the adults of F. occidentalis and F. intonsa evaluated using DAS-ELISA showed a significant difference in ELISA values among transmitter, viruliferous non-transmitter, and non-viruliferous individuals. These results clearly demonstrated that only transmitters that accumulated a threshold quantity of virus can transmit CSNV to plants.