Pest Control Approaches Research Articles

New Beauveria bassiana aerial conidia-based bioinsecticide obtained by spray-dried microencapsulation of the entomopathogenic fungi in biopolymers for crop protection

BackgroundDue to their environmentally friendly character, entomopathogenic fungi (EPF) are becoming increasingly used as microbial agents in biological pest control over chemical pesticides. However, EPF are sensitive to the influence of abiotic factors, such as temperature, radiation, and humidity. To improve their efficiency as bioinsecticides, in this work, the development of a new microparticles-based formulation loading EPF conidia (B. bassiana aerial conidia) into sodium alginate/maltodextrin microparticles obtained by spray-drying was proposed. Different concentrations of both polysaccharides were tested to reach the optimal ratio and ensure a high viability of encapsulated conidia.ResultsAll the produced formulations showed a moisture content < 10% and water activity (aw) < 0.4. Microparticles obtained with 2% sodium alginate and 8% maltodextrin were able to retain 89.5% of the viability of encapsulated conidia, thus being selected for further characterization. Scanning electron microscopy showed microparticles with a smooth surface, varied sizes, and irregular morphology. Microparticles retained 5.44 × 108 conidia/g, presented high hygroscopicity and high suspensibility rate, yet low wettability and water activity (aw) of 0.33. The pH value ranged from 6.46 to 6.62. Microparticles were able to complete release the loaded conidia after 30 min, under constant stirring. When exposed to thermal stress (45 °C), microparticles promoted thermal protection to conidia. Enhanced pathogenicity of B. bassiana conidia against P. xylostella was also confirmed achieving 83.1 ± 5.5%, whereas non-encapsulated conidia reached only 64.8 ± 9.9%.ConclusionsThis study confirms that the encapsulation of B. bassiana fungus conidia in sodium alginate/maltodextrin microparticles by spray-drying is a promising technological approach for the biological control of agricultural pests.

Characterization of CYP303A1 and its potential application based on ZIF-8 nanoparticle-wrapped dsRNA in Nilaparvata lugens (Stål).

RNA interference (RNAi) technology has been put forward as a promising method for pest control and resistance management. Mining highly efficient lethal genes and constructing stable double-stranded RNA (dsRNA) delivery systems are of great significance to improve the application potential of RNAi technology. In this study, we characterized a molting-related gene, NlCYP303A1, in Nilaparvata lugens that was highly expressed in the cuticle and at the end stages of each instar in nymphs. Silencing the expression of NlCYP303A1 in N. lugens resulted in a deformed phenotype and a significant increase in mortality. Furthermore, interfering with NlCYP303A1 changed the relative expression of key genes in the chitin synthesis and degradation pathway. Finally, we used the nanocarrier zeolitic imidazolate framework-8 (ZIF-8) to load dsNlCYP303A1, forming a complex denoted as dsNlCYP303A1@ZIF-8. The results of both feeding and rice-seedling dip experiments indicated that the expression of NlCYP303A1 was dramatically and persistently suppressed by the dsNlCYP303A1@ZIF-8 treatment, compared with treatment with dsNlCYP303A1, suggesting that ZIF-8 can enhance the interference efficiency as well as the stability of dsNlCYP303A1. Our results demonstrate that the lethal gene NlCYP303A1 can be employed as an excellent target for RNAi technology by loading onto a nano-delivery system, and provide new insights into the creation of innovative pest control approaches. © 2024 Society of Chemical Industry.

Identification and functional analysis of gut dsRNases in the beet armyworm Spodoptera exigua

RNA interference (RNAi)-based products have the potential to significantly contribute to insect pest control. However, RNAi efficiency varies widely among different insect orders, particularly in Lepidoptera, where it is often low. One key factor affecting RNAi efficiency is the presence of double-stranded ribonuclease (dsRNase) in the digestive tract, which can degrade dsRNA prior to uptake by gut cells. In this study, four dsRNases were identified in the beet armyworm, Spdoptera exigua, of which two were highly expressed gut dsRNases, SedsRNase1 and SedsRNase2. To assess their effect on dsRNA degradation activity via the oral route, CRISPR/Cas9-based gene editing was employed to knock out these gut dsRNases. The results indicate that all mutant strains, including SeKO1 (knockout SedsRNase1), SeKO2 (knockout SedsRNase2), and SeKO1KO2 (knockout SedsRNase1 and SedsRNase2), showed significantly decreased dsRNA degradation activity, particularly in the SeKO1KO2 mutant strain, where the weakest degradation occurred in both the gut and whole body. Additionally, we noticed that the lack of gut SedsRNases led to a slight extended developmental period and reduced reproductive capacity in S. exigua. Collectively, these findings deepen our understanding of gut SedsRNases and how they can impact the biology of the beet armyworm and can support the exploration dsRNA-based approaches for pest control.

Acetyl-CoA Carboxylase Proteolysis-Targeting Chimeras: Conceptual Design and Application as Insecticides.

Novel approaches for pest control are essential to ensure a sufficient food supply for the growing global population. The development of new insecticides must meet rigorous regulatory requirements for safety and address the resistance issues of existing insecticides. Proteolysis-targeting chimeras (PROTACs), originally developed for human diseases, show promise in agriculture. They offer innovative insecticides tailored to overcome resistance, opening avenues for agricultural applications. In this study, we developed small-molecule degraders by incorporating pomalidomide as an E3 ligand. These degraders were linked to a ligand (spirotetratmat enol) targeting the ACC protein through a flexible chain, aiming to achieve the efficient control of insects. Compounds 9a-9d were designed, synthesized, and evaluated for biological activities and mechanisms. Among them, 9b exhibited superior potency against Aphis craccivora (LC50 = 107.8 μg mL-1) compared to others and effectively degraded ACC proteins through the ubiquitin-proteasome system. These findings highlight the potential of utilizing PROTAC-based approaches in the development of insecticides for efficient pest control.

Phytochemical Characterization, Fumigant and Contact Toxicity Activities of Four Essential Oils Against Eriophyid Gall Mite, Aceria pongamiae Keifer (Acarina: Eriophyidae).

Plant-derived essential oils (EO) offer a natural alternative to chemical pesticides for eco-friendly pest control approaches. Aceria pongamiae Keifer, a notorious pest that affects Pongamia pinnata (L.) Pierre has mainly been controlled using synthetic acaricides leading to resistance development and environmental issues. EOs provide a natural and biodegradable option for pest control, with a unique mode of action. This study evaluates the acaricidal efficacy of EOs-eucalyptus Eucalyptus maculata Hook (EEO), lavender Lavandula angustifola L. (LEO), peppermint Mentha piperita L. (PEO), and black pepper Piper nigrum L. (BPEO) against A. pongamiae for the first time. We investigated the biological activity of EOs using fumigation and contact toxicity assays at concentrations ranging from 0.1 to 1 % and 0.6 to 0.9 % respectively, overexposure periods of 24, 48 and 72 h. Chemical characterization of EOs was performed using GC-MS analysis. Eucalyptol (62.88 %), linalyl acetate (39.11 %), menthol (44.35 %), and caryophyllene (32.77 %) were the main components of EEO, LEO, PEO and BPEO respectively. After 24 h of observation, EEO (LC50=1.01 %) and after 48 and 72 h, PEO had the highest fumigant toxicity (LC50=0.71 and 0.29 % respectively). The BPEO showed the most contact toxicity after 24, 48 and 72 h (LC50=0.92, 0.68 and 0.46 % respectively). This work reinforces the selection of adequate essential oils for implementation in future pest control strategies.

Improving the efficiency and environmental safety of emamectin benzoate through a pH-responsive metal–organic framework microencapsulation strategy

Herein, we developed a technique for loading nanopesticides onto Metal-Organic Frameworks (MOFs) to control Spodoptera litura. The average short-axis length of the synthesized carrier emamectin benzoate@PCN-222 @hyaluronic acid (EB@PCN-222 @HA) was ∼40 nm, with an average long-axis length of ∼80 nm. This enabled the manipulation of its size, contact angle, and surface tension on the surface of leaves. Pesticide-loading capacity, determined via thermogravimetric analysis, was measured at ∼16 %. To ensure accurate pesticide release in the alkaline intestine of Spodoptera litura, EB@PCN-222 @HA was engineered to decompose under alkaline conditions. In addition, the carrier delayed the degradation rate of EB, enhancing EB’s stability. Loading Nile red onto PCN-222 @HA revealed potential entry into the insect body through feeding, which was supported by bioassay experiments. Results demonstrated the sustained-release performance of EB@PCN-222 @HA, extending its effective duration. The impact of different carrier concentrations on root length, stem length, fresh weight, and germination rate of pakchoi and tomato were assessed. Promisingly, the carrier exhibited a growth-promoting effect on the fresh weight of both the crops. Furthermore, cytotoxicity experiments confirmed its safety for humans. In cytotoxicity assays, PCN-222 @HA showed minimal toxicity at concentrations up to 100 mg/L, with cell survival rates above 80 %. Notably, the EB@PCN-222 @HA complex demonstrated reduced cytotoxicity compared to EB alone, supporting its safety for human applications. This study presents a safe and effective approach for pest control using controlled-release pesticides with extended effective durations.

Locomotor Activity of Adult Olive Fruit Flies Recorded under Conditions of Food or Water Deprivation

The olive fruit fly, known as Bactrocera oleae (Rossi) (Diptera: Tephritidae), is causing substantial economic losses in olive crops worldwide. Studying the activity patterns of the insect may expand our knowledge to eventually adopt more sustainable and effective pest control approaches. In the present study, we investigated the impact of food and water deprivation on the mobility of olive fruit flies using a modified version of the LAM25 system (locomotor activity monitor)—Trikinetics, an automated locomotor activity electronic device. Both male and female flies at four different age groups, reared on olives in the laboratory, were individually placed in glass tubes. Their locomotor activity was recorded every minute by three monitors within the digital device over a three-day period. Our observations revealed that adults exhibited significantly reduced movement during nighttime compared to daytime. The greatest mobility was observed during the period of 15:00 to 20:59. Additionally, younger flies demonstrated higher levels of mobility compared to older ones. Flies subjected to both food and water deprivation exhibited higher mobility compared to the control group. These insights offer valuable insights for enhancing pest management strategies aimed at controlling olive fruit flies adopting a more sustainable approach.

An Advancing GCT-Inception-ResNet-V3 Model for Arboreal Pest Identification

The significance of environmental considerations has been highlighted by the substantial impact of plant pests on ecosystems. Addressing the urgent demand for sophisticated pest management solutions in arboreal environments, this study leverages advanced deep learning technologies to accurately detect and classify common tree pests, such as “mole cricket”, “aphids”, and “Therioaphis maculata (Buckton)”. Through comparative analysis with the baseline model ResNet-18 model, this research not only enhances the SE-RegNetY and SE-RegNet models but also introduces innovative frameworks, including GCT-Inception-ResNet-V3, SE-Inception-ResNet-V3, and SE-Inception-RegNetY-V3 models. Notably, the GCT-Inception-ResNet-V3 model demonstrates exceptional performance, achieving a remarkable average overall accuracy of 94.59%, average kappa coefficient of 91.90%, average mAcc of 94.60%, and average mIoU of 89.80%. These results signify substantial progress over conventional methods, outperforming the baseline model’s results by margins of 9.1%, nearly 13.7%, 9.1%, and almost 15% in overall accuracy, kappa coefficient, mAcc, and mIoU, respectively. This study signifies a considerable step forward in blending sustainable agricultural practices with environmental conservation, setting new benchmarks in agricultural pest management. By enhancing the accuracy of pest identification and classification in agriculture, it lays the groundwork for more sustainable and eco-friendly pest control approaches, offering valuable contributions to the future of agricultural protection.

Toxicity Assessment of Various Insecticides on Oxycarenus Hyalinipennis Costa (Lygaeidae: Hemiptera) in Laboratory Settings across Various Districts of Punjab, Pakistan

Cotton contributes 0.6% to the value added in GDP and 3.1% to the value added in the agriculture sector of Pakistan. The dusky cotton bug (DCB), Oxycarenus hyalinipennis (Hemiptera: Lygaeidae), is among the insect pest species of highest economic significance in cotton production in the country. Adults and nymphs feed on seeds and cotton bolls, affecting seed germination. The dusky cotton bug is a polyphagous insect that feeds on a variety of host plants. Its adults and nymphs typically feed on squares of the cotton plant, resulting in a pale yellow color of squares and subsequent shedding of infested squares. Insecticide resistance in cotton insect pests is an emerging threat to sustainable cotton production in Pakistan. A thorough understanding of resistance might be a valuable tool for implementing pest control approaches. In the present study, Clothianidin, Fipronil, Bifenthrin, Triazhophos, Deltamethrin, and Clothianidin + Imidacloprid insecticides were used in different cotton-growing districts of Punjab. Among all the insecticides used for controlling the DCB population, Clothianidin + Imidacloprid was found to be the most effective in all districts, while Deltamethrin was the least effective in District Khanewal, Bifenthrin in Dera Ghazi Khan, Rahim Yar Khan, and Vehari, and Clothainidin in Multan. Therefore, we recommend the use of a pesticide mixture (Clothianidin + Imidacloprid) as a beneficial strategy against the dusky cotton bug in various cotton-growing districts of Punjab.

Potential fumigant toxicity of essential oils against Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and its egg parasitoid Trichogramma evanescens (Hymenoptera: Trichogrammatidae)

Sitotroga cerealella is a serious pest of a wide range of stored cereal grains. An essential element of an integrated pest control approach is the application of plant oils as a substitute for chemical insecticides. This study aimed to investigate the fumigant toxicity of Allium sativum and Mentha piperita essential oils against S. cerealella adult moths and the egg parasitoid Trichogramma evanescens. Gas chromatography–mass spectrometry analyses detected that Diallyl trisulfide (37.97%) and dl-Menthol (47.67%) as main compounds in A. sativum and M. piperita, respectively. The results showed that, A. sativum at 10.0, 5.0, and 2.5 µL/L air resulted in 100% insect mortality after 24 h exposure. The concentrations of 10.0 and 5.0 µL/L air of M. piperita oil resulted in 100 and 96% insect mortality, respectively. The parasitoid adult emergence in the F1 reduced when exposed to LC99 of A. sativum and M. piperita oils by 10.89 and 9.67%, respectively. Also, the parasitism of emerged parasitoid decreased by 9.25 and 5.84% (class I-harmless), respectively. Therefore A. sativum and M. piperita have the potential to be used as bio-fumigant for the management of S. cerealella and can be used alongside the T. evanescens in integrated pest management.

Avicenna's views on pest control and medicinal plants he prescribed as natural pesticides.

The present study aimed to introduce Avicenna's views on pest control and the medicinal plants he proposed as natural pesticides. Also, we addressed the strategies that he leveraged to formulate and prescribe them, and, finally, we put his views into perspective with modern science. The data were collected using Al-Qanun Fi Al-Tibb (The Canon of Medicine) as well as scientific databases. According to Al-Qanun Fi Al-Tibb, 42medicinal plants are described as natural pest control agents. After introducing the pest control properties of each plant, Avicenna explained the appropriate strategies for use of these plants. These strategies or formulations included incensing, spraying, spreading, rubbing, smudging, and scent-dispersing, which are equivalent to the modern pesticide formulations of fumigants, aerosols, pastes and poisoned baits, lotions, creams, and slow-release formulations, respectively. This study revealed that Avicenna introduced the pest control approach with natural plants in his book Al-Qanun Fi Al-Tibb and, thus, harnessed the power of nature to control nature. Future research is recommended to find the pest control merits of the presented medicinal plants, in order to incorporate them into pest control programs and reduce environmental pollution resulting from the complications of current synthetic pesticides.

Critical Analysis and Ameliorative Strategies in Combating the Impact of Climate Variability on Pesticide Dynamics and Efficacy

Background: The importance of pesticides in the economy especially in agriculture, cannot be over-emphasized. It is therefore very crucial to uphold and maintain the efficacy of these pest control agents. This study seeks to explore the effect of climate variables on the potency of pesticides. Climate change has emerged as one of the most significant global challenges, disrupting weather patterns and altering ecosystems. These changes pose serious implications for pest dynamics, distribution, and behavior, thereby directly influencing the performance of pesticides. This study analyzed relevant articles related to climate change and pesticides systematically sourced from credible reference databases for a period of 21 years from 2002 to 2023, using the most suitable keywords. Recent scientific research and empirical evidence, analyzing the effects of rising temperatures, altered precipitation patterns, and changing humidity levels on pests and their interactions with pesticide applications were studied. The relevant impact of these effects is seen in reduced agricultural yield, loss of livelihood and source of income, infestation and destruction of agricultural crops, and reduced living standard in the society amongst others. The projected changes include; the development of adaptive agricultural practices and integration of climate-resilient pest management strategies that could improve the efficacy of pesticides. This involves exploring the potential of eco-friendly and biologically-based pest control approaches to reduce the destructive impacts that arise from climate change. These sustainable practices and novel technologies aimed at improving pest control under changing climatic conditions must be encouraged and upheld tenaciously.

Evaluation of the inheritance and dominance of behavioral resistance to imidacloprid in the house fly (Musca domestica L.) (Diptera: Muscidae).

The house fly, Musca domestica, is a cosmopolitan species known for its pestiferous nature and potential to mechanically vector numerous human and animal pathogens. Control of adult house flies often relies on insecticides formulated into food baits. However, due to the overuse of these baits, insecticide resistance has developed to all insecticide classes currently registered for use in the United States. Field populations of house flies have developed resistance to imidacloprid, the most widely used neonicotinoid insecticide for fly control, through both physiological and behavioral resistance mechanisms. In the current study, we conducted a comprehensive analysis of the inheritance and dominance of behavioral resistance to imidacloprid in a lab-selected behaviorally resistant house fly strain. Additionally, we conducted feeding preference assays to assess the feeding responses of genetic cross progeny to imidacloprid. Our results confirmed that behavioral resistance to imidacloprid is inherited as a polygenic trait, though it is inherited differently between male and female flies. We also demonstrated that feeding preference assays can be instrumental in future genetic inheritance studies as they provide direct insight into the behavior of different strains under controlled conditions that reveal, interactions between the organism and the insecticide. The findings of this study carry significant implications for pest management and underscore the need for integrated pest control approaches that consider genetic and ecological factors contributing to resistance.

The Investigation of Effect of Bacteria in Biological Control of Red Spider Mite (Tetranychus spp.) and Plant Yield Parameter in Cotton (Gossypium hirsutum L.)

The purpose of this study was to assess the usability of two bacterial strains, namely Bacillus subtilis PA1 and Paenibacillus azotofixans PA2, for the biological control of red spider species, and their effects on plant quality and yield in cotton under field conditions. The experiments were conducted at three different locations with multiple replications. As a control, a commercial preparation containing Lambda-Cyhalothrin as the active ingredient was used. The obtained results from the study revealed that the application of the bioagent formulation led to a significant decrease in the density of Tetranychus spp. at different biological stages, ranging from 59.22% to 61.07%, when compared to the control group. Additionally, several important plant growth parameters showed remarkable improvements. The number of fruit branches increased by 130.20%, plant crown diameter by 88.16%, plant height by 40.15%, the number of flowers by 21.25%, the number of wood branches by 18.13%, the average number of cocoons by 126.53%, and cocoon weights by 54.65% significantly across all three trial parcels. The successful implementation of the bacterial application for pest control had a positive impact on cotton yield. Bulk cotton yield increased by 80.03%, and fiber yield increased by 82.17%. Consequently, the bacterial formulation containing these two bacteria demonstrated its potential as a biopesticide in cotton cultivation, effectively controlling pests while also playing a crucial role in enhancing productivity. Overall, the study suggests that using the bioagent formulation consisting of Bacillus subtilis PA1 and Paenibacillus azotofixans PA2 could be an effective and environmentally friendly approach for pest control in cotton farming, leading to increased productivity.

Optimizing CRE and PhiC31 mediated recombination in Aedes aegypti.

Introduction: Genetic manipulation of Aedes aegypti is key to developing a deeper understanding of this insects' biology, vector-virus interactions and makes future genetic control strategies possible. Despite some advances, this process remains laborious and requires highly skilled researchers and specialist equipment. Methods: Here we present two improved methods for genetic manipulation in this species. Use of transgenic lines which express Cre recombinase and a plasmid-based method for expressing PhiC31 when injected into early embryos. Results: Use of transgenic lines which express Cre recombinase allowed, by simple crossing schemes, germline or somatic recombination of transgenes, which could be utilized for numerous genetic manipulations. PhiC31 integrase based methods for site-specific integration of genetic elements was also improved, by developing a plasmid which expresses PhiC31 when injected into early embryos, eliminating the need to use costly and unstable mRNA as is the current standard. Discussion: Here we have expanded the toolbox for synthetic biology in Ae. aegypti. These methods can be easily transferred into other mosquito and even insect species by identifying appropriate promoter sequences. This advances the ability to manipulate these insects for fundamental studies, and for more applied approaches for pest control.

The cotton charcoal rot causal agent, Macrophomina phaseolina, biological and chemical control.

The fungus Macrophomina phaseolina causes charcoal rot disease (CRD) in cotton, whose symptoms develop in the late stages of growth and result in wilting and death. Despite significant research efforts to reduce disease incidences, effective control strategies against M. phaseolina are an ongoing scientific effort. Today's CRD control tends toward green options to reduce the chemicals' environmental footprint and health risks. Here, different Trichoderma species were examined separately and in combination with Azoxystrobin (AS) in semi-field open-enclosure pots and a commercial field throughout a full season. In the pot experiment, the T. asperellum (P1) excelled and led to improvement in growth (13%-14%, day 69) and crops (the number of capsules by 36% and their weight by 78%, day 173). The chemical treatment alone at a low dose had no significant impact. Still, adding AS improved the effect of T. longibrachiatum (T7507) and impaired P1 efficiency. Real-time PCR monitoring of the pathogen DNA in the plants' roots at the harvest (day 176), revealed the efficiency of the combined treatments: T. longibrachiatum (T7407 and T7507) + AS. In a commercial field, seed dressing with a mixture of Trichoderma species (mix of P1, T7407, and Trichoderma sp. O.Y. 7107 isolate) and irrigation of their secreted metabolites during seeding resulted in the highest yields compared with the control. Applying only AS irrigation at a low dose (2,000 cc/ha), with the sowing, was the second best in promoting crops. The molecular M. phaseolina detection showed that the AS at a high dose (4,000 cc/ha) and the biological mix treatments were the most effective. Reducing the AS chemical treatment dosages by half impaired its effectiveness. Irrigation timing, also studied here, is proven vital. Early water opening during the late spring suppresses the disease outburst and damages. The results demonstrated the benefits of CRD bio-shielding and encouraged to explore the potential of a combined bio-chemo pest control approach. Such interphase can be environmentally friendly (reducing chemical substances), stabilize the biological treatment in changing environmental conditions, achieve high efficiency even in severe CRD cases, and reduce the development of fungicide resistance.

Genome-wide analysis of Panonychus citri microRNAs with a focus on potential insecticidal activity of 4 microRNAs to eggs and nymphs.

Panonychus citri McGregor (Acari: Tetranychidae), a destructive citrus pest, causes considerable annual economic losses due to its short lifespan and rapid resistance development. MicroRNA (miRNA)-induced RNA interference is a promising approach for pest control because of endogenous regulation of pest growth and development. To search for miRNAs with potential insecticidal activity in P. citri, genome-wide analysis of miRNAs at different developmental stages was conducted, resulting in the identification of 136 miRNAs, including 73 known and 63 novel miRNAs. A total of 17 isomiRNAs and 12 duplicated miRNAs were characterized. MiR-1 and miR-252-5p were identified as reference miRNAs for P. citri and Tetranychus urticae. Based on differential expression analysis, treatments with miR-let-7a and miR-315 mimics and the miR-let-7a antagomir significantly reduced the egg hatch rate and resulted in abnormal egg development. Overexpression or downregulation of miR-34-5p and miR-305-5p through feeding significantly decreased the adult eclosion rate and caused molting defects. The 4 miRNAs, miR-let-7a, miR-315, miR-34-5p, and miR-305-5p, had important regulatory functions and insecticidal properties in egg hatching and adult eclosion. In general, these data advance our understanding of miRNAs in mite biology, which can assist future studies on insect-specific miRNA-based green pest control technology.

Allelopathic Potential of Tropical Plants—A Review

The need to meet food demand becomes more urgent as it is forecasted to increase by 50% over the next century. Thus, agronomists promote sensible tools and approaches to eradicate factors that hamper crop production, mainly weeds. The constant use of chemical herbicides to control weeds leads to an increased risk of herbicide-resistant weed populations, environmental pollution, unsafe agricultural products, and negative effects on human health. These problems have caused an interest among researchers to replace synthetic herbicides with alternatives. The purpose of this review was to present the current knowledge base on allelopathic tropical plants and their potential for use in the development of natural product-based, environmentally friendly herbicides for sustainable agriculture, and to stimulate future discussion on this topic. The defence mechanisms of tropical plants have received particular attention because of their potential weed control ability as a natural pesticide that can prevent the overuse of synthetic pesticides. The ancient knowledge of the toxic properties of various tropical plants gives us a basis for creating a novel pest control approach. The synthesis of biopesticides based on allelochemicals opens up the possibility of utilizing natural compounds in crop protection and demonstrates the ability to deal with evolved pesticide resistance.

Plastid‐mediated RNA interference: A potential strategy for efficient pest control

AbstractRNA interference (RNAi) technology is a promising and effective approach for pest insect management. Owing to its sequence‐guided working mechanism, RNAi has a high degree of species‐selectivity, thus minimizing potential adverse effects on nontarget organisms. Recently, engineering plastid (chloroplast) genome, rather than the nuclear genome, to produce double‐stranded RNAs has emerged as a powerful way to protect plants from multiple arthropod pests. Here, we review the recent progresses in the plastid‐mediated RNAi (PM‐RNAi) approach for pest control and the factors influencing its efficacy, and propose the strategies for further efficiency improvement. We also discuss the current challenges and the biosafety‐related issues of PM‐RNAi technology that need to be addressed for commercial production.

Long non-coding RNAs regulate Aedes aegypti vector competence for Zika virus and reproduction.

Long non-coding RNAs (lncRNAs) play critical regulatory roles in various cellular and metabolic processes in mosquitoes and all other organisms studied thus far. In particular, their involvement in essential processes such as reproduction makes them potential targets for the development of novel pest control approaches. However, their function in mosquito biology remains largely unexplored. To elucidate the role of lncRNAs in mosquitoes' reproduction and vector competence for arboviruses, we have implemented a computational and experimental pipeline to mine, screen, and characterize lncRNAs related to these two biological processes. Through analysis of publicly available Zika virus (ZIKV) infection-regulated Aedes aegypti transcriptomes, at least six lncRNAs were identified as being significantly upregulated in response to infection in various mosquito tissues. The roles of these ZIKV-regulated lncRNAs (designated Zinc1, Zinc2, Zinc3, Zinc9, Zinc10 and Zinc22), were further investigated by dsRNA-mediated silencing studies. Our results show that silencing of Zinc1, Zinc2, and Zinc22 renders mosquitoes significantly less permissive to ZIKV infection, while silencing of Zinc22 also reduces fecundity, indicating a potential role for Zinc22 in trade-offs between vector competence and reproduction. We also found that silencing of Zinc9 significantly increases fecundity but has no effect on ZIKV infection, suggesting that Zinc9 may be a negative regulator of oviposition. Our work demonstrates that some lncRNAs play host factor roles by facilitating viral infection in mosquitoes. We also show that lncRNAs can influence both mosquito reproduction and permissiveness to virus infection, two biological systems with important roles in mosquito vectorial capacity.