Beetle Density Research Articles

Species Enriched Grass–Clover Pastures Show Distinct Carabid Assemblages and Enhance Endangered Species of Carabid Beetles (Coleoptera: Carabidae) Compared to Continuous Maize

There is an urgent global need for the ecological intensification of agricultural systems to reduce negative impacts on the environment while meeting the rising demand for agricultural products. Enriching grasslands with floral species is a tool to promote diversity and the associated services at higher trophic levels, and ultimately, to enhance the agricultural landscape matrix. Here, we studied an organic pastures-based dairy production system with plant species enhanced grass–clover pastures with respect to the effect on the activity density, functional traits, carabid assemblages, and species richness of carabid beetles. To understand the effect of land management on carabid beetles, we studied two types of grass–clover pastures with low and relatively high plant diversities in an integrated crop–livestock rotational grazing system (ICLS). As a comparison, organic permanent grasslands and conventionally managed maize were studied. We installed pitfall traps for three weeks in early summer, and for two weeks in autumn. In total, 11,347 carabid beetles of 66 species were caught. Grass–clover pastures did not differ in activity density, functional traits, habitat guilds, or species richness, but conventional maize did show a higher activity density in autumn and a higher proportion of eurytopic species and mobile species compared to grass–clover pastures. On grass–clover pastures, we found more endangered species, Carabus beetles, and a distinct carabid assemblage compared to maize. However, we attribute the lack of an effect of increased plant diversity of the grass–clover pastures on carabid species richness and functional traits to the intensive grazing regime, which resulted in the compositional and structural homogeneity of vegetation. Still, the presence of specialized and endangered species indicated the potential for organically managed grass–clover pastures to promote dispersal through an otherwise depleted and fragmented agricultural landscape. By increasing crop diversity in ICLS, more resources for foraging and nesting are created; therefore, organically managed grass–clover pastures add to the multi-functionality of agricultural landscapes.

Apparent niche differences between native and exotic lady beetles

Generalist predators can enhance biological control by filling unique niches and complementing other natural enemies, or disrupt it by preying upon other predators and parasitoids, complicating their net value for biological control. We searched for evidence of complementarity and/or interference between native (primarily Eriopis chilensis and E. eschscholtzi) and exotic (primarily Hippodamia variegata and Harmonia axyridis) lady beetles attacking aphids in alfalfa (Medicago sativa) fields near Santiago, Chile. Across 60 fields and three growing seasons, exotic lady beetle adults and larvae reached peak abundance relatively earlier in the growing season than the natives. Furthermore, exotic lady beetle peaks aligned more closely with aphid peak abundance than did native lady beetle peaks. Abundances of native lady beetle adults and larvae were weakly positively correlated with those of exotics, and peak aphid densities were generally lowest in fields where native and non-native lady beetle adults were similarly abundant. Therefore, we did not see evidence of strong interference between exotics and natives. Natural-agricultural habitat edges reduced native, but not exotic, larval lady beetle lag behind aphid peaks and was associated with greater lady beetle and lower aphid densities. Moreover, farms embedded in landscapes with greater natural habitat cover supported more exotic, but not native, lady beetles, and increased the lag between larval lady beetles and aphids for natives but not exotics. These findings support the idea that farms embedded within mosaics of natural and agricultural habitats may provide greater interaction potential between native lady beetles and aphid pests on farms as they move across the landscape, leading to greater top-down control. In contrast, exotic lady beetle lags were unaffected by landscape composition or configuration, but their greater densities in farms surrounded by more natural habitats might reflect a 'concentration effect' whereby exotic lady beetle abundance becomes concentrated in the agricultural habitats that they prefer. Our findings suggest that some lady beetles introduced for biocontrol may be better adapted to intensively managed habitats than natives, possibly leading to spatiotemporal complementarity between native and exotic lady beetles.

Varietal preference and efficacy of various chemicals against red pumpkin beetle (Aulacophora foveicollis L.) (Coleoptera: chrysomelidae) in different cucumber (Cucumis sativus) cultivars

Experiments were conducted to determine the resistance level of different cultivars and study the efficacy of various synthetic insecticides against red pumpkin beetle (Aulocohphora foveicollis) at the New Developmental Malakandir Farm, the University of Agriculture Peshawar, during 2018. In the first experimental trial, data were collected on the mean population density of red pumpkin beetle on three cultivars (Desi, Super Green and Madam-560) of cucumber crop. While in the second experiment, three insecticides (Carbaryl, Cypermethrin, Malathion) and an Untreated/Control were used to study the effect of these insecticides on Desi (susceptible) and Madam 560 (resistant) cultivars regarding red pumpkin beetle on cucumber cultivar. Randomized Complete Block Design (RCBD) was used in this experiment. The data on the relevant parameters were recorded at weekly intervals for eleven (1st experiment) and four weeks (2nd experiment) i.e., till termination of the experiments. During first experiment, it was observed that significantly lowest population density of red pumpkin beetle (0.82) per plant and highest yield (8981.3 kg ha-1) was observed from Madam 560, while significantly highest mean population density of red pumpkin beetle (4.06) per plant and lowest yield (7313.7 kg ha-1) was obtained from Desi cultivar. Significantly maximum mean number of red pumpkin beetle plant-1 was recorded in the seventh week (29 May) from Desi, Super Green and Madam 560 cultivars with 6.41, 4.50 and 1.62 beetle plant-1, respectively. During the cropping season, mean population density of red pumpkin beetle plant-1 reached its peak in the seventh week (29 May). After 7th week, a gradual decline was occurred in the mean population density of red pumpkin beetle plant 1. In second experiment, lowest mean population density of red pumpkin beetle adults plant-1 (0.12), area of consumption (3.12 mm2), percentage weight loss (1.60 %) and highest yield (21555 kg ha-1) was recorded from Madam 560 treated with Carbaryl, while highest mean population density of red pumpkin beetle adult plant-1 (7.09), area of consumption (36.11 mm2), percentage weight loss (17.27%) and lowest yield (7247 kg ha-1) was recorded from untreated Desi cultivar. It was followed by untreated Madam 560 cultivar where 5.40, 25.92 mm2, 13.20% and 8766 kg ha 1. Madam 560 is significantly better cultivar than Super Green and Desi, as this cultivar results in lowest population density of red pumpkin beetle and highest yield of cucumber fruit. Carbaryl is significantly better as compared to Malathion and Cypermethrin because it reduces the population of red pumpkin beetle.

Monitoring of the spread and development of pests and diseases in sugar beet stands

Goal. To determine the spread and development of pests and diseases in sugar beet crops and their threat to crop plants.
 Methods. Analysis of the reports of regional forecasting and signaling laboratories of the State Vetphytosanitary Service of Ukraine and the results of own observations conducted at research and breeding stations of the Institute of Bioenergy Crops and Sugar Beet of the National Academy of Sciences of Ukraine and beet farms of Ukraine regarding the prevalence and development of phytophages and pathogens, their reservation in agrocenoses. Determination of the threat from them to crops according to the Methodology of research in entomology and phytopathology and the Methodology of conducting research in beet growing.
 Results. It was established that certain types of pests have a significant reservation in agrocenoses and other stations and annually threaten sugar beet crops in various beet harvesting zones. In particular, from year to year, the greatest danger to crop seedlings and plants during their growing season is caused by beetles of the common beet weevil Asproparthenis punctiventris (Bothynoderes punctiventris Germ.), the number of which significantly exceeds the economic threshold of its harmfulness. Among other types of harmful insects that annually threaten sugar beet crops, the gray beet weevil (Tanymecus palliates F.), beet fleas (Chaetocnema sp.), shieldworms (Cassida sp.), stem weevil (Lixus sultilis Beh.) will be dangerous in future years.), the number of which varies within the thresholds of their harmfulness. Regarding diseases, there is still a threat of significant damage to culture plants by cercospora (Cercospora beticila Sacc.), fomosis (Phoma betae Frank), powdery mildew (Erysiphe communis (Wallr Grev f.betae Jacz.)), and others. In particular, according to observations, cercosporosis is gaining pace of intensive development due to favorable weather conditions, so we recommend farms to take measures to reduce plant damage. Precipitation, which passes through centers at the end of summer in most regions of Ukraine, can lead to significant susceptibility of root crops to various types of rot, which can also lead to a decrease in crop yield and quality deterioration.
 Conclusions. In recent years, favorable conditions have been created in Ukraine for the development and spread of many types of pests and diseases in sugar beet crops, which leads to an increase in their harmfulness compared to previous seasons. In particular, the population density of beetles of the common beet weevil was 2—18 specimens/m2, which is ten times higher than the standard. The same applies to other pests and diseases, a significant reserve of which may threaten crops in the coming year.

Differences in arthropod communities between grazed areas and grazing exclosures depend on arthropod groups and vegetation types

Livestock grazing is one of the most common management practices for grasslands and can greatly affect their biodiversity. However, arthropod diversity response patterns to grazing regimes are difficult to predict. We conducted a short-term grazing exclusion experiment in traditionally managed alkali grasslands in Hungary to investigate differences between grazed and ungrazed vegetation for different arthropod groups. The experiment was laid out in a full factorial design, with twelve 50 × 100 m short-term grazing exclosures in vegetation types with high (alkali wet meadow) and low productivity (alkali steppe). We sampled ground beetles and spiders with pitfall traps and true hoppers by sweep netting. We used vegetation type (wet meadow vs dry steppe), management (grazed vs ungrazed) and their interaction as fixed effects in mixed models. We found higher species richness and activity density of spiders and ground beetles in the more productive wet meadow vegetation, where the community structure of each arthropod group also shifted toward hygrophilous species. Significant interactions between vegetation type and management indicated a dependence of management effects on vegetation types: arthropod community structure shifted towards hygrophilous species in ungrazed meadows, but not in ungrazed steppe sites. True hopper abundance was higher in grazed meadow sites, but lower in grazed steppe sites, compared to ungrazed sites. True hopper community structure shifted toward generalist herbivores in ungrazed sites, regardless of vegetation type. We concluded that vegetation types determine arthropod communities and modulate the effects of grazing on arthropods. Our results suggest that moderate disturbance from low-intensity grazing has a positive or neutral effect in wetter, more productive vegetation, but a negative or neutral effect in drier, less productive vegetation, depending on the arthropod group. Herbivorous insects that dwell on plants are particularly affected by management because they are more susceptible to direct impacts, such as unintentional predation by grazing cattle, and because of asymmetrical competition between mammalian and insect herbivores.

Does IPPM bear fruit? Evaluating reduced‐risk insecticide programmes on pests, pollinators and marketable yield

Abstract Integrated pest and pollinator management (IPPM) has been touted as a novel approach to control pests while mitigating negative effects of insecticides on pollinators. In addition to non‐chemical approaches, IPPM programmes focus on insecticide treatments with low bee toxicity, threshold‐based applications and restricted timings to avoid sprays during pollinator foraging. However, the singular and combined effect of this approach on pollination services and pest management is understudied and generally lacks field validation. In two field studies, we evaluated the effect of IPPM insecticide programmes on striped cucumber beetle (Acalymma vittatum) management, pollination and watermelon yield. The first trial (2020) featured insecticide treatments representing a factorial combination of (1) products varying in bee toxicity (bifenthrin, cyclaniliprole and acetamiprid), (2) application frequencies (weekly vs. threshold‐based) and (3) application timings (AM vs. PM), as well as an untreated control. These data were then used to inform a second trial (2021) that applied two insecticide treatments (IPPM based or grower standard) to commercial‐scale (20–30 acres) fields in collaboration with regional watermelon farms. Weekly beetle densities, pollinator visitation and yield data were collected to determine programme efficacy. Overall, beetle infestations were successfully managed with all insecticide treatments, none of which compromised marketable yield. In 2020, threshold‐based insecticide programmes offered statistically similar levels of pest control but required 20%–80% fewer applications compared to a weekly programme. Furthermore, pollinator visitation was increased in threshold‐based programmes by ~42% across all products. The on‐farm validation trial in 2021 upheld these findings; IPPM fields had effective beetle control but with 1–7 fewer insecticide applications compared to grower standard fields. IPPM fields also had 62% greater pollinator visitation and 49% more melons during harvest compared to grower standard fields. Synthesis and applications. Our study demonstrates the capacity of IPPM programmes to manage pests while mitigating negative effects on pollinators. In particular, administering insecticide applications by pest thresholds led to the greatest enhancement in pollinator function. These findings also suggest that growers can benefit from this approach with reduced insecticide costs while encouraging pollination in pollinator‐dependent crops.

Rainforest conversion to smallholder cash crops leads to varying declines of beetles (Coleoptera) on Sumatra

AbstractSoutheast Asian arthropod biodiversity is in rapid decline, but the variability of responses within taxa has received little attention. Using canopy fogging, we collected ~50,000 beetles (Coleoptera) in (1) lowland rainforest, (2) jungle rubber (rubber agroforest), and smallholder monoculture plantations of (3) rubber and (4) oil palm in Sumatra, across two landscapes and seasons. On average, beetle abundance was more than 50%, and biomass over 75%, lower in rubber and oil palm plantations than in rainforest and jungle rubber. This pattern was influenced by landscape and season. Abundance and biomass declines were similar in Chrysomelidae, Elateridae, and Staphylinidae, but differed in Curculionidae, which were most abundant in oil palm due to the introduced oil palm pollinator Elaeidobius kamerunicus. Across beetle families, species richness in monocultures was reduced by at least 70% compared to rainforest, with beetle richness in jungle rubber being similar to rainforest. Community composition in oil palm plantations differed markedly from the other land‐use systems for Chrysomelidae and Curculionidae, but less for Elateridae and Staphylinidae. Turnover contributed more to overall beta diversity than nestedness for all families and land‐use systems. Likely undersampling of the beetle community in rainforest suggests that declines of beetle density and diversity are much more severe than reported here, especially for beetle families with many concealed species, such as Staphylinidae. This study provides first evidence that negative responses of beetles to tropical land‐use change vary among families, and is the first report of its kind from heavily understudied Sumatra.Abstract in Indonesia is available with online material.

Estimation of crop losses in Cajanus cajan (L.) Millsp. and Vigna radiata (L.) Wilczek caused by blister beetle, Mylabris pustulata Thunberg (Coleoptera: Meloidae)

Losses caused by Mylabris pustulata Thunberg in pigeonpea and mungbean at various beetle densities were assessed under net house/caged and field conditions. The observations revealed that the blister beetle caused considerable crop losses to both the pigeonpea and mungbean crops as under net house conditions, M. pustulata Thunberg at 200 beetles/cage caused the maximum reduction of 54.18, 20.15 and 64.88 per cent in pod setting, seed setting and grain yield in pigeonpea, respectively. Similarly, in mungbean, M. pustulata Thunberg at 4 beetles/cage caused maximum reduction up to 67.14, 26.65 and 75.29 per cent in pod setting, seed setting and grain yield, respectively. However, under unprotected conditions, 46.77 and 35.90 per cent of yield losses were recorded in pigeonpea and mungbean, respectively as compared to 0% under protected conditions. Thus, justifying that M. pustulata Thunberg is a major threat to both pulse crops and needs to be managed efficiently to avoid the significant crop losses caused by it.

Determining the Effect of Different Reproduction Factors on the Yield and Hatching of Tenebrio Molitor Eggs.

Simple SummaryThis study investigated the effect of various factors on the reproduction of the yellow mealworm Tenebrio molitor. More specifically, the effect of (1) the use of a grid, (2) oviposition duration, (3) age of the beetles and (4) beetle density were examined. For these parameters, it was investigated how they influence the number of eggs laid per beetle as well as the egg hatching rate and time. All these factors had a clear impact on the number of eggs. The results of this study will help producers to optimize their breeding method in order to obtain higher yields.Whereas the production of conventional livestock can rely on years of knowledge and experience, the mealworm production industry is still in its early stages. Although the yellow mealworm Tenebrio molitor has been cultivated as feed for pets and zoo animals for quite some time, the optimization of the reproduction process has not been widely explored. For reproduction, beetles are placed in crates supplemented with a substrate to oviposit their eggs. After a specified time, the beetles are removed, and the eggs are further cultivated to develop into larvae. Factors such as oviposition duration and beetle density influence the number of produced mealworms per beetle, partly due to the cannibalistic behavior of the beetles. However, reproductive success has mostly been assessed by determining the number of offspring several weeks after oviposition. As a result, the number of eggs laid and their hatch rates are unknown. In this research, eggs are separated from the oviposition substrate, i.e., harvested. This approach allows to determine the influence of beetle density, oviposition duration, beetle age and the use of a grid during oviposition on the number of eggs produced and the egg hatching rate and timing thereof. In addition, the influence of the harvesting method on the hatching of T. molitor′s eggs was determined.

Susceptibility assessment and mapping of Ips typographus (L.) (Coleoptera: Curculionidae) in oriental spruce forests in Artvin, Turkey

AbstractIps typographus, which was first identified in 1984 in the oriental spruce forests of Artvin, Turkey, has killed millions of cubic metres of trees. Severe outbreaks of I. typographus following storms resulting in fallen trees and salvage logging done as a part of control activities have caused gaps in the stand canopy of oriental spruce forests. These forests, which have many important functions, such as supplying water, soil conservation and preventing natural disasters in the area they spread, have a fragmented structure because of beetle damages and various traditional utilization practices of the local community. In this study, the local spread of I. typographus in the forests of Hatila Valley National Park and the neighbouring Taşlıca Forest Sub‐District was evaluated, and the areas susceptible to the beetle were determined using the frequency ratio method. A total of 120 pheromone traps were employed in the study. A beetle density map of the study area was produced using the inverse distance weighting interpolation method based on the total number of beetles caught by the traps. Then, the correlation between the regions with high I. typographus density and environmental factors that contributed to this situation were determined using the frequency ratio method. An average 6528.70 beetles were caught by the pheromone traps as a result of this study. The density of the beetles was high in 60.64% of the study area, and an average 10,844.25 beetles were caught by the pheromone traps in these areas. The difference in the total number of beetles between areas with high beetle density and those with low or medium beetle density was significant. It was determined that 32.53% of the study area had very high or high susceptibility to I. typographus. Different parameters such as altitude, slope, aspect, distance to forest roads, stand type, topographic wetness index and area solar radiation were found to be associated with the susceptibility of an area to I. typographus.

Varietal preference and efficacy of various chemicals against red pumpkin beetle (Aulacophora foveicollis L.) (Coleoptera: Chrysomelidae) in different cucumber (Cucumis sativus) cultivars

Experiments were conducted to determine the resistance level of different cultivars and study the efficacy of various synthetic insecticides against red pumpkin beetle (Aulocohphora foveicollis) at the New Developmental Malakandir Farm, the University of Agriculture Peshawar, during 2018. In the first experimental trial, data were collected on the mean population density of red pumpkin beetle on three cultivars (Desi, Super Green and Madam-560) of cucumber crop. While in the second experiment, three insecticides (Carbaryl, Cypermethrin, and Malathion) and an Untreated/Control were used to study the effect of these insecticides on Desi (susceptible) and Madam 560 (resistant) cultivars regarding red pumpkin beetle on cucumber cultivar. Randomized Complete Block Design (RCBD) was used in this experiment. The data on the relevant parameters were recorded at weekly intervals for eleven (1st experiment) and four weeks (2nd experiment) i.e. till termination of the experiments. During first experiment, it was observed that significantly lowest population density of red pumpkin beetle (0.82) per plant and highest yield (8981.3 kg ha-1) was observed from Madam 560, while significantly highest mean population density of red pumpkin beetle (4.06) per plant and lowest yield (7313.7 kg ha-1) was obtained from Desi cultivar. Significantly maximum mean number of red pumpkin beetle plant-1 was recorded in the seventh week (29 May) from Desi, Super Green and Madam 560 cultivars with 6.41, 4.50 and 1.62 beetle plant-1, respectively. During the cropping season, mean population density of red pumpkin beetle plant-1 reached its peak in the seventh week (29 May). After 7th week, a gradual decline was occurred in the mean population density of red pumpkin beetle plant-1. In second experiment, lowest mean population density of red pumpkin beetle adults plant-1 (0.12), area of consumption (3.12 mm2), percentage weight loss (1.60%) and highest yield (21555 kg ha-1) was recorded from Madam 560 treated with Carbaryl, while highest mean population density of red pumpkin beetle adult plant-1 (7.09), area of consumption (36.11 mm2), percentage weight loss (17.27%) and lowest yield (7247 kg ha-1) was recorded from untreated Desi cultivar. It was followed by untreated Madam 560 cultivar where 5.40, 25.92 mm2, 13.20% and 8766 kg ha-1. Madam 560 is significantly better cultivar than Super Green and Desi, as this cultivar results in lowest population density of red pumpkin beetle and highest yield of cucumber fruit. Carbaryl is significantly better as compared to Malathion and Cypermethrin because it reduces the population of red pumpkin beetle.

Факторы, оказывающие влияние на численность и пространственное распределение жужелиц (Coleoptera, Carabidae) в агроценозах с разным уровнем интенсификации агротехнологий

This paper describes the results of data analysis on species composition and population of ground beetles (Coleoptera, Carabidae) in agrocenoses of spring wheat and corn at different levels of intensification in the forest-steppe of Western Siberia in the period of 2019-2021. The research was aimed at identifying correlating factors with the abundance of ground beetle communities and assessing their significance. The data analysis methods were specified with regard to the peculiarities of the structure and nature of the initial data distribution. Analysis of the population dynamics was performed for 20 species common and abundant for all agrocenoses (represented by dominants and subdominants). A position of the crop in the crop rotation was a significant factor for the agrocenoses of spring wheat, given that the distance from the steam increases the total biomass of vegetation due to weeds, as well as the number of pests, which probably forms more favorable conditions for the activity of ground beetles. Another correlation was also established between the index of dynamic density of ground beetles in wheat crops and the sum of active temperatures (t>5 ºC), revealing the significant role of heat supply for poikilothermic organisms. The correlation between the index of dynamic density of ground beetles and the vegetation index NDVI values in corn pointed to the features of microclimate formation, given the biology of corn and the ability to build up a large volume of biomass already by mid-summer. No significant correlation between the technology of cultivation (level of intensification) and the dynamic density of ground beetles in agrocenoses was found. Therefore, the level of intensification (the use of crop protection agents and fertilizers regulated by the cultivation technology) does not have a significant effect on the number of ground beetles in the crops. Keywords: GROUND BEETLES, SPECIES DIVERSITY, COMMUNITY STRUCTURE, COMMUNITY DYNAMICS, AGROCENOSIS, INTENSIFICATION OF AGRICULTURAL TECHNOLOGY

Strip intercropping of wheat and oilseed rape enhances biodiversity and biological pest control in a conventionally managed farm scenario

Abstract Conventional agriculture in the global north is typically characterized by large monocultures, commonly managed with high levels of pesticide or fertilizer input and mechanization. Strip intercropping, that is, diversifying cropland by growing strips of different crops using conventional machinery, may be a viable strategy to promote natural predator diversity and associated biological pest control in such conventional farming systems. We tested the influence of strip intercropping of conventionally managed winter wheat with oilseed rape, using common machinery with 27–36 m broad strips, on arthropod predator diversity and biological pest control. We characterized spider and carabid beetle communities, calculated pest aphid and pollen beetle densities and recorded parasitism rates for both crops (number of mummified aphids on wheat and number of parasitized pollen beetle larvae on oilseed rape). We observed a significant reduction in the densities of wheat aphids (50% decrease) and pollen beetle larvae (20% decrease) in strip intercropping areas compared to monocultures. Parasitism rates of wheat aphids increased significantly from 10% in monocultures to 25% in strip intercropping areas. The number of parasitized pollen beetle larvae did not show the same pattern but was higher towards the centre of the oilseed rape strip. Overall, the composition of predator communities benefited from the close neighbourhood of the two crop species in the strips, as carabid beetles were more abundant in oilseed rape and spiders were more abundant in wheat fields. Overall, strip intercropping reduced the dominance of one predator group and allowed for an equal representation of both spiders and carabid beetles in the mixture. Synthesis and applications. Our study presents evidence of the benefits of adopting strip intercropping with relatively large strips (adapted to existing machinery) for natural predator diversity and biological pest control in a large‐scale conventionally managed farm scenario. Wheat–oilseed rape strip intercropping reduced pest densities, increased parasitism of wheat aphids and promoted equal representation of natural predator groups well beyond the areas of monoculture. Overall, by reducing the area dedicated to only one crop, the implementation of strip intercropping adapted to mechanized agricultural scenarios can be used to increase crop heterogeneity at regional scales and enhance biodiversity and biological control, even in simplified landscapes dominated by large‐scale conventional agriculture.

The impact of maize-bean intercropping on insect biodiversity

Intensive agriculture is one of the main reasons for recent insect declines. This loss of biodiversity has created the need to develop methods of intensive cultivation that combine high yields with biodiversity conservation. One promising method in maize cultivation is intercropping with beans. The objective of this study was to determine whether maize-bean intercropping could increase insect biodiversity. We examined the activity density, species richness and Shannon diversity of bees and carabid beetles in pure and intercropped maize under both organic and conventional management. We collected carabid beetles using pitfall traps and bees by doing transect walks. The study was carried out in an agricultural landscape, on a set of 17 study sites. We found that intercropping leads to significant increases in bumblebee and honeybee activity as well as in bee species richness. Differences between pure and intercropped maize were dependent on the year of data acquisition and the management style. Solitary wild bee species activity was not significantly affected. Carabid activity density and carabid species richness also did not differ significantly between the cropping systems. We conclude that maize-bean intercropping can contribute to insect biodiversity conservation but its contribution is limited to bumblebees. Despite its relatively low contribution per hectare, maize-bean intercropping could have a surprisingly positive impact, as maize now covers large areas of German farmland. Potential exists to increase the biodiversity value of maize intercropping even further by using varied plant mixes. Our results strongly encourage further research in this direction.

Arthropod overwintering in agri-environmental scheme flowering fields differs among pollinators and natural enemies

Arthropod diversity in agricultural landscapes is important to maintain numerous ecosystem services. Most arthropods, however, need shelter habitats for overwintering embedded in agricultural landscapes. Habitats created by perennial agri-environmental schemes (AES) such as flowering fields can provide such overwintering places in addition to nesting sites and food resources. However, it is unclear, to which extent arthropods use such flowering fields for overwintering. We assessed the emergence of six functionally relevant arthropod groups (wild bees, hoverflies, wasps, carabid beetles, staphylinid beetles and spiders) with emergence cages on wheat fields and on four types of flowering fields differing in temporal continuity (age and time since last soil disturbance). Wild bee richness and abundance was highest in flowering fields that had undergone soil disturbance in the previous year while recent soil disturbance was clearly detrimental. Natural enemies were mostly unaffected by temporal continuity and hoverflies emerged most abundantly from wheat fields. Carabid beetle richness and densities of carabid and staphylinid beetles were positively affected by recent soil disturbance while hoverfly densities were negatively affected. Further assemblage composition of emerging wild bees and carabid beetles differed between habitat types. Our results indicate that most natural enemies overwinter even in flowering fields with low temporal continuity and recent soil disturbance while wild bees need habitats of higher temporal continuity for overwintering. We thus propose a mix of flowering habitats with different degrees of temporal continuity embedded in the agricultural landscape to make AES more effective towards the provisioning of overwintering sites for ecosystem service providers. We conclude that a better understanding of the overwintering ecology of different arthropod groups is required to counteract current biodiversity decline in agricultural landscapes.

The concurrent assessment of agronomic, ecological and environmental variables enables better choice of agroecological service crop termination management

Abstract Although organic farming was originally promoted as an alternative farming system to address agronomic, environmental and ecological issues, its conventionalisation has led to an intensification and specialisation of production. In the light of this, several studies have questioned the environmental benefits of organic farming as well as its agronomic viability. Thus, there is a need to improve organic vegetable systems to reduce their environmental impact without affecting their productivity. To tackle this challenge, European farmers and researchers have recently started to focus on agroecological service crops (ASCs). However, few studies have simultaneously evaluated the agronomic, environmental and ecological aspects of ASC management under different European pedo‐climatic conditions. We evaluated effects of the ASC management strategies—no‐till roller crimping (NT‐RC) and green manuring (T‐GM) on cropping system performance using agronomic, environmental and ecological indicators—to exemplify the need for multidimensional analysis to understand management implications for addressing environmental and agronomic challenges. We combined the results from 11 organic vegetable field trials conducted in seven European countries over a period of 2 years to test for general trends. Our results provide solid evidence that NT‐RC management across different pedo‐climatic conditions in Europe enhances the activity density of ground and rove beetles and improves both the potential energy recycling within the system and weed control. However, in NT‐RC plots, lower cash crop yield and quality, energetic efficiency of production and activity density of spiders were observed compared to T‐GM. Synthesis and applications. Multidimensional analyses using agronomic, environmental and ecological indicators are required to understand the implications of agricultural management in agroecosystem functioning. Introducing agroecological service crops combined with the use of no‐till roller crimping is a promising strategy for improving agronomic performance (e.g. fewer weeds) and reducing environmental (e.g. increasing the potentially recyclable energy) and ecological (e.g. enhancing the activity density of beneficial taxa such as ground and rove beetles) impacts. However, our study also indicates a need for agronomic and environmental improvements while promoting a wider acceptance of this strategy.

Urban environments have species-specific associations with invasive insect herbivores

Abstract Urban forests are critically important for providing ecosystem services to rapidly expanding urban populations, but their health is threatened by invasive insect herbivores. To protect urban forests against invasive insects and support future delivery of ecosystem services, we must first understand the factors that affect insect density across urban landscapes. This study explores how a variety of environmental factors that vary across urban habitats influence density of invasive insects. Specifically, we evaluate how vegetational complexity, distance to buildings, impervious surface, canopy temperature, host availability and density of co-occurring herbivores impact three invasive pests of elm trees: the elm leaf beetle (Xanthogaleruca luteola), the elm flea weevil (Orchestes steppensis) and the elm leafminer (Fenusa ulmi). Insect responses to these factors were species-specific, and all environmental factors were associated with density of at least one pest species except for distance to buildings. Elm leafminer density decreased with higher temperatures and was influenced by an interaction between vegetational complexity and impervious surface. Elm flea weevil density increased with greater host availability, and elm leaf beetle density increased with higher temperatures. Both elm leaf beetle and elm flea weevil density decreased with greater leafminer density, suggesting that insect density is mediated by species interactions. These findings can be used to inform urban pest management and tree care efforts, making urban forests more resilient in an era when globalization and climate change make them particularly vulnerable to attack.

Vegetation attributes drive the taxonomic richness and functional composition of beetles and spiders in mountainous urban green spaces

Urban green spaces (UGS) enhance the quality of life in urban environments and serve as habitat corridors or refuge for organisms, including beetles and spiders. The attributes of UGS allow them to harbour species that offer essential ecosystem services. However, the ability of UGS to provide services is limited by the extent to which they have been altered anthropogenically. We described the taxonomic richness and functional composition of arthropods in a mountainous urban ecosystem of Ghana by focussing on the activity of both beetles and spiders at the family level. Two main land-use types (woodlands and built-up areas) were identified and characterised based on the presence or absence of certain vegetation attributes. Sixteen plots in each land-use type with sizes 20 × 20 m were demarcated and fitted with four pitfall traps in each plot to sample continuously for eight weeks, the activity density of both beetles and spiders. Samples were sorted into families and functional groups (detritivores, fungivores, herbivores and predators). The taxonomic richness and activity density were both significantly higher in the woodlands than in the built-up areas. Similarly, all functional groups showed a higher affinity to the woodlands than the built-up areas. Habitat attributes defined by plant diversity and structural complexity were the underlying drivers explaining the differences in arthropod communities between the land-use types. Though the built-up areas seem degraded and open, the remaining small vegetation patches still support the activities of some taxa that should merit the protection of such remnant vegetation in urban ecosystems.

Evergreen Abundance Drives Ground Beetle Diversity and Density in Eastern Temperate Forests

Evergreen Abundance Drives Ground Beetle Diversity and Density in Eastern Temperate Forests

Impact of the leaf-feeding beetle Zygogramma bicolorata Pallister on the growth of Parthenium hysterophorus L. in climatically different locations of Nepal

The leaf-feeding beetle, Zygogramma bicolorata Pallister, one of the biocontrol agents against Parthenium hysterophorus L., having been established at several locations of Nepal. However, the damage to P. hysterophorus by the beetle has not been assessed quantitatively under different climatic conditions so far. The study was carried out at two locations, namely Hetauda with a tropical climate (540 m asl) and Kathmandu with a subtropical climate (1300 m asl) to evaluate the impact of the beetle on P. hysterophorus. Beetles were released in two different densities (one and two beetles/plant) during the early flowering period (early August). Individual plants were harvested when the initial signs of senescence were observed in mid-September. Plant height and leaf, stem, root biomass of each harvested individual was measured. Plant height, leaf biomass, and stem biomass were significantly higher at the subtropical site than at tropical sites and declined with the increasing density of beetle at both locations. Root:shoot ratio increased with the increasing density of beetle at both locations. The plant height, leaf biomass, and shoot biomass decreased up to 35 %, 73 %, and 54 % respectively at the tropical site and 9 %, 58 %, and 26 % respectively at the subtropical site. Root:shoot ratio increased by 76 % in the tropical site and 30 % in the subtropical site. The present study, therefore, suggests that mass-rearing and releasing of the beetle could be an effective management tool for the biological control of P. hysterophorus in tropical and subtropical climates of Nepal.