Arthropod-Plant Interactions最新文献

A study was conducted to determine rates of recapture of marked Agriotes obscurus (AO) males released in a grassy field on four occasions in the centre of pheromone trap squares with traps spaced 2.5, 5.0, 7.5 and 10.0 m apart. Concurrent catches of naturally occurring and naturally dispersed (wild) AO were also recorded. Catch of marked AO was highest during peak emergence when maximum weekly temperatures ranged from 15.7 to 17 °C, and rainfall was light. Mean catch in the 2.5–10.0 m trap squares was, respectively, 82.0, 79.0, 77.0 and 65.0%, which occurred within one week of release. Catch of marked AO were lower (range in 2.5–10.0 m squares: 74.5–50.5%) when released early in the activity period, due to lower temperatures and higher rainfall, and catch was protracted over 3 weeks. Catch during two releases under favourable weather late in the activity period was also reduced (range: 25–58%), likely due to loss of AO vigour and/or pheromone trap efficacy. Catch of wild AO was highest in traps spaced 7.5 or 10.0 m apart, suggesting independence of these traps, and between-trap competition at 2.5 and 5.0 m spacings. From these data, we estimated that an effective spacing for traps in mass trapping arrays would be approximately 6 m. Significantly higher catch of marked or wild AO occurred in traps that were upwind in all trap squares, indicating wind direction should be considered in structuring the placement of trap arrays in mass trapping programs in non-farmed headland areas.

Insect herbivores co-occurring on the same host plant interact in various ways. In particular, early-season insect herbivory triggers a wide range of plant responses that can determine the performance of herbivores colonizing the plant later in the course of the season. But the strength and direction of such effects are debated, and virtually unknown in the case of novel interactions involving exotic insects in their introduction range. We conducted an observational field study in SW France, a region recently invaded by the Oak Lace Bug (OLB, Corythucha arcuata Say). We measured early chewing damage and subsequent OLB damage in four oak species (Quercus robur, Q. pubescens, Q. cerris and Q. ilex). We set up a complementary non-choice experiment in the laboratory, feeding OLB with leaves with or without prior herbivory. The four oak species differed in their sensitivity to OLB damage, Q. ilex being broadly resistant. Prior herbivory promoted OLB damage in the laboratory experiment, but not in the field. However, prior herbivory did not alter the rank of oak resistance to the OLB. Our results suggest possible synergistic effects between spring defoliators and the OLB. This study brings insight into herbivore-herbivore interactions and their possible implications for forest management.

Globally, large herbivores (e.g., cattle, elk) graze over 2.6 billion hectares of land. These lands can also be used to conserve pollinators that rely on similar resources, specifically diverse plant communities. Pollinator conservation will benefit from management in lands that are used for livestock grazing and wildlife conservation. However, maximizing ecosystem services provided in these areas is often nuanced and difficult. To improve our ability to support multiple ecosystem services in grazing lands, we reviewed published literature to investigate the mechanisms of indirect effects of large herbivores on pollinators via their resources (food plants, nesting sites). We used a framework from previous research on indirect effects of insect herbivores to explore and interpret how plant responses mediate large herbivore effects on pollinators through three mechanistic categories: resource abundance and availability, plant appearance, and plant chemistry. Using the broader conceptual model, we conducted a targeted literature review that found ~ 95% of studies investigating pollinators and large herbivores focused on resource abundance and availability. Consequently, more research is necessary to understand how large herbivores impact pollinators through multiple mechanisms. Future research could also test responses with both large herbivores and insect herbivores to determine their combined ecological consequences. This research will provide insights for managing large herbivores and pollinators simultaneously, while connecting concepts of pollinator ecology and grazing ecology. Filling research gaps on the mechanisms of indirect effects of large herbivores on pollinators will ultimately improve management of multiple ecosystem services and our ability to conserve declining pollinator species.

Wildflowers in uncultivated field margin are important resources supporting both pest and non-pest thrips populations in agroecosystems. Environmental factors related to wildflowers have never been used as predictors to model pest thrips density in adjacent crops. Wild and cultivated flowers were sampled in strawberry field agroecosystem in Orléans Island, near Quebec City, Canada. Pest flower thrips Frankliniella intonsa and F. tritici had a wide wildflower host range, with preferences toward Leucanthemum vulgare, Trifolium pratense, Sonchus asper, and Cichorium intybus. Regression modeling revealed significant positive relationships between pest thrips density on specific wildflowers (Vicia cracca, Sinapis arvensis, S. asper, C. intybus, L. vulgare) and their density in strawberry flowers. Furthermore, thrips density within the crop decreased with distance from uncultivated field margin. Regarding crop management, knowing the associations between thrips pests and preferred wild flora as well as their spatial distribution in strawberry fields is an undeniable advantage.

The first data on the interaction between a phytophagous hoverfly and holoparasitic broomrape plants in Europe is reported. Description of the new species Eumerus larvatus sp. nov. Aracil, Grković et Pérez-Bañón is presented from specimens feeding within the fleshy hypogeal stems of Cistanche phelypaea in different localities of Southeast of Iberian Peninsula. Both, adult and preimaginal morphology are studied, including also a molecular analysis based on COI gene sequences. The molecular data, together with the diagnostic morphological characteristics of the adult, indicate that the species belongs to the Eumerus tricolor species-group. This paper presents the first in-depth and detailed description of the preimaginal morphology of a representative of this species group, based on scanning electron microscopy (SEM) images.

With the process of urbanization and the development of cities, trees in the urban environment are becoming increasingly important. Those trees represent a habitat and a food source for many organisms, among which insects are the most numerous and diverse. The insect communities inhabiting them frequently differ from those found in the rural environment. However, the transition from rural to urban habitat is rarely sharp, as there are many intermediary habitats that often represent the species rich areas. We investigated how the urbanization gradient affects the black poplar endophagous herbivorous insect community. To determine that, we compared the leaf miner and gallicolous aphid species richness, abundance, and diversity along rural–urban gradients. The research was conducted in 2019, in three cities in Serbia, in rural, suburban, and urban areas. We concluded that urbanization significantly influences the black poplar leaf miner community, while it does not have a significant effect on the black poplar gallicolous aphid community. Significantly lower leaf miner species richness and diversity were recorded in the urban environment, while their abundance was significantly lower in suburban areas. Contrary to most species, Fenusella hortulana (Hymenoptera) reacted positively to urbanization, while Aulagromyza populi (Diptera) and Phyllonorycter extrematrix (Lepidoptera) were not significantly affected. As about 80% of leaf miner species and 40% of gallicolous aphid species still manage to survive in the urban environment, the trees present in the urban environment are important for the preservation of their fauna.

Wireworms (Coleoptera: Elateridae) are generalist insect pests that aggregate and feed on the roots of various crops, including maize. It remains unclear how they find and choose host plants. Several studies have focused on volatile organic compounds released by roots infested by wireworms, revealing the presence of 2-pentylfuran. We hypothesized that 2-pentylfuran could be a key aggregation cue that attracts wireworms towards roots colonized by conspecifics. In a series of olfactometer assays, we first investigated whether the larvae of click beetles indeed use volatile organic compounds (VOCs) as cues to locate maize roots that are already under attack by conspecifics. Surprisingly, wireworms were found to not only orient towards conspecific larvae feeding on the maize roots, but also to larvae alone. VOCs collections from plants and larvae revealed the presence of 2-pentylfuran, particularly in treatments where larvae were present. In subsequent dual-choice olfactometer assays wireworms exhibited significant attraction to 2-pentylfuran. These results imply that 2-pentylfuran is involved in wireworm aggregation behaviour, and open up opportunities for the development of an attract-and-kill strategy.

The aim of this study focussed on identifying chemical compounds (wood extractives) using different solvents, as well as their performance as a wood preservative against subterranean termites, Coptotermes gestroi (Wasmann) attack. The source of wood extractives was from Palaquium gutta (Hook.f.) Baillon and Pometia pinnata J.R. Forster & J.G. Forster, heartwood extracted with different solvents; absolute ethanol (EtOH), absolute methanol (MeOH) and petroleum ether (PETETHR). Compound identification was performed under Gas Chromatography and Mass Spectrometry (GC–MS). Besides that, the efficacy of extracts from both timber species was also assessed in various bioassays (antitermitic, repellent, antifeedant & test of wood extractives applied to Hevea brasiliensis). A total of 20 and 22 compounds were identified from P. gutta and P. pinnata heartwood extracts, respectively. Decalactone, isobornyl isobutanoate, carvacrol, rosifoliol, incensole acetate, citronellyl pentanoate, allyl cinnamate, thujic acid, cubebolo, citronellol, manool, neoisopulegol, widdrol and methyl decyl ketone were among the bioactive compounds of varying proportions among the studied timbers. The heartwood extracts from both timber species with MeOH solvent had a significantly lower percentage of paper consumption and higher percentage of feeding inhibition and repellent activity, followed by EtOH and PETETHR. Both timber species extracts had the potential to be developed as a new natural bio preservative in wood industries.

Plants live in association with a multitude of microorganisms, some of which may improve the plant’s defense toward herbivores. In a previous study, we showed that Metarhizium brunneum, a fungus mostly known as an insect pathogen, can associate with cabbage roots and prime an increased myrosinase activity upon attack by Plutella xylostella larvae. Here, we ask whether another Metarhizium species, M. robertsii, also primes plant defense and whether this involves leaf glucosinolate content in addition to myrosinase activity. In addition, we tested whether priming reverses after removal of larvae. M. robertsii established and could be reisolated from roots at the end of the experiment, 43 days after inoculation. Before larval herbivory, leaf glucosinolate content and myrosinase activity did not differ between fungal-inoculated and control plants. Immediately after herbivory, in contrast, both the glucosinolate content and myrosinase activity were higher in inoculated plants than in control plants and less leaf material was consumed of the inoculated plants. Twenty-four hours after herbivory, glucosinolates, and myrosinase activity had decreased again to levels like before herbivory. Total biomass and shoot–root ratio were not affected by M. robertsii colonization. In conclusion, Metarhizium fungi can associate with Brassica roots and prime above-ground glucosinolate content and myrosinase activity. The increased defense levels were down-regulated 24 h after herbivory. Root-associated Metarhizium species may thus affect above-ground herbivores indirectly by host plant priming, in addition to their well-known direct effects as insect pathogens.

Conventional agriculture has negative impacts on the ecosystems while ecological intensification can ameliorate these effects by enhancing ecological processes. Arbuscular mycorrhizal fungi (AMF) are plant root symbionts that improve access to soil nutrients affecting plant growth and biotic interactions. Agricultural managements differentially affect AMF communities, but how these changes feedback on aboveground plant interactions remains poorly studied. Lettuce (Lactuca sativa) is a common crop severely attacked by Liriomyza huidobrensis (Diptera: Agromizydae), a polyphagous leafminer that has developed resistance to various pesticides, for which managing plant defenses and tolerance represents a feasible option to regulate populations. The aim of this study was to investigate if AMF communities from ecological and conventional management produce differential effects on mycorrhizal interaction, tissue phosphorus content and growth of lettuce plants and on L. huidobrensis oviposition preference. In greenhouse, we compared the effects of soils from farms with conventional and ecological managements from central Argentina on lettuce plants, and exposed them to L. huidobrensis mated females. Mycorrhizal colonization was higher with AMF from ecological than conventional treatments, although plant biomass was lower in treatments with AMF than with sterile soils (Strl), or with soil microorganisms without AMF (MO), in both managements. Phosphorus content was significantly higher in plants with MO and AMF in comparison to Strl, with no difference between managements. Plants grown with AMF from ecological management soils were less attacked by leafminers. Also, the insect preferred to oviposit on plants with higher aerial biomass, and this preference increased in plants with lower P content.