Abundance Of Beneficial Arthropods Research Articles

Irrigation decreases flower cover and beneficial arthropod abundances in Mediterranean vineyards

Over the last decades, the use of irrigation in vineyards has grown exponentially in response to climate change. In the Mediterranean region, irrigation is the most widely used method of preventing water stress and high sugar content in grapes. However, little is known about potential irrigation effects on biodiversity. This study aims to understand the effect of irrigation on inter-row vegetation, on the abundance of beneficial arthropods and on the predation of pest insects. In the Luberon region of South-Eastern France, nine irrigated and nine non-irrigated vineyards were analysed. Drip irrigation was applied only during the two driest months of the growing season. We found lower flower cover in irrigated vineyards but no difference in species richness and total vegetation cover. Similarly, abundances of several beneficial arthropods were directly affected by irrigation, such as crab spiders, ladybirds, ladybird larvae and parasitic wasps. Structural equation modelling (SEM) revealed that negative irrigation effects on these arthropods were mediated by negative effects on flower cover. Predation rates were also lower in irrigated vineyards but only during daytime. Grapevine yield was not affected by irrigation. Experiments manipulating water availability under controlled conditions may help to understand this surprisingly strong effect of irrigation on flower cover and beneficial arthropod abundance.

Efficacy of bio-rational insecticide for eco-friendly management of pod borer of mung bean

Pod borer species Maruca vitrata (Geyer) and Euchrysops cnejus (Fab.) are the major limiting constraints in mung bean. The present experiment was conducted in the experimental field of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, Bangladesh during March to June 2021 to develop an ecofriendly management approach against pod borer attacking mung bean. Four eco-friendly biopesticides (Biomax 1.8 EC (Abamectin) @ 1.2 ml/L, Tracer 45 SC (Spinosad) @ 0.4 g/, Fytomax PM (0.1% Azadirachtin) @ 5.0 ml/L, Neem Seed kernel Extract (NSKE) @ 50.0 g/L) and clean cultivation were tested against pod borers of mung bean variety BU mug 4. An untreated control treatment was maintained for comparison. The marginal benefit-cost ratio of the treatments and the impact of the treatments on the abundance of beneficial arthropods in the experimental plots were recorded. The management approaches did not affect the abundance of beneficial arthropods in the bean field. The findings revealed that the lowest rate of pod infestation (1.9% by n/n and w/w) as well as the highest marketable yield (1.55 MT/ha) and marginal benefit- cost ratio (3.02) were obtained with the foliar spray with Tracer 45 SC (Spinosad) @0.4 g/L of water at 15 days interval. Tracer 45 SC (Spinosad) @ 0.4 g/L of water at 15 day intervals is an effective, suitable, and viable approach for suppressing pod borer complex without harm to beneficial arthropods in the mung bean field. Ann. Bangladesh Agric. (2023) 27 (1): 71-79

Effects of intercropping marigold, cowpea and an insecticidal soap on whiteflies and aphids in organic squash

AbstractThe silverleaf whitefly MEAM1 (Bemisia tabaci) Gennadius (Hemiptera: Aleyrodidae), the cowpea aphid (Aphis craccivora Koch), the green peach aphid (Myzus persicae Sulzer) and the melon aphid (Aphis gossypii Glover) Hemiptera: Aphididae are major insect pests of squash (Cucurbita pepo L.), causing significant yield losses of up to 80% in Florida. We hypothesized that intercropping African marigold (Tagetes erecta L.) and cowpea (Vigna unguiculata L. Walp.) with zucchini squash will encourage an abundance of beneficial arthropods and increase cultural and biological control against these key insect pests by significantly reducing their populations and consequently improve yields. In a 2‐year field experiment, five treatments were evaluated in a randomized complete block design consisting of four replicates. Three diversified cropping treatments were implemented: (1) intercropping squash with marigold, (2) intercropping squash with cowpea, (3) intercropping squash with marigold and cowpea (mixed). These treatments were compared with an organic grower standard insecticide, (4) M‐Pede (potassium salts of naturally derived fatty acids) sprayed on monocropped squash and (5) monocropped squash with no pest management (control). Results indicated that squash intercropped with marigolds accounted for the highest marketable yields. Squash intercropped with cowpea had marginally high yields but attracted the highest densities of aphids. M‐Pede did not increase squash yields, but reduced aphids, whiteflies and associated squash silverleaf (SSL) disorder ratings and showed no deleterious effect on populations of natural enemies. We conclude that a mixture of marigold and cowpea could be used to suppress pests by increasing beneficial arthropod diversity while enhancing marketable yields of organic squash. M‐Pede could be used as a last resort when experiencing high hemipteran pressure.

Influence of Turfgrass Parameters on the Abundance of Arthropods in Sod Farms.

Sod farms, where turfgrass is commercially produced, have a unique system, in which sod is harvested within 2 yr after planting. Understanding the turfgrass factors that influence the abundance of predators, herbivores, detritivores, and parasitoids that inhabit turfgrass paves the foundation for developing effective pest management programs. However, little is known about those factors in sod farms. The objective of the study was to determine the influence of turfgrass height, density, and thatch thickness on abundance of arthropod taxa in sod farms. The study was conducted at 18 and 10 sod field sites in 2019 and 2020, respectively. Four pitfall traps were deployed at each site. In 2019, each site was sampled in May, June, and July, whereas in 2020, each site was sampled in June and August. In 2019, the numbers of predatory heteropterans were two times greater in bermudagrass (Cynodon dactylon L.) than in zoysiagrass (Zoysia spp.). The numbers of predatory mirids, Spanogonicus albofasciatus (Reuter), and carabids significantly decreased with increases in turfgrass height. In 2020, the abundance of staphylinids increased as the thatch thickness increased. The abundance of Sphenophorus spp. adults were significantly greater in bermudagrass than in zoysiagrass in 2020 and were more abundant in the denser turfgrasses in both years. The predatory arthropods were positively correlated with increased densities of cicadellids, whereas predatory mirids were positively associated with cicadellids, delphacids, and chrysomelids. These results have implications on management of arthropod pests in sod farms as abundance of beneficial arthropods are influenced by turfgrass factors.

Sweep netting samples, but not sticky trap samples, indicate beneficial arthropod abundance is negatively associated with landscape wide insecticide use

Abstract Insecticide use and landscape context are major drivers for the abundance of beneficial arthropods, such as predators, parasitoids and pollinators. However, the relative importance of local and landscape‐wide insecticide use is not well understood, and it is unclear to what extent impacts of insecticides on beneficial arthropod populations are moderated by landscape composition. We collected and analysed data on beneficial arthropod abundance and local and landscape‐wide insecticide use across 38 Dutch landscapes. We used regression to study the associations between beneficial arthropod abundance (response), insecticide use and landscape factors. Insects were sampled by sweep netting and yellow sticky traps in field margins (‘sampling sites’) in the summer of 2017 and 2018. We paired organic and conventional sites in the same landscape setting. We used three indicators of insecticide use: management (organic vs. conventional), Treatment Frequency Index of insecticides applied in the field adjacent to the sampling site, and the estimated landscape‐wide average quantity of insecticides applied per ha within a 1 km radius around the sampling site. Abundances of beneficial arthropods in field margins, assessed by sweep netting, were negatively associated with the estimated quantity insecticide applied in the surrounding landscape, while arthropod sampling by sticky traps did not show this relationship. Pollinator abundance was negatively associated with conventional management and with the frequency of insecticide applications in the adjacent field, while predator and parasitoid abundance did not show significant associations with local insecticide use indicators. Negative impacts of insecticide use were not moderated in more diverse landscapes with higher proportions of semi‐natural habitats. Policy implications. Insecticide impacts on arthropod populations extend beyond the fields in which they are used. Awareness of the potential landscape‐wide effects of pesticides, either through drift of pesticides or insect movement, may encourage land managers to adopt practices to reduce insecticide drift and the frequency of insecticide applications, thereby reducing the impacts of landscape‐wide exposure on arthropods that provide services to agriculture. Risk assessments of insecticides and pesticide use regulations need to account for potential spill‐over effects and consider landscape‐scale consequences associated with the source–sink dynamics of arthropods.

Sown Wildflowers Enhance Habitats of Pollinators and Beneficial Arthropods in a Tomato Field Margin.

We evaluated the capacity of selected plants, sown along a processing tomato field margin in central Greece and natural vegetation, to attract beneficial and Hymenoptera pollinating insects and questioned whether they can distract pollinators from crop flowers. Measurements of flower cover and attracted pollinators and beneficial arthropods were recorded from early-May to mid-July, during the cultivation period of the crop. Flower cover was higher in the sown mixtures compared to natural vegetation and was positively correlated with the number of attracted pollinators. The sown Glebionis coronaria, Coriandrum sativum, Anethum graveolens, and Fagopyrum esculentum attracted mainly wild bees, which were the most abundant pollinating insects. In the natural vegetation, Rapistrum rugosum attracted mainly honeybees, while Asteraceae, Convolvulaceae, and Apiaceae species attracted wild bees. Beneficial arthropod abundance and diversity were higher in the sown mixture. Tomato flowers were visited by a small number of wild bees. Their number was not affected by the distance from the field margin, indicating no distraction effect from the sown or natural vegetation flowering plants. Our results suggest that selected flowering plants can improve the field margin habitats for pollinating insects and beneficial arthropods, but more work is needed to elucidate the effect on crop pollination.

Influence of Vineyard Inter-Row Groundcover Vegetation Management on Arthropod Assemblages in the Vineyards of North-Eastern Italy.

Simple SummaryHabitat simplification and use of pesticides in vineyard agro-ecosystems simplified arthropod communities, reducing natural pest control. In this context, habitat management practices could be useful strategies to provide fundamental sources for sustaining natural enemies. The effects of habitat management practices on pests and beneficial arthropods were evaluated in vineyards of North-eastern Italy through different field experiments. We reduced mowing frequency of inter-row spontaneous grasses, compared different timing of mowing of a green manure mixture, and different green manure mixtures. The abundance of key natural enemies (e.g., predatory mites, parasitic wasps and spiders) and some grapevine leafhoppers increased when the grass mowing frequency was reduced. Many beneficial arthropods increased in numbers in organic vineyards. Late mowing of green manure favored spiders and parasitic wasps but not herbivores associated with grapevines. The experiments on the comparison of green manure mixtures did not significantly affect the arthropod communities. Groundcover management practices could enhance beneficial arthropod abundance, but the adoption of this practice should be carefully evaluated when pests occur. In this study, the effects of habitat management practices on both pests and beneficial arthropods were evaluated in vineyards of North-eastern Italy through different field experiments: (1) mowing of inter-row spontaneous grasses in conventional and organic vineyards, (2) different timing of mowing of a green manure mixture, and (3) comparing different green manure mixtures. The first experiment followed a split-plot design, while randomized block design was used in the second and third experiment. In each experiment arthropods were sampled using different methods: leaf sampling, beating and sweep net sampling. Non-mowed spontaneous grasses in inter-rows of vineyards favored the abundance of natural enemies (e.g., predatory mites, parasitic wasps and spiders), and sometimes grapevine leafhoppers. Many arthropod species were recorded in higher numbers in organic vineyards. Late mowing of green manure favored beneficial arthropods (e.g., spiders and parasitic wasps), while it did not influence herbivore density. Groundcover management practices, aimed at increasing plant biodiversity in vineyards, could be a useful tool to enhance beneficial arthropod abundance, although the adoption of this practice should be carefully evaluated when pests occur. Semi-natural areas can contribute to create a more pest-stable agro-ecosystem and should be integrated with appropriate ecological infrastructures surrounding vineyards.

Arthropod Diversity Influenced by Two Musa-Based Agroecosystems in Ecuador

Banana and plantain (Musa spp.) are very important crops in Ecuador. Agricultural production systems based on a single cultivar and high use of external inputs to increase yields may cause changes in the landscape structure and a loss in biodiversity. This loss may be responsible for a decrease in the complexity of arthropod food webs and, at the same time, related to a higher frequency and range of pest outbreaks. Very little is known either about the ecological mechanisms causing destabilization of these systems or the importance of the diversity of natural enemies to keep pests under control. Few studies have focused on this issue in tropical ecosystems. Here, we address this problem, comparing two Musa-based agroecosystems (monocultivar and mixed-species plantations) at two sites in Ecuador (La Maná and El Carmen) with different precipitation regimes. The diversity of soil macro fauna, represented by arthropods, was established, as indicators of the abovementioned disturbances. Our ultimate goal is the optimization of pest management by exploring more sustainable cropping systems with improved soil quality. Arthropod abundance was higher in the mixed system at both localities, which was clearly associated with the quality of the soils. In addition, we found Hymenoptera species with predatory or parasitic characteristics over the pests present in the agroecosystems under study. These highly beneficial species were more abundant at the locality of La Maná. The mixed type of production system provides plant diversity, which favors beneficial arthropod abundance and permits lower agrochemical application without yield penalties in comparison to the monoculture. These findings will help in the design of Musa-based agroecosystems to enhance pest control.

Cover Crops Enhance Natural Enemies While Help Suppressing Pests in a Tea Plantation

Abstract Tea is an economically important crop, consumed by billions of people. Despite the increasing market for pesticide-free products, the use of pesticide in tea is still high. In order to investigate whether intercropping promotes biological control organisms, Chamaecrista rotundifolia (Pers.) Greene, Indigofera hendecaphylla Jacq., Trifolium repens L., and Vigna sinensis (L.) were separately intercropped with free weeding as control in a tea plantation at Yangli, China. Arthropods were collected by taking sweep-net samples, and treatment effects on assemblages were investigated. The combined species richness of all arthropods and that of parasitoids was significantly increased in intercropped treatments while the species richness of herbivores and predators was only greater in C. rotundifolia and I. hendecaphylla intercropped treatments. Compared with control, the combined abundance of all arthropods, and that of herbivores was lower, while the abundance of parasitoids and its taxa was greater in all intercropped treatments. The abundance of predators and its taxa was greater only in tea plantations intercropped with C. rotundifolia or I. hendecaphylla. Of the herbivores, the abundance of Empoasca onukii Matsuda, Sternorrhyncha, Aleyrodidae, and Pentatomidae was greater in the areas intercropped with C. rotundifolia in comparison with the control, but the abundance of Thysanoptera and Geometridae caterpillars was lower. The recorded increase in the abundance of beneficial arthropods may explain the lower abundance of Thysanoptera or Geometridae caterpillars detected in the intercropped tea plantations. Our results indicate that intercropping has the potential to enhance arthropod biodiversity, and to provide an option for sustainable pest control in tea plantations.

Identity and Seasonal Abundance of Beneficial Arthropods Associated with Big Sagebrush (Artemisia tridentata) in Central Washington State, USA.

Big sagebrush (Artemisia tridentata) characterizes and dominates the sagebrush steppe, the largest temperate semi-desert ecosystem in North America. The beneficial arthropod fauna hosted by A. tridentata is poorly known but could be of importance to nearby agriculture seeking to exploit biologically-based pest management. Over four years, we identified and assessed the seasonal abundance of beneficial arthropods (predators, parasitoids, pollinators) associated with A. tridentata during spring to autumn in the Yakima Valley of central Washington using sticky traps. During 2011–2014, 207 sticky traps were placed on non-blooming and blooming A. tridentata plants for a total of 966 trapping days. Overall, across all seasons, we trapped 259.7 beneficial arthropods per trap and 92% of these were parasitoid wasps. Significantly greater numbers of beneficial arthropods were associated with blooming A. tridentata during autumn (410/trap) than non-blooming plants in the spring (181.3/trap) or summer (85.1/trap). Parasitoid wasps and predatory true bugs were most abundant during the autumn, but ladybeetles, lacewings, spiders, bees, and predatory thrips were most common during spring. The association of high numbers of predators, parasitoids, and pollinators with A. tridentata during blooming and non-blooming periods indicates that this plant is an important reservoir of beneficial arthropods in the sagebrush steppe of central Washington. Consequently, biologically-based pest management programs in central Washington may benefit from careful management and retention of A. tridentata plants on crop borders.

Responses of Crop Pests and Natural Enemies to Wildflower Borders Depends on Functional Group.

Increased homogeneity of agricultural landscapes in the last century has led to a loss of biodiversity and ecosystem services. However, management practices such as wildflower borders offer supplementary resources to many beneficial arthropods. There is evidence that these borders can increase beneficial arthropod abundance, including natural enemies of many pests. However, this increase in local habitat diversity can also have effects on pest populations, and these effects are not well-studied. In this study, we investigated how wildflower borders affect both natural enemies and pests within an adjacent strawberry crop. Significantly more predators were captured in strawberry plantings with wildflower borders versus plantings without wildflowers, but this effect depended on sampling method. Overall, herbivore populations were lower in plots with a wildflower border; however, responses to wildflower borders varied across specific pest groups. Densities of Lygus lineolaris (Tarnished Plant Bug), a generalist pest, increased significantly in plots that had a border, while Stelidota geminata (Strawberry Sap Beetle) decreased in strawberry fields with a wildflower border. These results suggest that wildflower borders may support the control of some pest insects; however, if the pest is a generalist and can utilize the resources of the wildflower patch, their populations may increase within the crop.

Interplanting Floral Resource Plants with Vegetable Plants Enhances Beneficial Arthropod Abundance in a Home Garden

We examined whether interplanting vegetable and ornamental flowering plants reduces herbivory and enhances photosynthetic rate, plant growth, natural enemy abundance, and pollinator visitation relative to monoculture plantings. We found no evidence of physiological or growth costs due to growth in polyculture. Herbivore damage to plants did not differ with planting regime. Natural enemies occurred in greater abundance in polycultures compared to monocultures. Pollinator diversity was enhanced in some polyculture plots. We suggest that interplanting vegetable and flowering ornamental plants at small spatial scales may improve plant health and reproduction through natural pest control and a diversified pollinator pool.

Impact of neonicotinoid seed treatment of cotton on the cotton leafhopper, Amrasca devastans (Hemiptera: Cicadellidae), and its natural enemies.

Neonicotinoid seed treatments suppress populations of pest insects efficiently and can enhance crop growth, but they may have negative effects on beneficial arthropods. We evaluated the effects of either imidacloprid or thiamethoxam on the abundances of a sucking pest, the cotton leafhopper (Amrasca devastans), and its arthropod predators under field conditions. We also evaluated the impact of seed treatment on transgenic cotton plant growth, with pests and natural enemies present or absent. Imidacloprid and thiamethoxam reduced pest abundance, with greater effects when dosages were higher. Treatment at recommended doses delayed the pest in reaching the economic damage threshold by around 10-15 days (thiamethoxam) and 20 days (imidacloprid). Recommended doses also enhanced plant growth under all tested conditions; growth is affected directly as well as via pest suppression. Neonicotinoid applications reduced abundance of beneficial arthropods, with lower populations after higher doses, but negative effects of imidacloprid were not apparent unless the manufacturer-recommended dose was exceeded. Imidacloprid applied at the recommended dose of 5 g kg(-1) seed is effective against A. devastans and appears to be safer than thiamethoxam for natural enemies, and also enhances plant growth directly. We caution, however, that possible sublethal negative effects on individual beneficial arthropods were not evaluated. © 2015 Society of Chemical Industry.

Even the smallest non-crop habitat islands could be beneficial: distribution of carabid beetles and spiders in agricultural landscape.

Carabid beetles and ground-dwelling spiders inhabiting agroecosystems are beneficial organisms with a potential to control pest species. Intensification of agricultural management and reduction of areas covered by non-crop vegetation during recent decades in some areas has led to many potentially serious environmental problems including a decline in the diversity and abundance of beneficial arthropods in agricultural landscapes. This study investigated carabid beetle and spider assemblages in non-crop habitat islands of various sizes (50 to 18,000 square metres) within one large field, as well as the arable land within the field, using pitfall traps in two consecutive sampling periods (spring to early summer and peak summer). The non-crop habitat islands situated inside arable land hosted many unique ground-dwelling arthropod species that were not present within the surrounding arable land. Even the smallest non-crop habitat islands with areas of tens of square metres were inhabited by assemblages substantially different from these inhabiting arable land and thus enhanced the biodiversity of agricultural landscapes. The non-crop habitat area substantially affected the activity density, recorded species richness and recorded species composition of carabid and ground-dwelling spider assemblages; however, the effects were weakened when species specialised to non-crop habitats species were analysed separately. Interestingly, recorded species richness of spiders increased with non-crop habitat area, whereas recorded species richness of carabid beetles exhibited an opposite trend. There was substantial temporal variation in the spatial distribution of ground-dwelling arthropods, and contrasting patterns were observed for particular taxa (carabid beetles and spiders). In general, local environmental conditions (i.e., non-crop habitat island tree cover, shrub cover, grass cover and litter depth) were better determinants of arthropod assemblages than non-crop habitat island size, indicating that the creation of quite small but diversified (e.g., differing in vegetation cover) non-crop habitat islands could be the most efficient tool for the maintenance and enhancement of diversity of ground-dwelling carabids and spiders in agricultural landscapes.

Epigeal arthropod communities in intensively farmed landscapes: Effects of land use mosaics, neighbourhood heterogeneity, and field position

Trophic guilds of epigeal arthropods regulating insect pest populations may be affected by factors acting across spatial scales. Although the influence of landscape factors associated with farming effects on arthropod assemblages has received increasing attention in the last decades, most research was carried out in fine-grain landscapes by comparing conventional and organic cropping systems. Here, we aimed at identifying the role of fencerows and crop heterogeneity in defining arthropod diversity in intensively farmed, coarse-grain landscapes. Hence, we developed a multi-scale heterogeneity approach based on fitting linear-mixed models to elucidate the effects of three spatial scales (local, neighbouring crop types, and landscape) on arthropod diversity. Mixed models were fitted to arthropod data obtained by pitfall trap samplings in 22 field pairs. Field position was a major determinant of arthropod species diversity at local scale, due to the contrasting disturbance regimes of fencerows and adjoining field edges. Fence density at landscape scale contributed to retain diverse arthropod assemblages in farmland mosaics by supplying habitats and refuges. In addition, extended fence network may function as corridors for dispersal, increasing connectivity between dissimilar habitats. Fence habitats, as well as their density in the landscapes, enhance both richness and abundance of beneficial arthropods. Our findings indicate that the overall arthropod diversity was benefited by landscape complexity, being the presence and density of fencerows key landscape attributes. Contrasting disturbance regimes at different field positions emerged as a major driver modulating arthropod species diversity in intensively managed farmland mosaics. Non-cropped habitats associated with fencerows and field margins play key ecological functions that are of vital importance for providing ecosystem services in agro-ecosystems. Complex landscapes may help to conserve overall plant diversity in agro-ecosystems, as well as the spillover of arthropod species from fencerows towards crop fields. Even in heavily intensified landscapes, where crop diversity is the main source of heterogeneity, promoting measures intended for both restoring and managing fencerow and non-cropped habitats through landscape planning will contribute to maintain arthropod richness (almost 70% of total richness) across the entire landscape.

A comparison of arthropod abundance and arthropod mediated predation services in urban green spaces

Abstract The need to conserve biodiversity and ecosystem services in urban landscapes is widely recognised, yet specific planning and design strategies that promote conservation in urban areas are limited. Little is known about the ability of different types of urban green spaces to support biodiversity and provide ecosystem services. In this study, we compared the abundance of beneficial arthropods (predators and bees) and measured predation services in two different types of green space, areas of turf and prairies. Beneficial arthropods and predation services were measured three times during the 2011 field season in six Chicago (IL, USA) parks that contained both turf and prairie. Using a repeated measures analysis, we found bee abundance was significantly higher in the prairie compared to turf by August, and predator abundance was higher in the prairie throughout the summer. While predation services were not significantly different between the turf and prairie in June, predation steadily increased in the prairie over the course of the summer with significantly higher rates of predation by August. Of the predators measured, spiders were positively correlated with prairie habitat and negatively correlated with the survival of pest insects. We found turf and prairie differentially supported beneficial arthropod abundance and ecosystem services, suggesting the type of green space incorporated into urban areas may be an integral component to expanding the conservation potential of urban landscapes.

Insecticide drift and its effect on Kampimodromus aberrans (Oudemans) in an Italian vineyard-hedgerow system

When a pesticide is applied in a vineyard, the fraction can drift away from the target and affect the abundance of beneficial arthropods in adjacent crops or hedgerows. A field experiment was conducted in north-eastern Italy using an air-assisted sprayer in order to evaluate the spatial distribution of etofenprox drift in a vineyard-hedgerow system and its effect on the predatory mite Kampimodromus aberrans. Three scenarios of decreasing potential drift were compared, all in still wind conditions. In the worst case of free expansion of drift, 12% of the applied rate drifted for 6–7 m with minor effect on K. aberrans abundance, according to the dose–response assay results; the presence of a hedgerow reduced the drift by about 80%. The hedgerow was also effective when good agronomic practices were followed, and the effect of drift on K. aberrans was not significant, its abundance being mainly linked to the patchiness of the natural population. Because of lateral drift, i.e. not in the direction of air-flow from sprayer, spray was detected at very low concentration in the contiguous untreated vineyard. This had no effect on K. aberrans but had the capacity to contaminate organic crops and provide a risk to surface water and bystanders. This suggests that an environmental regulatory scheme taking hedgerows into account should be supported and implemented on a catchment or regional scale.

Impact of four turf management regimes on arthropod abundance in lawns

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. 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. 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.

Are arthropod communities in cotton really disrupted? An assessment of insecticide regimes and evaluation of the beneficial disruption index

Abstract Non-selective chemical control of crop pests disrupts beneficial insects and spiders. For Australian cotton crops, a beneficial disruption index (BDI) has been developed that ranks the impact of different insecticides on beneficial arthropods. To evaluate this index as a measure of natural enemy disruption, the abundance of beneficial arthropods was monitored in ten conventional and nine INGARD ® Bt cotton fields on ten commercial farms during the 2001–2002 season. Beneficial insects were more abundant in those fields subjected to a more selective insecticide regime (low BDI) than in fields that received broad-spectrum insecticide treatments (high BDI). However spider abundance did not change in relation to insecticide regime. Family composition of spider communities was affected by BDI and crop type (Bt or conventional), whereas family composition of insect communities only showed a trend to be affected by BDI and crop type. This difference may indicate that insects are more uniformly affected by the BDI than spiders. The beneficial disruption index is an effective measure of insecticide impacts on beneficial insects in Australian cotton crops.

Abundance of Beneficial Arthropods on Woody Landscape Plants at Professionally-Managed Landscape Sites

Abstract Eight 0.2–0.4 ha (0.5–1.0 A) sites managed by landscape professionals were monitored biweekly for beneficial arthropod activity. More than 30 generalist predator taxa were identified. Spiders and green lacewings were the most numerous taxa and both were found on all plant taxa sampled. Green lacewings, especially the egg stage, were the most numerous natural enemies detected on birch, crape myrtle, cherry, and oak trees accounting for 52.5, 49.9, 43.5, and 38.1%, respectively. Spiders accounted for 56.2% of the insectivorous arthropods observed on magnolia and were the most abundant predatory arthropod on azaleas comprising 46.5% of all arthropod predators/parasites across all properties. The most abundant predatory arthropods on junipers were spiders accounting for 75.5% of the beneficials encountered with ants (associated with an early season aphid outbreak), green lacewing larvae, lady beetles, harvestmen, and parasitic wasps comprising 15.8, 0.4, 4.3, 0.4, and 1.2%, respectively. Spiders were the most abundant predators on boxwood accounting for 70.6% of the natural enemies.