Hesperomyces virescens Thaxter is an obligate ectoparasitic fungus that parasitizes coccinellids in several countries. It transmits horizontally between coccinellid adults via social contact. The relative abundance of coccinellids in an agroecosystem may affect the transmission dynamics of H. virescens. We predicted that the prevalence and intensity of H. virescens would be greatest on the more abundant coccinellid species. We collected lady beetles from plant foliage in a 480 ha agroecosystem in Byron, Georgia, USA, from April through October 2007. The prevalence and intensity of the parasite was greatest on Harmonia axyridis (Pallas), which was the most abundant coccinellid collected in early spring and summer. There was a positive relationship between parasite infection of the exotic H. axyridis and the native Olla v-nigrum Mulsant; parasite infection increased as relative abundance of both species increased. The parasite was seldom on one of its original hosts, Hippodamia convergens Guérin-Méneville, and never on the exotic Coccinella septempunctata L. even though the latter species was the second most abundant coccinellid in the agroecosystem. Lack of infection of an abundant coccinellid such as C. septempunctata could result from low encounter rates and not just low susceptibility to infection. H. virescens transmission may vary depending on frequency of contact between infected and uninfected coccinellids in shared habitats.
Five species of social wasps were captured in trapping tests in Budapest (Hungary) that evaluated the attractiveness of acetic acid, isobutanol, 2-methyl-2-propanol, and heptyl butyrate. Both Vespula vulgaris (L.) and Vespula germanica (F.), were captured in traps baited with isobutanol, the combination of acetic acid and isobutanol, and the combination of acetic acid and 2-methyl-2-propanol. V. germanica did not respond to acetic acid or to heptyl butyrate. V. vulgaris also responded to acetic acid alone, and 2-methyl-2-propanol alone, but did not respond to heptyl butyrate. Both V. germanica and V. vulgaris responded more strongly to the combinations of acetic acid with isobutanol and acetic acid with 2-methyl-2-propanol, compared to any of these chemicals tested alone. Small numbers of European hornets, Vespa crabro L. were captured in traps baited with acetic acid with isobutanol, but not with any other lures. Small numbers of Dolichovespula media (Retzius) were captured in traps baited with acetic acid, and with the combination of acetic acid and isobutanol, but not with any other lures. The small numbers of Polistes nimpha (Christ) trapped were not large enough for any statistical analyses. These findings are the first European report of attracting and trapping vespid wasps with these chemicals.
The influence of oviposition experience on the response of the egg parasitoid Trichogramma evanescens Westwood (Hymenoptera Trichogrammatidae) towards the contact kairomones of two different host species, Mamestra brassicae (L.) and Pieris brassicae L., is described. The response of T. evanescens was influenced by the number of eggs it had laid, but time since oviposition did not result in a significant change in behaviour. Parasitoids readily accepted an egg of a second species and the time spent searching in a particular kairomone area would appear to depend on the reproductive state and expected survival of a parasitoid, rather than the development of any host preference. Trichogramma seems to select patches on the basis of reward probability rather than maximising reward size. Such behaviour would assist parasitoids to respond to fluctuations in host availability.
The possibility to use native Orius insidiosus (Say) (Rhynchota Anthocoridae) for control of thrips (Thysanoptera) on chrysanthemums in tropical Brazilian greenhouses was tested. First, thrips infested potted chrysanthemums in cages, cultivars ”White Reagan” (WR) and “Yellow Snowdon” (YS), were exposed to the predator O. insidiosus. The number of thrips/plant increased from 2.0 to 7.0 thrips after six weeks on control plants in the absence of O. insidiosus, while thrips numbers decreased from 2.0 to 0.2 thrips/plant in the presence of the predator on YS. Similar results were obtained for the chrysanthemum cultivar WR. Next, an experiment was carried out in a commercial chrysanthemum greenhouse with the same two cultivars and with a natural infestation of thrips. The predator was introduced five times at rates of 1.5 or 2.0 Orius/m2 (in total 9.5 Orius/m2). Thrips sampling was done by tapping two plants per flower bed per week, and by then counting thrips and predators. The average number of thrips decreased from 4.7 to 2.5 thrips/plant on YS and from 2.8 for 1.1 thrips/plant on WR after the first release. O. insidiosus reached a population peak in the sixth week after planting, with 0.5 Orius/plant on YS and 0.7 Orius/plant on WR, respectively. Thrips numbers decreased to 0.3 thrips/plant on YS and to 0.4 thrips/plant on WR seven weeks after planting. At this time no injury of thrips was found on chrysanthemum. Nine weeks after planting (chrysanthemum flowering period) the insecticide delthamethrin was sprayed for general pest control, and predatory bugs were eliminated from the greenhouse, resulting in a strong population increase of thrips. We conclude that thrips can be controlled effectively in tropical Brazilian chrysanthemum greenhouses with the native predator O. insidiosus, but that the selection of insecticides for control of other pests needs to be done carefully. Only those pesticides that are compatible with the use of the predator should be used to make commercial thrips biological control in greenhouses possible.
Experimental releases were performed to investigate the potential of thrips parasitoids as biological control agents of western flower thrips, Frankliniella occidentalis (Pergande). Strains of two larval parasitoid species (Hymenoptera: Eulophidae), Ceranisus menes (Walker) (a strain from France and from Brazil) and Ceranisus americensis (Girault) (Arizona strain), were released in different commercial greenhouse crops. In all crops only traces of parasitism were recorded. In an experimental rose crop (cv. 'Frisco'), releases were made of two parasitoid species, C. menes (a French strain) and C. americensis (Arizona strain) in two separate greenhouse compartments. An account is given on the release, dispersal, establishment, population dynamics and control capacity of both parasitoid species. Parasitoids spread readily and established themselves throughout the crops, but releases did not result in reduction of thrips during a five month period. Rates of parasitism stayed lower than 10% throughout the season, resulting in severe damage of the rose crop. The potential of parasitoids as biological control agents of thrips pests in ornamental crops is discussed.
A study of the constitutive resistance of the apple cultivar Florina, Malus domestica Borkh. (Rosaceae), to the rosy apple aphid, Dysaphis plantaginea (Passerini) (Homoptera Aphididae), was performed for the first time by the electrical penetration graph (DC-EPG) system, using the susceptible apple cultivar Smoothe as control. All experiments were conducted with apterous adult virginoparae. The results showed a constitutive resistance in Florina due to a much longer period before the first probe reflecting surface factors. Some weak indications were found for pre-phloem resistance and initiating phloem access was not affected as inferred from equal time to show phloem salivation. However, the complete absence of phloem ingestion indicates a major resistance factor in the phloem sieve elements, most likely in the sieve element sap. Surface factors could have affected tissue related variables and this should be studied further. Anyhow, the strong constitutive resistance in Florina, either on the surface alone or in the phloem as well, effectively prevented reliable experiments on induced resistance, previously detected by molecular methods.
Glue-sprayed maize plants were used to study dispersal behaviour of the egg parasitoid Trichogramma brassicae Bezdenko (Hymenoptera Trichogrammatidae) in maize fields. To estimate the distance covered during an initial flight, T. brassicae were studied in a field cage with 73 glue-sprayed plants. Most of the parasitoids were found close to the release point, but several reached plants at distances up to 180 cm showing that walking and jumping are not the only mechanisms involved in initial dispersal. Mean distance of recapture from the release point was 60 cm. In a second experiment, glue-sprayed plants were placed in a maize field in a cross-pattern with 1.5 m distance between plants. On plants neighbouring the glue-sprayed plants, egg masses were fixed to measure parasitism. Only 0.7 to 3% of the released parasitoids were recaptured in the field. During the first day there was a sharp gradient with distance in the numbers of parasitoids recaptured, but during the second and third day there was no longer a significant gradient. The numbers captured on the second and third day were much lower than those captured on the first day. There was little correlation between the number of wasps landing on a plant and parasitism. In the field, apparently 75% of the wasps had left the area within 7.5 meter of the release point at the end of the first day, and 95% had left this area at the end of the second day. It is concluded that T. brassicae disperses in maize fields mainly by short flights
Oviposition behaviour and egg distribution of Ostrinia nubilalis is reviewed based on published information and new research. The position of egg masses of O. nubilalis on maize plants and leaves were sampled in the field. Most egg masses were found on the lower leaf side, on the middle part of the leaf or close to the stem, and close to the mid-rib. Direct observations of oviposition behaviour were made in laboratory and field cages. O. nubilalis moved very little on the plants and only 10 % of the females that landed on the plants oviposited. The number of actual ovipositions was quite low compared to the number of landings, with females walking only a few centimetres if at all. Shed scales of adult moths were not abundant near egg masses with only 37% of egg masses associated with scales and 45% with only a few scales. Many scales were found on other places of the plants. At the leaf and plant level, scales might serve as a useful host-cue to Trichogramma brassicae, an egg parasitoid of O. nubilalis. However, scales are not an indicator for the presence of egg masses in their immediate vicinity.
Laboratory trials were carried out in order to determine biological traits and predation activity of four Orius species - the paleartic Orius majusculus (Reuter), O. laevigatus (Fieber) and O. niger Wolff and the neartic O. insidiosus (Say) - using Ephestia kuehniella (Zeller) eggs and Frankliniella occidentalis (Pergande) adults as prey. The intrinsic rates of natural increase (rm) were calculated for the four Orius species on the two preys and the rm was 0.094 (on F. occidentalis) and 0.068 (on E. kuehniella) for O. laevigatus, 0.097 (on F. occidentalis) and 0.080 (on E. kuehniella) for O. majusculus, 0.116 (on F. occidentalis) and 0.101 (on E. kuehniella) for O. insidiosus, 0.035 (on F. occidentalis) and −0.003 (on E. kuehniella) for O. niger, respectively. The killrate (km), a parameter that we designed to take into account the age-specific predation both during the nymphal and the adult stages, was calculated in order to compare the predation capacity of the Orius species. The km on the prey species F. occidentalis was 0.23 for O. laevigatus, 0.21 for O. majusculus, 0.25 for O. insidiosus, 0.19 for O. niger, respectively. In all species, the females that fed on E. kuehniella showed greater longevity and higher reproduction than those fed on F. occidentalis. O. niger was the most difficult species to rear, both during immature stages and as adults. O. niger showed a high preimaginal mortality, high consumption of E. kuehniella eggs, low predation of F. occidentalis adults, long development time, low fecundity and low rm on both preys. The development time of O. majusculus and O. laevigatus was similar when feeding on F. occidentalis. The total consumption of E. kuehniella eggs was significantly higher for O. laevigatus. O. majusculus showed a higher fecundity compared to O. laevigatus when fed E. kuehniella eggs, but no differences were recorded when both species were fed F. occidentalis adults. Most data for the neartic O. insidiosus were similar to those of O. laevigatus and O. majusculus. Performance of O. laevigatus was best at 26 °C. A mass-rearing method for O. laevigatus was developed and the main quality control parameters for this species were defined.
One of the main problems in biological control of thrips in the Mediterranean area is that Frankliniella occidentalis (Pergande) does not undergo diapause. Therefore, finding a non-diapausing species or strain of the genus Orius would be very useful for seasonal inoculative releases to control this species of thrips. Both the palearctic O. majusculus (Reuter) and the nearctic O. insidiosus (Say) show a reproductive diapause that is induced by photoperiod. No data were available about the occurrence of diapause in O. laevigatus (Fieber). The possibility of inducing a reproductive diapause in this palearctic species was therefore investigated in the laboratory using two strains: strain N collected in northern Italy (Po Valley; ca. 44° N latitude) and strain S collected in southern Italy (Sicily; ca. 37° N latitude). The influence of photoperiod on eggs at 18±1°C, RH=75±10 nd at several light regimes varying between 16L:8D and 8L:16D (experiment 1) and between 13L:11D and 11L:13D (experiment 2) was studied. O. laevigatus were fed on Ephestia kuehniella (Zeller) frozen eggs. Development time, adult emergence, sex ratio, pre-oviposition period, fecundity up to day 29 of adult life, and the presence of mature oocytes were recorded. Photoperiods of 11.5L:12.5D and 12L:12D induced a longer development time, a longer preoviposition period and a lower oviposition rate than the other photoperiods for both populations. The percentage of egg-laying females at 18°C was higher for strain S (70€than for strain N (44Ž Termination of diapause was investigated by exposing the Orius strains to an higher temperature (26°C) and a longer day-length (16L:8D). The females of both strains supposedly in diapause, rapidly started to lay a high amount of eggs independently from the environmental conditions to which they were previously exposed. Next, the two strains of O. laevigatus were reared at five temperature regimes (24°C/12.5°C; 26°C/15°C; 21.5°C/6°C; 22°C/12.5°C; 18°C constant) that matched the photoperiod which induced the lowest oviposition (11.5L:12.5D ) in the previous experiments. The longest development time was found for both strains at 26.5°C/6°C and the shortest at 26°C/15°C. A constant temperature of 18°C induced a slightly shorter development than the thermoperiod of 26.5°C/6°C in both populations. The lowest fecundity was recorded at 26.5°C/6°C and at 18°C constant for both strains, and 26°C/15°C induced the highest fecundity in the females of strain N. When the females were moved from thermoperiods of 18°C to 26°C and 16L:8D, oviposition did increase, and more than 80 f females of both strains laid eggs. In all the experiments the two strains of O. laevigatus gave different results. Wild populations of O. laevigatus were collected in the field in August-November in Sicily and in the Po Valley and maintained in cages in the field in northern Italy (44° latitude N). During the winter, once a month females were taken from the field cages and put into a climatic chamber at 26±1°C, RH 75±10&Eth;A high percentage of females laid eggs, particularly those of the Sicilian population. In conclusion, the two strains of O. laevigatus have a different way to overwinter: in the northern strain part of the population undergoes a weak reproductive diapause, while for the southern strain overwintering can be better described as quiescence.
Potato growers in the Columbia Basin of Washington and Oregon experienced an outbreak of the potato purple top disease in the 2002 growing season. This outbreak caused significant yield losses and reduced tuber quality. The disease was also observed during ensuing years, especially in potato fields not treated with insecticides. Using polymerase chain reaction, it was determined that the beet leafhopper-transmitted virescence agent (BLTVA) phytoplasma was the causal agent of the disease and that Circulifer tenellus was the major vector of the phytoplasma in this important potato growing region of the United States.
Increased vegetational diversity influences the behaviour of carabid beetles by changing plant-related abiotic factors. These abiotic factors (light, humidity and habitat structure) affect the selection of oviposition sites and egg survival of carabid beetles. In a field experiment, more larvae of Pterostichus melanarius (Illiger) (Coleoptera Carabidae) were caught in Brussels sprout intercropped with barley than in Brussels sprout alone. The influence of the presence of living barley and Brussels sprout plants on oviposition was studied in the laboratory. Also, the effects of wet/dry substrate, light/shadowed and structured/unstructured environment on the number of eggs laid were investigated under laboratory conditions. Results indicate a preference for moist, shadowed, structurally complex environments as egg laying sites. This preference results in significantly higher numbers of eggs laid by beetles in barley compared to Brussels sprout. Vegetation characteristics by themselves may influence egg-laying-site preferences, in addition to the availability of prey for adults and larvae in the different cropping systems. Vegetables intercropped with cereals provide a more favourable microclimate for the reproduction of P. melanarius than vegetables grown alone
As part of a project to evaluate parasitoid species as biological control agents against western flower thrips, Frankliniella occidentalis (Pergande), a survey was made in its native (United States) and newly invaded areas of distribution (Europe). In addition, parasitoids were collected form closely related Frankliniella and Thrips species, either by active search or by correspondence. Two parasitoid species, the eulophids Ceranisus menes (Walker) and Ceranisus americensis (Girault) were collected as female adults and parasitised hosts from wild vegetation and cultured crops, infested with F. occidentalis and related species at several locations in Europe and elsewhere. They were subsequently processed, shipped and reared in the laboratory, together with their thrips hosts. Methods for collecting, processing and shipment of both thrips and parasitoids are described and preliminary rearing results are presented.
Maize redness (MR) causes midrib, leaf and stalk reddening and abnormal ear development in maize in Serbia, Romania and Bulgaria. High populations of the ciixid Reptalus panzeri (Löw) were found in MR affected maize fields in the southern Banat region of Serbia in 2005 and 2006, and stolbur phytoplasma was detected in 20% of the insects. Stolbur phytoplasma was detected in 85% of symptomatic maize from these fields. Typical MR symptoms developed in healthy maize plants exposed to stolbur phytoplasma infected R. panzeri, and these plants were positive for the phytoplasma.
A microarray detecting phytoplasma 16Sr groups -I, -II, -III, -V, -VI, -X and -XII was developed based on probes targeting 16S-23S spacer region. Despite that it is considered as more suitable than 16S rDNA for the fine differentiation of phytoplasmas, the microarray did not demonstrate discriminatory potential higher than the only phytoplasma microarray published so far based on 16S rDNA. Nevertheless the method used was cheaper and faster bringing the microarray towards routine analysis.
Coptotermes, found in urban areas, is regarded as the most abundant building termite pest genus, widely distributed in Vietnam. The objectives of this study were to classify the Coptotermes found in certain provinces in Vietnam and assess the feasibility proposed PCR method by Szalanski et al., 2004 for identification of Coptotermes species. The proposed PCR method distinguishes species by the presence or absence of DNA fragments amplified with universal (LR-J-13007, LR-N-13398) and Coptotermes for-mosanus Shiraki specific (FST-F, FST-R) primer pairs. For this purpose, we collected six Coptotermes samples from five localities in Ha Noi (Van Quan-Ha Dong, Thai Ha-Dong Da, Vong Thi-Tay Ho, Tan Linh-Ba Vi, Bui Xuong Trach-Dong Da) and from Van Lam-Hung Yen province, Vietnam and employed the proposed simple PCR-based diagnosis for Coptotermes species (Szalanski et al., 2004). We amplified the universal 430-bp region from DNA templates of all six individual termite samples and the 151-bp regions of mtDNA 16S rRNA from DNA templates extracted from Tan Linh and Van Quan termites. Appearance of the species specific DNA fragments suggested that two Coptotermes samples can be classified as C. formosanus. However, by comparing the nucleotide sequences of the 430 bps and the 126 bps (eliminating the primer sequences from 151-bp region) with the corresponding sequences from Coptotermes species from GenBank, we found all six samples belonged to Coptotermes gestroi (Wasmann). Thus, in this case, PCR products were obtained employing primers with mismatches to the mtDNA 16S rRNA gene of C. gestroi. Therefore, the nucleotide sequencing is necessary for the identification of Coptotermes species including C. formo-sanus or C. gestroi based on the 430-bp and 151-bp regions of mtDNA 16S rRNA gene.
The usefulness of RFLP analyses on a 435 bp fragment of the tuf gene for preliminary identification of phytoplasmas from a number of phytoplasma ribosomal groups and/or 'Candidatus Phytoplasma' was verified. The strains employed belong to thirteen 16Sr DNA groups and 22 different subgroups and were obtained from both experimentally and naturally infected plants. The combined RFLP patterns obtained with the three restriction enzymes employed allow the distinction of a total of 18 different pro-files, however no discrimination was provided for some of the ribosomal groups for which sequencing remains the main tool for phytoplasma identification.
A phytoplasma strain belonging to group 16SrI, subgroup B ('Candidatus Phytoplasma asteris'), the most widely spread phyto-plasma worldwide, was detected in diseased larch (Larix sp.) in Ukraine. Detection, identification, and classification of the larch infecting phytoplasma were accomplished through RFLP and sequence analysis of 16S rRNA and ribosomal protein (rp) gene sequences amplified in polymerase chain reactions. The larch infecting phytoplasma was named larch dwarfed needle prolifera-tion (LDNP) phytoplasma. The findings revealed Larix as a previously unknown host of phytoplasma and indicated that 'Ca. P. asteris' is capable of infecting a gymnosperm, while raising questions concerning the identity of possible insect vector(s) involved in transmission of 'Ca. P. asteris' to larch and perhaps to other gymnosperms.
A Ribes rubrum plant showing malformation and twisting of branches was found in a private garden in South Bohemia. Observa-tion of ultrathin sections of tissues from symptomatic shoots revealed the presence of phytoplasma-like bodies. Different primer sets were used for amplification of the 16S-23S ribosomal gene segment. RFLP analysis and sequencing for phytoplasma identifi-cation classified the detected phytoplasma in the aster yellows group, subgroup 16SrI-C. Successful transmission of detected phy-toplasma by dodder (Cuscuta campestris Yuncker) to periwinkle (Catharanthus roseus L.) was confirmed by detection of numer-ous phytoplasma bodies in ultrathin sections of C. roseus and by PCR from dodder and periwinkle. RFLP analyses of PCR prod-ucts as well as nucleotide sequences of the currant plant and symptomatic periwinkles were identical. Sequenced data obtained from both currant and indicator plant, were aligned and sequences of 1,613 bp were found to be identical. Transmissions of phy-toplasma by grafting to healthy currant rootstocks were unsuccessful.
During surveys, papaya plants showing dieback symptoms with yellowing and necrosis of leaves were collected from the Sugarcane Research Station campus, Gorakhpur, Eastern Uttar Pradesh, India in September 2010. DNA was extracted from infected and healthy plants and indexed in nested PCR with phytoplasma generic primers P1/P7 and R16F2n/R16R2. Nested PCR amplicons of 1.2 kbp were obtained from dieback symptomatic papaya samples. Following RFLP analysis, infected papaya samples exhibited identical HaeIII and RsaI profiles, which were typical of a 16SrII phytoplasma. None of the healthy papaya samples evaluated was found positive for the phytoplasmas. The amplification with phytoplasma primers and their RFLP profiling suggests that the dieback phytoplasma associated with papaya in India is a phytoplasma member of the 16SrII group ('Candidatus phytoplasma aurantifolia'). This is the first record of this phytoplasma associated with dieback disease of papaya in India.
Chenopodium album L. plants showing symptoms of leaf yellowing, small leaves development, proliferation, plant and inflores-cence stunting were examined for phytoplasma infection using PCR with universal phytoplasma primers R16F1/R0 and fU5/rU3. Only in two samples out of the 38 tested, the phytoplasma infection was confirmed. RLFP and sequence analyses based on partial 16S rDNA fragment confirmed that C. album is harbouring phytoplasmas belonging to 16SrIII (X-disease) group. This species has been also found infected with phytoplasmas belonging to 16SrXII group in Czech Republic.
Diseased plants of family Poaceae (Gramineae) were observed in cereal crop and forage feed plant fields in the Vilnius, K dainiai and Raseiniai regions of Lithuania. Disease symptoms included yellowing of leaves and spikes, general stunting, sterility and deformation of spikes, dwarfed spikes, and twisted awns, indicating possible phytoplasmal infections. A phytoplasma-characteristic fragment of 16S rDNA was amplified from all the symptomatic plants that were tested in nested polymerase chain reaction (PCR), using phytoplasma-specific primers. RFLP analysis of the amplified 16S rDNA indicated that detected phytoplasmas infecting gramineous plants in Lithuania belong to several different subgroups in group 16SrI (aster yellows phytoplasma group): 16SrI-A (in Avena sativa); 16SrI-B (in A. sativa, Hordeum vulgare, Triticosecale and Bromopsis inermis); 16SrI-L (in A. sativa and Lolium multiflorum) and 16SrI-C (in Poa pratensis and Festuca arundinaceae).
A severe disease was observed in the potato variety 'Criolla Colombiana'. Main symptomatology consisted of discoloration or yellowing of the whole plant, apical leafroll, dwarfing, axillary buds and thicker internodes. Phytoplasmas related to 16SrV and 16SrXII groups were identified by nested PCR assays followed by real and virtual RFLP and sequence analyses. This is the first report of phytoplasma presence in potato in Colombia and the first identification of group 16SrV phytoplasmas in this crop.
In order to evaluate the risk represented by the wild reservoir as a possible source of 'flavescence dorée' outbreaks in Hungary, diverse wild perennial plants growing in vineyard areas were tested for the presence of 16SrV-C and D subgroup phytoplasmas. 16SrV phytoplasmas were detected by nested PCR-RFLP on the 16SrDNA in alders (86% infected) and in clematis (71% infected). Further characterisation by sequencing of the map gene revealed in both plants strains having the same map gene sequence as 'flavescence dorée' strains.
Phytoplasmas are responsible for a range of diseases in the Gramineae in Sub-Saharan Africa and Asia including sugarcane grassy shoot (white leaf), rice yellow dwarf, napier grass stunt and Bermuda grass white leaf. In previous work, we have designed uni-versal nested PCR primers based on the secA gene for amplification of DNA from phytoplasmas in most 16Sr groups. However, these primers did not appear to work well on phytoplasmas in the 16SrXI and XIV groups. In this work, we have designed spe-cific sets of primers based on the secA gene that can be used in a nested PCR assay to amplify either the napier grass stunt phyto-plasma or the sugarcane phytoplasma or the rice/bermudagrass phytoplasmas. These assays and secA sequences have also been used to redefine the taxonomic relationships between these phytoplasmas.
The suitability of a light trap (from 1999 to 2016), and pheromone traps and pheromone + phenylacetaldehyde (PAA) baited traps (from 2010 to 2012), in the monitoring of European corn borer (ECB), Ostrinia nubilalis (Hubner), moth flights in Slovenian hop gardens was studied. In 18 years light trap collected a total of 13381 specimens (with an average of 743 specimens per year), the number of ECB varied from a minimum of 184 specimens in 2014 to a maximum of 2060 specimens collected during 2003. From 2010 to 2016, of the 5327 specimens captured, 3778 were males (70.70%) and 1566 were females (29.30%). In general, during the ECB first annual fly the captured moths increased after the third week of May, with a peak on 10 June; between the last week of June and the second week of August, the ECB second fly can be observed with a peak during the last week of July; third annual fly was revealed from last week of August to last week of September with a peak of adults at the end of August. Pheromone and pheromone + PAA traps (wing sticky and mesh netting cone models) demonstrated low suitability for capturing ECB males and females. Adult trapped by light trap and pheromone and pheromone + PAA traps, respectively, displayed similar pattern. Average daily temperature and precipitation level influenced the flight patterns of ECB moths. ECB field infestations in hop gardens could be surveyed by counting egg masses on plants and observing signs of early damages by first-instar larvae. Monitoring of moth flights by means of easily handled pheromone traps provides valuable information.
The activity of eleven enzymes involved in development, ageing and in metabolism of xenobiotics in insects, was investigated under the influence of 2,4-D (2,4-Dichlorophenoxyacetic acid), in the mustard aphid, Lipaphis erysimi (Kaltenbach) (Rhynchota Aphididae), after treating the 2nd instar nymphs for 13, 25 and 37 h. Studies of two hydrolases and one group transfer enzyme revealed significant effects of 2,4-D on the activity of these enzymes. The activity of esterases and glutathione S-transferases increased and that of ATPase decreased with the treatment. Observations on the activity of eight oxidoreductases revealed a significant induction in superoxide dismutase and catalase activity and no effect on the activity of NADH dehydrogenase, NADH oxidase, glutathione reductase and glutathione peroxidase, and a significant reduction in the activity of O-demethylase and succinate dehydrogenase. It was concluded that the increase in activity of esterases, glutathione S-transferases, superoxide dismutase and catalase might be due to their involvement in the metabolism and degradation of 2,4-D.
We investigated the biology of Idaea inquinata (Scopoli) (Lepidoptera Geometridae), the rusty wave moth, to determine the number and duration of larval instars and the duration of the pupal stage. The study was conducted at 21, 26, 29, and 34 ± 1 °C; for each temperature tests were conducted at 35 and 70 ± 5% relative humidity (RH), with a photoperiod of 16:8 (light:dark). At 35% RH, five larval instars were observed at 26, 29, and 34 °C, whereas eight instars were found at 21 °C. At 21 °C and 70% RH, only one larva pupated after the fifth instar, two completed the sixth instar and one reached the seventh instar. At 21 °C and 35% RH an increase of mortality and in the number of larval instars was observed; the few larvae that reached the tenth instar did not survive. The shortest larval developmental periods were observed at 26 and 29 °C at 70% RH and were 31.9 ± 2.26 and 30.6 ± 3.12 days respectively. The longest developmental period was recorded at 21 °C and 35% RH, and was 172.5 ± 16.26 days. The pupal stage was longer at 21 °C at 35 and 70% RH, and lasted 22.5 ± 2.12 and 22 ± 3.65 days respectively. In all other conditions, the pupal periods lasted from 9 to 10 days. The highest adult emergence was observed at 26 and 29 °C at 70% RH and corresponded to 90% and 83% respectively. I. inquinata did not complete development at 34 °C and 35% RH. At 34 °C and 70% RH, only 13% of the specimens reached the adult stage. At 26 °C and 35% RH there was 66% adult emergence but this declined to 30% at 29°C and 35% RH. Percentage of adult emergence at 21 °C and 35% and 70% RH were 6 and 13% respectively. Considering the reduction in adult emergence at 21 °C, we recommend that a temperature of 18° C is maintained in air conditioned warehouses for the storage of dried medicinal plants to prevent I. inquinata infestations.
Agathis fuscipennis (Zetterstedt) (Hymenoptera Braconidae) was collected for the first time from larvae of the tomato leafminer Tuta absoluta (Meyrick) (Lepidoptera Gelechiidae) infesting Solanum nigrum (L.) plants in Tuscany (Central Italy). The knowledge about this parasitoid is still scarce. Its role in the biological or integrated control of T. Absoluta remains to be evaluated.
The genus Orius Wolff includes generalist predators revealed to be very effective in thrips control worldwide. During the years 2005-2007, Orius species were sampled on some horticultural crops (strawberry, sweet leek, and sweet pepper), and on wild flora surrounding crops to identify alternative host plants in Piedmont, northwestern Italy. In the three-year survey, Orius horvathi (Reuter), Orius laevigatus (Fieber), Orius majusculus (Reuter), Orius minutus (L.), Orius niger Wolff, and Orius vicinus (Ribaut) were collected on crop and non-crop plants in the surveyed area. On pepper, the major number of species was recorded, depending on environmental and cultivation conditions. O. niger was the predominant species on strawberries and wild flora, while O. majusculus was the primary species on sweet leek. By contrast, O. laevigatus was never found on the crops, and rarely collected on wild flora in the areas where it has been usually released. On the wild flora larger amounts of Orius were sampled on Galeopsis tetrahit L., Medicago sativa L., Malva sylvestris L., Matricaria chamomilla L., Urtica dioica L., Carduus sp., Lythrum salicaria L., Erigeron annuus L., and Trifolium pratense L., which proved to be important sites for population development and overwintering. The conservation of plant biodiversity as a whole in and near agro-ecosystems is the most reliable way to achieve beneficial insect populations for an effective crop control.
The European tarnished plant bug Lygus rugulipennis Poppius and the alfalfa plant bug Adelphocoris lineolatus (Goeze) (Rhyn-chota Miridae) are widespread in Italy and in many other European countries, where they are often noxious to several crops. Since the chemical control of these plant bugs is difficult, a three-year study was carried out in Piedmont (NW-Italy), to assess the pres-ence of nymphal parasitoids, and evaluate their efficacy in controlling pest infestations. From May to September in 2001, 2002 and 2003, plant bug populations were sampled on different crops (alfalfa, meadow habitat, peach orchard groundcover, straw-berry, sunflower, wheat). Overall 4092 and 1529 nymphs of L. rugulipennis and of A. lineolatus, respectively, were field-collected and reared in the laboratory to allow parasitoid development. Parasitism levels varied in relation to the year and the crop, but it was generally lower than 10%; higher percentages, between 10 and 30%, were found for L. rugulipennis nymphs collected on al-falfa, meadow habitat and wheat. Peristenus digoneutis Loan (86.0%) and Peristenus relictus (Ruthe) (9.9%) (Hymenoptera Bra-conidae) emerged from parasitized plant bug nymphs. In the surveyed agroecosystems P. digoneutis completed three generations as did its host L. rugulipennis: after overwintering in the cocoons in the soil, adults emerged in late March. In spring they attacked plant bug nymphs mainly on winter cereals; adults of the new generation emerged in late May-early June, and migrated to other plants in search of hosts. Subsequent adult emergences overlapped over the summer.
The use of sex pheromones as an option to control wireworms via mass trapping and the biology of Agriotes lineatus (L.) were investigated in a long-term field experiment at an organic research farm in North Rhine-Westphalia, Germany. Plots supplied with sex pheromone traps were compared with untreated control plots. Over 5 years, a total of 12,378 male adults of A. lineatus, Agriotes obscurus (L.) and Agriotes sputator (L.) were captured in six traps located at 40 m distance in a grass-clover ley. The swarming period of the males lasted from late April to late August with one major and a small peak in the successive years for all three species. During 2006 and 2008 A. lineatus was the dominant species trapped with 4,005 male adults followed by A. obscurus (3,045) and A. sputator (1,213). The total number of wireworms captured over all sampling dates only slightly differed between the two pheromone treated plots (201 individuals) and the two control plots (230 individuals) suggesting no effect of mass trapping on wireworm abundance. The peak oviposition period of A. lineatus lasted from May to early June. Over a 30 month period the larvae passed through 8 instar stages (life cycle not completed) and attaining L4 instar stage before the first and L8 before the second overwintering. Non-chemical wireworm control will have to focus on cultural approaches including soil tillage and rotation design taking data on biology into account.
Availability of mulberry leaf of high nutritional quality, under temperate climatic conditions, is restricted to the spring-summer season, a situation that represents a limiting factor in selecting Bombyx mori L. strains. Therefore, we coupled traditional rearing on mulberry leaf (the natural food of the monophagous silkworm) with rearing on an artificial diet, therefore obtaining increased larval efficiency in converting food and high silk production. Nineteen nutritional indexes were recorded on both foods by using the gravimetric method, and a computer-assisted calculation. Results suggest that this strategy can be used to select highly performing strains adapted to both foods and that selection on artificial diet indirectly ameliorates food conversion efficiency by larvae. Obtained pure lines can also be used to produce hybrids suitable for rearing on both leaves and diet.
The location, acceptance and suitability of the phytophagous Spodoptera littoralis (Boisduval) by the tachinid larval parasitoid Exorista larvarum (L.) was studied in the laboratory. A test was conducted in a cage environment to assess whether E. larvarum displays a difference in locating and accepting the laboratory host Galleria mellonella (L.) vs. S. littoralis and whether the host plant plays a role in host location by the parasitoid. Inexperienced E. larvarum females were similarly attracted to, and accepted, G. mellonella and S. littoralis larvae, but weakly responded to S. littoralis larvae feeding on a bean leaf. Since the latter were ap-parently less mobile compared to the other two targets, the results may support the hypothesis that, at close range, tachinid fe-males use visual cues and, in particular, motion signals in host location. Host acceptance and suitability of S. littoralis vs. G. mel-lonella by E. larvarum were then further compared. Based on the time needed to obtain the oviposition of 4-6 eggs per larva, ac-ceptance was not significantly different between the two host species. Puparia were however obtained from 1.3% of S. littoralis larvae vs. 75% of G. mellonella larvae. Despite the low successful parasitization, in parasitized S. littoralis larvae mortality was higher compared to control (unparasitized) larvae. This result suggests that E. larvarum may be a candidate for biological control of S. littoralis.
Phytoplasmas are cell wall-less bacteria that cause numerous diseases in diverse crops worldwide. Phytoplasma-infected plants often exhibit symptoms suggestive of hormone disorders. Indole-3-acetic acid (IAA), a naturally-occurring auxin, is involved in multiple essential plant growth and developmental processes. It has been shown that exogenous application of IAA can effectively remit symptoms caused by phytoplasma infections. The present study was designed to learn whether exogenously applied IAA would modify phytoplasma-induced changes in host gene expression profiles at the protein level and to understand the role of IAA in phytoplasma pathogenesis.
This paper compares the development of the polyphagous aphid Myzus persicae Sulzer, considered as a generalist, and the oligo-phagous aphid Macrosiphoniella millefolii (De Geer), considered as a specialist, on yarrow (Achillea collina Becker ex Reichen-bach). Yarrow is a medicinal plant rich in bioactive secondary metabolites that have possible effects on the development of phy-tophages, including aphids. Age specific life tables for cohorts developing under different constant temperatures were constructed and analyzed using standard techniques, and complemented with Jackknife estimates of the intrinsic rate of increase and its stan-dard error. The parthenogenetic wingless morphs of the two species differed in the immature developmental time and survival, and in adult fecundity and life span. At high temperatures, the intrinsic rate of increase as the overall metric of performance tended to be higher for the generalist than for the specialist aphid species, while the opposite appears to occur at low and medium temperatures. Further insight into the complex interactions between yarrow and aphids requires that their genetic diversity is taken into account. The study of yarrow-aphid-natural enemy population interactions requires additional information on biomass dy-namics, aphid morph differentiation and the performance of biological control agents.
As an environmentally compatible alternative to the use of conventional insecticides to control cereal aphids, the possibility of exploiting natural resistance to insect pests in wheat species was investigated. Previous work, comparing the antibiotic and antixenotic effects of hexaploid wheat (Triticum aestivum, AABBDD), tetraploid wheat (Triticum durum, AABB) and some A genome diploid species on the bird cherry-oat aphid, Rhopalosiphum padi L., found little difference between accessions in the higher ploidy plants, but the diploid species contained attributes that could be important in the breeding for resistance against aphids in the future. This study concentrated on wild accessions of diploid Aegilops species to which the closest ancestor of the B genome donor of hexaploid wheat belongs. The aphid R. padi showed reduced attraction and an increase in the intrinsic rate of population growth on the B genome species tested by compared to the hexaploid control. Investigation of a group of secondary metabolites, the hydroxamic acids or benzoxazinones showed that leaf tissue of one of these (Aegilops speltoides) contains high levels of DIMBOA-glucoside and of the main aglucone, 2,4-dihidroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) while no hydroxamic acids were found in the leaf tissue of Ae. longissima, Ae. bicornis and Ae. sharonensis and only trace levels in Ae. searsii. In those species, an unknown compound was present, which may have an effect on aphid behaviour. The effect of aphid feeding on levels of hydroxamic acids in Ae. speltoides and Ae. sharonensis was also examined. While a localised defence reaction to aphid feeding had been identified in the hexaploid and tetraploid species, a more systemic effect was observed in the diploid Ae. speltoides.
In Actias selene (Hubner) (Lepidoptera Saturniidae) there is at least one female specific protein limited to the fat body. Sodium do-decyl sulfate polyacrylamide gel electrophoresis performed on the fat body proteins from male and female pupas of A. selene and a female-specific protein with a molecular weight of about 24 kDa was revealed. This protein was purified for determination of the N-terminal amino acid sequence. Conventional polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE) PCR were also carried out to clone the cDNA encoding 24 kDa protein (As-24K) based on the amino acid residues. The As-24K cDNA consists of 832 bp and the amino acid sequence shares 71% similarity with the 24 kDa proteins from Antheraea pernyi (Guerin-Meneville) and Antheraea yamamai (Guerin-Meneville) (Lepidoptera Saturniidae). In female pupa western blotting using antiserum against As-24K revealed that 24 kDa protein was restricted to the fat body. It was not found in any other pupal tissues.
The repellent and fumigant activities plant essential oils of Eucalyptus globulus Labill. and Artemisia carvifolia Buch. Ham. ex Roxb. on red imported fire ants (RIFAs) Solenopsis invicta Buren (Hymenoptera Formicidae) were evaluated by using digging bioassay and feeding/climbing behavior tests. Oil of Eucalyptus and Artemisia (mugwort) showed significant repellency at 100 mg/kg. However, slight digging facilitation was observed at 1 mg/kg. The attack and feeding rates of RIFAs on Tenebrio molitor L. (Co-leoptera Tenebrionidae) daubed with 5 μl of the two essential oils were evaluated. Eucalyptus oil showed a complete repellent effect and prevented RIFA attacks on T. molitor. The time for complete repellency was 16 h. Mugwort oil showed weaker results than Eucalyptus oil. The feeding ability of RIFAs treated with the two essential oils decreased. The feeding, attack, and climbing rates of RIFA were observed 30 min after fumigation with the essential oils. Eucalyptus oil showed a greater effect on the climbing rate of RIFAs than mugwort oil. The feeding and attack rates after fumigation with the two essential oils were significantly lower than the control. Eucalyptus and mugwort oils could be used as alternatives to commercial repellents and fumigants.
The effect of some species of family Fabaceae plants on the non-enzymatic and enzymatic antioxidants of the pea aphid, Acyrtho-siphon pisum (Harris) has been studied. The highest concentration of ascorbate was noted for aphids fed on Pisum sativum L.. The content of another non-enzymatic antioxidant, GSH, was the highest within the tissues of the morphs fed on Vicia faba L.. The aphids reared on this host plant had 3-fold higher activity of the antioxidant enzymes than the ones fed on Pisum sativum L. and Vicia sativa L.. The influences of the host plants on antioxidant defence mechanisms within the pea aphid species are discussed.
In this comprehensive paper the importance of species is emphasized. It is demonstrated that careful biosystematic studies on the two species of the genus Philaenus known until recently, increased the number of species up to eight so far. These discoveries appear to be fundamental in explaining the expression, role, and evolution of polymorphism in this genus.
Witches' broom disease of lime (WBDL) associated with 'Candidatus Phytoplasma aurantifolia' presence, is responsible for ma-jor losses of Mexican lime trees (Citrus aurantifolia L.). Iranian witches' broom disease of lime Network (IWBDLN) comprises of 10 mega projectswhich have been carried out since 2008 with the contribution of 15 different national institutes. Here, we will present the program and the results obtained and demonstrate how this program could contribute in controlling this destructive agent of WBDL. Furthermore, we will demonstrate how our genomics, transcriptomics, epigenomics, proteomics and metabolom-ics analyses of lime infected by witches' broom disease provided new insight into plant stress tolerance mechanisms. Several strategies to maximize the success of our program in controlling the disease will be presented.
Using sex pheromone traps baited with 1 mg of Z, E-7-11-hexadecadien-1-yl acetate (or HDA), observations of male adult presence and dispersion of the Angoumois grain moth, Sitotroga cerealella (Olivier) (Lepidoptera Gelechiidae), in warehouse and in field-plots were carried out. The studies were realised during 2012 and 2013 in a conventional small-farm of 10.5 ha located in hilly areas of Benevento, Campania region, Central-Southern Italy. The farm was divided into plots as follows: nursery truffle plants, vineyard, spring wheat, clover, oak grove, corn, tobacco, oats, barley, and olive grove. According to the results, infestations of S. cerealella occurred during both preharvest plantation and postharvest storage. The field occurrence showed various levels of presence, with different insect abundances in the plots. The highest numbers of males were trapped in the warehouse in which different cereals are stored all year long. S. cerealella activity suggests adult dispersal from the warehouse to field-plots during the spring-summer season up to 600 meters from the warehouse. The activity of S. cerealella in the Southern-Central Italy agricultural territory is mainly affected by the presence of small traditional warehouses. The crop succession in the fields does not seem to be very important for the presence and dispersion of the moth. Copyright 2015, Universita degli Studi di Bologna, Department of Agroenvironmental Sciences and Technologies, All Rights Reserved.
Exorista larvarum (L.) (Diptera Tachinidae) is a polyphagous larval parasitoid of lepidopterans, including forest defoliators. Laboratory studies were conducted to investigate the side effects on adult parasitoid longevity and parasitization capacity of con-ventional and transgenic Bacillus thuringiensis galleriae (Btg) toxins, active against the pine processionary moth Thaumetopoea pityocampa (Denis et Schiffermuller) and the wax moth Galleria mellonella (L.). The flies were fed on lump sugar soaked with the bacterial suspensions and were thus treated by direct ingestion. In a first experiment, the Cry9Aa entomocidal toxin from Btg was administered at 3-times the dose to which the target lepidopterous species previously proved to be highly susceptible. E. lar-varum male and female longevity from emergence and parasitization capacity (expressed as eggs/female laid on G. mellonella larvae and percentages of eggs which gave puparia) were not significantly affected by the treatment with the Cry9Aa toxin com-pared to the commercial Bt preparation Foray 48B or to distilled water (control). No significant differences were also found be-tween the two controls. In a second experiment, adult longevity and parasitization capacity were not significantly affected by the treatment with a suspension of the epiphytic bacterium Pseudomonas Clb01 carrying the cry9Aa Btg gene compared to wild type Pseudomonas or distilled water. These results indicate that E. larvarum adults were not affected either by the conventional or transgenic Btg Cry9Aa toxin according to the parameters and under the conditions tested. To complement this study, future inves-tigations will have to be performed in a more realistic scenario than in a laboratory situation.