Search

Flower strips are a prominent agri‐environmental scheme with the central objective to promote biodiversity and maintain associated ecosystem services. The promotion of natural enemies by increasing resource availability through flower strips is a promising approach for integrated pest management.In a 3‐year field study, two annual and two perennial flower strip mixtures, as well as a grass mixture, were tested regarding their attractiveness for natural enemies at three different study sites in Germany. Natural enemies were sampled annually in nine sampling rounds at a 10‐day rhythm using sweep netting and pitfall traps. To assess available floral resources, we estimated the species‐specific flower cover and classified species into flower types.Flower strip mixtures differed in their attractiveness to natural enemies. Treatment effects on arthropod activity density were most pronounced in the second and third year. Overall, perennial were more attractive than annual flower strip mixtures for most natural enemies, however, the response to flower strip mixtures varied significantly among taxa. For example, perennial flower strips showed a two‐ to fourfold increase of plant‐dwelling spider and parasitoid wasp activity density as well as higher numbers of juvenile stages of predatory bugs and rove beetles compared to annual flower strips. In contrast, annual flower strip mixtures showed the highest attractiveness for ground beetles. Moreover, different natural enemy taxa were associated with varying flower strip characteristics such as flower type proportion, herbivore availability and plant species richness.Synthesis and applications. We found taxon‐specific responses of natural enemies to different flower strips, which provide guidance for the floral composition of flower strips in order to maximize their effectiveness for natural pest control. We suggest the use of perennial mixtures with high proportion of flower heads (Asteraceae) and disk flowers (esp. Apiaceae, Rubiaceae, Brassicaceae) in particular, but also flag blossoms (Fabaceae) as these flower types were positively associated with several natural enemy groups. However, since we found mixed responses to flower types, specific flower strip composition will ultimately depends on its objective. [ABSTRACT FROM AUTHOR]

Intensification of conventional agriculture is a leading cause of negative environmental impact, loss of biodiversity, and reduced delivery of ecosystem services in agroecosystems. Maize, due to its growth habits and cultivation management, provides a poor habitat for beneficial arthropods. Several strategies are available to make maize cropping systems more sustainable and to promote biodiversity at field level. The present study evaluates the effects of various maize cropping systems – precisely, maize continuous monoculture, maize multiple cropping, and three mixed cropping systems (maize‐runner bean, maize‐sorghum, and maize‐flower strips) – on generalist predators and their biological control potential. Overall, we found that the reference system with maize continuous monoculture and conventional crop management had the lowest activity of generalist predators compared in particular to the low‐input mixed cropping systems. Higher activity density and biocontrol potential were found in the systems that provided a dense and permanent vegetation cover of the ground (i.e., maize/sorghum, maize/flower strip). Although these effects were not consistent for all the parameters investigated and for every sampling date, we conclude that generalist predators can benefit from more conservative management practices in maize systems, thereby enhancing their biological pest control potential. Furthermore, spatial intercropping may represent a valid alternative to the conventional monocultural crop system to support the delivery of biodiversity‐mediated ecosystem services towards a more sustainable system. [ABSTRACT FROM AUTHOR]

Insects of the order Coleoptera play an essential role in agricultural sustainability by supporting many ecosystem services (such as biological control, nutrient cycling or pollination). In agroecosystems, the Coleoptera community may be influenced by the surrounding landscape, which can provide living resources, like food or shelter, during different seasons, originating spillover movements between different environments.The present study aimed to evaluate the response of the Coleoptera community to the landscape surrounding vineyards at different buffers. For that, Coleoptera were sampled in six wine protected designation of origin (PDO) regions of Portugal (35 vineyards), and landscape configuration and composition metrics were calculated at buffers of 500, 750, 1000, 1500 and 2000 m radii around the vineyards.In total, 2954 Coleoptera individuals belonging to 36 families were collected. The most abundant families were Chrysomelidae, Coccinellidae and Latridiidae. Results indicated that intermediate habitat fragmentation levels, particularly in semi‐natural areas and vineyards, favoured Coleoptera biodiversity in vine‐producing regions. Moreover, the range of activity of Coleoptera seems to be larger than 1000 m.This work constitutes an important contribution to understanding the response of the Coleoptera community to the landscape context in vineyards in Portugal and contributes to the theoretical framework about the influence of habitat fragmentation on biodiversity. [ABSTRACT FROM AUTHOR]

Abstract: Semi‐natural habitats (SNH) provide essential resources for many organisms in agricultural landscapes and can increase biodiversity at the local and landscape scale. For the management of ecosystem services, it is crucial to understand how local characteristics of SNH and the surrounding landscape complexity affect beneficial species. We investigated this for hoverflies (Diptera: Syrphidae)—an important functional group providing both pest control and pollination services—in a total of 138 SNH within 35 agricultural landscapes in Switzerland and Germany. SNH differed in type (woody, herbaceous), shape (areal, linear) and availability of food resources (floral resources and aphids). They were located along a gradient of landscape complexity (1%–75% SNH in a 1 km radius). In total, 9,030 hoverflies belonging to 89 species were collected. In both countries, hoverfly community composition was mainly driven by SNH type and SNH shape, in addition to landscape complexity in Switzerland. Species richness of hoverflies increased with additional SNH at the landscape scale. However, the ubiquitous and dominant aphidophagous species Episyrphus balteatus was indifferent to landscape composition. Species richness of total and aphidophagous hoverflies was higher in woody than in herbaceous SNH. Hoverfly species richness was similar in linear and areal SNH, but non‐aphidophagous hoverflies were more vulnerable to landscape simplification in linear than areal SNH. Effects of the SNH type partly differed between the two countries. In Germany, the dominant aphidophagous species E. balteatus preferred woody over herbaceous SNH, while no such difference was found in Switzerland. Overall, local richness and abundance of floral resources were poor predictors for hoverfly abundance, richness or community composition. Synthesis and applications. Hoverfly species richness and community composition in semi‐natural habitats (SNH) were mainly driven by the SNH type and landscape complexity. Conservation and restoration of complex agricultural landscapes with a high proportion of different SNH types is therefore key for the conservation of hoverfly diversity, and thus likely to promote pest control and pollination services provided by them. Thereby, local improvement of SNH to promote hoverflies has to consider regional differences in habitat characteristics. [ABSTRACT FROM AUTHOR]

Lycosid spiders are among the most abundant and diverse insectivores occurring in all agroecosystems. Certain pest management practices, such as the application of pesticides, can disrupt their role in insect pest control. Therefore, understanding the effects of pesticides, including sublethal effects, is essential for the assessment of chemical effects on beneficial arthropods. We investigated the sexual chemical communication of the beneficial agrobiont spider Pardosa agrestis and its disruption by two widely used pesticides, the glyphosate-based herbicide Roundup and the pyrethroïd-based insecticide Nurelle D. A two-choice olfactometer and Y-maze were used to study the effectiveness of female airborne and dragline pheromone cues and the disruptive effect of the pesticides. Males of P. agrestis did not locate females via airborne cues, but were very receptive to female dragline silk and male dragline silk. When both female dragline silk and male dragline silk were provided at the same time, the males preferred female silk. Pesticide treatments significantly affected the male ability to follow female cues deposited on dragline silk. The 3-h residues of both Roundup and Nurelle D significantly disrupted the male ability to follow female cues deposited on dragline silk. Treatment by 48-h residues significantly disrupted the male ability only in the case of Nurelle D. Our results demonstrate that pesticides reduce the ability of male spiders to search for a mate due to the disruption of the male's ability to detect the silk cues of the female. [ABSTRACT FROM AUTHOR]

1 Weed harrowing is an alternative to herbicides but it may have negative effects on epigaeic arthropods. We assessed the effects of frequent (four) versus two harrowings during the growing season on the density and diversity of generalist arthropods and the weed flora. Collection by flooding was used to estimate arthropod densities, after collection of weeds and crop for biomass estimation. 2 The predatory guild of spiders Tachyporus spp. carabids was reduced by frequent harrowing. Spiders and Tachyporus spp. were the most sensitive, with up to 38% higher density in plots harrowed only twice compared with four times. Furthermore, a marginally significant decrease in arthropod diversity was found after four harrowings. The negative effect of frequent harrowing on arthropods was probably caused by a combination of direct lethal effects and habitat disruption. Additional harrowings reduced weeds with weed seed biomass, on average, being 77% higher and species diversity being 48% higher in plots harrowed only twice compared with four times. There was a positive relationship between weed biomass and predatory arthropod guild density, supporting the hypothesis that weeds promote generalist arthropod predators. 3 Weed harrowing should be carried out early and limited to a minimum to protect flora and fauna. Frequent harrowing had no positive effect on yield, suggesting that more weeds can be tolerated to support biodiversity and biocontrol. [ABSTRACT FROM AUTHOR]

The use of the surrogate species concept is widespread in environmental risk assessment and in efforts to protect species that provide ecosystem services, yet there are no standard protocols for the choice of surrogates. Surrogates are often chosen on the basis of convenience or vague resemblances in physiology or life history to species of concern. Furthermore, our ability to predict how species of concern will fare when subjected to disturbances such as environmental contaminants or toxicants is often based on woefully misleading comparisons of static toxicity tests. Here we present an alternative approach that features a simple mathematical model parameterized with life history data applied to an assemblage of species that provide an important ecosystem service: a suite of parasitoid wasps that provide biological control of agricultural pests. Our results indicate that these parasitoid wasp species have different population responses to toxic insult--that is, we cannot predict how all four species will react to pesticide exposure simply by extrapolating from the response of any one species. Furthermore, sensitivity analysis of survivorship and reproduction demonstrates that the life stage most sensitive to pesticide disturbance varies among species. Taken together, our results suggest that the abihty to predict the fate of a suite of species using the response of just one species (the surrogate species concept) is widely variable and potentially misleading. [ABSTRACT FROM AUTHOR]

Declines in species diversity resulting from anthropogenic alterations of the environment heighten the need to develop management strategies that conserve species and ecosystem services. This study examined how native plant species and their diversity influence the abundance and richness of beneficial arthropods, a functionally important group that provides ecosystem services such as pollination and natural pest suppression. Beneficial arthropods were sampled in replicated study plots containing native perennials planted in one‐, two‐, and seven‐species mixtures. We found plant diversity had a positive impact on arthropod richness but not on arthropod abundance. An analysis of arthropod community composition revealed that each flower species attracted a different assemblage of beneficial arthropods. In addition, the full seven‐species mixture also attracted a distinct arthropod community compared to single‐species monocultures. Using a multivariate approach, we determined whether arthropod assemblages in two‐ and seven‐species plots were additive and could be predicted based on assemblages from their component single‐species plots. On average, assemblages in diverse plots were nonadditive when compared to assemblages predicted using single‐species plots. Arthropod assemblages in two‐species plots most closely resembled those of only one of the flower species in the mixture. However, the arthropod assemblages in seven‐species plots, although statistically deviating from the expectation of an additive model, more closely resembled predicted communities compared to the assemblages found in two‐species plots, suggesting that variability in arthropod community composition decreased as planting diversity increased. Our study demonstrates that careful selection of plants in managed landscapes can augment beneficial arthropod richness and support a more predictable arthropod community, suggesting that planning and design efforts could shape arthropod assemblages in natural as well as managed landscapes to meet targeted conservation or management goals. [ABSTRACT FROM AUTHOR]

BACKGROUND: Turfgrass management practices, especially the use of chemical pesticides, may be detrimental to beneficial arthropods such as predators and decomposers. However, little is known about the impact of other practices or pest control products on these beneficials. The impact of four different management regimes, consisting of synthetic pesticide cover sprays or combinations of more targeted applications of natural pesticides, on selected groups of non-targeted arthropods in lawns of different age was studied over 3 years. The short-term effect of diazinon and carbaryl on Carabidae and Collembola was also evaluated. RESULTS: Formicidae and Araneae were the most abundant taxa at both sites, representing 74-80% of total captures. With a few short-term exceptions, no persistent and significant difference between turfgrass management regimes on arthropod abundance was observed over the 3 year study. Diazinon and carbaryl significantly reduced Carabidae abundance, but only one year out of three, while Collembola abundance was only transiently affected by carbaryl application in 2003. CONCLUSION: The study showed that practices and products used in the four management regimes did not disrupt the populations of specific groups of arthropods. These results provide useful information to professionals for the development of ecological turf practices to maintain beneficial arthropod abundance and diversity in urban landscapes. Copyright © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Six insecticides, a carbamate (pirimicarb), four pyrethroid/mixtures (tao-fluvalinate, zeta-cypermethrin, deltamethrin, and pirimcarb1deltamethrin), and an organophosphate (dimethoate), registered for use within cereals, were field-tested for toxicity to beneficial nontarget invertebrate groups important as food for farmland birds. Compared to the control and the other compounds, pirimicarb was the least toxic for most invertebrate groups examined. The pyrethroids and pyrethroid mixture significantly reduced numbers of many of the nontarget groups compared to the control and pirimicarb. Tao-fluvalinate was the least toxic pyrethroid tested when compared to the other compounds. Toxicity was further tested on larvae of graminivorous sawflies, an important chick-food group, using field-sprayed plants in laboratory and semifield trials. None of the pyrethroid and carbamate compounds and mixtures was as toxic as the organophosphate, but all were more toxic than the control. The semifield experiments provided a useful way of determining potential insecticide impact on this nontarget group where field populations are often too low for field trials to have statistically conclusive results. [ABSTRACT FROM AUTHOR]