Balancing Disturbance and Conservation in Agroecosystems to Improve Biological Control

Assessment of the USDA Biomass Harvest Trap (USDA-BHT) device as an insect harvest and mosquito surveillance tool

Insects are a promising source of high-quality protein, and the insect farming industry will lead to higher sustainability when it overcomes scaling up, cost effectiveness, and automation. In contrast to insect farming (raising and breeding insects as livestock), wild insect harvesting (collecting agricultural insect pests), may constitute a simple sustainable animal protein supplementation strategy. For wild harvest to be successful sufficient insect biomass needs to be collected while simultaneously avoiding the collection of nontarget insects. We assessed the performance of the USDA Biomass Harvest Trap (USDA-BHT) device to collect flying insect biomass and as a mosquito surveillance tool. The USDA-BHT device was compared to other suction traps commonly used for mosquito surveillance (Centers for Disease Control and Prevention (CDC) light traps, Encephalitis virus surveillance traps, and Biogents Sentinel traps). The insect biomass harvested in the USDA-BHT was statistically higher than the one harvested in the other traps, however the mosquito collections between traps were not statistically significantly different. The USDA-BHT collected some beneficial insects, although it was observed that their collection was minimized at night. These findings coupled with the fact that sorting time to separate the mosquitoes from the other collected insects was significantly longer for the USDA-BHT, indicate that the use of this device for insect biomass collection conflicts with its use as an efficient mosquito surveillance tool. Nevertheless, the device efficiently collected insect biomass, and thus can be used to generate an alternative protein source for animal feed.

Induced plant resistance and its influence on natural enemy use of plant-derived foods

In response to herbivory, plants employ several inducible defenses to mitigate herbivore damage. These plant-induced responses can trigger subtle changes in plant metabolite composition, altering the profiles of plant-produced exudates such as (extra-) floral nectar and plant guttation. Natural enemies consume these plant-produced exudates, which serve as consistent and nutrient-dense food sources. There is mounting evidence that natural enemies' access to plant-produced exudates impacts their fitness, performance, and life history traits. Nonetheless, the role of induced plant defense on plant-produced exudates and the subsequent effect on natural enemies remains under-researched. This review, thus, highlights the potential role of induced plant defense on the profiles of plant-produced exudates, with a particular emphasis on altered metabolic changes affecting resource nutritional value and consequently the fitness and performance of natural enemies. Future directions and potential implications in biological control practices are also highlighted.

Harnessing artificial intelligence for analysing the impacts of nectar and pollen feeding in conservation biological control

Plant-derived foods, such as nectar and pollen, have garnered substantial research attention due to their potential to support natural enemies of pests. This review is a pioneering exploration of the potential for artificial intelligence approaches to provide insights into the factors that drive the success of conservation biological control (CBC). Nectar and pollen were confirmed as key plant food resources for natural enemies. These have been widely used across differing crop systems and provided by a wide range of CBC interventions, such as field margin flower strips. The combined use of parasitoids and predators is revealed as more successful than either of these guilds alone. CBC success was greater in field crops than in vine and berry crops, whilst interventions using dicotyledonous species that produce nectar in addition to pollen were more successful than using grassy interventions.

An insect's energy bar: the potential role of plant guttation on biological control

Plant guttation is an exudation fluid composed of xylem and phloem sap secreted at the margins of leaves of many agricultural crops. Although plant guttation is a widespread phenomenon, its effect on natural enemies remains largely unexplored. A recent study showed that plant guttation can be a reliable nutrient-rich food source for natural enemies, affecting their communities in highbush blueberries. This review highlights the potential role of plant guttation as a food source for natural enemies, with a particular emphasis on its nutritional value, effects on insect communities, and potential use in conservation biological control. We also discuss possible negative implications and conclude with some open questions and future directions for research.

Landscape structure influences natural pest suppression in a rice agroecosystem

Agricultural landscapes are constantly changing as farmers adopt new production practices and respond to changing environmental conditions. Some of these changes alter landscape structure with impacts on natural pest control, pesticide use, and conservation of biodiversity. In rice agroecosystems the effect of landscape structure on natural enemies and pest suppression is often poorly understood. Here we investigate the effect of landscape composition and configuration on a key pest of rice, the brown planthopper (Nilaparvata lugens). Using N. lugens as sentinel prey coupled with predator exclusions, we investigated landscape effects on herbivore suppression and rice grain yield at multiple spatial scales in two regions of Bangladesh. Ladybird beetles and spiders were the most abundant natural enemies of N. lugens with landscape effects observed at all scales on ladybird beetles. Specifically, ladybird beetles were positively influenced by road edges, and fallow land, while spiders were strongly influenced only by rice phenology. Predator exclusion cages showed that N. lugens abundance significantly increased in caged plots, reducing rice gain yield. We also used an estimated biocontrol service index that showed a significant positive relationship with landscape diversity and a significant negative impact on pest density and yield loss. These results suggest that promoting fallow lands and fragmented patches between rice fields could lead to more sustainable insect pest management in rice agroecosystems, potentially reducing the practice of prophylactic insecticide use.

Effects of wild, local, and cultivated tobacco varieties on the performance of Spodoptera litura and its parasitoid Meteorus pulchricornis

BACKGROUND

Plant domestication can alter plant and insect interactions and influence bottom-up and top-down effects. However, little is known about the effects of wild, local, and cultivated varieties of the same plant species in the same region on herbivores and their parasitoids. Here, six tobacco varieties were selected: wild Bishan and Badan tobaccos, local Liangqiao and Shuangguan sun-cured tobaccos, and cultivated Xiangyan 5 and Cunsanpi. We examined how wild, local, and cultivated tobacco types affect the tobacco cutworm herbivore Spodoptera litura and its parasitoid Meteorus pulchricornis.

RESULTS

Levels of nicotine and trypsin protease inhibitor in leaves and the fitness of S. litura larvae varied significantly among the varieties. Wild tobacco had the highest levels of nicotine and trypsin protease inhibitor, which reduced the survival rate and prolonged the development period of S. litura. The tobacco types significantly influenced the life history parameters and host selection of M. pulchricornis. The cocoon weight, cocoon emergence rate, adult longevity, hind tibia length, and offspring fecundity of M. pulchricornis increased, whereas the development period decreased from wild to local to cultivated varieties. The parasitoids were more likely to select wild and local varieties than cultivated varieties.

CONCLUSION

Domestication of tobacco resulted in reduced resistance to S. litura in cultivated tobacco. Wild tobacco varieties suppress S. litura populations, adversely affect M. pulchricornis, and may enhance bottom-up and top-down control of S. litura. © 2023 Society of Chemical Industry.

Navigating Agricultural Expansion in Harsh Conditions in Russia: Balancing Development with Insect Protection in the Era of Pesticides

As the world's population continues to increase, ensuring food security becomes a major problem. This often leads to the expansion of agricultural production, even in harsh conditions and becomes a key problem for many countries, including Russia. However, such expansion may entail certain costs, including the potential loss of insect populations, which are vital for ecological balance and agricultural productivity. The development of fallow lands in these regions is necessary to increase food production and increase food security; it is important to balance this with protection from harmful insects and sustainable farming methods. Research into the effects of insecticides on insects is an ongoing challenge, and new, sustainable farming methods are needed to ensure that protection from harmful insects and sustainable development can coexist. This article discusses the use of pesticides to protect the well-being of mankind, the problems of studying the effects of pesticides on insects and the vulnerability of insects to pesticides in regions with harsh conditions. It also discusses successful methods of sustainable agriculture and the importance of the legal framework governing the use of pesticides. The article emphasises the importance of balanced development with insect protection to ensure the sustainability of agricultural expansion in harsh conditions.

Herbivore-Dependent Induced Volatiles in Pear Plants Cause Differential Attractive Response by Lacewing Larvae

Biological control may benefit from the behavioral manipulation of natural enemies using volatile organic compounds (VOCs). Among these, herbivore-induced plant volatiles (HIPVs) provide potential tools for attracting or retaining predators and parasitoids of insect pests. This work aimed to characterize the VOCs emitted by pear plants in response to attack by Cacopsylla bidens (Hemiptera: Psyllidae), a major pest in pear orchards, to compare these with VOCs induced by a leaf chewing insect, Argyrotaenia sphaleropa (Lepidoptera: Tortricidae), and to evaluate the behavioral response of Chrysoperla externa (Neuroptera: Chrysopidae) to HIPVs from pear plants damaged by either herbivore. The results demonstrated that plants damaged by the pear psylla emitted VOC blends with increased amounts of aliphatic aldehydes. Leafroller damage resulted in increased amounts of benzeneacetonitrile, (E)-4,8-dimethylnona-1,3,7-triene, β-ocimene and caryophyllene. In olfactometer bioassays, larvae of C. externa were attracted to herbivore-damaged plants when contrasted with undamaged plants. When plant odors from psylla-damaged were contrasted with those of leafroller-damaged plants, C.externa preferred the former, also showing shorter response lag-times and higher response rates when psylla-damaged plants were present. Our results suggest that pear plants respond to herbivory by modifying their volatile profile, and that psylla-induced volatiles may be used as prey-specific chemical cues by chrysopid larvae. Our study is the first to report HIPVs in pear plants attacked by C. bidens, as well as the attraction of C. externa to psyllid-induced volatiles.

Solid-State Fermentation: Applications and Future Perspectives for Biostimulant and Biopesticides Production

With the expansion of the green products market and the worldwide policies and strategies directed toward a green revolution and ecological transition, the demand for innovative approaches is always on the rise. Among the sustainable agricultural approaches, microbial-based products are emerging over time as effective and feasible alternatives to agrochemicals. However, the production, formulation, and commercialization of some products can be challenging. Among the main challenges are the industrial production processes that ensure the quality of the product and its cost on the market. In the context of a circular economy, solid-state fermentation (SSF) might represent a smart approach to obtaining valuable products from waste and by-products. SSF enables the growth of various microorganisms on solid surfaces in the absence or near absence of free-flowing water. It is a valuable and practical method and is used in the food, pharmaceutical, energy, and chemical industries. Nevertheless, the application of this technology in the production of formulations useful in agriculture is still limited. This review summarizes the literature dealing with SSF agricultural applications and the future perspective of its use in sustainable agriculture. The survey showed good potential for SSF to produce biostimulants and biopesticides useful in agriculture.

Food provisioning to Pardosa spiders decreases the levels of tissue-resident endosymbiotic bacteria

The diversity, host specificity, and physiological effects of endosymbiotic bacteria in spiders (Araneae) are poorly characterized. We used 16S rDNA sequencing to evaluate endosymbionts in the cephalothorax and legs of a wolf spider Pardosa agrestis. We tested the effects of feeding once or twice daily with fruit flies, aphids, or starved and compared them to those of syntopically occurring Pardosa palustris. The feeding increased traveled distance up to five times in some of the groups provisioned with food relative to the starved control. The Shannon diversity t-test revealed significant differences between these component communities of the two spider species. The increased frequency of feeding with fruit flies, but not aphids, increased the dominance and decreased the alpha diversity of OTUs. The obligate or facultative endosymbionts were present in all analyzed spider individuals and were represented mostly by Rickettsiella, Rhabdochlamydia, Spiroplasma, and the facultative intracellular parasite Legionella. Vertically transmitted endosymbionts were less common, represented by Wolbachia pipientis and Rickettsia sp. H820. The relative abundance of Mycoplasma spp. was negatively correlated with provisioned or killed aphids. In conclusion, the tissues of Pardosa spiders host tremendously diverse assemblages of bacteria, including obligate or facultative endosymbionts, with yet unknown phenotypic effects.

Ecological function of key volatiles in Vitex negundo infested by Aphis gossypii

Herbivore induced plant volatiles (HIPVs) are key components of plant-herbivorous-natural enemies communications. Indeed, plants respond to herbivores feeding by releasing HIPVs to attract natural enemies. The present study analyses the effect of HIPVs of Vitex negundo (Lamiaceae), an indigenous plant species in northern China, on the predatory ladybug species Harmonia axyridis. Y-tube olfactometer bioassay showed that H. axyridis adults were significantly attracted by V. negundo infested by the aphid Aphis gossypii. We analyzed and compared volatile profiles between healthy and A. gossypii infested V. negundo, screened out the candidate active HIPVs mediated by A. gossypii which could attract H. axyridis, and tested the olfactory behavior of the candidate active compounds on H. axyridis. The gas chromatography-mass spectrometry analysis showed that five volatile compounds were significantly up-regulated after V. negundo infestation by A. gossypii, and five substances were significantly down-regulated in the terpenoid biosynthesis pathway. The olfactory behavior response showed that H. axyridis has significant preference for sclareol, eucalyptol, nonanal and α-terpineol, indicating that this chemical compounds are the important volatiles released by V. negundo to attract H. axyridis. This study preliminarily clarified that V. negundo release HIPVs to attract natural enemies when infected by herbivorous insects. The description of the volatile emission profile enriches the theoretical system of insect-induced volatile-mediated plant defense function of woody plants. Applications in crop protection would lie in designing original strategies to naturally control aphids in orchards.

Tritrophic defenses as a central pivot of low-emission, pest-suppressive farming systems

The ongoing COVID-19 pandemic has spotlighted the intricate connections between human and planetary health. Given that pesticide-centered crop protection degrades ecological resilience and (in-)directly harms human health, the adoption of ecologically sound, biodiversity-driven alternatives is imperative. In this Synthesis paper, we illuminate how ecological forces can be manipulated to bolster 'tritrophic defenses' against crop pests, pathogens, and weeds. Three distinct, yet mutually compatible approaches (habitat-mediated, breeding-dependent, and epigenetic tactics) can be deployed at different organizational levels, that is, from an individual seed to entire farming landscapes. Biodiversity can be harnessed for crop protection through ecological infrastructures, diversification tactics, and reconstituted soil health. Crop diversification is ideally guided by interorganismal interplay and plant-soil feedbacks, entailing resistant cultivars, rotation schemes, or multicrop arrangements. Rewarding opportunities also exist to prime plants for enhanced immunity or indirect defenses. As tritrophic defenses spawn multiple societal cobenefits, they could become core features of healthy, climate-resilient, and low-carbon food systems.

Systematic review on ensuring the global food security and covid-19 pandemic resilient food systems: towards accomplishing sustainable development goals targets

Covid-19, one of the most critical and widespread global pandemics, has resulted in extraordinary risk corollaries engulfing millions of people's lives and has caused an unprecedented economic downturn while amplifying food insecurity. A systematic review of 132 scientific communications was performed over a 15-year period, using articles from the ScienceDirect and Web of Science databases (2006-2021). In addition, 24 policy briefs, country papers, and publications from the UN, WHO, FAO, and OECD were cited. The aim of this paper is to provide a comprehensive review of existing literature on the adverse effects of the Covid-19 pandemic on agricultural food systems, as well as potential strategies for building robust, resilient, and sustainable food systems to ensure global food security, safety, and endeavors regarding future global emergencies, as well as new research policies while achieving SDG targets. This would fill a research gap while also having long-term implications for health, agricultural, and food resilience policy development in a rapidly changing world. Covid-19 demonstrates how human, animal, and environmental health are all interconnected, emphasizing the need for one health legislation and a paradigm shift in planetary health. Furthermore, it identifies potential mechanisms for rebuilding better systems by shifting priorities toward policy coherence, innovative food system governance, re-engineering market access, and nexus thinking in the food system approach. According to our findings, the COVID-19 posed unavoidable impediments to achieving SDG targets for food security and household poverty.

Graphical abstract

Sticky Pi is a high-frequency smart trap that enables the study of insect circadian activity under natural conditions

In the face of severe environmental crises that threaten insect biodiversity, new technologies are imperative to monitor both the identity and ecology of insect species. Traditionally, insect surveys rely on manual collection of traps, which provide abundance data but mask the large intra- and interday variations in insect activity, an important facet of their ecology. Although laboratory studies have shown that circadian processes are central to insects' biological functions, from feeding to reproduction, we lack the high-frequency monitoring tools to study insect circadian biology in the field. To address these issues, we developed the Sticky Pi, a novel, autonomous, open-source, insect trap that acquires images of sticky cards every 20 minutes. Using custom deep learning algorithms, we automatically and accurately scored where, when, and which insects were captured. First, we validated our device in controlled laboratory conditions with a classic chronobiological model organism, Drosophila melanogaster. Then, we deployed an array of Sticky Pis to the field to characterise the daily activity of an agricultural pest, Drosophila suzukii, and its parasitoid wasps. Finally, we demonstrate the wide scope of our smart trap by describing the sympatric arrangement of insect temporal niches in a community, without targeting particular taxa a priori. Together, the automatic identification and high sampling rate of our tool provide biologists with unique data that impacts research far beyond chronobiology, with applications to biodiversity monitoring and pest control as well as fundamental implications for phenology, behavioural ecology, and ecophysiology. We released the Sticky Pi project as an open community resource on https://doc.sticky-pi.com.

Early-season plant cover supports more effective pest control than insecticide applications

Growing evidence suggests that conservation agricultural practices, like no-till and cover crops, help protect annual crops from insect pests by supporting populations of resident arthropod predators. While adoption of conservation practices is growing, most field crop producers are also using more insecticides, including neonicotinoid seed coatings, as insurance against early-season insect pests. This tactic may disrupt benefits associated with conservation practices by reducing arthropods that contribute to biological control. We investigated the interaction between preventive pest management (PPM) and the conservation practice of cover cropping. We also investigated an alternative pest management approach, integrated pest management (IPM), which responds to insect pest risk, rather than using insecticides prophylactically. In a 3-year corn (Zea mays mays L.)-soy (Glycine max L.) rotation, we measured the response of invertebrate pests and predators to PPM and IPM with and without a cover crop. Using any insecticide provided some small reduction to plant damage in soy, but no yield benefit. In corn, vegetative cover early in the season was key to reducing pest density and damage, likely by increasing the abundance of arthropod predators. Further, PPM in year 1 decreased predation compared to a no-pest-management control. Contrary to our expectation, the IPM strategy, which required just one insecticide application, was more disruptive to the predator community than PPM, likely because the applied pyrethroid was more acutely toxic to a wider range of arthropods than neonicotinoids. Promoting early-season cover was more effective at reducing pest density and damage than either intervention-based strategy. Our results suggest that the best pest management outcomes may occur when biological control is encouraged by planting cover crops and avoiding broad-spectrum insecticides as much as possible. As part of a conservation-based approach to farming, cover crops can promote natural-enemy populations that can help provide biological effective control of insect pest populations.

Ecological Infrastructures May Enhance Lepidopterans Predation in Irrigated Mediterranean Farmland, Depending on Their Typology and the Predator Guild

Ecological infrastructures (EIs) are considered relevant components in agricultural landscapes to support biodiversity and ecosystem services. We used the predatory attacks on lepidopteran dummies as a proxy to assess predation rates in the agricultural matrix and different EIs types according to their location and vegetation structure. We aimed at comparing the effect of different types of EI on the predation intensity in two intensively irrigated agricultural areas located in the Sorraia and Tagus river valleys in central Portugal. We hypothesized that: (1) the predation rate would be higher near EIs compared with the agricultural matrix, (2) the positive effect of EIs on predation rate would differ with their typologies, and (3) the EIs’ proximity and proportion in the surrounding landscape would have a positive effect on the predation rate in agricultural fields. The EI typologies influenced differently the predator groups and the overall predation rate. Major differences were observed for bird predation, being higher in woody EIs. A positive correlation between predation rate and EIs area of the surrounding landscape, as well as a negative correlation with the distance to the nearest riparian and woody EIs, was observed for birds. The observed dissimilarities in the predators’ response may be related to habitat differences and its functional connectivity. The overall monthly low predation rates are possibly related to the intensive agricultural system and the small area occupied by EIs.

Bottom-Up Forces in Agroecosystems and Their Potential Impact on Arthropod Pest Management

Bottom-up effects are major ecological forces in crop-arthropod pest-natural enemy multitrophic interactions. Over the past two decades, bottom-up effects have been considered key levers for optimizing integrated pest management (IPM). Irrigation, fertilization, crop resistance, habitat manipulation, organic management practices, and landscape characteristics have all been shown to trigger marked bottom-up effects and thus impact pest management. In this review, we summarize current knowledge on the role of bottom-up effects in pest management and the associated mechanisms, and discuss several key study cases showing how bottom-up effects practically promote natural pest control. Bottom-up effects on IPM also contribute to sustainable intensification of agriculture in the context of agricultural transition and climate change. Finally, we highlight new research priorities in this important area. Together with top-down forces (biological control), future advances in understanding ecological mechanisms underlying key bottom-up forces could pave the way for developing novel pest management strategies and new optimized IPM programs.

Life History, Biology, and Distribution of Pterostichus melanarius (Coleoptera: Carabidae) in North America

Pterostichus melanarius (Illiger, 1798) is a Palearctic generalist predator native to Europe. It was unintentionally introduced to North America at least twice in the mid 1920s and has since become widespread in Canada and the United States. Although P. melanarius is a valuable natural enemy in many different agricultural systems, we are not aware of any effort to compile in one publication details of its life history, diet, distribution, and factors that influence its populations. Some studies in North America have investigated the effects of P. melanarius on pest species and native carabid assemblages. Moreover, given that it is an exotic species whose range appears to still be expanding, it will be valuable to predict its potential distribution in North America. Therefore, the goals of this paper are to: 1) compile information on the life history and biology of P. melanarius, 2) review the effects of various agricultural practices on this species, and 3) use ecological niche modeling to determine the potential range of P. melanarius in the United States and which climate variables are most important for range expansion. Our review revealed that P. melanarius appears to provide benefits most consistently in diverse agricultural systems managed with no-till or reduced till methods, whereas our modeling revealed that P. melanarius likely occupies, or will occupy, more of the northern U.S. than is currently recognized, particularly in the Appalachian and Rocky Mountain regions.

Diversity and Parasitism by Parasitic Wasps That Attack Dalbulus maidis (Hemiptera: Cicadellidae) on Year-Round and Seasonal Maize Agroecosystems

Agroecosystems undergo frequent anthropogenic disturbance that may affect the diversity, community, and abundance of natural enemies living there. In the tropics, annual crops such as maize are planted two times (year-round crops) or one time (seasonal crops) per year. Little is known about how natural enemies of insect pests respond to maize agroecosystems planted one vs. two times during each annual cycle. The objective was to investigate the diversity and parasitism of egg parasitoids of the pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) in maize agroecosystems planted year-round and seasonally. Potted maize plants with D. maidis eggs were placed within these two maize agroecosystems to attract egg parasitoids during the maize-growing wet season in Mexico. In these two maize agroecosystems, similar levels of diversity were found, using the Shannon-Wiener index (H'). Communities of parasitic wasps were found attacking the eggs of D. maidis in both maize agroecosystems, but there were differences in the composition of these communities. In the year-round maize agroecosystem, Paracentrobia sp. near subflava (Girault) (Hymenoptera: Trichogrammatidae) was the most common, while Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) was most common in the seasonal maize. A greater total abundance and total rate of parasitoid emergence were found in the year-round maize agroecosystem compared with the seasonal maize. In addition, a positive relationship between the number of D. maidis eggs and parasitoid abundance was found in both maize agroecosystems. However, a negative density dependence between the number of D. maidis eggs and the percentage of parasitism was found in both maize agroecosystems.

Can Wolf Spider Mothers Detect Insecticides in the Environment? Does the Silk of the Egg-Sac Protect Juveniles from Insecticides?

The use of pesticides for plague control in agroecosystems generates a threat to wildlife and a major problem for human health. Pesticide compounds are also an important source of water and atmosphere contamination. Although insecticides are effective on their target organisms, they often affect organisms that are not their target. The aim of the present study was to research the effects of 3 types of neurotoxic insecticides-a pyrethroid (cypermethrin), a neonicotinoid (imidacloprid), and an organophosphate (chlorpyrifos)-on behavioral and physiological parameters of Pardosa saltans spider (Lycosidae). Our study analyzed for the first time the exploratory behavior of the spider mothers in the presence of these 3 insecticides on their egg-sacs and also on the ground. We also evaluated the oxidative stress effects on the juveniles hatched in the egg-sac protected by silk in relation to variations in detoxification enzymes (catalase, glutathione reductase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase) and lipid peroxidation (reactive oxygen species [ROS]). The results show that these insecticides are repellents for mothers (cypermethrin is the most repellent), and maternal behavior is modified after detection of an insecticide on their egg-sac but mothers do not abandon their egg-sacs. These neurotoxic insecticides affect the juveniles inside their egg-sac. Cypermethrin and chlorpyrifos caused more oxidative stress in juveniles than did imidacloprid. The ROS generated by these insecticides seemed to be adequately eliminated by the juveniles' antioxidant systems. Environ Toxicol Chem 2021;40:2861-2873. © 2021 SETAC.

Ground Predator Activity-Density and Predation Rates Are Weakly Supported by Dry-Stack Cow Manure and Wheat Cover Crops in No-Till Maize

Because it keeps land in production, conservation programs that focus on in-field habitat manipulations may help farmers better support predators than by building predator habitat around fields. We investigated two in-field habitat manipulations that benefit producers and soil quality: fertilizing with dry-stack cow manure and planting a wheat cover crop. We hypothesized that, compared with inorganic fertilizer and fallow plots, both treatments augment habitat and residue and support more small arthropods that can serve as alternative prey for larger predators. As a result, we expected manure and the cover crop to increase ground-active predators. In turn, these predators could provide biological control of pests. Each year in a 3-yr field experiment, we applied manure and in 2 yr planted a wheat cover crop. We found that both planting a cover crop and applying dry-stack manure increased the plant cover in May. In the last year, this translated to greater soil mite (Acari) density. At the end of the experiment, however, neither manure nor the wheat cover crop had increased residue on the soil surface. As a result, our treatments had inconsistent effects on predator activity-density, especially for carabids and spiders. We observed strong edge effects from neighboring grass alleys on carabid activity-density. Regardless of treatment, we observed high predation of sentinel prey. We conclude that even without cover crops or organic fertilizer, the stability of no-till maize and increased weeds in fallow treatments generate sufficient habitat complexity and alternative prey to support robust predator communities.

Beyond the Headlines: The Influence of Insurance Pest Management on an Unseen, Silent Entomological Majority

For most of the last two decades, insect pest management in key grain and oilseed crops has relied heavily on an insurance-based approach. This approach mandates a suite of management tactics prior to planting and in the absence of pest data. Because there is little flexibility for using these tactics individually, most producers have adopted this full suite of practices despite mounting evidence that some components do not provide consistent benefits. In North America in particular, this preventive approach to insect pest management has led to steep increases in use of neonicotinoid insecticides and subsequent increases in neonicotinoids in soil and water within crop fields and beyond. These increases have been accompanied by a host of non-target effects that have been most clearly studied in pollinators and insect natural enemies. Less attention has been given to the effects of this practice upon the many thousands of aquatic insect species that are often cryptic and offer negligible, or undefined, clear benefits to humans and their commerce. A survey of the literature reveals that the non-target effects of neonicotinoids upon these aquatic species are often as serious as for terrestrial species, and more difficult to address. By focusing upon charismatic insect species that provide clearly defined services, we are likely dramatically under-estimating the effects of neonicotinoids upon the wider environment. Given the mounting evidence base demonstrating that the pest management and crop yield benefits of this approach are negligible, we advocate for a return to largely-abandoned IPM principles as a readily accessible alternative path.

How Does Improve Farmers’ Attitudes toward Ecosystem Services to Support Sustainable Development of Agriculture? Based on Environmental Kuznets Curve Theory

Agroecosystems are complex socio-ecological systems that are managed by farmers to achieve desired outcomes, including economic income and environmental benefits contributed by ecosystem services (ES). Therefore, understanding farmers’ attitudes for ES will provide references for targeted agricultural environment management, which is critical to achieving the sustainable development of agriculture. The aim of this study is to identify the attitudes of farmers regarding ES, and to test whether and how annual household income and social demographic characteristics affect farmers’ attitudes toward ES. Using face-to-face interviews to collect data and the hypothesis of environmental Kuznets curve (EKC) to provide an analytical framework, the results reveal that, in general, the perceptions of farmers’ attitudes on ES are highly complex, caused by characteristics of the farmers. Furthermore, the inflection points of the U-shaped curves, where priorities change from increasing income to paying more attention to waste assimilation and biological pest control, are identified at 17,091 and 25,071RMB, respectively. Initiatives that aim to achieve sustainable agricultural development by strengthening ES provisions should be sensitive to farmers’perceptions. Therefore, it is necessary to strengthen farmers’ educational attainment, concentrate fragmented cultivation area and create reasonable incentives for preserving and restoring of ES and increasing farmers’ income together, which then can enhance the positive outcomes from income growth.

Influence of Cover Crop Termination on Ground Dwelling Arthropods in Organic Vegetable Systems

A key aspect in cover crop management is termination before the cash crop is planted. The aim of this study was to assess the effects of termination methods on ground-dwelling arthropods. The conventional mechanical termination method-i.e., green manuring by means of a disc harrow-was compared to flattening using a roller crimper. Two different crop systems were investigated for two growing seasons; cauliflower was grown in autumn after the termination of a mixture of cowpea, pearl millet, and radish, and tomato was cropped in spring and summer after the termination of a mixture of barley and vetch. Ground beetles (Coleoptera: Carabidae), rove beetles (Coleoptera: Staphylinidae), and spiders (Araneae) were sampled by means of standard pitfall traps throughout the growing season of both cash crops. The roller crimper increased the overall abundance of ground beetles in the first growing season of both cash crops, whereas in the second year, no significant effect could be detected. Rove beetles were more abundant in plots where the cover crops were terminated by the roller crimper. Finally, green manuring increased the abundance of spiders, especially on the first sampling date after cover crop termination. Albeit different taxa showed different responses, the termination of cover crops by a roller crimper generally increased the abundance of ground dwelling arthropods. Given that most of the sampled species were generalist predators, their increased abundance could possibly improve biological control.

Methyl Salicylate Increases Attraction and Function of Beneficial Arthropods in Cranberries

Methyl salicylate (MeSA) is an herbivore-induced plant volatile (HIPV) known to attract the natural enemies of herbivores in agro-ecosystems; however, whether this attraction leads to an increase in natural enemy functioning, i.e., predation, remains largely unknown. Here, we monitored for 2 years (2011-2012) the response of herbivores and natural enemies to MeSA lures (PredaLure) by using sticky and pitfall traps in cranberry bogs. In addition, European corn borer, Ostrinia nubilalis, egg masses were used to determine whether natural enemy attraction to MeSA leads to higher predation. In both years, MeSA increased adult hoverfly captures on sticky traps and augmented predation of O. nubilalis eggs. However, MeSA also attracted more phytophagous thrips and, in 2012, more plant bugs (Miridae) to sticky traps. Furthermore, we used surveillance cameras to record the identity of natural enemies attracted to MeSA and measure their predation rate. Video recordings showed that MeSA lures increase visitation by adult lady beetles, adult hoverflies, and predatory mites to sentinel eggs, and predation of these eggs doubled compared to no-lure controls. Our data indicate that MeSA lures increase predator attraction, resulting in increased predation; thus, we provide evidence that attraction to HIPVs can increase natural enemy functioning in an agro-ecosystem.