Reduce Pesticide Use Research Articles

Bactrocera oleae (Rossi) (Diptera: Tephritidae) Response to Different Blends of Olive Fruit Fly-Associated Yeast Volatile Compounds as Attractants

The olive fruit fly, Bactrocera oleae (Rossi) is economically the most important olive pest, causing yield losses in all olive growing areas where is detected. Considering that EU requires the reduction of pesticide use by up to 100% by 2050, more effective non-pesticide lures for B. oleae monitoring and/or controlling are needed. This research was aimed at investigating the attractiveness of different blends of olive fruit fly-associated yeast volatiles toward B. oleae. Three blends of olive fruit fly-associated yeast volatiles: isoamyl alcohol and 2-phenethyl alcohol; isoamyl alcohol, 2-phenethyl alcohol and 2-phenethyl acetate; and isoamyl alcohol, 2-phenethyl acetate and isobutyl acetate were selected and tested on yellow sticky traps for attraction of B. oleae in olive orchard. Results showed that traps containing all tested blends of olive fruit fly-associated yeast volatile compounds, in total, were significantly more attractive to B. oleae and were not significantly attractive to green lacewings, compared to the control. Among them, the most promising was the one containing the blend of isoamyl alcohol, 2-phenethyl acetate and isobutyl acetate because its attractiveness was constantly significant during investigation compared to the others. This blend in the future could lead us to the discovery of a new attractant for the monitoring and/or controlling of B. oleae.

Pesticide Toxicity Footprints of Australian Dietary Choices.

Pesticides are widely used in food production, yet the potential harm associated with their emission into the environment is rarely considered in the context of sustainable diets. In this study, a life cycle assessment was used to quantify the freshwater ecotoxicity, human toxicity carcinogenic effects, and human toxicity noncarcinogenic effects associated with pesticide use in relation to 9341 individual Australian adult daily diets. The three environmental indicators were also combined into a pesticide toxicity footprint, and a diet quality score was applied to each diet. Energy-dense and nutrient-poor discretionary foods, fruits, and protein-rich foods were the sources of most of the dietary pesticide impacts. Problematically, a dietary shift toward recommended diets was found to increase the pesticide toxicity footprint compared to the current average diet. Using a quadrant analysis, a recommended diet was identified with a 38% lower pesticide toxicity footprint. This was achieved mainly through a reduction in the discretionary food intake and by limiting the choice of fresh fruits. As the latter contradicts dietary recommendations to eat a variety of fruits of different types and colors, we concluded that dietary change may not be the best approach to lowering the environmental impacts of pesticides in the food system. Instead, targeted action in the horticultural industry may be more effective. Consumers might encourage this transition by supporting growers that reduce pesticide use and apply less environmentally harmful active ingredients.

Pesticide-free but not organic: Adoption of a large-scale wheat production standard in Switzerland

The sustainable intensification of agriculture requires solutions for a large-scale reduction of pesticide use while sustaining agricultural yields. Pesticide-free production standards, which bring together the strengths of all the food value chain actors, could be a cornerstone of this transformation. In Switzerland, a non-organic, private–public standard for pesticide-free wheat production is currently being introduced by the producer organization IP-SUISSE. It is the first of its kind in Europe and may reach a market share of 50% of Swiss wheat production. We here assess the determinants of farmers' participation and willingness to participate in the future. For our analysis, we combine a survey of the entire population of IP-SUISSE wheat producers (4749 farmers, 23.3% response rate) with data on historical farm-level wheat yields, soil properties, weather, climate, weed pressure, and spread of herbicide resistance. Our results indicate that a large-scale establishment of pesticide-free wheat production in Switzerland is possible. We find that farmers' perceptions of positive environmental effects of the production program are key for adoption. Moreover, farmers' expectations of the program’s production effects play a central role. Farmers perceiving large yield losses and increases in production risks are less likely to enter the program. Based on our results, we discuss implications, leverage points, and challenges for designing and implementing large-scale pesticide-free production programs.

Bioinformatic-Based Approaches for Disease-Resistance Gene Discovery in Plants

Pathogens are among the most limiting factors for crop success and expansion. Thus, finding the underlying genetic cause of pathogen resistance is the main goal for plant geneticists. The activation of a plant’s immune system is mediated by the presence of specific receptors known as disease-resistance genes (R genes). Typical R genes encode functional immune receptors with nucleotide-binding sites (NBS) and leucine-rich repeat (LRR) domains, making the NBS-LRRs the largest family of plant resistance genes. Establishing host resistance is crucial for plant growth and crop yield but also for reducing pesticide use. In this regard, pyramiding R genes is thought to be the most ecologically friendly way to enhance the durability of resistance. To accomplish this, researchers must first identify the related genes, or linked markers, within the genomes. However, the duplicated nature, with the presence of frequent paralogues, and clustered characteristic of NLRs make them difficult to predict with the classic automatic gene annotation pipelines. In the last several years, efforts have been made to develop new methods leading to a proliferation of reports on cloned genes. Herein, we review the bioinformatic tools to assist the discovery of R genes in plants, focusing on well-established pipelines with an important computer-based component.

Reverse chemical ecology guides the screening for Grapholita molesta pheromone synergists.

Pheromone-based management is a leading nonpesticidal strategy among integrated pest management options. Improving the potency of pheromone products by adding synergists would be a practical way to popularize pheromone-based management as well as to reduce pesticide use. Using reverse chemical ecology, synergists for Grapholita molesta sex pheromone were screened. Combined molecular docking and in vitro binding assay led to the determination of four potentially active odorants showing high affinity to G. molesta pheromone binding protein 2 (GmolPBP2). Thereafter, the high affinity between Codlemone and GmolPBP2 was further verified by exploration of GmolPBP2-Codlemone interactions. As the only sex pheromone synergist validated by both laboratory behavioral tests and field trapping, Codlemone was used to optimize commercial sex attractants currently used in G. molesta control. The recommended formulation [(Z)-8-dodecenyl acetate:(E)-8-dodecenyl acetate:Codlemone=95:4:10] was found to trap about five to six times more G. molesta adults than the commercial sex attractant [(Z)-8-dodecenyl acetate:(E)-8-dodecenyl acetate: (Z)-8-dodecenol=95:4:1]. Codlemone is an excellent pheromone synergist that can be potentially sensed by GmolPBP2, which can remarkably improve the potency of G. molesta sex attractants. It is believed that the introduction of reverse chemical ecology would increase the chance of discovering pheromone synergists, promoting the development of more efficacious pheromone products that can be used in controlling G. molesta and beyond. © 2021 Society of Chemical Industry.

PENGELOLAAN PENGGUNAAN PESTISIDA DALAM MENDUKUNG PEMBANGUNAN BERKELANJUTAN DI INDONESIA

<p><em>The use of pesticides in rice production has an impact on the environment. Pesticides are chemicals used to kill or control pests. The use of pesticides carries some risks, but farmers are used to using pesticides. However, the use of pesticides may lead to the contamination of groundwater. Therefore, the research question in this study was whether there any differences in rice production before and after pesticide reduction in Indonesia. This study aimed to analyze the difference between rice production before and after pesticide reduction in Indonesia. The secondary data in this study were rice production data from FAO. Data from 1968 to 1992 were data about rice production before reducing pesticide use in Indonesia, while data from 1993 to 2017 were data about rice production after reducing pesticide use in Indonesia. The applied data analysis was paired sample t-test using SPSS 25. The results indicated that there is a significant difference between rice production before and after reducing pesticide use in Indonesia. </em></p>

'Resistance Mixtures' Reduce Insect Herbivory in Strawberry (Fragaria vesca) Plantations.

The transition toward more sustainable plant protection with reduced pesticide use is difficult, because there is no “silver bullet” available among nonchemical tools. Integrating several plant protection approaches may thus be needed for efficient pest management. Recently, increasing the genetic diversity of plantations via cultivar mixing has been proposed as a possible method to reduce pest damage. However, previous studies have not addressed either the relative efficiency of exploiting cultivar mixing and intrinsic plant herbivore resistance or the potential utility of combining these approaches to increase cropping security. Here, using a full factorial experiment with 60 woodland strawberry plots, we tested for the relative and combined effect of cultivar mixing and intrinsic plant resistance on herbivore damage and yield. The experiment comprised two levels of diversity (“high” with 10 varieties and “low” with two varieties) and three levels of resistance (“resistant” comprising only varieties intrinsically resistant against strawberry leaf beetle Galerucella tenella; “susceptible” with susceptible varieties only; and “resistance mixtures” with 50:50 mixtures of resistant and susceptible varieties). The experiment was carried out over two growing seasons. Use of resistant varieties either alone or intermixed with susceptible varieties in “resistance mixtures” reduced insect herbivory. Interestingly, resistant varieties not only reduced the mean damage in “resistance mixtures” by themselves being less damaged, but also protected intermixed susceptible varieties via associational resistance. The effect of higher genetic diversity was less evident, reducing herbivory only at the highest level of herbivore damage. In general, herbivory was lowest in plots with high diversity that included at least some resistant varieties and highest in low diversity plots consisting only of susceptible varieties. Despite this, no significant difference in yield (fruit biomass) was found, indicating that strawberry may be relatively tolerant. Our results demonstrate that combined use of high genetic diversity and resistant varieties can help reduce pest damage and provide a useful tool for sustainable food production. “Resistance mixtures” may be particularly useful for sensitive food crops where susceptible varieties are high yielding that could not be completely replaced by resistant ones.

Biology, Ecology, and Pest Management of the Tarnished Plant Bug, Lygus lineolaris (Palisot de Beauvois) in Southern Row Crops.

Simple SummaryThe tarnished plant bug, Lygus lineolaris, is a polyphagous, sap-feeder that causes significant economic damage in several field crops, especially cotton (Gossypium hirsutum L.) in the mid-southern United States. In 2020, it was reported that 4.8 million acres of cotton were infested by Lygus spp. in the United States. A broad host range, polyphagous feeding behavior and high mobility of this pest along with resistance development to conventional pesticides helped them establish as a significant pest of concern for cotton growers in the mid-south. Since the publication of a review by Layton (2000) on damage caused by Lygus lineolaris, many new research studies have been published on the Lygus biology, ecology, and integrated pest management strategies. A comprehensive review paper that summarizes these latest research developments and Lygus management strategies will be useful for researchers and cotton growers. In this review, we report and discuss the latest developments in Lygus research and the new control strategies that have been developed in the last two decades.The tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), (Hemiptera: Miridae) is considered the most damaging pest of cotton (Gossypium hirsutum L.) in the mid-southern United States, although it is established throughout the United States, southern Canada, and northern Mexico. The introduction of transgenic crops for the control of moths in the Heliothine complex and eradication of the boll weevil, Anthonomus grandis, from much of the United States led to greatly reduced pesticide use in cotton fields, which allowed L. lineolaris to emerge as a new primary pest of cotton in the mid-southern United States. Since the publication of a review by Layton (2000) on damage caused by Lygus lineolaris, many new studies have been published on the changes in host range, population dynamics, sampling methods and thresholds, cultural practices, sex pheromones and attractant blends, novel pesticides and insecticide resistance mechanisms, olfactory and feeding behaviors, introduction of biological control agents, host-plant resistance mechanisms, and new molecular and genetic tools for integrated pest management of Lygus species in cotton and other important crops. Here, we review and discuss the latest developments in L. lineolaris research in the last two decades.

Farm size and pesticide use: evidence from agricultural production in China

PurposeChina is the world's largest consumer of pesticides. To increase the use efficiency and achieve more sustainable and environmentally friendly use of pesticides in China, it is crucial to understand why Chinese farmers use such a large amount of pesticides.Design/methodology/approachThe relationship between farm size and pesticide use was investigated by using national household-level panel data from 1995 to 2016.FindingFarms that are small and fragmented lead to the use of large amounts of pesticides in China. For a given crop type, three factors contribute to a negative relationship between farm size and pesticide use: the spillover effect from the use of pesticides by other farmers in the same village, the level of mechanization and the management ability of farmers. The first two factors play important roles in the cultivation of grain crops, while the last factor is the main reason why farmers with larger plots of land use fewer pesticides in the cultivation of vegetables. In addition, the effect of agricultural machinery services on reducing the use of pesticides is currently limited, and the service system in China is still insufficient, which has been pointed out that it is also due to the prevalence of small and fragmented farms.Originality/valueThe authors investigate and compare the farm size–pesticide use relationship in both grain and cash crop production. Moreover, the authors systematically explore and explain how farm size is related to a reduction in pesticide use in the cultivation of grain crops and cash crops. These results can help to better understand the role of land scale in pesticide use, lay a foundation for the formulation of policies to reduce pesticide use and provide valuable knowledge about pesticide use for other developing countries around the world.

Reducing ground and airborne drift losses in young apple orchards with PWM-controlled spray systems

Pulse Width Modulated (PWM) solenoid valves can be used to control nozzle flow rates for precision spray applications to reduce pesticide use, thereby reducing environmental risk and production cost. Field tests in a two-year-old young apple orchard were conducted to investigate spray losses to the ground and in the air for an air-blast sprayer equipped with three spray systems: 1) manually controlled constant-rate system enabled with the PWM spray system (Manual-PWM), 2) laser-guided variable-rate system enabled with the PWM spray system (Laser-PWM); and 3) conventional constant-rate system with disabled PWM valves (Disabled-PWM). Artificial targets (plastic plates and water sensitive papers) were placed under twelve trees randomly selected from four rows of the orchard to collect spray losses to the ground. Airborne spray losses were determined by using nylon screens, mounted at five heights on each of seven poles distributed at different distances from the first sprayed row. Laser-PWM and Manual-PWM produced significantly lower airborne and ground spray drift losses inside and outside the orchard than Disabled-PWM, and these losses decreased significantly as the distance away from the first sprayed row increased. Laser-PWM reduced the total airborne drift by 90.3% and total ground loss by 85.0% compared to Disabled-PWM whereas Manual-PWM decreased the same airborne and ground drift by 84.1% and 7.9%, respectively. Disabled-PWM produced detectable airborne losses that reached 88.4 m away from where the sprayer was operated. Thus, the air-blast orchard sprayer equipped with PWM solenoid valves controlled by either the automatic laser-guided system or manual system would have great potentials to improve pesticide application efficiency with significant reductions in both pesticide consumption in young apple orchards, and off-target drift loss to the environment.

Can ‘On-Farm’ Seed Priming and Chitosan Seed Treatments Induce Host Defences in Winter Barley (Hordeum vulgare L.) under Field Conditions?

Enhancing host defences through induced resistance, disease tolerance, and/or escape, in combination with current disease management regimes may be a valuable strategy to reduce pesticide use. Since both ‘on-farm’ seed priming (OSP) and chitosan priming (CHP) have been reported to confer varying levels of host defence, this study sought to investigate their potential to deliver disease control as a strategy for sustainable management of foliar pathogens in winter barley. Field experiments were conducted to determine the effects of OSP and CHP at two different field sites using three different cultivars under fungicide/non-fungicide regimes. Overall, no evidence was found to suggest that CHP or OSP can induce effective resistance in temperate field conditions. However, these field trials enabled the identification of candidate traits to deliver disease tolerance (and escape) for the primary and secondary spread of powdery mildew, i.e., large canopies and rapid stem elongation respectively. Thus, these seed treatments may deliver disease tolerance and escape traits, but these benefits are dependent upon successful establishment and vigour first. The integration of seed treatments into sustainable crop protection may be better undertaken with spring crops or in semi-arid agriculture where the added vigour at emergence can help compensate for negative environmental interactions.

Does crop insurance reduce pesticide usage? Evidence from China

We test how crop insurance participation affects the intensity of pesticide use in China using data on staple crop production from eight provinces. Our preferred specification instruments farmers' decisions of participation in insurance by village-level intensities of promotional activities and controls for province fixed effects. We find crop insurance participation significantly reduces pesticide use intensity. The reduction effect is greater for smaller plots, older farmers, and farmers who are more risk averse.

A Regional, Honey Bee-Centered Approach Is Needed to Incentivize Grower Adoption of Bee-Friendly Practices in the Almond Industry

Managed and wild bee populations contribute over $15 billion in pollination services to US agriculture, yet both are declining or becoming increasingly vulnerable to parasites and disease. The loss of healthy and diverse forage is a key driver in bee declines, so incentivizing land managers to adopt diversified bee-friendly management practices such as forage plantings and reduced pesticide use can directly increase food security, pollinator health, and farmer adaptive capacity. To better understand what might incentivize growers to adopt bee-friendly practices, we conducted a survey of California almond growers, whose orchards are entirely dependent on bee pollination and draw nearly 88% of US bee colonies each February to pollinate almond bloom. We asked 329 respondents across all major almond growing regions of CA about their adoption rate and incentives for planting cover crops, pollinator habitat, and practicing the recommended and legally required bee-friendly best management practices, as well as their interest in bee-friendly certification programs. Using a model selection framework, we evaluated which geographic, social, operational, and pollination-service related factors were predictive of bee-friendly practice adoption. We found that no single factor was a statistically significant predictor of adoption across all models, suggesting there is no silver bullet determining bee-friendly practice adoption. However, we discovered that region and concerns about future pollination services consistently emerged as important factors related to all the practices we investigated, except the adoption of legally required BMPs. These findings suggest that a regionally flexible pollinator conservation strategy focused on supporting honey bee colonies might have the highest likelihood of grower participation and adoption.

Does it matter who gives information? The impact of information sources on farmers’ pesticide use in China

The timely delivery of scientific information regarding pesticide use to farmers is essential to address negative externalities. Farmers have four information sources regarding pesticide use in China: public agricultural extension agents (PAEAs), pesticide sellers, peer farmers, and farmers’ own experience. A better understanding of which information source is the most effective in reducing pesticide use would be a principal step toward designing policy strategies for sustainable agricultural production. In this study, we examine the relative effectiveness of each information source on farmers’ pesticide use, based on nationally representative data from 603 rice farmers in seven major rice-producing provinces in China. We adopt a multinomial endogenous switching regression model to correct for selection bias due to observed and unobserved factors. Results show that compared with farmers’ own experience, PAEAs significantly increase farmers’ pesticide expenditure by 8.7 %, while pesticide sellers and peer farmers significantly decrease farmers’ pesticide expenditure by 18.5 % and 10.1 % respectively, with the largest reduction coming from pesticide sellers. Discouraging PAEAs’ commercial activities, working with pesticide sellers, and using peer farmers as social multipliers to disseminate knowledge may be effective ways to develop education programs that aim to reduce pesticide use.

Spray nozzle selection contributes to improved postemergence herbicide crabgrass control in turfgrass

For optimum postemergence crabgrass (Digitaria spp.) control, a single quinclorac herbicide application could be properly timed and delivered with spray nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm) in size to maximize target coverage and minimize the potential for drift. Crabgrass is an invasive annual grass weed of cool-season turfgrass maintain as lawns, golf courses, and sports pitches. Postemergence herbicide applications for crabgrass control in turfgrass swards often rely on repeated applications for effective control. Optimizing postemergence crabgrass applications can reduce pesticide inputs and contribute to sustainable turfgrass management practices. Two field studies evaluating crabgrass control were conducted in 2020 in a mixed stand of Kentucky bluegrass (Poa pratensis L.) with perennial ryegrass (Lolium perenne L.) in Ohio (USA) and in perennial ryegrass in Pennsylvania (USA). Both sites have histories of natural crabgrass [Digitaria sanguinalis (L.) Scop.] infestation. A postemergence herbicide, quinclorac, was applied at the product label rate and tank-mixed with methylated seed oil at the crabgrass plant stage of three-leaf to one tiller. Different spray nozzles were selected to deliver the following spray droplet classifications and sizes at 275 kPa: Delavan Raindrop 1/4, ultra coarse (>650 μm); TurfJet 1/4TTJO4, extremely coarse (501-650 μm); Air Induction AA8004 or XRTeeJet 8015, very coarse (401-500 μm); XR TeeJet 8008 or GreenLeaf TDAD04, coarse (326-400 μm); XR TeeJet 8004, medium (226-325 μm); and XRTeeJet 8003 fine (145-225 μm). Crabgrass pressure was low in Ohio, and herbicide efficacy at 60 days after treatment was considered acceptable when applied from all spray nozzles that produced spray droplet sizes ranging from ultra coarse to fine. Crabgrass pressure was severe in Pennsylvania, and herbicide efficacy at 60 DAT was considered marginally acceptable when applied from spray nozzles that produced spray droplet sizes ranging from very coarse to medium. Future research should consider cultural practices that would be complementary to postemergence herbicide applications with the goal to reduce pesticide use further and minimize any potential environmental impacts related to spray drift. Highlights - In turfgrass sites with low crabgrass pressure, one postemergence application of quinclorac herbicide could potentially achieve acceptable control with spray nozzles that produce spray droplets ranging from ultra coarse (>650 μm) to fine (145-225 μm). - In turfgrass sites with heavy crabgrass population and pressure, one postemergence application of quinclorac herbicide is best optimized with spray nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm). - Overall, turfgrass management practitioners should avoid using spray nozzles that produce a hollow cone spray pattern with ultra coarse (>650 μm) spray droplets which can result in poor or irregular herbicide coverage, or fine (145-225 μm) spray droplets which are subject to potential drift and possible negative off-target effects. - Overall, in an effort to reduce herbicide use for postemergence crabgrass control, a single quinclorac herbicide application could be properly timed and optimized with nozzles that produce spray droplets ranging from very coarse (401-500 μm) to medium (226-325 μm) in size, however, future research should consider cultural practices that would further optimize and also reduce herbicide applications.

An illuminated respiratory activity monitoring system identifies priming-active compounds in plant seedlings

BackgroundGrowing large crop monocultures and heavily using pesticides enhances the evolution of pesticide-insensitive pests and pathogens. To reduce pesticide use in crop cultivation, the application of priming-active compounds (PrimACs) is a welcome alternative. PrimACs strengthen the plant immune system and could thus help to protect plants with lower amounts of pesticides. PrimACs can be identified, for example, by their capacity to enhance the respiratory activity of parsley cells in culture as determined by the oxygen transfer rate (OTR) using the respiration activity monitoring system (RAMOS) or its miniaturized version, µRAMOS. The latter was designed for with suspensions of bacteria and yeast cells in microtiter plates (MTPs). So far, RAMOS or µRAMOS have not been applied to adult plants or seedlings, which would overcome the limitation of (µ)RAMOS to plant suspension cell cultures.ResultsIn this work, we introduce a modified µRAMOS for analysis of plant seedlings. The novel device allows illuminating the seedlings and records the respiratory activity in each well of a 48-well MTP. To validate the suitability of the setup for identifying novel PrimAC in Arabidopsis thaliana, seedlings were grown in MTP for seven days and treated with the known PrimAC salicylic acid (SA; positive control) and the PrimAC candidate methyl 1-(3,4-dihydroxyphenyl)-2-oxocyclopentane-1-carboxylate (Tyr020). Twenty-eight h after treatment, the seedlings were elicited with flg22, a 22-amino acid peptide of bacterial flagellin. Upon elicitation, the respiratory activity was monitored. The evaluation of the OTR course reveals Tyr020 as a likely PrimAC. The priming-inducing activity of Tyr020 was confirmed using molecular biological analyses in A. thaliana seedlings.ConclusionWe disclose the suitability of µRAMOS for identifying PrimACs in plant seedlings. The difference in OTR during a night period between primed and unprimed plants was distinguishable after elicitation with flg22. Thus, it has been shown that the µRAMOS device can be used for a reliable screening for PrimACs in plant seedlings.

Suicidality among South Brazilian tobacco growers

ObjectiveTo assess prevalence of suicidal ideation and suicide attempt among South Brazilian tobacco growers and to analyze the associated factors related to the suicidal ideation. MethodsA cross-sectional study was conducted in 2011 with a random sample of 2469 tobacco growers in São Lourenço do Sul/RS. Suicidal ideation was characterized by the question “Has the thought of ending your life been on your mind?”. Suicide attempt was assessed by the question “Have you ever tried to kill yourself?”. Investigation of factors associated with suicidal ideation was done by means of Poisson regression. ResultsPrevalence of suicidal ideation and suicide attempt was 2.5 % and 1.2 % respectively. In the adjusted analysis, suicidal ideation was associated with being female, older age, moderate participation in religious activities and difficulty in paying debts. Those who worked in activities that required inadequate postures (hunched over or other forced positions), as well as farmers who performed 6–9 pesticide-related tasks demonstrated greater risk of suicidal ideation. Regarding health conditions, medical diagnosis of asthma, chronic low back pain, number of lifetime green tobacco sickness episodes and lifetime pesticide poisoning were positively associated with suicidal ideation. ConclusionSuicidal thoughts and attempts are relevant mental health problems among tobacco growers. Reducing pesticide use, as well as exposure to nicotine and improving socio-economic conditions, can reduce suicidal ideation and improve the mental health of exposed workers.

Cropland heterogeneity drives frequency and intensity of pesticide use

Agricultural landscapes across the planet have replaced natural habitat with crop production that is less diverse at field and landscape scales. Loss of cropland heterogeneity can increase pest colonization rates and decrease predation rates, thereby exacerbating pest pressure and leading to increased use of pesticides. Linking landscape pattern, crop pest pressure, and pesticide use is emerging as critical step for understanding the benefits, and potential trade-offs, of diversified agriculture. We advance this work by exploring how cropland heterogeneity drives pesticide use, and whether this effect is modified by pesticide class (i.e. fungicide, herbicide or insecticide). We focus on a diverse growing region, California’s Central Valley, and use spatial auto-regressive models to test for consistent class-based differences in the relationship between pesticide use and cropland heterogeneity (i.e. mean field size and landscape-level crop diversity). We find reduced pesticide use, in terms of both frequency and intensity of application, in diversified, spatially-heterogenous landscapes. Additionally, we see (a) more consistent responses of fungicides and insecticides to landscape pattern, (b) pesticide use increases as cropland becomes more homogenous with respect to crop identity, and (c) this effect is more consistent for perennial crops than annual crops. The modifying influence of pesticide class is largely consistent with expectations from ecological theory. Our results support increasing focus on whether enhancing the heterogeneity of the crop mosaic itself can benefit biodiversity, ecosystem services, and human well-being.

Organic Farming Lessens Reliance on Pesticides and Promotes Public Health by Lowering Dietary Risks

Organic agriculture is a production system that relies on prevention, ecological processes, biodiversity, mechanical processes, and natural cycles to control pests and maintain productivity. Pesticide use is generally limited or absent in organic agroecosystems, in contrast with non-organic (conventional) production systems that primarily rely on pesticides for crop protection. Significant differences in pesticide use between the two production systems markedly alter the relative dietary exposure and risk levels and the environmental impacts of pesticides. Data are presented on pesticide use on organic and non-organic farms for all crops and selected horticultural crops. The relative dietary risks that are posed by organic and non-organic food, with a focus on fresh produce, are also presented and compared. The results support the notion that organic farms apply pesticides far less intensively than conventional farms, in part because, over time on well-managed organic farms, pest pressure falls when compared to the levels on nearby conventional farms growing the same crops. Biopesticides are the predominant pesticides used in organic production, which work by a non-toxic mode of action, and pose minimal risks to human health and the environment. Consequently, eating organic food, especially fruits and vegetables, can largely eliminate the risks posed by pesticide dietary exposure. We recommend ways to lower the pesticide risks by increased adoption of organic farming practices and highlight options along organic food supply chains to further reduce pesticide use, exposures, and adverse worker and environmental impacts.

Improving pest monitoring networks using a simulation-based approach to contribute to pesticide reduction

Conventional pest management mainly relies on the use of pesticides. However, the negative externalities of pesticides are now well known. More sustainable practices, such as Integrated Pest Management, are necessary to limit crop damage from pathogens, pests and weeds in agroecosystems. Reducing pesticide use requires information to determine whether chemical treatments are really needed. Pest monitoring networks (PMNs) are key contributors to this information. However, the effectiveness of a PMN in delivering relevant information about pests depends on its spatial sampling resolution and its memory length. The trade-off between the monitoring efforts and the usefulness of the information provided is highly dependent on pest ecological traits, the damage they can cause (in terms of crop losses), and economic drivers (production costs, agriculture product prices and incentives). Due to the high complexity of optimising PMNs, we have developed a theoretical model that belongs to the family of Dynamic Bayesian Networks in order to compare several PMNs performances. This model links the characteristics of a PMN to treatment decisions and the resulting pest dynamics. Using simulation and inference tools for graphical models, we derived the proportion of impacted fields, the number of pesticide treatments and the overall gross margins for three types of pest with contrasting levels of endocyclism. The term “endocyclic” refers to an organism whose development is mostly restricted to a field and highly depends on the inoculum present in the considered field. The presence of purely endocyclic pests at a given time increases the probability of reoccurrence. Conversely, slightly endocyclic pests have a low persistence. The simulation analysis considered ten scenarios: an expected margin-based strategy with a spatial resolution of four PMNs and two memory lengths (one year or eight years), as well as two extreme crop protection strategies (systematic treatments on all fields and systematic no treatment). For purely and mainly endocyclic pests (e.g. soil-borne pathogens and most weeds, respectively), we found that increasing the spatial resolution of PMNs made it possible to significantly decrease the number of treatments required for pest control. Taking past observations into account was also effective, but to a lesser extent. PMN information had virtually no influence on the control of non-endocyclic pests (such as flying insects or airborne plant pathogens) which may be due to the spatial coverage addressed in our study. The next step is to extend the analysis of PMNs and to integrate the information generated by PMNs into sustainable pest management strategies, both at the field and the landscape level.