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.     

Demography and population projection of <Emphasis Type="Italic">Myzus persicae</Emphasis> (Sulz.) (Hemiptera: Aphididae) on five pepper (<Emphasis Type="Italic">Capsicum annuum</Emphasis> L.) cultivars

The green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae), is a major pest of pepper. In this study, we collected data on the development, survival, fecundity, and proportion of apterous and alate forms of green peach aphid reared on five commercial pepper cultivars (Amiral, Erciyes, Mert, Mertcan, and Naz) at 25?±?1°C, 60?±?5% RH, and a photoperiod of 16:8 (L:D) h. We analyzed the life history raw data by using the age-stage, two-sex life table. The shortest development time (6.66 days) and highest fecundity (62.68 individuals) occurred on the Erciyes cultivar. The highest intrinsic rate of increase (r?=?0.332 d^?1), finite rate of increase (λ?=?1.394 d^?1), net reproductive rate (R₀?=?62.7 offspring) and shortest mean generation time (T?=?12.45 d) also occurred on the Erciyes cultivar; while the lower fitness occurred on the Amiral, Mertcan and Naz cultivars. Our results compared differences in the population growth rate of M. persicae on different pepper cultivars. This information will be useful to individuals working in pest management programs particularly those involving M. persicae.     

Long-term dynamics of causative agents of stem base diseases in winter wheat and reaction of Czech <Emphasis Type="Italic">Oculimacula</Emphasis> spp. and <Emphasis Type="Italic">Microdochium</Emphasis> spp<Emphasis Type="Italic">.</Emphasis> populations to prochloraz

Trichoderma aggressivum is an aggressive contaminant mould in the cultivation of Agaricus bisporus leading to severe reductions in mushroom yields. Production of fully colonised A. bisporus substrate in Europe is commonly carried out in large tunnels (Phase III), after which the substrate undergoes several bulk handling (mixing) operations before ending up on shelves in mushroom growing facilities. The work presented here studied the effect of Trichoderma aggressivum inoculum, substrate mixing and supplementation on Agaricus bisporus yields and evaluated four methods to detect T. aggressivum in bulk handled substrate. Inoculum dilution level was shown to correlate well with mushroom yield (P < 0.0001) with reductions of 2–6 % at the most dilute level (10^?4) and 60–100 % at the most concentrated level (10^?1), depending on the experiment. Supplementation, with or without T. aggressivum, had no significant effect on mushroom yield (P ≥ 0.85) but a high degree of substrate mixing was shown to significantly increase (P < 0.0001) T. aggressivum-associated crop losses. Four T. aggressivum detection methods were evaluated and a quantitative polymerase chain reaction (qPCR) method gave the most consistent and least variable results. Cycle threshold (CT) values ranged from 24 to 40, depending on the experiment and the inoculum dilution level, and false negatives (CT = 40) were reported on one occasion with the most dilute samples. The results indicate that Phase III mushroom substrate is vulnerable to infection by T. aggressivum when the fully colonised substrate is broken up and mixed during bulk handling operations, identifying a previously unidentified risk for Phase III substrate producers.     

Phytosynthesis of Silver Nanoparticles using Leaf Extracts from <Emphasis Type="Italic">Ocimum basilicum</Emphasis> and <Emphasis Type="Italic">Mangifira indica </Emphasis>and their Effect on some Biochemical Attributes of <Emphasis Type="Italic">Triticum aestivum</Emphasis>

In this investigation, leaf extracts of Ocimum basilicum and Mangifira indica were used as reducing agents for biosynthesis of silver nanoparticles (AgNPs). The biosynthesized AgNPs were authorized by UV-vis spectrophotometry and X?ray diffraction (XRD) analysis. AgNPs were obtained after 5?min of reaction at 80^oC. The formation of AgNPs was confirmed by the presence of absorption peaks at 439?nm using extract from O. basilicum and at 442.5?nm from M. indica. X?ray spectra showed strong peaks for the crystalline Ag. Shape and size of the biosynthesized AgNPs were studied using high resolution transmission electron microscope (HR-TEM). Size of the produced AgNPs was found to be 9–35?nm. Effect of the synthesized nanosilver was then investigated on some biochemical attributes of wheat plant (Triticum aestivum cultivar saka 92). The growth parameters such as shoot lengths, fresh and dry weight of shoot, chlorophyll, carbohydrate and protein contents in shoot of wheat plant were investigated. Application of AgNPs synthesized from Ocimum basilicum and from Mangifira indica at the concentrations of 20,40?ppm showed an increase in shoot length, fresh and dry weight of shoot, chlorophyll, total carbohydrate and protein content in shoot of wheat plants, beyond these concentrations an inhibitory effects were shown.     

Effect of <Emphasis Type="Italic">Metarhizium guizhouense</Emphasis> infection on mating competition and mate choice of <Emphasis Type="Italic">Bactrocera latifrons</Emphasis> (Diptera: Tephritidae)

Metarhizium guizhouense PSUM02 treated males of Bactrocera latifrons were investigated for the mating competition among males and mating choice by female flies to develop an auto-dissemination for the control of B. latifrons. In the present study, on day 1–4 of experiment, M. guizhouense–treated male flies were equally competitive with the normal male flies as we did not observe any differences in mating by treated and normal male flies of B. latifrons. Further, mating competitiveness were found low in treated adult male B. latifrons than normal male B. latifrons from 5th days of treatment until death. Kaplan-Meier survival analysis of treated male flies gave average survival times (AST) of 4.3?±?0.1 days, while the healthy female and male flies in the same cage showed AST of 9.3?±?0.3 and 8.3?±?0.4 days, respectively. The AST of untreated flies in control experiment ranged from 14.2–14.5 days. In mating preference experiment, M. guizhouense–treated male flies were chosen by virgin female than gravid female flies for mating. The treated male flies caused mortality in both virgin and gravid female flies in the same cage with AST of 4.4?±?0.1, 5.6?±?0.1 and 7.4?±?0.2 days, respectively, while untreated flies showed AST ranged from 13.9–14.3 days in control. The treated male flies could transmit the fungus infection to both untreated female and male flies as well as in virgin and gravid female flies by mating and contact. Our experiments showed the potentiality of M. guizhouense PSUM02 in management of B. latifrons by auto-dissemination with treated male flies, which transmit the fungus to a healthy population to reduce insect pest infestations.     

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.     

Influence of abiotic factors on behaviour and adult emergence pattern of coconut white grub, <Emphasis Type="Italic">Leucopholis coneophora</Emphasis> Burmeister (Coleoptera: Scarabaeidae)

Leucopholis coneophora Burmeister is a subterranean pest associated with coconut based cropping systems in south India. Feeding damage causes yellowing of fronds and yield reduction. To develop appropriate IPM strategy a basic knowledge on insect behaviour is essential. Four years studies indicated that, adult emergence of L. coneophora was commenced with summer shower in April in Kerala. Delay in summer shower delayed the emergence. After a pause in May, the emergence resumed with the setting of south west monsoon in June. The beetles did not emerge during dry spells in between the rainy days, when the soil temperature (at 10 cm depth) was ≥34.5 °C. Emergence of the beetles started at an illuminance of 124.37?±?75.5 l in evening and remained active till 2?±?0.4 l with a maximum swarming at 32.6?±?15.1 l. Female emergence and mating occurred at 12.04?±?8.1 l. Female based sex pheromone mediated communication is evident. Strong competition among the males for mating with emerging female, which was evident by a wider operational sex ratio in the initial period (1:10.11) that narrowed down to 1:4.33 in later days. The beetles neither congregate on any host plant nor exhibit phototaxis. Number of beetles entrapped in light traps varied from 1.5–16.5% and hand picking is highly significant over light trapping. Hence hand picking of beetles daily in the evening for 2 weeks commencing from the onset of south west monsoon in Kerala, in Indian subcontinent is suggested as a tool in IPM.     

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.     

Survival and development of spotted bollworm, <Emphasis Type="Italic">Earias vittella</Emphasis> (Fabricius) (Lepidoptera: Nolidae) on different transgenic <Emphasis Type="Italic">Bt</Emphasis> and isogenic non-<Emphasis Type="Italic">Bt</Emphasis> cotton genotypes

Four Bt cotton hybrids, each with one of four different events, viz., MRC 6301 Bt (cry1Ac gene), JKCH 1947 Bt (modified cry1Ac gene), NCEH 6R Bt (fusion cry1Ac/cry1Ab gene) and MRC 7017 Bollgard II (cry1Ac and cry2Ab genes) were compared for survival and development of Earias vittella (Fabricius) along with their isogenic non-Bt genotypes. None of the neonates were able to complete the larval period and reach pupal stage on squares of 90, 120 and 150 days old crop of all Bt hybrids. Likewise, on bolls also, zero per cent larval survival was observed in all Bt hybrids except JKCH 1947 Bt where 0.67 per cent larvae could manage to reach pre-pupal stage at 120 and 150 days old crop but failed to form cocoon and enter pupal stage. The surviving larva took more development time (3.7 to 5.4 days) as compared to larvae fed on bolls of JKCH 1947 non-Bt. The average survival period (ASP) of larvae was in order of 150 > 120 > 90 days old crop among the crop ages; JKCH 1947 Bt > MRC 6301 Bt > NCEH 6 R Bt > MRC 7017 Bollgard II among Bt hybrids; and bolls > squares between fruiting bodies. However, reverse was true for speed index of toxic effect. The concentration of Cry toxin varied significantly in squares and bolls and also among the crop ages. The amount of Cry toxin in squares and bolls had significant negative correlation with ASP of the E. vittella larvae.     

<Emphasis Type="Italic">Alternaria alternata</Emphasis> apple pathotype (<Emphasis Type="Italic">A. mali</Emphasis>) causes black spot of European pear

A disease caused by Alternaria alternata occurred on the leaves of European pear cultivar Le Lectier in Niigata Prefecture, Japan, and was named black spot of European pear. In conidial inoculation tests, the causal pathogen induced not only small black lesions on the leaves of European pear cultivar Le Lectier, but severe lesions on the leaves of apple cultivar Red Gold, which is susceptible to the A. alternata apple pathotype (previously called A. mali) causing Alternaria blotch of apple. Interestingly, the apple pathotype isolate showed the same pathogenicity as the European pear pathogen. HPLC analysis of the culture filtrates revealed that A. alternata causing black spot of European pear produced AM-toxin I, known as a host-specific toxin of the A. alternata apple pathotype. AM-toxin I induced veinal necrosis on leaves of Le Lectier and General Leclerc cultivars, both susceptible to the European pear pathogen, at 5?×?10^?7 M and 10^?6 M respectively, but did not affect leaves of resistant cultivars at 10^?4 M. PCR analysis with primers that specifically amplify the AM-toxin synthetase gene detected the product of expected size in the pathogen. These results indicate that A. alternata causing black spot of European pear is identical to that causing Alternaria blotch of apple. This is the first report of European pear disease caused by the A. alternata apple pathotype. This study provides a multiplex PCR protocol, which could serve as a useful tool, for the epidemiological survey of these two diseases in European pear and apple orchards.     

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.     

Identification of resistance to bacterial canker (<Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">syringae</Emphasis>) disease on apricot genotypes grown in Turkey

Bacterial canker caused by Pseudomonas syringae pv. syrinage (Pss) in apricot has widely spread in Turkey, especially in Malatya province, in recent years. The main objective of this study was to determine resistance of apricot cultivars to bacterial canker caused by Pss in apricot cultivars grown in Turkey. During the 2006–2007 growing period, bacterial isolations were taken from diseased apricot trees in Malatya and 53 Pseudomonas syringae isolates were obtained. Forty-two isolates were determined as Pseudomonas syringae pv. syringae and 11 isolates as pv. morsprunorum. In a pathogenicity test, leaves of cv. Hacihalilo?lu were used and five Pss isolates (K24, K25, K43, K47 and K51) were detected to be the most virulent and were used to test for cultivar resistance to Pss. Leaves of fifteen apricot cultivars (Alyanak, Çatalo?lu, Çölo?lu, Erken A?erik, Hacihalilo?lu, Hasanbey, ?smaila?a, Kabaa?i, Karacabey, Sakit 2, So?anci, ?am, ?ekerpare, Tokalo?lu (Erzincan) and Turfanda Eski Malatya) were tested for resistance to Pss. Green shoots were spray-inoculated with a concentration of 10⁸ cfu ml^?1 Pss mixed culture. Sprayed shoots were covered with moist plastic bags for 3 days and maintained in the growth chamber and monitored for symptom development. Hasanbey, Çölo?lu, So?anci and ?ekerpare apricot cultivars were resistant and ?am, Tokalo?lu (Erzincan) and Erken A?erik apricot cultivars were susceptible to Pss. This is the first report of a resistance source in apricot cultivars grown in Turkey against Pss.     

Infection of <Emphasis Type="Italic">Sorghum bicolor</Emphasis>, selected grass species and <Emphasis Type="Italic">Zea mays</Emphasis> by G<Emphasis Type="Italic">loeocercospora sorghi</Emphasis>, causal pathogen of zonate leaf spot

Zonate leaf spot (Gloeocercospora sorghi) is a common disease in Sorghum bicolor producing areas of the U.S., but little is known about its biology, virulence and severity on S. bicolor, Zea mays, and related crop grassweeds. Greenhouse studies were conducted to determine and compare the virulence and severity of G. sorghi on 10 commercially available sorghum hybrids, four Z. mays hybrids and selected grassweed species including Sorghum bicolor (grain sorghum and shattercane biotypes) and Sorghum halepense (Johnsongrass), two of the most problematic arable weeds. Plants from the respective species were inoculated with a local G. sorghi isolate and maintained in a dew-chamber at 24 °C for 24 h and then incubated under greenhouse conditions for 4 weeks. Plants were observed for lesion expression and rated using a modified Horsfall-Barrett scale (0–10). The first symptoms of infection were visible within 24 h following inoculation on shattercane and S. bicolor hybrids. Symptoms consisted of small, non-diagnostic purple lesions on the leaves. Results showed that S. bicolor, S. halepense and shattercane were susceptible to G. sorghi. All other species tested in this study were not infected. More particularly, disease severity, increased from a rating of 3 to 10 on sorghum and from 2 to 7 on S. halepense between 2 and 23 days after inoculation, respectively. However, disease severity on shattercane increased rapidly from 3.5 to 10 between 2 and 8 days after inoculation, respectively. Among the sorghum hybrids tested, FFR-322 appeared to be the most resistant to G. sorghi while Pioneer 83G66 appeared to be the most susceptible. Z. mays hybrids were not infected by the fungus used in this study. G. sorghi could be used effectively to manage shattercane and S. halepense infestations occurring in Z. mays and S. bicolor fields consisting of specific G. sorghi-resistant hybrids.     

Development of <Emphasis Type="Italic">Tetranychus ludeni</Emphasis> (Acari: Tetranychidae) on transgenic soybean cultivars

The aim of this study was to assess the influence of transgenic soybean [Glycine max L. (Fabaceae)] cultivars on the biological cycle of Tetranychus ludeni Zacher (Acari: Tetranychidae) in laboratory conditions. We used three cultivars: a conventional soybean (CO), a glyphosate-resistant with insertion of genes of Agrobacterium sp., Roundup Ready (RR), and a glyphosate-resistant with insertion of genes of Bacillus thuringiensis var. israelensis (BT). Duration of developmental stage, mite viability, number of laid eggs, and female longevity of T. ludeni were evaluated. The duration of the deutonymph phase was shorter in RR (2.1?±?0.12 days) than in CO (2.6?±?0.12) and BT (2.5?±?0.08). The duration of egg, larval, and protonymph phases were similar for T. ludeni on the three cultivars. The mean duration of each generation (T), net reproduction rate (R_o), intrinsic rate of natural increase (r_m), and doubling time (DT) were similar on the three cultivars. Results showed that population growth are not influenced by transgenesis at the laboratory level. Females died without a post-oviposition period on all soybean cultivars. The intrinsic rate of natural increase of T. ludeni on soybean cultivars was low (between 0.15 and 0.17).     

<Emphasis Type="Italic">Fusarium</Emphasis> head blight incidence and detection of <Emphasis Type="Italic">Fusarium</Emphasis> toxins in wheat in relation to agronomic factors

We investigated incidences of Fusarium head blight (FHB) and concentrations of six mycotoxins (deoxynivalenol, nivalenol, 3-acetyldeoxynivalenol, T-2 toxin, HT-2 toxin and zearalenone) in wheat from 2010 to 2013. Field trials were conducted at the Experimental Station of Cultivar Testing in Chrz?stowo, Poland (53^o11’N, 17^o35’E). We examined the effects of four agronomic factors, including pre-crop type (corn, sugar beets and wheat), date of sowing (late autumn: November 8–December 9 or spring: March 29–April 19), fungicidal application (untreated or treated with two applications) and cultivar (Monsun, Cytra), on FHB index (FHBi) and mycotoxin levels in order to minimize the risk of wheat grain contamination by mycotoxins via integrated pest management methods. The dominant Fusarium species observed on wheat heads were F. culmorum, F. avenaceum (Gibberella avenacea) and F. graminearum (Gibberella zeae), at 21.1%, 17.2% and 7.1%, respectively. A monthly rainfall sum of 113.9 mm and a relatively low air temperature (monthly average 15.5 °C) resulted in the highest FHBi in untreated wheat (25.1%). Agronomic factors crucial for the FHB incidence were the pre-crop, fungicidal treatments and cultivar selection. In wheat planted after wheat or corn, the FHBi was higher compared with a pre-crop of sugar beet. A double application of fungicides at BBCH 30–32 with prothioconazole and spiroxamine and at a BBCH 65 with fluoxastrobin and prothioconazole effectively reduced the FHBi and mycotoxin concentrations, respectively, in grain. The cultivar ‘Cytra’ had a greater FHBi (10.4%) than ‘Monsun’ (4.6%), and grain infestations by Fusarium species were also greater in ‘Cytra’, at 16.5%, than in ‘Monsun’, at 11.2%. Untreated cv. Cytra grown after corn in spring produced grains with the highest amounts of the mycotoxins, deoxynivalenol, 3-acetyldeoxynivalenol, zearalenone and HT-2 (605, 103, 17.5 and 5.53 μg/kg, respectively). Total mycotoxin levels in wheat were correlated with five determinants: duration of the period between the end of flowering and the beginning of kernel abscission, FHBi, F. culmorum isolation, G. zeae isolation and Fusarium ratio (FR) as a % of total mould isolations. Although, the mean concentration of mycotoxins in grain did not exceed the maximum permissible values for unprocessed wheat our study suggests necessity to monitor and mitigate FHB risk for susceptible cultivars, when wheat spring sowing follows corn or wheat.     

The effect of some cucumber cultivars on the biology of <Emphasis Type="Italic">Aphis gossypii</Emphasis> Glover (Hemiptera: Aphididae)

The development, reproduction, and population growth parameters of cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), were studied on three different Cucumis sativus cultivars (Beith Alpha Bal?kesir, B.T. Bursaalpha, Beith Alpha MR,) under controlled conditions (25?±?1 °C, 65?±?5% RH, and a photoperiod of 16:8 (L:D) h. Life table parameters were estimated according to age-stage, two-sex life table method. Results indicated that the Bt Bal?kesir are favorable hosts for A. gossypii because of the shorter preadult developmental time, lower preadult mortality rate, and higher total fecundity on this cultivar. The intrinsic rate of increase (r?=?0.4214 d^-1), the net reproduction rate (R₀?=?51.80 offspring), and the finite rate of increase (λ?=?1.5242 d^-1) values were higher on the Bt Bal?kesir. The effect of cucumber cultivars on the biology of A. gossypii was determined as significant and it was found that cv. Bt Bal?kesir was the most convenient cucumber cultivar in terms of the life cycle of A. gossypii. For an ecological and economic pest control, against aphids use of resistant or less favourable crop cultivars is considered one of the important components of integrated pest management. Therefore, results acquired might be used in pest management program that will be prepared for this aphid.     

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.     

The Eurotiomycete <Emphasis Type="Italic">Apinisia graminicola</Emphasis> as the causal agent of a leaf spot disease on the energy crop <Emphasis Type="Italic">Miscanthus</Emphasis> x <Emphasis Type="Italic">giganteus</Emphasis> in Northern Germany

Miscanthus x giganteus is a fast growing, perennial energy crop for temperate climates. Because of its high annual biomass production rates and its characteristics as a low-input crop, an expansion of field cultivation can be anticipated to cover increasing demands for sustainable biomass production. However, knowledge about pathogens that could have an impact on biomass production is still limited for M. giganteus. Here, we report about the isolation of the filamentous fungus Apinisia graminicola from necrotic leaf lesions of M. giganteus grown on a field trial plot in Northern Germany. Inoculation assays with the isolated A. graminicola strain confirmed its capacity to cause a leaf spot disease on M. giganteus. Additional inoculation assays revealed that A. graminicola also caused necrotic lesions on leaves of the model grass Brachypodium distachyon. Generally, symptoms of A. graminicola-caused leaf spot disease were stronger on B. distachyon compared to M. giganteus. Incubation temperatures above 22 °C during A. graminicola infection resulted in stronger disease symptoms on both, M. giganteus and B. distachyon leaves. Microscopic analysis of cross sectioned, infected leaf tissue revealed an epiphytic mycelium formation on the surface and an endophytic colonization of the mesophyll leave tissue, especially in M. giganteus. Our results revealed that the isolated A. graminicola strain is a causal agent of a leaf spot disease on grass leaves. Its potential on endophytic growth in M. giganteus might open new possibilities in studying this type of plant-fungal interaction on a cellular and molecular level in an energy crop.