Conventional Synthetic Pesticides Research Articles

'The Garlic Gambit': an alternative strategy for controlling vine weevil (Otiorhynchus sulcatus F.; Coleoptera: Curculionidae).

Plant protection products derived from plant material are proposed to be a sustainable alternative to conventional synthetic chemical pesticides. This study determines the efficacy of a commercially available bioinsecticide based on garlic (Allium sativum L.; Asparagales: Amaryllidaceae) extract against vine weevil (Otiorhynchus sulcatus F.; Coleoptera: Curculionidae) eggs and larvae in contact, fumigation and a combination of contact and fumigation bioassays under laboratory conditions. Results showed that garlic significantly reduced egg hatch rate compared to the control group when applied as a fumigant. Similarly, the egg hatch rate was reduced compared to the control group when garlic was applied as combined contact and fumigant applications. No effect was observed when the garlic product was applied as a contact application. The bioinsecticide significantly reduced larval survival when either contact or fumigant applications were used. A combined contact and fumigant effect was shown also when vine weevil eggs were exposed to the bioinsecticide for 30 days in plastic containers containing growing media. The number of larvae recovered after this period was significantly reduced compared to the control group. This study demonstrates the potential of garlic-based bioinsecticides, such as Pitcher GR, for vine weevil control. Further studies are, however, needed to determine the efficacy of such bioinsecticides under field conditions and investigate how these products can be most effectively used as a part of a wider vine weevil integrated pest management program.

Harnessing Koelreuteria paniculata Seed Extracts and Oil for Sustainable Woolly Apple Aphid Control

The woolly apple aphid—WAA (Eriosoma lanigerum Hausmann, 1802) poses a significant threat to intensive apple production. Given the limitations of conventional synthetic pesticides, there is an urgent need for effective and sustainable pest management strategies. Botanical extracts derived from plants with insecticidal properties mitigating aphid populations without adverse environmental impacts are scarce where WAA is concerned. Thus, the pertinent study aimed to investigate the aphicidal potential of Koelreuteria paniculata seed ethanolic extract (derived from the seed coat) and mechanically extracted oil (derived from the seed itself). At concentrations of 2.5% and 5%, both solutions expressed undeniable insecticidal potential, providing absolute (100%; oil) or significant (86–100%; ethanolic extract) mortality rates both in vivo and in vitro. Predominant phenolic compounds determined in the ethanolic extract were gallic and protocatechuic acids and three derivates—p-coumaric, quercetin, and luteolin acid derivates—contributing to more than 90% of the total phenolic content, while phenolic compounds were not detected in the oil, indicating activity of different active compounds. Although deriving from different seed parts and distinct extraction methods, both ethanolic extract and oil exhibited significant aphicidal effects against WAA. The integration of botanical extracts from invasive species into pest management practices supports ecological balance and sustainable agricultural productivity, fostering a healthier environment and more resilient agricultural systems.

Exploiting volatile organic compounds in crop protection: A systematic review of 1‐octen‐3‐ol and 3‐octanone

AbstractThe 21st century has brought new challenges to the agri‐food industry due to population growth, global warming, and greater public awareness of environmental issues. Ensuring global food security for future generations is crucial. However, pests, weeds, and diseases still significantly contribute to crop losses, and the availability of effective conventional synthetic pesticides is decreasing. To address this, new and diverse pest management tools are needed. One pest management tool showing potential for invertebrate pest management is the exploitation of volatile organic compounds (VOCs)—in particular, the compounds 1‐octen‐3‐ol and 3‐octanone. This review aims to explore the extent to which 1‐octen‐3‐ol and 3‐octanone show potential in the future management of invertebrate crop and animal pests. A significant increase in the rate of publication of literature on the use of 1‐octen‐3‐ol and 3‐octanone in crop protection since 2018 is identified by this review, therefore, showing the potential importance of these compounds for use in future pest management. This review also identifies key interactions between naturally occurring biosynthesised 1‐octen‐3‐ol and 3‐octanone, and a range of invertebrate targets. Many of these interactions with key crop pests are sourced from the taxonomic families Lamiaceae, Fabaceae, and Trichomaceae. However, analysis of the practical application of these sources in an integrated pest management programme identifies clear limitations with the use of naturally occurring biosynthesised 1‐octen‐3‐ol and 3‐octanone. Rather, future focus should be placed on the development and exploitation of synthesised nature identical 1‐octen‐3‐ol and 3‐octanone for use as a biopesticide product. Overall, 1‐octen‐3‐ol and 3‐octanone show potential for exploitation in future crop protection, being abundant in source and diversity of invertebrate interactions. However, their use as a naturally occurring biosynthesised chemical is likely not practical for direct implementation in crop protection. Rather, focus should be placed on the development and exploitation of synthesised nature identical variants of these compounds for use as a biopesticide.

Natural farming improves crop yield in SE India when compared to conventional or organic systems by enhancing soil quality

Zero Budget Natural Farming (ZBNF) is a grassroot agrarian movement and a state backed extension in Andhra Pradesh, and has been claimed to potentially meet the twin goals of global food security and environmental conservation. However, there is a lack of statistically evaluated data to support assertions of yield benefits of ZBNF compared to organic or conventional alternatives, or to mechanistically account for them. In order to fill this gap, controlled field experiments were established in twenty-eight farms across six districts, spanning over 800 km, over three cropping seasons. In these experiments, we compared ZBNF (no synthetic pesticides or fertilisers, home-made inputs comprising desi cow dung and urine with mulch) to conventional (synthetic fertilisers and pesticides) and organic (no synthetic pesticides or fertilisers, no mulch, purchased organic inputs, e.g. farmyard manure and vermicompost) treatments, all with no tillage. Comparisons were made in terms of yield, soil pH, temperature, moisture content, nutrient content and earthworm abundance. Our data shows that yield was significantly higher in the ZBNF treatment (z score = 0.58 ± 0.08), than the organic (z= −0.34 ± 0.06) or conventional (−0.24 ± 0.07) treatment when all farm experiments were analysed together. However, the efficacy of the ZBNF treatment was context specific and varied according to district and the crop in question. The ZBNF yield benefit is likely attributed to mulching, generating a cooler soil, with a higher moisture content and a larger earthworm population. There were no significant differences between ZBNF and the conventional treatment in the majority of nutrients. This is a particularly important observation, as intensive use of synthetic pesticides and fertilisers comes with a number of associated risks to farmers’ finances, human health, greenhouse gas emissions, biodiversity loss and environmental pollution. However, long-term field and landscape scale trials are needed to corroborate these initial observations.

RNA interference machinery in the two-spotted spider mite, Tetranychus urticae Koch

RNA interference (RNAi) or post-transcriptional gene silencing is a biological process conserved in a broad range of eukaryotes and triggered by endogenous or exogenous double-stranded RNA (dsRNA). RNAi suppresses the endogenous expression of the target gene of which the mRNA sequence is complementary to the dsRNA sequence. RNAi has been widely used as a gene functional analysis technology, and recently, exogenous dsRNA has begun to be applied to a sprayable biopesticide with a different mode-of-action from conventional synthetic pesticides. The two-spotted spider mite, Tetranychus urticae Koch (Trombidiformes: Tetranychidae), is distributed worldwide and has been known as one of the most difficult agricultural pests to control due to its rapid development of resistance to synthetic pesticides. Therefore, the development of RNAi-based biopesticide targeting this species is highly anticipated. However, the function of RNAi machinery in this species remains unclear. Processing dsRNA into small RNA is a fundamental process contributing to RNAi efficacy. Here we performed functional analysis of TuDcr1 and TuDcr2 genes, homologues of Drosophila melanogaster Dicer-1 and Dicer-2, which belong to the RNase III family. The nucleotide sequences of TuDcr1 (tetur19g00520), TuDcr2 (tetur07g00990), and an intergenic region as a negative control (NC) were obtained from the ORCAE database and used for PCR amplification of each DNA fragment. RNA synthesized by in vitro transcription from each DNA fragment was used to prepare dsRNA specific to TuDcr1, TuDcr2, and NC (dsRNA-TuDcr1, dsRNA-TuDcr2, and dsRNA-NC, respectively). A nylon-mesh-based feeding device was used to orally deliver dsRNA to age-synchronized adult female mites for 24 h. Both TuDcr1 and TuDcr2 were upregulated after oral administration of dsRNA-NC, which indicates the activation of RNAi machinery by orally-delivered dsRNA. Downregulations of TuDcr1 and TuDcr2 were observed in mites fed on dsRNA-TuDcr1 and dsRNA-TuDcr2 when compared to dsRNA-NC. However, no significant effects were observed in the susceptibility to RNAi targeting an essential gene Vacuolar-type H+-ATPase after oral administration of dsRNA-TuDcr1, dsRNA-TuDcr2, or dsRNA-NC. The dsRNA-cleaving assay revealed that the dicing activity was reduced in mites fed on dsRNA-TuDcr1 and dsRNA-TuDcr2 when compared with dsRNA-NC and that the activity seemed to be higher in TuDcr2 than TuDcr1. Our results suggest that TuDcr1 and TuDcr2 possess the activity of dsRNA cleavage and that TuDcr2 is responsible for dicing exogenous dsRNA.

Phytochemical constituents and larvicidal efficacy of Calopogonium mucunoides leaf and Chrysophyllum albidum seed extracts against the Aedes aegypti larvae

The larvicidal efficacy of Calopogonium mucunoides leaf and Chrysophyllum albidum seed extract against 2nd and 3rd larval instars of Aedes aegypti was investigated in an acute bioassay. The larvicidal bioassay was done in triplicate of ten laboratory-reared larvae of Ae. aegypti at four different concentrations (250, 500, 750, and 1000 ppm) with a simultaneous control at 24 h, 48 h, and 72 h of exposure. Phytochemical screening revealed the presence of alkaloids, terpenoids, tannins, and saponins in the extracts. The larvicidal bioassay of C. mucunoides leaf and C. albidum seed extracts varied significantly with concentration and exposure time (p < 0.05). Lethal concentrations (LC50 and LC90) for C. mucunoides were 2.935 and 7.608 ppm, 2.096 and 6.302 ppm, and 1.626 and 5.866 ppm for 24 h, 48 h, and 72 h (2nd instar larvae), and 2.923 and 11.067 ppm, 2.096 and 9.686 ppm, and 2.033 and 6.946 ppm (3rd instar larvae), while C. albidum had values of 3.231 and 7.393 ppm, 2.755 and 6.123 ppm, and 2.278 and 4.584 ppm at 24 h, 48 h, and 72 h (2nd instar larvae), and 3.731 and 7.021 ppm at 24 h, 2.843 and 4.526 ppm at 48 h, and 2.774 and 4.202 ppm at 72 h (3rd instar larvae). The chloroform fraction of C. mucunoides partitioning gave 100% mortality for 3rd instar larvae, with its leaf extract being more potent than C. albidum seed extract. The potential bioactive compound extant in these plants could become a substitute for conventional insecticides and synthetic pesticides and ought to be further explored for control of mosquito larvae.

Larvicidal and adulticidal activity of essential oils from plants of the Lamiaceae family against the West Nile virus vector, Culex pipiens (Diptera: Culicidae)

Culex pipiens mosquitoes are the most widely distributed primary vector of the West Nile virus worldwide. Many attempts for investigation of botanical pesticides to avoid the development of pesticide resistance to conventional synthetic pesticides that are recognized as a threat to the diversity of ecosystems. The study aimed to determine the components of three essential oils of Lamiaceae family, lavender (Lavandula angustifolia), peppermint (Mentha piperita L.), and rosemary (Rosmarinus officinalis L.) by gas chromatography-mass spectrometry (GC–MS) analysis. Furthermore, aimed to validate the insecticidal activities of these oils as larvicidal agents against the third instar larvae of Culex pipiens using five different concentrations (62.5, 125, 250, 500, and 1000 ppm) for each oil in five replicates and as an adulticidal agent against approximately three-day-old female adults of Cx. Pipiens using 0.5, 1, 2, 4, and 5% concentrations in three replicates. The results generally showed a dose-related response. At 1000 ppm, rosemary oil showed the highest larvicidal (100%) (LC50, 214.97 ppm), followed by peppermint oil (92.00% mortality and LC50 (269.35 ppm). Lavender oil showed the lowest efficacy with 87.20% mortality and LC50 (301.11 ppm). At 5% oil concentration, the highest knockdown rate at 1 h was recorded for lavender oil (95.55%), followed by peppermint oil (88.89%) and lastly rosemary oil (84.44%). After 24 h, rosemary oil showed the lowest adult mortality rate (88.89%; LC50, 1.44%), while lavender and peppermint oils both showed a 100% mortality rate, with (LC50, 0.81% and 0.91%, respectively). The chemical constituents of the oils consisted of monoterpenes and sesquiterpenes that determined their insecticidal activities against the target insect stage. The study proposed that rosemary essential oil may be useful for the control of Cx. pipiens larvae as part of an integrated water treatment strategy, and lavender and peppermint oils may be used in an integrated plan for adult’s control.

Antioxidant, Antimicrobial, and Insecticidal Properties of a Chemically Characterized Essential Oil from the Leaves of Dittrichia viscosa L.

Since some synthetic insecticides cause damage to human health, compounds in plants can be viable alternatives to conventional synthetic pesticides. Dittrichia viscosa L. is a perennial Mediterranean plant known to possess biological activities, including insecticidal properties. The chemical composition of an essential oil (EOD) from D. viscosa, as well as its antioxidant, antimicrobial, and insecticidal effects on the cowpea weevil (Callosobruchus maculatus) were determined. Forty-one volatile compounds were identified in EOD, which accounted for 97.5% of its constituents. Bornyl acetate (41%) was a major compound, followed by borneol (9.3%), α-amorphene (6.6%), and caryophyllene oxide (5.7%). EOD exhibited significant antioxidant activity in all tests performed, with an IC50 of 1.30 ± 0.05 mg/mL in the DPPH test and an EC50 equal to 36.0 ± 2.5 mg/mL in the FRAP assay. In the phosphor-molybdenum test, EOD results ranged from 39.81 ± 0.7 to 192.1 ± 0.8 mg AAE/g E. EOD was active on E. coli (9.5 ± 0.5 mm), S. aureus (31.0 ± 1.5 mm), C. albicans (20.4 ± 0.5 mm), and S. cerevisiae (28.0 ± 1.0 mm), with MICs ranging from 0.1 mg/mL to 3.3 mg/mL. We found that 1 µL of EOD caused 97.5 ± 5.0% insect mortality after 96 h in the inhalation test and 60.0 ± 8.3% in the ingestion assay. The median lethal concentration (LC50) was 7.8 ± 0.3 μL EO/L, while the effective concentration in the ingestion test (LC50) was 15.0 ± 2.1 μL EO/L. We found that 20 µL of EOD caused a reduction of more than 91% of C. maculatus laid eggs.

Floating chitosan-alginate microspheres loaded with chlorantraniliprole effectively control Chilo suppressalis (Walker) and Sesamia inferens (Walker) in rice fields

Striped rice stem borer, Chilo suppressalis (Walker) and pink stem borer, Sesamia inferens (Walker) are two important pests, causing substantial yield loss in rice production. Application of conventional synthetic pesticides, such as suspension concentrates and water-dispersible granules, is a primary method for control of the two pests. Due to the flow of water in rice field, spray drift, and soil adsorption, applied such pesticides are often out of the target, resulting in low control efficacy, potential contamination of soil or surface water, and also threat to human health. Thus, there is an urgent need for developing environmentally friendly and highly targeted pesticide formulations to meet the challenges. The present study synthesized chlorantraniliprole loaded chitosan-alginate floating hydrogel microspheres (CCAM) through physical embedding, ionic crosslinking, and incorporation of citronellol as an oil phase. The morphology, particle size, entrapment efficiency, loading capacity, in vitro slow-release kinetics, and floating ability of the CCAM were tested in laboratory conditions. The CCAM and two commercial formulations (suspended and granulated) of chlorantraniliprole were respectively evaluated in two rice fields located in two provinces of China. The CCAM was able to float on the surface of rice field, gather around rice stems, and slowly release chlorantraniliprole, which resulted in significantly higher concentrations of chlorantraniliprole in rice stems and leaves for a prolonged time than suspended and granulated controls. The application of CCAM provided an on-target control of both striped stem borer and pink stem borer. Furthermore, CCAM application had very low residue of chlorantraniliprole in soils. As far as is known, this is the first report of chlorantraniliprole loaded on chitosan-alginate floating hydrogel microspheres for rice stem borer control. Our results indicate that the synthesized CCAM could potentially be used as a controlled-release product for effective control of the two rice pests, while reducing the residual chlorantraniliprole in the soil and avoiding pesticide drift.

Residual and Direct Contact Toxicities of Crude Extracts and Essential Oils from Acorus calamus L. (Acoraceae) Rhizomes against Cassava Red Mites (Acari: Tetranychidae)

Abstract Tetranychus truncatus Ehara (Acari: Tetranychidae) is a serious economic pest of many plants in Thailand and other countries. The use of plant extracts is an alternative to conventional synthetic pesticides for controlling mite pests. This study was conducted to evaluate the residual and direct contact toxicities of crude extracts and essential oils obtained from Acorus calamus L. (Acoraceae) rhizomes against T. truncatus eggs and adult females under laboratory conditions. Residual toxicity was assayed by applying compounds on leaf discs and then releasing adult female mites on the discs; direct contact toxicity was assayed by spraying the compounds on eggs and adult females. In residual assays, a 10% (v/v) concentration of essential oils extracted from fresh A. calamus rhizomes caused 73.8% mortality of T. truncatus adults, while treatment with oils from dried rhizomes caused 91.8% mortality of adults. In direct-contact toxicity assays, essential oils from fresh rhizomes reduced egg hatch by 96.3% at 5% (v/v) concentration and 100.0% at 10%. Oils extracted from dried rhizomes reduced egg hatch by 28.8% at 5% and 91.8% at 10%. The respective median lethal concentrations (LC50s) were 2.18% and 5.91%, based on cumulative mortality at 7 d after treatment. Methylene chloride extracts from fresh and dried rhizomes (individual extraction method) caused a cumulative adult mite mortality of 100% and 91.4% at 5% (v/v) concentration, with LC50s of 1.31% and 2.52%. Based upon our results, essential oils and methylene chloride extracts from A. calamus rhizomes appear as suitable botanical acaricides for further development for the management of T. truncatus.

Sunflower seed hulls waste as a novel source of insecticidal product: Pyrolysis bio-oil bioactivity on insect pests of stored grains and products

The edible oil industry produces abundant sunflower seed hulls (SSH) as waste. Pyrolysis offers a sustainable method for producing high-value bioproducts from this lignocellulosic residue. This paper reports on the bioefficacy of SHH pyrolysis bio-oils from raw SSH (named SSH bio-oil) and acid pretreated hulls (named PTH bio-oil) as bioinsecticides against Sitophilus oryzae, Lasioderma serricorne and Tribolium castaneum. Raw SSH and pretreated hulls with 10% H3PO4 were subjected to fast pyrolysis in a vertical reactor at 450 °C. Results show that PTH bio-oil is a furfural enriched bio-liquid with storage stability and a yield of 33%. SSH bio-oil was unsuitable for evaluating biological activity since it produce high variability in mortality data. In contrast, PTH bio-oil produces high insecticidal activity in S. oryzae (LC50 = 0.51 mg cm−2) by contact toxicity bioassay, followed by L. serricorne and T. castaneum. In behavioral assays, PTH bio-oil shows a slight repellent effect and mobility reduction. Moreover, PTH bio-oil affects the nutritional physiology of S. oryzae and T. castaneum producing a modification of nutritional indices and antifeedant effects. Our study provides information on the potential of fast pyrolysis bio-oils from SSH waste to develop novel bioinsecticides as an alternative to the use of conventional synthetic pesticides.

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) on the "Offensive" in Africa: Prospects for Integrated Management Initiatives.

Simple SummaryThe past decade has seen Africa being invaded by an invasive and destructive insect pest of tomato, the South American tomato pinworm. To date, the pest insect has since spread to almost the entire continent at lightning speed. Farmers have responded to this pest pressure through the sole injudicious use of chemical pesticides. However, this method of control is expensive, not effective (owing to reported insecticide resistance) and has potential adverse effects on the environment (including humans). To mitigate this, more environmentally friendly, bio-based and sustainable alternatives need to be put in place. Natural substances (NSs), for example, the use of pesticidal plant extracts, naturally occurring antagonists and related substances, can be used in this regard. A literature review was conducted explaining various factors that contributed to successful invasion by the pinworm. The review also explored various control mechanisms (e.g., biological control agents) that can be used in combination with natural and other low risk substances in a holistic way for successful pest control. Focus was also taken on the enabling and limiting factors that influence farmers in embracing the use of these NSs in an integrated approach.The South American tomato pinworm Tuta absoluta (Meyrick) has aggressively invaded the African continent. Since its first detection in North Africa in Morocco and Tunisia in 2008, it has successfully invaded the entire southern, eastern and western Africa, where it has been on the offensive, causing significant damage to Solanaceous food crops. While control of this prolific invader is primarily based on conventional synthetic pesticides, this form of control is consistently losing societal approval owing to (1) pesticide resistance development and consequential loss of field efficacy; (2) growing public health concerns; (3) environmental contamination and loss of biological diversity and its associated ecological services; and (4) unsustainable costs, particularly for resource-poor African farmers. As such, more ecologically sound pest management strategies, e.g., the use of natural substances (NSs), may offer a more sustainable approach to tackling this offensive. A systematic literature search through digital libraries and online databases (JSTOR, PubMed, Web of Science, SCOPUS and Google Scholar) was conducted using predetermined keywords on T. absoluta, e.g., South American tomato pinworm. We use this to explain the invasion of T. absoluta in Africa, citing mechanisms facilitating African invasion and exploring the potential of its control using diverse biological control agents, natural and low-risk substances. Specifically, we explore how botanicals, entomopathogens, semiochemicals, predators, parasitoids, host plant resistance, sterile insect technique and others have been spatially employed to control T. absoluta and discuss the potential of these control agents in African landscapes using more integrated approaches. We discuss the use of NSs as assets to general insect pest control, some potential associated liabilities and explain the potential use and barriers to adoption in African systems from a legislative, economic, ecological and social standpoint.

Agricultural Uses of Juglone: Opportunities and Challenges

Application of conventional synthetic pesticides and agrochemicals has boosted the yield and productivity of crops by reducing pest infestation and promoting crop growth yet increasing reliance on many of these products poses serious environmental threats. This has led to growing interest in obtaining more environmentally friendly alternatives to conventional pesticides and agrochemicals. Allelochemicals produced by plants, fungi, and microbes offer options for developing novel natural product-based pesticides and agrochemicals that are effective but with lower environmental half-lives. Here, we review the current state of knowledge about the potential use of juglone (5-hydroxy-1,4-naphthoquinone), the allelochemical produced by black walnut trees (Juglans nigra), which has been investigated for applications across a range of different agricultural purposes. We then offer our perspective on what opportunities and challenges exist for harnessing juglone as a component of sustainable agriculture.

Transcriptome Analysis of Solanum Tuberosum Genotype RH89-039-16 in Response to Chitosan.

Potato (Solanum tuberosum L.) is the worldwide most important nongrain crop after wheat, rice, and maize. The autotetraploidy of the modern commercial potato makes breeding of new resistant and high-yielding cultivars challenging due to complicated and time-consuming identification and selection processes of desired crop features. On the other hand, plant protection of existing cultivars using conventional synthetic pesticides is increasingly restricted due to safety issues for both consumers and the environment. Chitosan is known to display antimicrobial activity against a broad range of plant pathogens and shows the ability to trigger resistance in plants by elicitation of defense responses. As chitosan is a renewable, biodegradable and nontoxic compound, it is considered as a promising next-generation plant-protecting agent. However, the molecular and cellular modes of action of chitosan treatment are not yet understood. In this study, transcriptional changes in chitosan-treated potato leaves were investigated via RNA sequencing. Leaves treated with a well-defined chitosan polymer at low concentration were harvested 2 and 5 h after treatment and their expression profile was compared against water-treated control plants. We observed 32 differentially expressed genes (fold change ≥ 1; p-value ≤ 0.05) 2 h after treatment and 83 differentially expressed genes 5 h after treatment. Enrichment analysis mainly revealed gene modulation associated with electron transfer chains in chloroplasts and mitochondria, accompanied by the upregulation of only a very limited number of genes directly related to defense. As chitosan positively influences plant growth, yield, and resistance, we conclude that activation of electron transfer might result in the crosstalk of different organelles via redox signals to activate immune responses in preparation for pathogen attack, concomitantly resulting in a generally improved metabolic state, fostering plant growth and development. This conclusion is supported by the rapid and transient production of reactive oxygen species in a typical oxidative burst in the potato leaves upon chitosan treatment. This study furthers our knowledge on the mode of action of chitosan as a plant-protecting agent, as a prerequisite for improving its ability to replace or reduce the use of less environmentally friendly agro-chemicals.

Genomic effects of a nanostructured alumina insecticide in human peripheral blood lymphocytes in vitro

Nanotechnology is providing new tools for precision agriculture, such as agrochemical agents and innovative delivery mechanisms to improve cropping efficiency. Powder nanoinsecticides, such as experimental nanostructured alumina (NSA), show great potential for sustainable agriculture as an alternative to conventional synthetic pesticides because their mechanism of insecticide action is based on physical rather than on biochemical phenomena. However, even in highly non-reactive and hardly soluble substances such as alumina, reduced particle size may lead to an increased toxicity of the material. In order to determine whether NSA induces DNA and chromosomal damage, its toxicity was assessed in human peripheral blood lymphocytes (PBL) and contrasted with commercial nanostructured alumina, natural insecticide powders and a conventional pesticide. PBL from healthy donors were exposed for 24 h to increasing concentrations (50, 100 and 200 μg/mL) of NSA particle agglomerates (<350 nm); positive and negative NSA-particles, respectively; bulk Al2O3 (4.5 μm) or Diatomaceous Earth (SiO2, <4.5 μm). Alkaline comet assay and micronuclei (MNi) test were used to assess DNA damage and chromosomal breakage, respectively. Cell viability was tested with resazurin assay. Comet assay results revealed no significant increase in DNA damage by NSA compared to other natural substances. As expected, DNA breaks were significantly higher in cells exposed to an organophosphate [OPP] control (P < 0.05). No statistically significant differences were found in terms of cellular viability at 50 and 100 μg/mL of NSA but cell survival decreased at 200 μg/mL as well as in OPP group. Positively charged NSA particles significantly reduced cell viability and increased DNA migration and oxidative DNA damage (8-oxoG). NSA as well as the electrically charged NSA particles had no significant effect on MNi induction. Our results indicate that NSA particles are non-cytotoxic and non-genotoxic at the tested doses and do not cause obvious DNA damage in human PBL in vitro.

Research and Development of Biopesticides: Challenges and Prospects

Even though pesticides have greatly contributed to boosting agricultural productivity and farmer income over the years, there have been concerns about the safety of some of these pest control products. Besides, there has been a growing demand for good quality and safe food in the recent past – as reflected in the stringent regulations on pesticide residue levels in produce. Biopesticides in comparison with conventional synthetic chemical pesticides are usually less toxic, generally affect only the target pest and closely related organisms, are often effective in relatively small quantities and decompose faster, resulting in lower exposure. Consequently, over the last few years, biopesticides have attracted global attention as a safer pest control strategy for incorporation into Integrated Pest Management (IPM) programmes. Besides, in the last decade, adoption of IPM programmes has significantly enhanced pest management practices and, in some cases, reduced pesticide use, consequently reducing the rise in demand for synthetic chemical pesticides. Also, the development of new synthetic chemical pesticides has declined considerably in the recent past, as regulations have become tighter, with products being withdrawn from the market, resulting in a more limited choice of chemical solutions such that biopesticides have become a more feasible option. Many countries have also increasingly lowered chemical Maximum Residue Levels for agricultural imports which have made it increasingly necessary to explore pest control options which would ensure reduced reliance on the use of synthetic chemical pesticides. In this paper, avenues of addressing challenges to biopesticide research and development are evaluated by seeking the inputs of a wide range of stakeholders, building on a recent international workshop with biopesticides practitioners from across the globe. Prospects for biopesticide application are detailed using a case study on the fall armyworm (Spodoptera frugiperda) in Africa.

Botanical Biopesticides – Where to Now?

Like Apollo 13 in the eponymously named 1995 film, crop protection has a problem, well actually, more than one problem. Unlike the Apollo disaster there is however, no quick fix on the horizon. The first, and for growers often the more serious problem, is that populations of insects and other pests, are developing resistance to pesticides; indeed there are almost 600 species of arthropod for which resistance to the most commonly used crop protection products has been reported. The situation with weeds and plant pathogens is equally parlous, with cases of resistance to herbicides and fungicides growing at an alarming rate worldwide. The second problem, and one that potentially poses a danger to us all is the realization that the use of some conventional synthetic pesticides, widely perceived by the public and some scientists, as a danger to beneficial insects such as pollinators, may also be a threat to insects in general. The pressure put on growers by the public condemnation of the use and the reducing commercial availability of effective conventional synthetic pesticides means that the development of viable alternatives is of increasing importance. The obvious, and the option favoured by the European Union, is to increase the wholehearted uptake of Integrated Pest Management (IPM) by growers of all kinds. Given that successful IPM programmes and those likely to do not preclude the use of pesticides it would be foolish, in most cropping situations at least, to advocate reliance on biological control options on their own. Where approaches to prevent pest problems, such as through the use of host-plant resistance and crop rotations, have been unsuccessful, this effectively leaves us with the biopesticides to combat pest outbreaks. Biopesticides are typically either derived from plants (the botanicals) or from microbial agents such as entomopathogenic fungi. We desperately need further work in this area, without increased funding and just as importantly, changes in the regulatory framework and the attitudes of growers, improvements in developing sustainable and environmentally friendly crop production will be a long time coming.

Effect of Trichoderma velutinum and Rhizoctonia solani on the Metabolome of Bean Plants (Phaseolus vulgaris L.).

The common bean (Phaseolus vulgaris L.) is one of the most important food legume crops worldwide that is affected by phytopathogenic fungi such as Rhizoctonia solani. Biological control represents an effective alternative method for the use of conventional synthetic chemical pesticides for crop protection. Trichoderma spp. have been successfully used in agriculture both to control fungal diseases and to promote plant growth. The response of the plant to the invasion of fungi activates defensive resistance responses by inducing the expression of genes and producing secondary metabolites. The purpose of this work was to analyze the changes in the bean metabolome that occur during its interaction with pathogenic (R. solani) and antagonistic (T. velutinum) fungi. In this work, 216 compounds were characterized by liquid chromatography mass spectrometry (LC-MS) analysis but only 36 were noted as significantly different in the interaction in comparison to control plants and they were tentatively characterized. These compounds were classified as: two amino acids, three peptides, one carbohydrate, one glycoside, one fatty acid, two lipids, 17 flavonoids, four phenols and four terpenes. This work is the first attempt to determine how the presence of T. velutinum and/or R. solani affect the defense response of bean plants using untargeted metabolomics analysis.

Biology and Management of the New Zealand Endemic Wheat Bug, Nysius huttoni (Hemiptera: Lygaeidae)

Abstract The wheat bug, Nysius huttoni White, mainly reported as a pest of wheat and forage brassicas, is native to New Zealand. This pest has been accidentally introduced into The Netherland and Belgium during apple exports from New Zealand. The bug population is abundant in open sparse vegetations and hot-dry habitats, and feeds on dropping seeds. It damages wheat grains during milk-ripe stage by piercing through the glumes into the developing grains that can reduce gluten protein and reduce baking quality. Bugs also suck phloem fluid from seedlings, which can reduce plant establishment in forage brassicas. Early scouting and field monitoring are suggested before making pest management decisions. Seed treatment with neonicotinoids, permethrin, and chlorpyrifos spray in the standing crops are chemical methods of management in New Zealand. These conventional synthetic pesticides have nontarget effects on human health, the environment, and biodiversity. However, preventive measures such as the use of less-susceptible cultivars, and using potential trap crops is other important pest management options. Alyssum (Lobularia maritima L. Desv. Brassicales: Brassicaceae) and wheat (Triticum aestivum L. Poales: Poaceae) are two potential trap crops of wheat bug. Kale (Brassica oleracea L.) cultivars, such as Corka and Regal, and wheat (Triticum aestivum) cultivars, such as Batten, Domino, and Oroua, are less-susceptible cultivars. Understanding the biology and ecology of the pest, and utilizing preventative pest management measures such as the use of trap crops and less-susceptible cultivars, and integrating these with ‘soft’ chemicals make a suitable integrated pest management strategy for this pest.

Characteristics and production constraints of smallholder tomato production in Kenya

Abstract Tomato is among the promising commodities in horticultural production in Kenya. Over the years, tomato production in Kenya has intensified. Yields, however, continue to remain low due to a myriad of constraints. This paper describes production practices and identifies challenges and opportunities for increased tomato productivity in smallholder production in Kenya. The study uses plant health clinics as primary providers of data. Association between variables is tested using multinomial logistic regression, and Goodness-of-fit test used to examine how well the model fits the data. In addition, ANOVA and Student's t -test were used to compare group means. Smallholder tomato production in Kenya is characterised by a decline in the area under tomato cultivation. Furthermore, production is dominated by male farmers while participation by youth is minimal. Coupled with these, a diverse range of biotic constraints impede tomato production, and for their management, use of conventional synthetic pesticides is the preferred practice by farmers. The findings of this study underscore the need to increase women and youth participation in tomato production. In addition, there is a need to explore initiatives that enable farmers to access available technologies such as improved seed. For the management of biotic constraints, smallholder farmers should be encouraged to consider alternatives other than an overreliance in the use of synthetic pesticides.