Predaceous Arthropods Research Articles

Fallows and permanent grasslands conserve the species composition and functional diversity of carabid beetles and linyphiid spiders in agricultural landscapes

Abstract The European Union reformed the Common Agricultural Policy (CAP 2013) to include greening measures with the aim to decrease negative impacts of farming on the environment and biodiversity. The degree to which greening measures such as permanent grassland or fallows of different ages enhance biodiversity is still debated. We investigate the effect of fallows in two different age classes and permanent grassland in the surrounding landscape on the taxonomic and functional diversity of two numerically dominant groups of natural enemies in cereal fields: soil‐emerging carabid beetles (Family Carabidae, Order Coleoptera) and ground‐active linyphiid spiders (Family Linyphiidae, Order Araneae). The species richness, abundance and Hill–Shannon diversity of carabids and linyphiids did not differ significantly between fallows and cereal fields and was not significantly related to the proportion of permanent grassland in the surrounding landscape. The species composition of both communities differed significantly between cereal fields and fallows. The functional distinctness, as an index reflecting the similarity among species in terms of functional traits, of linyphiids was significantly higher in fallows than in cereal fields. The trait composition of carabids was significantly related to the proportion of permanent grassland depending on field type (cereal or fallow). Our results document considerable species turnover in natural enemy communities of adjacent cereal fields and fallows, and support the assumption that older fallows (>8 years) produce functionally more diverse natural enemy communities. Maintaining fallows for a long period is an important measure to promote the functional diversity in predaceous arthropod communities.

Trade-Offs and Synergies Between Food and Fodder Production and Other Ecosystem Services in an Actively Restored Forest, Natural Forest and an Agroforestry System in Ghana

Active restoration of degraded areas with multi-purpose tree species has been proposed as a measure to counter the losses from deforestation and mitigate consequences for local human communities. In a restoration project at a former mining site in Ghana, ecosystem services (ES) proxies in an actively restored forest were compared to a local agroforestry system and a natural forest. The results provide information about trade-offs and synergies between proxies of multiple ES(s). ES proxies were assessed according to the following categories: (a) food-tree ES: biomass of food and fodder trees, (b) other trees ES: biomass of fuelwood, medicine or mulch trees, (c) ES-providing arthropods: the number of detritivorous and predaceous arthropods, (d) carbon storage, and (e) tree diversity. Eight replicated plots with sizes of 20 m × 20 m were established in each forest type, and the following ES proxies were quantified: tree diversity was estimated as taxonomic richness of all trees with a diameter at breast height ≥ 10 cm in each plot. Tree species were then classified into ES categories (food, fodder, fuelwood, medicine, or mulch). Ground-dwelling arthropods were sampled for 10 weeks with five pitfall traps in each plot and categorized as decomposers and predators. Tree above-ground biomass was estimated based on the measured tree diameter, height, and specific wood density using an improved allometric equation. The above-ground biomass was later converted into carbon storage by assuming 50% of the above-ground biomass of each tree. ES proxies based on tree biomass were highest in the natural forest. Fodder, medicine, fuelwood, and mulch ES proxies were significantly higher in the restored forest than the agroforestry system. Decomposer arthropods were most dominant in the natural forest, followed by the restored forest and the agroforestry system. Predacious arthropods were more dominant in the restored forest than in the other forest types. Carbon storage was highest in the natural forest, followed by the agroforestry system and the restored forest. The actively restored forest took an intermediate position between the agroforestry system and the natural forest regarding values for all nine ES proxies. Out of the 14 possible relationships between food or fodder and other ES proxies, five were significantly positive (synergies) with no observed trade-offs (significant negative relationships). High fodder production in the restored and natural forests went along with higher values of other biomass ES proxies and numbers of beneficial arthropods, while higher food biomass also correlated positively with numbers of decomposing arthropods. Our results document that active restoration of degraded sites provides a valuable framework to promote ES provision to local communities compared to agroforestry system, but at the cost of lower food and fuelwood biomass and carbon storage compared to natural forests.

Associating Site Characteristics With Distributions of Pestiferous and Predaceous Arthropods in Soybean.

Although site-specific pest management has the potential to decrease control costs and environmental impact associated with traditional pest management tactics, the success of these programs relies on the accurate characterization of arthropod distributions within a crop. Because potential correlation of insect counts with remotely sensed field attribute data could help to decrease the costs associated with and need for fine-scale spatial sampling, we chose to determine which within-field variables would be informative of soybean arthropod counts in an attempt to move toward site-specific pest management in this crop. Two soybean fields were grid-sampled for pestiferous and predaceous arthropods, plant productivity estimates, and abiotic variable characterization in 2017-2018. Negative binomial, zero-inflated models were used to estimate presence and counts of soybean arthropod taxa based on normalized difference vegetation index (NDVI), soybean plant height, soil electrical conductivity (ECa), elevation, and calendar week. Among all variables, calendar week was the most reliable predictor of arthropod counts, as it was a significant predictor for a majority of all taxa. Additionally, counts for a majority of pestiferous taxa were significantly associated with distance from the field edge, elevation, soybean plant height, and NDVI. Although site-specific pest management has the potential for reduced management inputs and increased profitability over conventional management (i.e., whole-field) practices, management zones must first be clearly defined based on the within-field variability for the variables of interest. If site-specific pest management practices are to be applied in soybean, calendar week (and associated soybean phenology), soybean plant height (and associated elevation), and NDVI may be useful for describing the distributions of pests, such as kudzu bug, Megacopta cribraria (Hemiptera: Plataspidae) (Fabricius), green cloverworm, Hypena scabra (Lepidoptera: Erebidae) (Fabricius), velvetbean caterpillar, Anticarsia gemmatalis (Lepidoptera: Erebidae) (Hübner), and soybean looper, Chrysodeixis includens (Lepidoptera: Noctuidae) (Walker).

Abundance and diversity of arthropods in transgenic Bt and non-Bt cotton fields under Indian conditions

Two-year field studies during Kharif 2015 and 2016 were conducted to assess the abundance and diversity of arthropod communities of Bt cotton carrying Cry1Ac and Cry2Ab proteins and non-Bt cotton under sprayed and unsprayed conditions. The experiment was conducted in a randomized block design with four treatments of BG-II and non-Bt cotton. The treatments were non- transgenic cotton with no insecticide treatment, non-transgenic cotton with insecticide treatment, transgenic cotton with no insecticide treatment and transgenic cotton with an insecticide treatment. Arthropod community categorized as target insect pests, sucking insect pests, natural enemies and non-target insects were recorded at different phases of the cotton crop. The sucking insect pests contributed the highest abundance among the total arthropods recorded during the period of study. The abundance and diversity of bollworms that were recorded from non-Bt cotton only suggested effectiveness of BG II cotton against target insect pests. The abundance, species richness and diversity indices with respect to populations of beneficial predaceous arthropods and non-target insects were similar in BG-II and its non-Bt counterpart under unsprayed conditions. On the contrary, these parameters were significantly on the lower side under sprayed regimes for both genotypes. The spray of insecticides in early season against sucking insect pests significantly reduced their abundance and diversity indices in both BGII and non-Bt cotton. As monocropping of BG-II cotton is common on large parts of India, there is a need to monitor the populations of non-target insect species with special emphasis on sucking insect pests on a continuous basis to understand the long-term impact of Bt crops on insect biodiversity for sustainable integrated pest management practices.

Crop diversity benefits carabid and pollinator communities in landscapes with semi‐natural habitats

Abstract In agricultural landscapes, arthropods provide essential ecosystem services such as biological pest control and pollination. Intensified crop management practices and homogenization of landscapes have led to declines among such organisms. Semi‐natural habitats, associated with high numbers of these organisms, are increasingly lost from agricultural landscapes but diversification by increasing crop diversity has been proposed as a way to reverse observed arthropod declines and thus restore ecosystem services. However, whether or not an increase in the diversity of crop types within a landscape promotes diversity and abundances of pollinating and predaceous arthropods, and how semi‐natural habitats might modify this relationship, are not well understood. To test how crop diversity and the proportion of semi‐natural habitats within a landscape are related to the diversity and abundance of beneficial arthropod communities, we collected primary data from seven studies focusing on natural enemies (carabids and spiders) and pollinators (bees and hoverflies) from 154 crop fields in Southern Sweden between 2007 and 2017. Crop diversity within a 1‐km radius around each field was positively related to the Shannon diversity index of carabid and pollinator communities in landscapes rich in semi‐natural habitats. Abundances were mainly affected by the proportion of semi‐natural habitats in the landscape, with decreasing carabid and increasing pollinator numbers as the proportion of this habitat type increased. Spiders showed no response to either crop diversity or the proportion of semi‐natural habitats. Synthesis and applications. We show that the joint effort of preserving semi‐natural habitats and promoting crop diversity in agricultural landscapes is necessary to enhance communities of natural enemies and pollinators. Our results suggest that increasing the diversity of crop types can contribute to the conservation of service‐providing arthropod communities, particularly if the diversification of crops targets complex landscapes with a high proportion of semi‐natural habitats.

Effect of Time of Day on Efficacy of Sweep Net Sampling of Arthropod Predators in Maize Agro-Ecosystems in the North West Province, South Africa

Various abiotic factors influence the biology and behaviour of arthropods, one of the most prominent abiotic factors is temperature. Thus, it is essential to know the optimal time of day during which sampling of target species should be done to allow for accurate arthropod biodiversity studies. This study considered species richness, abundance and diversity of predaceous arthropods of the Chrysopidae, Mantodea, Araneae and Coccinellidae throughout the day in and around maize fields in the extensively cultivated highveld grasslands of South Africa. Sweep net sampling was done at the following times: 07:00, 12:00, 15:00 and 17:00. Sampling was conducted at three different localities and repeated on three occasions over two growing seasons. At each locality there were three replicates in each of three zones in the agro-ecosystem, i.e. maize field, field margin and untransformed grassland. Shannon diversity index values did not differ significantly between the different sweep net sampling times. Predacious arthropods were, although not significantly so, more abundant within maize fields in the mornings (07:00) and in adjacent grasslands during late afternoon (15:00). This study indicated no particular time to be significantly better suited for sampling of the diversity of the four groups of predacious arthropods in maize agro-ecosystems.

Effects of Strip Tillage in Sugar Beet on Density and Richness of Predatory Arthropods.

Strip tillage, in which tillage and seedbed preparation are limited to a narrow band where the subsequent crop is planted, provides many potential agronomic benefits, including reduced fuel and labor costs, reduced erosion, and improved soil tilth. Lower soil disturbance and enhanced water retention associated with strip tillage also may affect density and diversity of predatory arthropods, which have been little studied in sugar beet. We examined the effects of tillage (conventional versus strip) on the predatory epigeal arthropod fauna in sugar beet. Studies were conducted over three growing seasons (2010-2012) in Idaho using both fenced and unfenced pitfall traps to sample arthropods. Unfenced pitfall traps often captured a greater activity density and richness of predators, and showed no bias of higher captures in conventionally tilled plots as has been shown elsewhere. Total density of predators was higher in strip tillage only during 2011. Density and species richness of carabid beetles did not differ between tillage treatments during the course of the study. Density of the other major taxa (staphylinid beetles, spiders, and Opiliones) was higher under strip tillage during some years, especially early in the season, but richness showed little or no relationship with tillage. Predaceous arthropods might be favored by enhanced ground cover, higher humidity, more moderate temperatures, and/or less habitat disturbance associated with strip-tilled plots. The results suggest that certain groups of soil-dwelling predatory arthropods can be favored by strip tillage in sugar beet, which further adds to the benefits of conservation tillage in this system.

Artificial Light Increases Local Predator Abundance, Predation Rates, and Herbivory.

Human activity is rapidly increasing the radiance and geographic extent of artificial light at night (ALAN) leading to alterations in the development, behavior, and physiological state of many organisms. A limited number of community-scale studies investigating the effects of ALAN have allowed for spatial aggregation through positive phototaxis, the commonly observed phenomenon of arthropod movement toward light. We performed an open field study (without restricted arthropod access) to determine the effects of ALAN on local arthropod community composition, plant traits, and local herbivory and predation rates. We found strong positive phototaxis in 10 orders of arthropods, with increased (159% higher) overall arthropod abundance under ALAN compared to unlit controls. The arthropod community under ALAN was more diverse and contained a higher proportion of predaceous arthropods (15% vs 8%). Predation of immobilized flies occurred 3.6 times faster under ALAN; this effect was not observed during the day. Contrary to expectations, we also observed a 6% increase in herbivory under ALAN. Our results highlight the importance of open experimental field studies in determining community-level effects of ALAN.

Diversity patterns of selected predaceous arthropod groups in maize fields and margins in South African Highveld grassland

Abstract Conservation biological control focuses on enhancing arthropod predator habitats by increasing the natural resources required for survival and reproduction. However, this requires knowledge about the specific requirements of these predators, which can only be acquired from species‐level data. We provide a description of species‐level diversity patterns of the arthropod predator groups Araneae, Coccinellidae, Mantodea and Neuroptera from maize agro‐ecosystems in South Africa. Predators were sampled by sweep‐net at regional and local scales within the Dry Highveld Grassland Bioregion. A list is provided of predators that occurred naturally inside maize agro‐ecosystems, which may be good candidates for the biological control of pests. Diversity indices displayed significantly lower values in maize fields compared with uncultivated vegetation. Marginal and rangeland vegetation had similar diversity levels. Predator diversity of maize was probably dependent on source populations from uncultivated vegetation, highlighting the importance of field margins with respect to maintaining predator diversity in pest management regimes for maize fields. Some predators frequented maize fields, suggesting adaptability to agricultural disturbance. Generalists including Cheilomenes lunata, Chrysoperla congrua and Enoplognatha molesta may be suitable for conservation biocontrol because they can persist in annual agro‐ecosystems year‐round provided that they have access to field margins.

Yield Losses in Transgenic Cry1Ab and Non-Bt Corn as Assessed Using a Crop-Life-Table Approach.

In this study, we constructed crop life tables for Bacillus thuringiensis Berliner (Bt) Cry1Ab and non-Bt corn hybrids, in which yield-loss factors and abundance of predaceous arthropods were recorded during 2 yr at two locations. Corn kernel/grain was the yield component that had the heaviest losses and that determined the overall yield loss in the corn hybrids across years and locations. Yield losses in both corn hybrids were primarily caused by kernel-destroying insects. Helicoverpa zea (Boddie) and Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) were the key loss factors at one location, while at the other, the key loss factor was the silk fly larvae, Euxesta spp. (Diptera: Ulidiidae). Although the realized yield of corn grains was not different (P > 0.05) between Cry1Ab and non-Bt corn hybrids, the Bt corn hybrid reduced (P < 0.05) the damage by H. zea and S. frugiperda in three of the four field trials, particularly at the location where Lepidoptera were the key loss factors. As expected, no reduction in the abundance of predaceous arthropods was observed in Cry1Ab corn fields. Various species of natural enemies were recorded, particularly the earwig Doru luteipes (Scudder) (Dermaptera: Forficulidae), which was the most abundant and frequent predaceous insect. These results indicate that integration of pest management practices should be pursued to effectively minimize losses by kernel-destroying insects during corn reproductive stages when growing non-Bt or certain low-dose Bt corn cultivars for fall armyworm and corn earworm, such as those producing Cry1Ab or other Cry toxins.

Characterisation of protein families in spider digestive fluids and their role in extra-oral digestion

BackgroundSpiders are predaceous arthropods that are capable of subduing and consuming relatively large prey items compared to their own body size. For this purpose, spiders have evolved potent venoms to immobilise prey and digestive fluids that break down nutrients inside the prey’s body by means of extra-oral digestion (EOD). Both secretions contain an array of active proteins, and an overlap of some components has been anecdotally reported, but not quantified. We systematically investigated the extent of such protein overlap. As venom injection and EOD succeed each other, we further infer functional explanations, and, by comparing two spider species belonging to different clades, assess its adaptive significance for spider EOD in general.ResultsWe describe the protein composition of the digestive fluids of the mygalomorph Acanthoscurria geniculata and the araneomorph Stegodyphus mimosarum, in comparison with previously published data on a third spider species. We found a number of similar hydrolases being highly abundant in all three species. Among them, members of the family of astacin-like metalloproteases were particularly abundant. While the importance of these proteases in spider venom and digestive fluid was previously noted, we now highlight their widespread use across different spider taxa. Finally, we found species specific differences in the protein overlap between venom and digestive fluid, with the difference being significantly greater in S. mimosarum compared to A. geniculata.ConclusionsThe injection of venom precedes the injection with digestive fluid, and the overlap of proteins between venom and digestive fluid suggests an early involvement in EOD. Species specific differences in the overlap may reflect differences in ecology between our two study species. The protein composition of the digestive fluid of all the three species we compared is highly similar, suggesting that the cocktail of enzymes is highly conserved and adapted to spider EOD.

Effects of bird and bat exclusion on coffee pest control at multiple spatial scales

Despite the key role of biological control in agricultural landscapes, we still poorly understand how landscape structure modulates pest control at different spatial scales. Here we take an experimental approach to explore whether bird and bat exclusion affects pest control in sun coffee plantations, and whether this service is consistent at different spatial scales. We experimentally excluded flying vertebrates from coffee plants in 32 sites in the Brazilian Atlantic Forest, encompassing a gradient of forest cover at landscape (2 km radius) and local (300 m) spatial scales, and quantified coffee leaf loss, as an indicator of herbivory, and fruit set. Leaf loss decreased with higher landscape forest cover, but this relation was significantly different between treatment and control plants depending on local forest cover. On the other hand, fruit set responded to the interaction between treatment and local forest cover but was not affected by landscape forest cover. More specifically, fruit set increased significantly with local forest cover in exclusion treatments and showed a non-significant decrease in open controls. These results suggest that services provided by flying vertebrates are modulated by processes occurring at different spatial scales. We posit that in areas with high local forest cover flying vertebrates may establish negative interactions with predaceous arthropods (i.e. intraguild predation), but this would not be the case in areas with low local forest cover. We highlight the importance of employing a multi-scale analysis in systems where multiple species, which perceive the landscape differently, are providing ecosystem services.

Molecular scatology and high-throughput sequencing reveal predominately herbivorous insects in the diets of adult and nestling Western Bluebirds (Sialia mexicana) in California vineyards

ABSTRACT Determining the ecosystem function of high-order predators is critical for evaluation of food web interactions. Insectivorous birds are abundant predators in many ecosystems yet because they forage upon small taxa, it remains largely unknown whether birds are providing ecosystem services in the form of pest control or disservices by preying upon predaceous arthropod species. We extracted DNA from noninvasive fecal samples of adult and nestling Western Bluebirds (Sialia mexicana) in California vineyards. Using universal arthropod-specific primers, we sequenced prey items via massively parallel sequencing on the Illumina MiSeq platform. Bluebirds consumed a broad diet comprising 66 unique arthropod species from 6 orders and 28 families. Aedes sp. (mosquitoes: Culicidae), a previously unknown prey, was the most common item recovered, occurring in 49.5% of the fecal samples. Ectoparasitic bird blowfly (Protocalliphora) DNA was found in 7% of adult and 11% of nestling samples, presenting clear evidenc...

Diet of the ladybird spiderEresus kollari(Araneae: Eresidae) in an arid system of southeastern Spain

Spiders are a diverse and abundant group of predaceous arthropods in arid environments. Spiders in the genus Eresus Walckenaer, 1805 are widely distributed in mesic and arid regions of the Palaearctic, but data on their diet are scarce. The goal of this study was to analyze the diet of Eresus kollari Rossi, 1846 in an arid habitat of the southeastern Iberian Peninsula. A total of 64 webs of Eresus kollari with prey remnants were collected in a field site at the Guadix-Baza Basin, and prey were identified to species or the lowest possible taxonomic level, and counted. Prey size was estimated based on remains from the webs and voucher specimens from the study area. In addition, laboratory observations of prey capture were made. The results showed that E. kollari has a broad diet, including prey from a total of 106 taxa. Prey included large arthropods (mostly tenebrionids) as well as relatively small insects (e.g., ants, which constituted a high proportion of prey). Laboratory observations showed that adult E. kollari actively captured tenebrionid beetles crawling on silk threads around the web, and ants moving on the surface of the web sheets. The high proportion of large-size prey in the webs studied, especially tenebrionids, indicate that this spider has a diet similar to that of Latrodectus lilianae Melic, 2000 in the study area, but the different hunting techniques used by the two spiders probably account for the dissimilar proportion of ants and predacious arthropods in the two diets.

Non-target effects of insect biocontrol agents and trends in host specificity since 1985.

Abstract Non-target impacts of parasitoids and predaceous arthropods used for classical biological control of invasive insects include five types of impact: (1) direct attacks on native insects; (2) negative foodweb effects, such as competition for prey, apparent competition, or displacement of native species; (3) positive foodweb effects that benefited non-target species; (4) hybridization of native species with introduced natural enemies; and (5) attacks on introduced weed biocontrol agents. Examples are presented and the commonness of effects discussed. For the most recent three decades (1985-2015), analysis of literature on the host range information for 158 species of parasitoids introduced in this period showed a shift in the third decade (2005-2015) towards a preponderance of agents with an index of genus-level (60%) or species-level (8%) specificity (with only 12% being assigned a family-level or above index of specificity) compared with the first and second decades, when 50 and 40% of introductions had family level or above categorizations of specificity and only 21-27 (1985-1994 and 1995-2004, respectively) with genus or 1-11% (1985-1994 and 1995-2004, respectively) with species-level specificity. In all three decades, 11-12% of introductions could not be classified in this manner due to lack of information. Recommendations for future actions to improve this record are made: (1) distinguish host use from population-level impact; (2) develop country-level online summaries of relevant information; (3) plan biological control projects with conservation partners; and (4) conduct post-release comparisons of actual impact to predicted risk based on quarantine studies.

Natural Predatory Enemies of Mango Red Mite Oligonychus mangiferus (Tetranychidae) in Eastern Egyptian Mango Orchards

Survey for natural predatory enemies of the mango red spider mite, Oligonychus mangiferus (Rhaman and Sapra), on mango trees were carried out in Ismailia governorate, Egypt to determine prospective species for the biological control of this pest. One peak of O. mangiferus during the year, from April to June was noticed. Total averages of 218.84 specimens of natural predatory enemies were found in 240 collected samples. Of these, 176.57 were predatory mites and 42.27 were predatory insects. Twelve species of predaceous arthropods, including mites and insects, have been reported in association with O. mangiferus, of which Typhlodromus pyri Schueten was the most abundant representing 14.06% of the total collected predaceous mites. Most of collected predatory mites and insects were generalist predators. Orius albidipennis (Reuter) was the most abundant representing 46.49 % of the total collected predatory insects. The distribution patterns of natural enemies always correlated with abundance of the mango red spider mite.

A Comparative Analysis of the Venom Gland Transcriptomes of the Fishing Spiders Dolomedes mizhoanus and Dolomedes sulfurous

Dolomedes sulfurous and Dolomedes mizhoanus are predaceous arthropods catching and feeding on small fish. They live in the same area and have similar habits. Their venoms exhibit some similarities and differences in biochemical and electrophysiological properties. In the present work, we first performed a transcriptomic analysis by constructing the venom gland cDNA library of D. sulfurous and 127 novel putative toxin sequences were consequently identified, which were classified into eight families. This venom gland transcriptome was then compared with that of D. mizhoanus, which revealed that the putative toxins from both spider venoms might have originated from the same gene ancestors although novel toxins were evolved independently in the two spiders. The putative toxins from both spiders contain 6–12 cysteine residues forming seven cysteine patterns. As revealed by blast search, the two venoms are rich in neurotoxins targeting ion channels with pharmacological and therapeutic significance. This study provides insight into the venoms of two closely related species of spider, which will be of use for future investigations into the structure and function of their toxins.

Wildflower plantings enhance the abundance of natural enemies and their services in adjacent blueberry fields

Wildflower plantings can support local abundance of natural enemies, but their influence on biological control of pests in adjacent crop fields is less well documented. To test whether biological control is enhanced by these plantings, we established native, perennial wildflowers in areas adjacent to highbush blueberry fields. Once wildflowers were established we found greater abundance of natural enemies in the fields adjacent to wildflower plantings compared with those adjacent to unenhanced control field perimeters. Predaceous arthropods, including spiders, hoverflies, and lady beetles, were among the most common natural enemies observed and collected in the blueberry fields. Using corn earworm eggs, Helicoverpa zea (Lepidoptera: Noctuidae), as sentinel prey, we found a similar pattern of biological control, with higher biological control services index values in fields adjacent to the wildflower plantings than in the unenhanced control fields. Our results provide evidence for the ability of wildflower plantings to support natural enemy populations in agricultural landscapes, and to potentially provide local enhancement of biological control in adjacent crops.

Should I fight or should I flight? How studying insect aggression can help integrated pest management.

Aggression plays a key role all across the animal kingdom, as it allows the acquisition and/or defence of limited resources (food, mates and territories) in a huge number of species. A large part of our knowledge on aggressive behaviour has been developed on insects of economic importance. How can this knowledge be exploited to enhance integrated pest management? Here, I highlight how knowledge on intraspecific aggression can help IPM both in terms of insect pests (with a focus on the enhancement of the sterile insect technique) and in terms of biological control agents (with a focus on mass-rearing optimisation). Then, I examine what implications for IPM can be outlined from knowledge about interspecific aggressive behaviour. Besides predator-pest aggressive interactions predicted by classic biological control, I focus on what IPM can learn from (i) interspecific aggression among pest species (with special reference to competitive displacement), (ii) defensive behaviour exhibited by prey against predaceous insects and (iii) conflicts among predaceous arthropods sharing the same trophic niche (with special reference to learning/sensitisation practices and artificial manipulation of chemically mediated interactions).

Effects of invasive plants on arthropods.

Non-native plants have invaded nearly all ecosystems and represent a major component of global ecological change. Plant invasions frequently change the composition and structure of vegetation communities, which can alter animal communities and ecosystem processes. We reviewed 87 articles published in the peer-reviewed literature to evaluate responses of arthropod communities and functional groups to non-native invasive plants. Total abundance of arthropods decreased in 62% of studies and increased in 15%. Taxonomic richness decreased in 48% of studies and increased in 13%. Herbivorous arthropods decreased in response to plant invasions in 48% of studies and increased in 17%, likely due to direct effects of decreased plant diversity. Predaceous arthropods decreased in response to invasive plants in 44% of studies, which may reflect indirect effects due to reductions in prey. Twenty-two percent of studies documented increases in predators, which may reflect changes in vegetation structure that improved mobility, survival, or web-building for these species. Detritivores increased in 67% of studies, likely in response to increased litter and decaying vegetation; no studies documented decreased abundance in this functional group. Although many researchers have examined effects of plant invasions on arthropods, sizeable information gaps remain, specifically regarding how invasive plants influence habitat and dietary requirements. Beyond this, the ability to predict changes in arthropod populations and communities associated with plant invasions could be improved by adopting a more functional and mechanistic approach. Understanding responses of arthropods to invasive plants will critically inform conservation of virtually all biodiversity and ecological processes because so many organisms depend on arthropods as prey or for their functional roles, including pollination, seed dispersal, and decomposition. Given their short generation times and ability to respond rapidly to ecological change, arthropods may be ideal targets for restoration and conservation activities.