Contact Toxicity and Repellent Effects of Essential Oils from Toddalia asiatica against Two Stored-Product Insects.

Insect infestations continually endanger stored goods, underscoring the significance of discovering eco-friendly insecticides for pest management. Essential oils (EOs) from different parts of Toddalia asiatica (leaf, fruit and branch) were extracted by hydrodistillation and analyzed by GC-MS. Carvene, p-cymene and muurolene are the principal compounds of T. asiatica leaf (TAL), T. asiatica fruit (TAF) and T. asiatica branch (TAB) EO respectively. Our work aimed to assess the contact toxicity and repellent effects of EOs on two storage pests, Tribolium castaneum and Lasioderma serricorne. All tested EOs exhibited obvious contact toxicity, especially, TAL EO against T. castaneum (33.48 µg/adult) and TAF EO against L. serricorne (16.42 µg/adult). Repellency tests revealed that TAL and TAF EOs, at a concentration of 78.63 nL/cm2, achieved nearing 100% efficiency against T. castaneum. These results suggest that EOs of T. asiatica could be used as effective botanical insecticides for managing stored-product insects.

Surface-Templated Polymer Microparticle Synthesis Based on Droplet Microarrays.

Polymer microparticle synthesis based on the surface-templated method is a simple and environmentally friendly method to produce various microparticles. Unique particles with different compositions can be fabricated by simply annealing a polymer on a liquid-repellent surface. However, there are hurdles to producing particles of homogeneous sizes with large quantities and varying the shape of particles. Here, a new approach to synthesizing multiple polymer microparticles using micropatterns with wettability contrast is presented. Polymer microparticles are formed in two steps. First, a layer of poly(sodium-4-styrenesulfonate) is deposited on the hydrophilic regions by dipping and withdrawing this micropattern from a polymer solution, and an array of microdroplets is formed. A dewetting-inducing layer on the pattern is introduced, and then target polymer patches are sequentially generated on it. By annealing over Tg, the contact line of the target polymer patch is freely receded, creating a particle form. The size and shape of the microparticle can be controlled by varying the micropatterns. In addition, it is demonstrated that microparticles made of polymer blends or polymer/nanoparticle composite are easily produced. This versatile method offers the potential of surface-templated synthesis to tailor polymer microparticles with different sizes, shapes, and functionalities in various research and applications.

Advancing spatial repellents for malaria control: effectiveness and cost-effectiveness of a spatial repellent under operational use in Northern Uganda-study protocol for a cluster randomized controlled trial.

BACKGROUND: Spatial repellents (SRs) have been widely used for the prevention of mosquito bites, and preliminary findings suggest efficacy against both malaria (1) and Aedes-borne viruses (2) but their effectiveness in reducing mosquito-borne diseases under operational use has never been evaluated. SRs have the potential of being critical tools in the prevention of mosquito-borne diseases in contexts where typical vector control strategies, such as insecticide-treated nets (ITNs) and indoor residual spraying, are inaccessible or underutilized such as among displaced persons or in emergency relief settings. METHODS: Children will be enrolled in 3 separate cohorts to establish the effectiveness of SRs in reducing malaria infection in different distribution channels. One cohort will estimate the direct effect of the SR distributed through a reference channel (study personnel distribution). The two remaining cohorts will estimate the protection of the SR distributed through a voucher channel and the Village Health Team channel. Cohorts will be followed twice a month (approximately every 15 days): during the first scheduled household visit in the month, a blood sample will be taken for malaria rapid diagnostic test (Monthly Visit #1); and, during the second scheduled household visit, a blood sample will only be taken if the participant has a recent history of fever (Monthly Visit #2). The incidence of malaria in each cohort will be estimated and compared to the reference cohort to determine the benefit of using a SR in an area with high, year-round transmission of malaria. DISCUSSION: This study will address the knowledge gap of whether or not SRs are effective in reducing human malaria disease in humanitarian assistance and emergency response settings in sub-Saharan Africa where underlying transmission rates are historically high and ITNs may or may not be widely deployed. This research will inform policy makers on whether to recommend SRs as a means to further reduce malaria transmission for such operational programs. TRIAL REGISTRATION: ClinicalTrials.gov NCT06122142. Registered on November 8, 2023.

In vivo mosquito repellency effect of citronella (Cymbopogon nardus (L.) Rendle) essential oil bath bomb formulation in dogs.

Background and Aim: Mosquitoes carry numerous diseases of medical and veterinary significance. While citronella essential oil is safe as a mosquito repellent, extensive research does not document its ability to deter mosquitoes from animals. This study assessed the citronella essential oil bath bomb's ability to repel Culex quinquefasciatus mosquitoes in dogs. Materials and Methods: Citronella essential oil's chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS). Through freeze-thaw testing, a bath bomb formulation containing 6% w/w citronella essential oil was assessed for its physical and chemical stability. Thirty-two healthy client-owned mixed-breed dogs were employed to test the mosquito-repellency effects of citronella essential oil (treatment group) and olive oil (control group) bath bomb formulations. Bath bombs were tested for irritation effects on animal skin for 15-day post-application. Results: Thirty-six compounds were identified through GC-MS, with citronellal (23.38%), δ-cadinene (12.25%), and geraniol (9.09%) being the most prevalent constituents. The bath bomb maintained its original physical properties after undergoing six freeze-thawing cycles and retained over 90% of its citronella essential oil. About 100%, 69.28%, and 65.58% mosquito repellency were displayed by the citronella essential oil bath bomb at 3 h, 6 h, and 8 h, respectively. None of the test animals exhibited skin irritation during the study. Conclusion: The citronella bath bomb effectively repelled C. quinquefasciatus in dogs without irritating their skin. The formulation's physical and chemical stability is demonstrated by the results of freeze-thaw stability testing. Further studies should be conducted to evaluate the repelling activity against other mosquito species.

Electrospun Polyvinylidene Fluoride Membranes: Waterproofing and Acoustic Performance for Air and Acoustic Vents in Electronics.

Advancements in electronic devices demand materials capable of exceptional performance in various challenging environments. This study presents polyvinylidene fluoride (PVDF) nonwoven membranes with controlled porosity, created using an air-guided electrospinning method, followed by a calendaring process. These membranes exhibit a combination of water-repellent properties and sound transmission capabilities, making them ideal candidates for use in air and acoustic vents in electronic systems. A key feature of our membrane is the three-dimensional nanostructured pores, ranging from 0.20 to 0.76 µm, with a mean pore size of 0.51 µm, achieved through the formation of randomly arranged long nanofibers. By employing both experimental and theoretical methods, we achieved impressive performance metrics: air permeability of 0.86 cm3/cm2/s, water contact angles up to 139.3°, and breakthrough pressure as low as 0.27 MPa. Our PVDF nonwoven membranes maintain an optimal balance of stiffness, density, and air permeability, leading to exceptionally low sound transmission loss values ranging between -10 and -40 dBV/Pa, all while preserving their structural integrity. These findings contribute to the development of next-generation waterproof and acoustically permeable membranes, offering enhanced performance capabilities in demanding operational scenarios. This work advances the field of nanomaterials, environmental engineering, and acoustic technologies, with the potential to influence the design of future electronic devices.

Designing Plastrons for Underwater Bubble Capture: From Model Microstructures to Stochastic Nanostructures.

Bubbles and foams are often removed via chemical defoamers and/or mechanical agitation. Designing surfaces that promote chemical-free and energy-passive bubble capture is desirable for numerous industrial processes, including mineral flotation, wastewater treatment, and electrolysis. When immersed, super-liquid-repellent surfaces form plastrons, which are textured solid topographies with interconnected gas domains. Plastrons exhibit the remarkable ability of capturing bubbles through coalescence. However, the two-step mechanics of plastron-induced bubble coalescence, namely, rupture (initiation and location) and subsequent absorption (propagation and drainage) are not well understood. Here, the influence of 1) topographical feature size and 2) gas fraction on bubble capture dynamics is investigated. Smaller feature sizes accelerate rupture while larger gas fractions markedly improve absorption. Rupture is initiated solely on solid domains and is more probable near the edges of solid features. Yet, rupture time becomes longer as solid fraction increases. This counterintuitive behavior represents unexpected complexities. Upon rupture, the bubble's moving liquid-solid contact line influences its absorption rate and equilibrium state. These findings show the importance of rationally minimizing surface feature sizes and contact line interactions for rapid bubble rupture and absorption. This work provides key design principles for plastron-induced bubble coalescence, inspiring future development of industrially-relevant surfaces for underwater bubble capture.

Biomass-activated carbon-based superhydrophobic sponge with photothermal properties for adsorptive separation of waste oil.

The increasing discharge of oily wastewater from life poses a serious threat to the ecological environment and human health. To develop green, efficient, and low-cost materials for oil-water separation, a superhydrophobic photothermal oil-absorbing sponge (CAC-PDA@MF) was prepared by using nanoscale coconut shell activated carbon (CAC) loaded on a melamine sponge in this study. The sponge had excellent superhydrophobicity (WCA of 159.53°) due to the reduction of surface energy by grafting long-chain silanes. The adsorption capacity of the sponge was 69.04 g/g-158.27 g/g for a wide range of oils and organic solvents, and the sponge had excellent mechanical properties for multiple adsorption and recovery of oil. After 50 cycles of oil-water separation, its separation efficiency was maintained at over 98 %. In addition, the material had high acid, alkali, and salt resistance as well as excellent photothermal conversion properties. Its surface temperature rose rapidly to 100 °C and above, at a light intensity of 1.0 kW/m2. The material was capable of adsorbing and recovering high-viscosity oils that were solid or semi-solid at room temperature. Its versatility and commercial value made it a promising candidate for a wide range of applications.

Exploring the viability of anti-microbial, superhydrophobic jute bags as an approach to sustainable food packaging system.

Jute in food packaging offers several advantages, including cost-effectiveness, biodegradability, renewability, and low environmental impact. Nevertheless, its hydrophilic characteristic makes it susceptible to airborne humidity and precipitation moisture. We combated this by chemically treating jute to make it water-resistant. The coated jute (WCA = âˆ¼162°) exhibits high mechanical endurance against exposure to air (>1 month), ultrasonic washing (6 h), brush scrubbing (>50 cycles), and mutual abrasion (>150 cycles), along with good thermal stability. During a 2-month experiment involving seed storage in an RH of 85%, wheat grains stored in the coated bag showed 8.08% less moisture content than that stored in control. Furthermore, the preserved grains in the control jute exhibited altered colour, texture, and fungal development. Additionally, compared to the control, the coated jute delivers >50% bacterial growth reduction in 48 h. The proposed jute offers a sustainable packaging solution that promotes eco-friendly practices and reduces plastic waste.

Hydrophobic Aerogels from Vinyl Polymers Derived from Radical Polymerization: Proof-of-Concept.

Hydrophilicity is one important drawback of bio-based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of cross-linked bio-based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influence of monomers with different nonpolar ester groups (methyl, vanillin, tetrahydrofurfuryl) on textural properties and water contact angles of the dry products is assessed. Final aerogels show generally high overall porosities (≈96%), low densities (0.07-0.11 g cm-3) as well as fine, mainly mesoporous networks, and specific surface areas in the range of 120-240 m2 g-1. Hereby, choice of the methacrylate ester groups results in differences of the resulting pore-size distributions. Water repellency tests show stable static water contact angles in the hydrophobic range (≈100°) achieved for the substrate containing the vanillin ester group. On the contrary the other substrates absorb water quickly, which indicates a decisive role of the ester group. The presented approach opens up a new pathway to bio-based aerogels with intrinsic hydrophobicity. It is suggested that the properties are tailored by the choice of the monomer structure, hence enabling further adaption and optimization of the products.

Essential oil nanoemulsion: An emerging eco-friendly strategy towards mosquito control.

Mosquito borne diseases are impeding to human health due to their uncontrolled proliferation. Various commercial insecticides currently used become ineffective due to the resistance acquired by mosquitoes. It is necessary and a priority to combat mosquito population. Plant-based products are gaining interest over the past few decades due to their environment friendliness and their effectiveness in controlling mosquitoes along with their lack of toxicity. Essential oil nanoemulsions are found to be highly effective when compared to their bulk counterparts. Due to their nano size, they can effectively interact and yield 100 % mortality with the mosquito larvae and encounter with minimal concentrations. This is the main advantage of the nano-sized particles due to which they find application in various disciplines and have also received the attention of researchers globally. There are various components present in essential oils that have been analysed using GC-MS. These findings reflect the challenge to mosquitoes to gain resistance against each component and therefore it requires time. Commercially used repellants are synthesised using materials like DEET are not advisable for topical application on human skin and essential oil nanoemulsions could be an ideal non toxic candidate that can be used against mosquito adults and larvae. However, there are other synthesis, optimisation parameters, and toxicity towards non-target organisms that have to be taken into account when essential oil nanoemulsions are considered for commercial applications. Here we review the strategies used by the nanoemulsions against the mosquito population. Apart from the positive effects, their minor drawbacks also have to be scrutinised in the future.

[A Pilot Test of Olive Weevil Repellents in an Olive Orchard].

Recently, feeding damage by the olive weevil Pimelocerus (Dyscerus) perforatus Roelofs, which utilizes olive trees (Olea europaea Linne) as a host plant, has become the biggest obstacle to olive cultivation in Japan. We previously identified several volatile plant-derived natural products that exhibit repellent activity against olive weevils. In this study, we conducted a pilot test of repellents in an olive orchard along with the use of insecticide. During three consecutive years from 2021 to 2023, the first year was the observation period, and the second and third years were set aside for a trial period for o-vanillin and geraniol as repellents, respectively. Using o-vanillin, the number of adult olive weevil outbreaks decreased to almost half a year in the experimental area, the use of geraniol then resulted in a drastic reduction of the number of individual olive weevils in the experimental area. In contrast, adults and larvae outbreaks increased in the control area without a repellent, despite the use of insecticide. These results indicate that the volatile repellents drove the olive weevils away and kept them at bay in the field. Based on the observations, we will be able to provide a new approach for the control of olive cultivation, including fruit and leaves used for commercial purposes, following integrated pest management (IPM) practices, such as reducing environmental poisoning from intense insecticides, and returning olive weevils to their original habitat outside of olive orchards.

Impact of tightening environmental regulations against long-chain perfluoroalkyl acids on composition of durable water repellents containing side-chain fluorinated polymers.

Tightening of environmental regulations against long-chain perfluoroalkyl acids (PFAAs) since the 2000s may have led to significant increases in the occurrence of short-chain PFAAs in the environment. Understanding the impact of the regulations on composition of durable water repellents (DWRs) is imperative to guide implementation of pragmatic actions during their use and end-of-life treatment. Substantial decreases in the frequencies of detection and concentrations of long-chain PFAAs and long-chain PFAA-precursors, and substantial increases in those of short-chain PFAAs and short-chain PFAA-precursors, have been observed in the impurities and hydrolysis products of side-chain fluorinated polymers (SCFPs). Comparison of profiles among the DWRs containing fluorinated ingredients in 2011 indicated that DWRs containing C8F17- and C10F21-SCFPs were the dominant products and accounted for 90 % of the samples, whereas DWRs containing C4F9- and C6F13-SCFPs were the dominant products and accounted for 70 % of the samples collected in 2021. Tightening of the regulations have caused decreasing applications of long-chain SCFPs and increasing use of short-chain SCFPs in DWRs containing fluorinated ingredients. The ingredients of one DWR were changed from PFAS-free alternatives to short-chain SCFPs, whereas those of another DWR were changed from short-chain SCFPs to PFAS-free alternatives. The presence of unexplained extractable organic fluorine has been observed in DWRs containing fluorinated ingredients, which may be difficult to be hydrolyzed and form known compounds. A historical series of DWRs available from before and after the tightening of regulations and a multifaceted analytical technique consisting of combustion ion chromatographic and mass spectrometric approaches combined with two extraction techniques involving ultrasonic treatment and alkaline hydrolysis revealed the impact of tightening regulations on composition of DWRs.

Inhibitory activity of some short-chain aliphatic aldehydes on pheromone and ammonium carbonate-mediated attraction in olive fruit fly, Bactrocera oleae.

BACKGROUND: The olive fruit fly (OFF), Bactrocera oleae (Rossi), is the main insect pest of olive trees worldwide. Legislation limits to the use of some synthetic larvicidal insecticides is leading to the development of new control options for preventive control of adult flies. In the present study, the biological activity of four short-chain aliphatic aldehydes, namely hexanal, (E)-2-hexenal, heptanal and (E)-2-heptenal, previously reported as repellents to the OFF adults was investigated. RESULTS: Electroantennography (EAG) recordings showed that antennae of OFF males and females are able to perceive the test compounds in a wide range of doses. In field trapping experiments, reservoir-type polypropylene (PP) membrane dispensers loaded with individual compounds did not elicit a significant attraction of OFF males and females. On the contrary, a significant reduction of male catches was noticed when sex pheromone dispensers and PP membrane dispensers, loaded with one of the test compounds, were applied on the same white sticky traps ≈20 cm apart. Likewise, male and female catches in yellow sticky traps baited with ammonium carbonate (AC) dispensers as food attractant were significantly reduced by the presence of PP membrane dispensers of individual aliphatic aldehydes on the same traps. In small plots control trials, solid formulations of the four aldehydes into a bentonite clay support induced a significant reduction of the OFF active infestation mainly when C6 and C7 aldehyde-activated bentonites were used. CONCLUSION: Short-chain aliphatic aldehydes showed inhibitory effects on sex pheromone and food attractant-mediated attraction of OFF. Results of field trials suggest potential of short-chain aliphatic aldehydes to develop new semiochemical-based OFF control options. © 2024 Society of Chemical Industry.

Insecticidal Activities and Phenological Variations of Characteristic Component from Michelia yunnanensis.

Volatile secondary metabolites of plants interact with environments heavily. In this work, characteristic components of Michelia yunnanensis essential oils (EOs) were isolated, purified and identified by column chromatography, GC-MS and NMR. Leaves of M. yunnanensis were collected monthly and extracted for EOs to investigate chemical and insecticidal activity variations as well as potential influencing environments. Different organs were employed to reveal distribution strategies of characteristic components. Results of insecticidal activities showed that all EOs samples exerted stronger contact activity to Lasioderma serricorne, but repellent effect was more efficient on Tribolium castaneum. One oxygenated sesquiterpene was isolated from EOs, basically it could be confirmed as (+)-cyclocolorenone (1). It exerted contact toxicity to L. serricorne (LD 50 = 28.8 µg/adult). Chemical analysis showed that M. yunnanensis leaves in reproductive period would produce and accumulate more 1 than in vegetative period. Moreover, reproductive organs (flowers and fruits) contained more 1 than vegetative organs (leaves and twigs). Partial correlation analysis indicated that temperature-related elements positively correlated with the relative content of 1.

Comparison of the cytotoxicity and zebrafish embryo toxicity of insect repellent ingredients: p-Menthane-3,8-diol synthesized by green chemistry from Eucalyptus citriodora and N,N-diethyl-meta-toluamide.

Bio-sourced insect repellents are becoming more popular due to their safer applications. Known for its strong fly-repellent property, Cis, trans-para-menthane-3,8-diol (PMD) is the main component of the lemon eucalyptus essential oil and is synthesized from citronellal. In April 2005, US Centers for Disease Control approved two fly repellents that do not contain N,N-diethyl-meta-toluamide (DEET), including PMD. Due to the intentional and pervasive human exposure caused by DEET as insect repellent, concerns have been raised about its toxicological profile and potential harm to people. We hypothesized PMD would have a different toxicological profile than DEET. We synthesized PMD from Eucalyptus citriodora using green chemistry methods and analyzed its structures by 1H-NMR,13C-NMR, and GC/MS spectral methods. We used MTS assay to determine the percentage inhibition of PMD and DEET on keratinocyte (human epidermal keratinocyte [HaCaT]) cells. The xCelligence system was used and followed at real time. Effects of PMD and DEET on zebrafish embryo development were monitored and levels of lipid peroxidation, glutathione-S-transferase (GST), superoxide dismutase (SOD), and acetylcholinesterase (AchE) were evaluated at 72 h post-fertilization using spectrophotometric methods. Our results showed that while DEET inhibited human keratinocyte cell growth, while imporved cell viability and proliferation was exposed in PMD exposed group. In zebrafish embryos, PMD was less toxic in terms of development, oxidant-antioxidant status, and AChE activities than DEET. Based on these results we suggest an efficient method using green chemistry for the synthesis of PMD, which is found to be less toxic in zebrafish embryos and human keratinocyte cells.

Antioxidant, insecticidal, antifeedant, and repellent activities of oregano (Origanum vulgare).

This study aimed to assess the antioxidant capacity, the insecticidal, feeding deterrence, repellent effects against Tribolium confusum of the essential oil (EO) and the organic extracts (ME) of Origanum vulgare. The chemical composition of the EO revealed the presence thirty-nine components dominated by carvacrol (81%). With respect to the EO, the ME acted as a potent free radical scavenger with IC50 values of 0.127 and 0.058 mg/mL, respectively. The EO exhibited the most significant toxicity compared to the ME with a mortality of 62 and 20% at 0.08 µL/insect after 24h whereas the EO expressed the highest repellency compared to the ME with a PR of 70 and 38% after 24h. As for feeding deterrence, both samples influenced all nutritional indexes. The findings found in this work might help in the promotion of oregano as natural antioxidant, antifeedant, repellent and insecticide as an alternative to conventional harmful ones.

Polyvinyl Butyral Loading with Combined Repellents Showed Effective Protection Against Leech Bites in Diverse Situations.

Background: Leech bites have long been a persistent problem for individuals engaged in outdoor activities, particularly in environments such as moors, jungles, and grasslands. Methods to prevent leech bites are anecdotal and individual, highlighting the need for the development of universal and effective repellent formulations. This study developed a novel approach for repelling leeches using combined repellent agents and a film-forming material (polyvinyl butyral), to enhance efficiency in multi-scenario applications. Material and methods: This study demonstrates that citronellal, icaridin and DDAC (didecyl dimethyl ammonium chloride) showcasing active avoidance and contact toxicity on leeches. the optimized repellent formulation (MSRS, containing citronellal, icaridin and DDAC as repellent agents) enables specific sustained release properties of constituents in both air and water conditions. Results: MSRS could effectively achieve the purposes of "proactive repelling", "contact repelling", and "bite detaching". The effectiveness could last for several hours. Additionally, the hydrophobic polyvinyl butyral membrane reduced the transdermal absorption of repellent agents. Moreover, the formulation is biocompatible and environmentally friendly. Conclusions: This study provides a new feasible strategy for the prevention and removal of leech bites.

Evaluating human landing catches as a measure of mosquito biting and the importance of considering additional modes of action.

Entomological evaluations of vector control tools often use human landing catches (HLCs) as a standard measure of a direct human-vector contact. However, some tools have additional characteristics, such as mortality, and HLCS are not sensitive for measuring other effects beyond landing inhibition. Therefore, additional measures may need to be considered when evaluating these tools for public health use. This study has two main aims (1) the evaluate the accuracy of HLCs as a proxy for feeding and (2) to compare the predicted reduction in vectorial capacity when we do and do not consider these additional characteristics. To achieve this, we analyse previously published semi-field data from an experiment which used HLCs and another where mosquitoes were allowed to feed in the presence of different dosages of the volatile pyrethroid spatial repellent, transfluthrin. We compare results for two mathematical models: one which only considers the reduction in feeding effect and one which also considers mortality before and after feeding (using data gathered by the aspiration of mosquitoes after the semi-field feeding/landing period and 24 h survival monitoring). These Bayesian hierarchical models are parameterised using Bayesian inference. We observe that, for susceptible mosquitoes, reduction in landing is underestimated by HLCs. For knockdown resistant mosquitoes the relationship is less clear; with HLCs sometimes appearing to overestimate this characteristic. We find HLCs tend to under-predict the relative reduction in vectorial capacity in susceptible mosquitoes while over-predicting this impact in knockdown-resistant mosquitoes. Models without secondary effects have lower predicted relative reductions in vectorial capacities. Overall, this study highlights the importance of considering additional characteristics to reduction in biting of volatile pyrethroid spatial repellents. We recommend that these are considered when evaluating novel vector control tools.

Attractant and repellent properties of Senna didymobotrya plant extracts to Amblyomma variegatum and Rhipicephalus appendiculatus.

The growing challenge of acaricide resistance and geographical range expansion of invasive tick species demands other interventions, like plant-based alternatives, for sustainable tick control. Leaves, flowers, seedpods, and twig branch extracts of Senna didymobotrya were analyzed using coupled gas chromatography mass spectrometry (GC-MS). Response of adult Amblyomma variegatum and Rhipicephalus appendiculatus to extracts was evaluated. The most attractive plant extract was fractionated and ticks' responses to its fractions assessed. Potential tick attractants in the attractive plant part extract and its fractions were identified by GC-MS analysis. Non- significant qualitative and quantitative differences were observed in the plant parts' extract composition (R = 0.6178). Flower extracts attracted both species, with a 0.1-fold higher attraction in A. variegatum compared to the standard attraction aggregation attachment pheromone (AAAP). Leaf and seedpod extracts repelled ticks at various concentrations. Bioassays after fractionating flower extracts identified hexane and ethyl acetate fractions as most attractive to A. variegatum (P < 0.001) and R. appendiculatus (P < 0.001), respectively. Chemical analysis of the most attractive extracts and fractions identified compounds, including documented acarine attractants, squalene and linoleic acid. A squalene and linoleic acid blend (1:1) at 1 mg/mL significantly attracted adult A. variegatum (P < 0.01) and R. appendiculatus (P < 0.001). The results of this study broaden comprehension of how ticks respond to plants in nature, and showcase the promising potential for integrating these insights into effective tick management programs.

Effects of natural Ionones and derived novel analogues with simplified structures on behavioral responses of whiteflies.

BACKGROUND: Whiteflies are major pests in agriculture, causing damage to crops and transmitting plant viruses. Using Volatile Organic Compounds (VOCs) as semiochemicals offers a sustainable approach for combating whiteflies. One such group of compounds, represented by ß-ionone, has been found to possess repellent/attractant properties. To further explore the behavioral effects of these compounds on whiteflies, we selected five natural ionone compounds and synthesized six novel analogues to examine the impact of structural variations on whitefly behavior. RESULTS: Our results demonstrated that ß-ionone and its analogues have a significant impact on the behavior of whiteflies. Among them, 0.01% pseudo ionone solution exhibited an attractant effect on whiteflies. Notably, the application of 1% ß-ionone and 0.1% ß-ionol solution demonstrated a notable repellent effect and oviposition deterrent effect on whitefly. We also found that the novel ionone analogue (±)1A exhibited a strong repellent effect. Both ß-ionol and compound (±)1A possess high logP values and low saturation vapor pressures, which contribute to enhanced lipophilicity, making them more likely to penetrate insect antennae and prolong their presence in the air. CONCLUSION: The newly discovered ionone analogue (±)1A and ß-ionol exhibit improved repellent effects, while pseudo ionone shows an attractant effect. These three compounds hold promising potential for development as novel biological control agents. Our work highlights the efficacy of VOCs as a protection method against whiteflies. These findings indicate that our new technology for a 'push-pull' control method of B. tabaci can offer a novel tool for integrated pest management (IPM). © 2024 Society of Chemical Industry.