Host Plant Characteristics Research Articles

Structure Analysis of Arbuscular Mycorrhizal in Roots from Different Shrubs in Karst Regions

To explore if there are species-preferential characteristics of arbuscular mycorrhizal (AM) and host plants in karst regions, 13 shrub plants (including leguminosae and non-leguminosae) were selected to study the AM community structure of root samples. The soil nutrients in rhizosphere soils significantly differ among shrubs; they are higher in leguminosae than in non-leguminosae. Cluster analysis shows that all 13 shrubs can be infected by AM. Significant differences of the AM community structure were observed among root samples from different shrubs, especially leguminosae and non-leguminosae. Redundancy analysis shows that soil Olsen-P, pH, and total nitrogen significantly influence the AM community structure of plant roots, although the factors affecting this fungus in leguminosae and non-leguminosae differ. These results indicate species-preferential characteristics of AM and host plants in karst regions, especially of the plant function group compared with plant species, suggesting that these characteristics should be taken into account when AM fungi are used for vegetation restoration in karst regions.

Host range expansion may provide enemy free space for the highly invasive emerald ash borer

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an aggressive invader from Asia that has killed millions of trees in North America, causing substantial ecosystem effects and economic losses. All North American ash, Fraxinus spp., are thought to be susceptible, but recently emerald ash borer has been documented developing in a novel host, white fringetree, Chionanthus virginicus. We evaluated larval performance in two common ash species and white fringetree by infesting bolts with emerald ash borer eggs. In addition we evaluated cambial nitrogen, carbon, carbon:nitrogen, stem density, and response to artificial wounding, to determine which host plant characteristics most influence larval development. We also conducted choice and no choice assays using the classical biological control agent, Tetrastichus planipennisi Yang (Hymenoptera: Eulophidae), to assess its ability to locate larval emerald ash borer in the different host plants. We found significantly lower survival rates of emerald ash borer larvae in white fringetree compared to white ash, F. americana. Larval phloem consumption and larval growth were lower in fringetree than in either white or blue ash, F. quadrangulata. Carbon content and density were greater in fringetree than in either ash species. Response to wounding, measured by callus tissue formation, was greatest in white ash. In choice assays, T. planipennisi only parasitized emerald ash borer larvae in ash bolts, and in no-choice tests failed to parasitize larvae in fringetree. Our findings corroborate studies showing that fringetree is a suitable host for emerald ash borer larvae. Failure of T. planipennisi to parasitize larvae within fringetree has implications for the efficacy of this classical biological control agent in regulating emerald ash borer populations. Coupled with the use of white fringetree as a reservoir host, the enemy free space provided to emerald ash borer through use of this alternate host may have significant repercussions for emerald ash borer invasion dynamics.

Scale-dependent resource use in the Euphydryas aurinia complex

Butterflies of the European Euphydryas aurinia complex include a series of taxa, showing morphological and eco-ethological differences. All of them are threatened by changes in land use affecting both the structural and functional connectivity of habitat patches, as well as habitat quality. In this framework, we analysed the use of resources by two of the three taxa occurring in Italy, E. (a.) glaciegenita (Alpine) and E. (a.) provincialis (Mediterranean), at ‘landscape’, ‘patch’ and ‘microhabitat’ scale. We collected data on spatial distribution of adults by Mark-Release-Recapture to understand which parameters affect adult distributions at landscape scale and to test the degree of adult aggregation at patch scale. We sampled first instar larvae within fixed plots and compared the microhabitat characteristics of occupied vs. unoccupied host plants. We found that both populations were affected by management at landscape scale, with contrasting patterns depending on both sites and sex. The food plants were not a limiting factor for adult distribution, probably because they were abundant in the study areas. Within patches, males of E. (a.) glaciegenita showed aggregate distributions in comparison to those of E. (a.) provincialis, suggesting the existence of a “lek strategy”. At microhabitat scale, we observed that females carefully chose their egg-laying sites according to host plant density and microclimatic cues, even though selection was driven by distinct factors in the two populations. Understanding the ecological requirements of all life stages is essential to develop appropriate conservation strategies to preserve butterflies of the E. aurinia complex in Italy.

Instar‐specific effects of host plants on survival of endangered butterfly larvae

1. Outcomes for butterfly conservation can hinge on interactions with host plants during early larval instars. Ontogenetic changes in larvae may cause predictors of survival to shift quickly over time.2. Survival from instar to instar was measured for an endangered oligophagous butterfly,Euphydryas edithassp.taylori(Taylor's checkerspot), which was experimentally released in the field on three host plants:Castilleja levisecta,Castilleja hispida, andPlantago lanceolata. Survival rates were quantified, from hatching to the second instar, from the second to the third instar, and from the third to the fourth instar.3. This study tested whether host plant characteristics (degree of senescence and anthocyanin pigmentation) affected survival during each instar; the effects of oviposition timing and larval group size on survival were also tested, as these vary by group and could affect outcomes for larvae differently on different hosts.4. Survival rates depended on the host species being consumed, mostly because of a disparity in survival during the transition from the second to the third instar. Survival was lowest onC. levisecta, intermediate onC. hispida, and highest onP. lanceolata.5. Plant senescence, oviposition timing, and group size were predictors of survival, but their relevance depended on both the host plant being used and the instar being considered.6. Host plant suitability can vary strongly both within and among species, changing quickly with caterpillar ontogeny during early instars.

Alternanthera mosaic potexvirus: Several Features, Properties, and Application.

Alternanthera mosaic virus (AltMV) is a typical member of the Potexvirus genus in its morphology and genome structure; still it exhibits a number of unique features. They allow this virus to be considered a promising object for biotechnology. Virions and virus-like particles (VLPs) of AltMV are stable in a wide range of conditions, including sera of laboratory animals. AltMV VLPs can assemble at various pH and ionic strengths. Furthermore, AltMV virions and VLPs demonstrate high immunogenicity, enhancing the immune response to the target antigen thus offering the possibility of being used as potential adjuvants. Recently, for the first time for plant viruses, we showed the structural difference between morphologically similar viral and virus-like particles on AltMV virions and VLPs. In this review, we discuss the features of AltMV virions, AltMV VLP assembly, and their structure and properties, as well as the characteristics of AltMV isolates, host plants, infection symptoms, AltMV isolation and purification, genome structure, viral proteins, and AltMV-based vectors.

Persisting responses of salt marsh fungal communities to the Deepwater Horizon oil spill

The plant microbiome, composed of diverse interacting microorganisms, is thought to undergird host integrity and well-being. Though it is well understood that environmental perturbations like oil pollution can alter the diversity and composition of microbiomes, remarkably little is known about how disturbance alters plant-fungal associations. Using Next-Generation sequencing of the 18S rDNA internal transcribed spacer (ITS1) region, we examined outcomes of enduring oil exposure on aboveground leaf and belowground endophytic root and rhizosphere fungal communities of Spartina alterniflora, a highly valued ecosystem engineer in southeastern Louisiana marshes affected by the 2010 Deepwater Horizon accident. We found that aboveground foliar fungal communities exhibited site-dependent compositional turnover with consequent loss in diversity according to oiling history. Rhizosphere soil communities also exhibited shifts in community composition associated with oiling history, whereas root endophytic communities did not. Oiling did not increase or decrease similarities among aboveground and belowground communities within an individual host, indicating that host plant characteristics exert stronger control than external factors on fungal community composition. These results show that fungal community responses to oiling vary within tissues of the same host plant, and that differences in the local environment, or alternatively, site-specific differences in residual oil constrain the magnitude of exposure responses. Our study offers novel perspectives on how environmental contaminants and perturbations can influence plant microbiomes, highlighting the importance of assessing long-term ecological outcomes of oil pollution to better understand how shifts in microbial communities influence plant performance and ecosystem function. Our findings are relevant to coastal management programs tasked with responding to oil spills and increasing pressures arising from intensifying development and climate change. Understanding how modification of plant-microbiome associations influences plant performance, particularly of ecosystem engineers like S. alterniflora, can help guide efforts to protect and restore at-risk coastal ecosystems.

Herbivore regulation in urban agroecosystems: Direct and indirect effects

Urban agroecosystems can provide habitat for biodiversity and can benefit human communities through urban food provisioning. Moreover, urban agroecosystems could be managed so as to optimize ecosystem services like natural pest control provided by trophic interactions between natural enemies and herbivores. As in other ecosystems, predation and parasitism regulate herbivores in urban settings, but less is known about the relative importance of direct and indirect effects at local and landscape scales in highly managed urban agroecosystems. We collected data on herbivore (cabbage aphid) density and parasitism ratios (proportion of parasitized aphid “mummies”) in 25 community gardens in three counties in the California central coast, USA. We used structural equation modeling to examine the effects of direct factors (host plant characteristics and parasitism) and indirect factors (soil, garden, and landscape characteristics) on herbivore density changes at two time points in the growing season (June and August). Aphid density, but not parasitism, varied across counties over the season, and there was a strong negative relationship between aphid density and parasitism. Direct effects were strong drivers of aphid density but not parasitism. In June, aphid density increased with host plant volume but decreased with greater floral density, while parasitism was only influenced by aphid density. In August, host plant volume similarly positively affected aphid density, and soil water holding capacity increased host plant volume. In addition, host plant density had a strong negative effect on parasitism. Urban gardeners may be able to reduce aphid pest densities by increasing floral resource density and strategically spatially distributing host plants throughout garden beds, though these processes depend on the season. The indirect effects of soil water holding capacity on aphid densities further suggest a critical role of human management on pest populations and pest control services through soil amendments and irrigation.

Insect herbivory patterns in late Eocene coastal lowland riparian associations from central Germany

The study comprises a first detailed analysis of insect herbivory patterns in a Paleogene megaflora from the central German Leipzig Embayment (former Weißelster Basin). The compression plant assemblage comes from the upper Eocene (upper Bartonian or lower Priabonian) Luckenau Clay Complex (lignite-bearing Borna Formation) that represents sediments of a coastal alluvial braidplain. In total 26 insect damage types (DT's) were distinguished on 1588 fossil leaves resulting in a damage frequency of 6.1%. Overall 18 of 36 dicotyledonous angiosperm taxa provided evidence for an associated insect herbivore fauna. Particular statements about insect folivory are restricted to evergreen taxa, which provided a sufficient number of leaves. The overall highest diversity and frequency of DT's was detected on Sloanea nimrodi (Elaeocarpaceae). Based on the abundance and distribution of functional feeding groups (FFG's) the diversity of insects herbivores as well as specific host plant characteristics such as plant defense strategies and leaf morphology are discussed. Hence, the study provides key information on the ecology of feeding associations and the linkage between plants and their insect herbivores for a lowland riparian forest ecosystem. Furthermore, the investigation of the “kaolinite-enriched” Luckenau Clay Complex yields important insights in syn- and postdepositional processes and landscape evolution.

Host plant preference in the protected myrmecophilous Transylvanian Blue (Pseudophilotes bavius hungarica) butterfly (Lepidoptera: Lycaenidae) and its relationship with potential ant partners

When selecting specific host plants, caterpillars of many lycaenid butterflies, such as the protected Pseudophilotes bavius hungarica, are known to engage in various interactions with ants, which help them survive. Although P. bavius is a protected species, data about its host plant selection is very scarce, and little information is available on its myrmecophilous relationships. Our aim was to identify the host plant characteristics that determine the occurrence of the caterpillar and to clarify the specificity of its myrmecophily. We conducted a series of field surveys regarding host plant characteristics. Laboratory experiments were carried out to investigate the nature of interactions between the caterpillar and its potential ant partners. Control experiments involving non-visiting ants were also performed. On the basis of our findings, the physical characteristics of host plants do not seem to influence host plant choice, but the absence of aphids and the presence of different ant species proved important. According to the results of behavioural assays, neutral reactions to the caterpillars were recorded in the case of ant species that regularly visited the host plant (Lasius paralienus, Camponotus aethiops), in contrast to Tapinoma subboreale, which was not observed at all on the host plants and which behaved aggressively towards the larvae. Therefore, the caterpillar is expected to show a certain ant host selectivity. The study constitutes an essential contribution to our knowledge of the natural history of a protected butterfly species, which can be used as a basis for more appropriate management strategies, while also shedding light on aspects of myrmecophilous relationships in Lycaenidae in general.

Reproductive capacity of Heterodera schachtii on Thlaspi arvense, Capsella bursa-pastoris and varying populations of Chenopodium album

Weed management in field crops is based on threshold levels. Direct yield reductions by weeds can be quantified, but indirect effects by serving as alternate hosts of plant–parasitic nematodes are more difficult to assess. In Germany, intensive cultivation of sugar beet in 3-year rotations with cereals provides long fallow periods between harvest and planting of the following crop. Weeds developing during this period could serve as hosts of Heteroderaschachtii, the sugar beet cyst nematode. In previous studies, only limited nematode population density effects were detected during the stubble period. Physiology and population characteristics of the potential host plants may impact reproduction potential of H. schachtii. In a microplot experiment, reproduction of H. schachtii was measured under Capsellabursa-pastoris, Chenopodiumalbum and Thlaspiarvense, and compared to that under susceptible Betavulgaris during the vegetation period from spring to late summer. There was no difference in population density of H. schachtii on the weed species, but all were much lower than under B. vulgaris. In a greenhouse study, the reproduction of H. schachtii on nine populations of C. album from different regions of Germany was compared to that on each of a susceptible and resistant cultivar of B. vulgaris and Raphanussativus. All C. album populations supported lower reproduction (<2 %) than the susceptible sugar beet and oilseed radish. Lower nematode population density and negligible reproductive potential on a diverse selection of C. album support the hypothesis that the risk of H. schachtii population buildup under these weeds is limited.

Revisión de las influencias de los insectos minadores de hojas en sus plantas huésped

Los insectos minadores de hojas son un grupo de herbívoros cuyas larvas viven y se alimentan del interior de las hojas. Lo que denominamos minas son las diferentes marcas que quedan en las hojas y que pueden proporcionar valiosa información acerca de las relaciones planta-insecto. La mayoría de minadores son monófagos u oligófagos. Los ecólogos y paleontólogos los usan para estudiar las interacciones y la coevolución entre plantas, insectos y sus enemigos naturales. Existen numerosos tipos de patrones de minas en las hojas, que pueden producir diferentes impactos en la planta hospedadora. Si los comparamos con los insectos ectófagos, los minadores de hojas pueden tener una influencia muy característica en numerosos aspectos de la planta hospedadora, como por ejemplo la morfología y la química foliar, la fisiología de la planta y su crecimiento y producción. Entre los impactos más evidentes, podemos nombrar asimetría foliar, formación de callos, fotosíntesis e «islas verdes». La tipología y el gravedad de estos impactos varían según en tipo de insecto minador y de planta hospedadora. Además, los cambios funcionales que se producen en la planta hospedadora pueden a su vez tener efectos positivos o negativos en la oviposición y la alimentación de los minadores. El estudio de los mecanismos de defensa de la planta hospedadora para combatir a los minadores puede resultar de gran utilidad para entender la coevolución entre ambos organismos.

First insights into the influence of aster yellows phytoplasmas on the behaviour of the leafhopperMgenia fuscovaria

Phytoplasmas can alter the behaviour of their insect vectors by modifying host plant and insect characteristics. In a dualchoice cage experiment, field-collected adult Mgenia fuscovaria were preferentially attracted by grapevine (cultivar Colombard) branches infected with aster yellows phytoplasma compared with uninfected branches. The influence of colour as a visual stimulus for M. fuscovaria was determined in a field trial. More adults were trapped on yellow and lime green than red, blue, white, and dark grey sticky colour cards. Within the green-yellow wavelength range more adults were attracted by the colour with the highest peak reflectance. Yellow is suitable for monitoring M. fuscovaria.

The role of ecological availability and host plant characteristics in determining host use by the bogus yucca moth Prodoxus decipiens

1. Specialisation in host plant use is strongly correlated with speciation in many plant‐feeding insects. Specialised taxa, however, could be restricted in host range due to limits in ecological availability of host plant species rather than trade‐offs in using alternate host species.2. Moths in the genus Prodoxus are extreme specialists on Yucca and speciation is closely tied to host plant shifts. However, many Yucca ranges are allopatric. This study examined whether the bogus yucca moth Prodoxus decipiens is limited in host range because of biogeographic factors or due to differences in the characteristics of host plant species.3. In a common garden, local P. decipiens moths that use Yucca filamentosa were exposed to individuals of five Yucca species, two that are known hosts of P. decipiens in other parts of its range and three that are used by its sister species, Prodoxus quinquepunctellus.4. Local moths were attracted to flowers of all Yucca species and females attempted oviposition in the flowering stalks of all species. However, larvae successfully completed development to diapause in only one of the five host plant species. Larval development on non‐natal Yucca species was significantly reduced compared with the local host.5. The results suggest that differences in host plant characteristics among Yucca species would result in strong natural selection during a host shift. Thus, specialisation in host plant use is probably due to trade‐offs involved with using novel host plant species as well as ecological availability.

Importance of local vs. geographic variation in salt marsh plant quality for arthropod herbivore communities

Summary An important recent advance in food web ecology has been the application of theory regarding spatial gradients to studies of the factors that affect animal population dynamics. Building on extensive studies of the Spartina alterniflora food web at the local scale, we hypothesized that geographic variation in S. alterniflora quality is an important bottom-up control on food web structure and that geographic variation in S. alterniflora quality would interact with the presence of predators and top omnivores to mediate herbivore densities. We employed a four-factor fully crossed experiment in which we (i) collected plants from high- and low-latitude locations and grew them in a common garden and varied (ii) plant fertilization status (mimicking the plant quality differences due to marsh elevation), (iii) mesopredator density and (iv) omnivore density. Our results suggest that the single most important factor mediating insect herbivore densities is local variation in plant quality – induced in our experiment by fertilization and demonstrated repeatedly as a consequence of marsh elevation. Top-down effects were generally weak and in those cases where predators did exert a significant suppressing effect on herbivores, that impact was itself mediated by host-plant characteristics. Finally, despite observed variation in plant quality with latitude, and the separately measurable effects of this variation on herbivores, geographic-scale variation in plant quality was overwhelmed by local conditions in our experiments. Synthesis. We suggest that a first-order understanding of variation across large latitudinal ranges in the Spartina alterniflora arthropod food web must begin with local variation in plant quality, which provides strong bottom-up forcing to herbivore populations. A second-order understanding of the arthropod food web should consider the role of predation in controlling herbivores feeding on low-quality plants. Finally, while latitudinal variation in plant quality probably explains some variation in herbivore densities, it is probably more of a response to herbivore pressure than a driver of the herbivore dynamics. Although extrapolating from local to geographic scales presents multiple challenges, it is an essential task in order for us to develop an understanding that is general rather than site-specific.

Influence of host plant species on the development, fecundity and population density of pest Tetranychus urticae Koch (Acari: Tetranychidae) and predator Neoseiulus pseudolongispinosus (Xin, Liang and Ke) (Acari: Phytoseiidae)

The two-spotted spider mite, Tetranychus urticae Koch (Tetranychidae), is a pest of agricultural crops that could potentially be controlled by the predatory mite Neoseiulus pseudolongispinosus (Xin, Liang and Ke) (Phytoseiidae). This study investigated the development, fecundity and population density of these two mite species on three different species of bean (Phaseolus lunatus L., Lablab purpureus [L.] and Phaseolus vulgaris L. [Papilionaceae: Leguminosae]). The morphological characteristics of the host plants, including leaf area, thickness and hairiness, main stem diameter and plant height affected development rate, fecundity and population density of T. urticae and also the searching success and abundance of the predatory species, N. pseudolongispinosus. L. purpureus was found to be a superior host plant for both predator and prey species. These findings emphasize the importance of host plant characteristics on the performance of species used for biological control.

Different emergence phenology of European grapevine moth (Lobesia botrana, Lepidoptera: Tortricidae) on six varieties of grapes

The phenology of insect emergence affects reproductive success and is especially critical in short-lived species. An increasing number of studies have documented the effects of thermal and other climatic variations and of unpredictable habitats on the timing of adult insect emergence within and between populations and years. Numerous interacting factors may affect the phenology of adult emergence. Host-plant quality and availability is a key factor that has been largely neglected in studies of the phenology of phytophagous insects. The purpose of this study was to determine the effect of host plant characteristics on the rate of larval growth and the pattern of emergence in a wild population of Lobesia botrana (European grapevine moth), a significant pest in European vineyards. The phenology of emergence differed significantly among the six tested varieties of grapes. The percentage of bunches harboring pupae was similar among the different grape varieties, and the total number of pupae collected was similar to the number of emerging adults per bunch. Among the six varieties of grapes, 0-25 pupae were produced on each bunch. Each of the grape varieties had a single wave of emergence, in which males emerged before females, but their emergence phenology differed significantly in Chardonnay, Chasselas, and Pinot grapes. Both genders had extended durations of emergence in Merlot grapes. Together, the present results show that the characteristics of the grape host plant affect the emergence phenology of L. botrana.

Thinking Outside the Asclepias Box: Oleander Aphids and Honeyvine Milkweed

Abstract The oleander aphid, Aphis nerii Boyer de Fonscolombe, feeds on milkweeds in the Apocynaceae family. In Kentucky, A.nerii colonizes several common Asclepias species and honeyvine milkweed, Cynanchum laeve (Michaux). Previous studies investigating whether and how host plant characteristics influence A.nerii fitness have produced conflicting results. Our observations suggested that A.nerii more readily colonized C.laeve than Asclepias species. We hypothesized that aphid fitness differed among host plant species having different characteristics, and specifically, that A.nerii performance would be greatest on host plants having low cardenolide concentrations and few physical defenses. Physical and chemical characteristics were measured on C.laeve and three Asclepias species. Laboratory and field experiments were conducted to compare A.nerii performance among these four milkweed species in the absence of natural enemies. Changes in aphid densities over time were examined in the presence of natural enemies. Plant characteristics and aphid performance were found to differ among milkweed species. In the absence of natural enemies, A.nerii performance was best on C.laeve. When exposed to natural enemies, A.nerii densities remained higher on A.incarnata and C. laeve than on A.syriaca and A.tuberosa. Physical differences between C.laeve, a vining milkweed, and tested Asclepias species may increase suitability of honeyvine milkweed for A.nerii colonization. Our results suggest that C.laeve may rely more on tolerance and less on nonpreference or antibiosis resistance to herbivores.

In Vitro Studies Regarding the Control of Cryphonectria parasitica with Hydroalcoholic

Cryphonectria parasitica  (Murr.) Bar [syn. Endothia parasitica (Murr. And.] (anamorf: Endothiella sp .) is the causal agent of chestnut bark disease or chestnut blight. This disease produced great damages throughout the world, it has nearly eliminated the American chestnut tree ( Castanea dentata (Marsh.) Borkh.) from its natural range and has heavily affected the European chestnut tree ( Castanea sativa (P.) Mill). Successful protection against Cryphonectria parasitica is a very difficult problem because the conventional control methods against the fungus are not applicable with a great success because of the extreme fungus pathogenity and on the other hand because of the characteristics of sites and host plants. In our experiments the isolates of C. parasitica were picked from the Baia Mare area and for the control with plant extracts the isolates were inoculated on PDA medium that contained the extract using the poison food technique. The different extracts in three different concentrations were tested in 80 mm diameter Petri plates incubated at 25ºC and assessed after three, six and nine days of incubation. The fungistatic effect of the extracts was established by examining the presence or the absence of the colony growth. The colonies were measured establishing the colony area that appeared on the treated plates using the ellipse area formula. The results were expressed as the inhibition percent of the tested plant extracts.

Plant Water Stress Effects on the Net Dispersal Rate of the Insect Vector &lt;I&gt;Homalodisca vitripennis&lt;/I&gt; (Hemiptera: Cicadellidae) and Movement of Its Egg Parasitoid, &lt;I&gt;Gonatocerus ashmeadi&lt;/I&gt; (Hymenoptera: Mymaridae)

Homalodisca vitripennis (Germar), a vector of Xylella fastidiosa, is associated with citrus plantings in California. Infested citrus orchards act as a source of vectors to adjacent vineyards where X. fastidiosa causes Pierce's disease. An analysis of the pattern and rate of movement of H. vitripennis and its egg parasitoid, Gonatocerus ashmeadi Girault, was conducted in a citrus orchard by using a protein mark-capture technique to quantify movement and net dispersal rates in the experimental areas. Treatments included irrigation at 100% of the crop evapotranspiration rate (ET(c)), 80, and 60% ET(c). Sex-specific net dispersal rates showed that H. vitripennis males and females moved consistently and contributed equally to the level of population change within treated areas. Trees irrigated at 60% ET(c) were the least preferred by H. vitripennis. Among all protein-marked individuals captured in the 60% ET(c) treatment, ≈ 75 and 88% in 2005 and 2006, respectively, were inflow individuals. Movement toward less preferable plants indicates that in agricultural landscapes dominated by perennial monocultures, there is a random component to H. vitripennis movement, which may result from the inability of H. vitripennis to use plant visual cues, olfactory cues, or both to make well-informed long-range decisions. The 80% ET(c) areas were a significant source of adult H. vitripennis and G. ashmeadi compared with the other treatments. Colonization rates by parasitoids were synchronized with the spatiotemporal distribution of H. vitripennis eggs. Results suggest that H. vitripennis movement from citrus into adjacent vineyards could be a result of random dispersal rather than oriented movement in response to host-plant characteristics.

Using arbuscular mycorrhizal fungi to improve the nutrient quality of crops; nutritional benefits in addition to phosphorus

While arbuscular mycorrhizal (AM) fungi are well known to increase plant phosphorus uptake, there is mounting evidence that AM fungi are important for enhancing the uptake of other minerals. As most crops are capable of forming AM symbioses, these fungi could have the potential to improve the nutritional value of the food we eat. However, we do not yet know which other nutrients are affected by the AM symbiosis, nor whether different AM fungal isolates differ in their ability to acquire nutrients for their hosts. In two separate greenhouse experiments, we tested 5 fungal isolates for their contribution to shoot concentration of 11 macro- and micronutrients in two plants and found that AM fungi influenced nutrient concentrations for all nutrients examined. Allium was highly responsive to AM fungi and showed increased foliar nutrient concentration when nutrients were abundant whereas Plantago did not respond significantly to inoculation from AM fungi. Only plants grown with Glomus intraradices had universally improved nutrient levels. Our study shows that the identity of AM fungi can influence many nutrients besides phosphorus, but the magnitude and direction of this response is also affected by host plant characteristics and soil nutrient status.