Phytochemical Investigations, Antioxidant and Insecticidal Properties of Essential Oil and Extracts from the Aerial Parts of Pelargonium graveolens from Morocco.

The essential oil and the aqueous and ethanolic extracts obtained from the aerial parts of Pelargonium graveolens cultivated in Morocco were studied for their antioxidant and insecticidal activity against rice weevils (Sitophylus oryzae). The total phenolic content of the extracts was determined by a spectrophotometric method and the phenolic compounds were extensively characterized by HPLC-PDA/ESI-MS. To evaluate antioxidant potential, three in vitro assays were used. In the DPPH test, the ethanolic extract was the most active, followed by the aqueous extract and the essential oil. In the reducing power assay, excellent activity was highlighted for both extracts, while in the Fe2+ chelating activity assay, weak activity was observed for both the essential oil and the ethanolic extract and no activity for the aqueous extract. Concerning insecticide activity, the toxicity of the essential oil and the extracts was tested against rice weevils; the lethal concentrations LC50 and LC99 were determined, as well as the lethal time required for the death of 50% (LT50) and 99% (LT99) of the weevils. The essential oil had the highest activity; 100% mortality of S. oryzae was observed around 5, 9, and 8 days for the essential oil and the aqueous and ethanolic extracts, respectively.

Sublethal effect of emamectin benzoate on age-stage, two-sex life table and population projection of red palm weevil, Rhynchophorus ferrugineus.

The red palm weevil (RPW), Rhynchophorus ferrugineus Olivier, is a devastating insect-pest of 29 plants including date palm. It feeds inside the tree bark thus it is difficult to manage using insecticides. Only a few insecticides have been found effective against RPW. Among these insecticide, emamectin benzoate (EMB) is widely used. This insecticide can pose threat human and environmental health as it is used in the form of tree injection. Thus, keeping in view its possible, its sublethal effect on RPW was studied using Age-stage, two sex life table. Life table parameters of the progeny of exposed larvae to LC10, LC25, and LC50 of EMB were computed. Statistically higher fecundity (161.12 per female) was observed in control treatment, while less fecundity was observed in LC50 treatment. Significantly higher values for intrinsic rate of increase (r), finite rate of increase (λ), and net reproductive rate (Ro) (0.0376, 1.0383, and 67.13 per day, respectively) were recorded for the control treatment. Contrarily, lower values for r, Ro, and λ i.e. 0.0318, 23.82, and 1.0324 per day, respectively were recorded in the LC50 treatment. Decreased population parameters suggest that EMB can be successfully used in for the management of RPW.

Toxicity and Sublethal Effects of Piper hispidinervum Essential Oil on Behavioral and Physiological Responses of Sitophilus zeamais Populations.

This study aimed to evaluate the toxicity of Piper hispidinervum essential oil (PHEO) against 11 Brazilian populations of Sitophilus zeamais (Coleoptera: Curculionidae). The effects of sublethal doses of PHEO on the behavior (walking and flying), respiration, and population growth (ri) of the insect populations were investigated. PHEO toxicity was determined through concentration-mortality bioassays, with mortality curves established using increasing PHEO concentrations ranging from 140.00 to 1000.00 µL kg-1. Behavior was evaluated based on walking distance, walking time, walking speed, walking time proportion, flight height, and flight takeoff success. Respiration was measured via the respiratory rate, while population growth (ri) was assessed through the instantaneous growth rate. All 11 populations of S. zeamais were susceptible to PHEO, showing no signs of resistance. The populations exhibited varying behavioral and physiological responses to sublethal exposure to PHEO, indicating different mitigation strategies. The results confirm that PHEO possesses insecticidal potential for controlling S. zeamais populations. However, the observed behavioral and physiological responses should be considered when establishing control measures in pest management programs for stored products.

Graphene powders as new contact nanopesticides: Revealing key parameters on their insecticidal activity for stored product insects.

The overuse and reliance on pesticides has caused insects to develop resistance with global concerns. To address this problem extensive research is directed to find new and sustainable alternatives using chemical-free and resistance-free solutions for pest control. This paper presents a comprehensive investigation of the insecticidal properties of several types of industrially produced graphene powder materials such as graphene and graphene oxide (GO) with micro- and nano size and different structural and chemical properties as new contact nanopesticides against three major stored grain insects: the rice weevil Sitophilus oryzae (L.), the lesser grain borer, Rhyzopertha dominica (F.)˙ and the larger grain borer, Prostephanus truncatus Horn. Bioassays were performed using different concentrations, i.e., 0, 100, 500 and 1000 ppm of graphene powders on the mortality of selected adult insects recorded after 3, 7, 14, and 21 days of exposure and progeny production after 65 days. Results showed that graphene oxide (GO) has no insecticidal efficacy while graphene powders with nano-size particles showed significantly enhanced insecticidal performance compared to micron-size graphene powders. The observed insecticidal effects are explained by the higher probability that nano-sized graphene particles adhere on the insect body compared to large particles. The mortality is proposed as the result of physical mode of action of attached graphene nanoparticles causing stronger interruption of the protective cuticle layer, gas respiratory functions and faster mortality. The findings of this study revealed that it is important to select graphene materials with optimal structural and interfacial properties to achieve the highest insecticidal performance in potential development of a new generation of sustainable insecticides.

Effects of sulfur dioxide fumigation on mortality of confused flour beetle (Coleoptera: Tenebrionidae) and rice weevil (Coleoptera: Curculionidae).

Sulfur dioxide (SO2) fumigation was studied in laboratory to determine its potential as an alternative treatment for postharvest control of stored product insects, confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae), and rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae). Three-hour fumigations with 0.1%-2.0% SO2 were conducted against eggs, immature stages, and adults of the 2 insects at 20 °C. Effective control of both insects was achieved. However, there were considerable variations between the 2 insects and among different life stages. Confused flour beetle was more susceptible to SO2 fumigation than rice weevil. Complete control of adults and all life stages of confused flour beetle was achieved in 3-h fumigations with 0.5% and 2.0% SO2, respectively. For rice weevil, 3-h fumigation with 1.5% SO2 resulted in 96.5% adult mortality and the fumigation with 2.0% SO2 resulted in 99.27% mortality of adults and 87.5% mortality of immature stages. Three-hour fumigations with 1% SO2 resulted in <5% egg survival to adults. The study demonstrated high efficacy of SO2 fumigation against the insects and suggested that SO2 fumigation has good potential for postharvest pest control on stored products.

Insecticidal activity of Thymus pallescens de Noë and Cymbogon citratus essential oils against Sitophilus zeamais and Tribolium castaneum.

The thrust of the study was to determine the chemical composition of the essential oils extracted from Thymus pallescens de Noé and Cymbogon citratus Stapf. as well as to evaluate their efficacy in controlling Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) in either single or combined populations. Carvacrol (56.04%) and geraniol (20.86%) were identified as the major constituents of T. pallescens and C. citratus respectively. The tested essential oils showed pronounced insecticidal activity against the pest species in relation with the applied doses. T. pallescens EO had the highest efficacy and S. zeamais was found to be more susceptible to both individual and combined treatments. With reference to the contact and fumigation assessments, T. pallescens EO effectuated corrected mortality rates ranging from 42.5-100% to 25-100% in S. zeamais with corresponding lethal concentration (LC50) values of 17.7 µl/ml and 15µL/L air respectively. Whereas, the T. pallescens EO exhibited corrected mortality rates of 42.5-100% and 20-100% with corresponding LC50 values of 18.1 µl/ml and 15.5 µL/L air against T. castaneum in contact and fumigation assessments, respectively. The corrected mortality rates increased for both insect species when using combination treatments, with significant increases in the LC50 values, ranging from 8.59 to 49.9% for both pest species. Analysis of energy biomarkers in the treated insects indicate significantly increased protein and carbohydrate contents and decreased lipids levels. The study therefore demonstrated the bio-insecticidal toxicity of the EOs from T. pallescens and C. citratus against two important maize post-harvest pests, concurrently revealing significant positive and negative insecticidal activity gradients in relation to single or combined populations.

An enhanced lure for eastern populations of the North American spruce beetle, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae).

Regional variation in pheromone production and response has practical implications for the use of semiochemical lures to monitor and control bark beetle populations. We tested 4 lure formulations including 2 new formulations that reflect the pheromone production profiles of western and eastern populations of spruce beetles, Dendroctonus rufipennis Kirby (Coleoptera: Curculionidae), as well as 2 commercially available formulations (current Rocky Mountain lure and current Atlantic lure), in 2 locations in New Brunswick, Canada. In 2 separate years, the new eastern lure containing seudenol, MCOL, and spruce terpenes captured 4 times (2021) and 11 times (2022) more spruce beetles than the current Atlantic lure that consisted of frontalin, seudenol, and spruce terpenes. In 2021, we also captured more eastern larch beetles, Dendroctonus simplex LeConte (Coleoptera: Curculionidae), with the new eastern lure, whereas in 2022, we captured the most D. simplex with the current Atlantic lure, suggesting that more research is needed on D. simplex pheromone production and response across its range. The bark beetle predator, Thanasimus dubius (Fabr.; Coleoptera: Cleridae), did not respond well to the new eastern blend that lacks frontalin, suggesting that response to frontalin is important in finding prey and might be conserved in predator populations. The reduced trap catch of T. dubius to the enhanced lure is beneficial because it does not inhibit natural population control by removing predators from the community. Our study reveals an improved trap lure for eastern populations of spruce beetles and highlights gaps and research needs in bark beetle pheromone ecology.

Enantiomeric composition of α-pinene affects catches of bark and wood boring beetles, and associated species, in ethanol-baited multiple-funnel traps.

In 2009, we determined the effects of the enantiomeric composition of the kairomone, α-pinene, on trap catches of arboreal beetles (Coleoptera) in stands of eastern pine trees with resin dominated by (+)-α-pinene. We hypothesized that the responses of beetles would correlate with the predominant enantiomer of α-pinene found in host pines. Lures of (+)-, racemic (±), and (-)-α-pinene were added separately to ethanol-baited multiple-funnel traps. Species such as Monarthrum mali (Fitch), Dendroctonus terebrans (Olivier), Ips grandicollis (Eichhoff), and Pachylobius picivorus (Germar) (Coleoptera: Curculionidae) showed a preference for traps co-baited with (-)-α-pinene. α-Pinene enhanced attraction of Hylastes salebrosus Eichhoff, Hylastes porculus Erickson and Hylastes tenuis Eichhoff (Coleoptera: Curculionidae) to ethanol-baited traps with no effects from enantiomeric composition of α-pinene. The attraction of the ambrosia beetles, Xyleborinus saxesenii (Ratzeburg) and Dryoxylon onoharaense (Murayama) (Coleoptera: Curculionidae) to ethanol-baited traps was interrupted by the addition of α-pinene, regardless of enantiomeric composition. Species such as Xylosandrus germanus (Blandford), Cnestus mutilatus (Blandford) and Stenoscelis brevis (Boheman) (Coleoptera: Curculionidae) were unaffected by the presence of α-pinene. Trap catches of some species of longhorn beetles and bark beetle predators (Coleoptera: Cerambycidae, Cleridae, Elateridae, Histeridae, and Trogossitidae) were increased by the addition of α-pinene, although results varied by location. Platysoma spp. (Coleoptera: Histeridae) showed a marked preference for traps co-baited with (+)-α-pinene in Florida and Georgia. In summary, we found that the enantiomeric composition of α-pinene in hosts was not a good predictor of enantiomeric preferences by beetles.

Exploring market-available pheromone lures and traps for monitoring Anthonomus testaceosquamosus (Coleoptera: Curculionidae).

The hibiscus bud weevil (HBW), Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae), is a significant threat to tropical hibiscus (Hibiscus rosa-sinensis) in Florida, USA, since its invasion in 2017. As a regulated pest in the state, early detection is crucial. Based on the success of pheromone-based monitoring programs for other weevil pests, such as the boll weevil, cranberry weevil, and pepper weevil, this study explores the potential use of these pheromone lures for early detection of HBW. To account for differences in efficacy based on trap color, height, and design, different pheromone lure sizes (4 mm, 10 mm, full-size), trap types (Yellow sticky trap, Japanese beetle trap, Boll weevil trap), and heights (0 m, 1.1 m) were also tested in this study. In laboratory assays, males and females exhibited higher attraction to full-size cranberry weevil lure discs than other lure size-type combinations. In semi-field trials, yellow sticky traps baited with cranberry weevil lures captured more weevils than Japanese beetle or boll weevil traps baited with cranberry weevil lures, while trap height did not influence HBW capture. In semi-field, 4-choice bioassays, yellow sticky traps baited with cranberry weevil lures captured more HBW compared to yellow sticky traps baited with pepper weevil, boll weevil, or unbaited traps. Further research is required to thoroughly evaluate the cranberry weevil lure's efficacy in capturing HBW. Our study suggests the potential for utilizing yellow sticky traps baited with lures for early HBW detection and highlights the importance of selecting the appropriate lure, trap type, and height for optimal efficacy.

Preparation and indoor virulence determination of a temperature-sensitive insecticide against Zeugodacus cucurbitae (Coquillett).

Zeugodacus cucurbitae (Coquillett) is an important fruit and vegetable pest, especially in high-temperature seasons. In our previous research, we developed a temperature-sensitive sustained-release attractant for Z. cucurbitae, that not only can control the release rate of cuelure according to the temperature change, but also shows an excellent trapping effect on Z. cucurbitae. To further enhance the killing effect of the temperature-sensitive attractant on Z. cucurbitae, this study proposed using it in combination with an insecticide to prepare a temperature-sensitive insecticide for Z. cucurbitae. Based on the controlled release technology of pesticides, a temperature-sensitive Z. cucurbitae insecticide was developed by using PNIPAM gel as a temperature-sensitive switch to carry both cuelure and insecticide at the same time. In addition, the lethal effect of different pesticides on Z. cucurbitae were tested by indoor toxicity test, and the best pesticide combination was screened out. The temperature-sensitive insecticide prepared in this study not only had excellent thermal response and controlled release ability, but also enhanced its toxicological effects on Z. cucurbitae because it contained insecticides. Among them, combining thiamethoxam and clothianidin with the temperature-sensitive attractants was the most effective, and their lethality reached more than 97% against Z. cucurbitae. This study is not only of great practical significance for the monitoring and controlling Z. cucurbitae, but also provides theoretical basis and reference value for the combination of temperature-sensitive attractant and insecticide.

Assessment of Boll Weevil Susceptibility to Isocycloseram and Ethiprole and Differential Toxicity to Natural Enemies.

Insecticides efficient against the target species while conserving natural enemies in the agroecosystem are required for IPM. With the imminent discontinuation of fipronil, a broad-spectrum insecticide, ethiprole, which belongs to the same group as phenylpyrazole (2B), and isocycloseram, a novel isoxazoline insecticide with distinct mode of action (30), provide options for controlling boll weevil. The susceptibility of the boll weevil, Anthonomus grandis grandis (Boh.), and two natural enemies [Eriopis connexa (Germar) and Bracon vulgaris Ashmead] to these insecticides were studied. Furthermore, the survival and biological traits of the lady beetle, E. connexa, exposed to fipronil, isocycloseram, and ethiprole were assessed. The LC50s values for fipronil, ethiprole, and isocycloseram for A. grandis grandis were 2.71, 0.32, and 0.025 mg a.i./L, respectively; 0.86, > 200, and 3.21 mg a.i./L for E. connexa; and 2.31, 592.94, and 0.18 mg a.i./L for B. vulgaris, respectively. The recommended rates of ethiprole did not cause mortality in adult lady beetles, although fipronil and isocycloseram were highly toxic. Lady beetle larvae and adults survived more than 80% when exposed to dried residues of ethiprole, but less than 10% when exposed to fipronil and isocycloseram. Lady beetle larvae development, reproduction, and predation rates of adults were similar between ethiprole and the control group. Although fipronil and ethiprole belong to the same insecticide group, the difference in toxicity to boll weevils and natural enemies is presented and discussed. Ethiprole was more toxic to boll weevils than to its parasitoid and lady beetle, and isocycloseram was highly toxic to all three species.

The Repellent Capacity against Sitophilus zeamais (Coleoptera: Curculionidae) and In Vitro Inhibition of the Acetylcholinesterase Enzyme of 11 Essential Oils from Six Plants of the Caribbean Region of Colombia.

The repellent capacity against Sitophilus zeamais and the in vitro inhibition on AChE of 11 essential oils, isolated from six plants of the northern region of Colombia, were assessed using a modified tunnel-type device and the Ellman colorimetric method, respectively. The results were as follows: (i) the degree of repellency (DR) of the EOs against S. zeamais was 20-68% (2 h) and 28-74% (4 h); (ii) the IC50 values on AChE were 5-36 µg/mL; likewise, the %inh. on AChE (1 µg/cm3 per EO) did not show any effect in 91% of the EO tested; (iii) six EOs (Bursera graveolens-bark, B. graveolens-leaves, B. simaruba-bark, Peperomia pellucida-leaves, Piper holtonii (1b*)-leaves, and P. reticulatum-leaves) exhibited a DR (53-74%) ≥ C+ (chlorpyrifos-61%), while all EOs were less active (8-60-fold) on AChE compared to chlorpyrifos (IC50 of 0.59 µg/mL). Based on the ANOVA/linear regression and multivariate analysis of data, some differences/similarities could be established, as well as identifying the most active EOs (five: B. simaruba-bark, Pep. Pellucida-leaves, P. holtonii (1b*)-leaves, B. graveolens-bark, and B. graveolens-leaves). Finally, these EOs were constituted by spathulenol (24%)/ß-selinene (18%)/caryophyllene oxide (10%)-B. simaruba; carotol (44%)/dillapiole (21%)-Pep. pellucida; dillapiole (81% confirmed by 1H-/13C-NMR)-P. holtonii; mint furanone derivative (14%)/mint furanone (14%)-B. graveolens-bark; limonene (17%)/carvone (10%)-B. graveolens-leaves.

Chemical Composition and Evaluation of Insecticidal Activity of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum Essential Oils against Stored Products Pests.

The problems of the environment and human health related to the use of synthetic and broad-spectrum insecticides have increasingly motivated scientific research on different alternatives and among these, the use of green systems, such as essential oils, have been explored. Several species of the Apiaceae and Asteraceae families, aromatic herbs rich in secondary bioactive metabolites, are used in the industrial field for pharmaceutical, cosmetic, and food purposes. Different essential oils extracted from some species of these families have shown acute toxicity and attractive and/or repellent effects towards different insects. In our work, we investigated the toxic potential of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum essential oils against four insect species, Sitophilus oryzae, Lasioderma serricorne, Necrobia rufipes, and Rhyzoperta dominica, which are common pests of stored products. The composition of both oils, extracted by hydrodistillation from the aerial parts of the two plants, was evaluated by GC×GC-MS. Calendula incana subsp. maritima essential oil was rich in oxygenated sesquiterpenoids, such as cubebol (35.39%), 4-epi-cubebol (22.99%), and cubenol (12.77%), while the Laserpitium siler subsp. siculum essential oil was composed mainly of monoterpene hydrocarbons, such as ß-phellandrene (42.16%), limonene (23.87%), and ß-terpinene (11.80%). The toxicity Petri dish bioassays indicated that C. maritima oil killed a mean of 65.50% of S. oryzae and 44.00% of R. dominica adults, indicating a higher biocidal activity in comparison with L. siculum oil, while toward the other species, no significant differences in mortality were recorded. Calendula maritima oil could be, then, considered a promising candidate for further tests as an alternative biocide toward S. oryzae and R. dominica. The possibility that the relatively high content of oxygenated sesquiterpenoids in C. maritima essential oil determines its higher biocidal activity is discussed.

Evaluation of the Potential of a Lectin Extracted from Polygonumpersicaria L. as a Biorational Agent against Sitophilusoryzae L.

Rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is one of the most destructive stored-product pests that is resistant to a wide range of chemical insecticides. In the present study, we investigated whether a lectin extracted from Polygonum persicaria L. (PPA) can be used as a biorational agent to control such insect pests. Along with the lethal digestive assay, the sub-lethal insecticidal activities of PPA, including the effects on digestive, detoxifying, and antioxidant enzyme activities, were evaluated against S. oryzae adults. The effect of feeding a diet containing PPA and carob extract as a food attractant on the mortality of S. oryzae adults was also investigated. Feeding on the diet containing PPA resulted in a significant mortality of S. oryzae adults with a LC50 (Lethal Concentration to kill 50% of insects) of 3.68% (w/w). The activity of digestive enzymes, including α-amylase, α-glucosidase, TAG-lipase, trypsin, chymotrypsin, elastase, and carboxy- and aminopeptidase, were decreased by the sub-lethal concentration of PPA. Detoxifying and antioxidant enzymes, including esterase, superoxide dismutase, catalase, glutathione-S-transferase, ascorbate peroxidase, glucose 6-phosphate dehydrogenase, and malondialdehyde, were activated in adults affected by PPA. These findings indicated that PPA, in addition to causing digestive disorders, leads to oxidative stress in S. oryzae. The presence of carob extract had no effect on the PPA-induced mortality of the insect. According to the results of the present study, PPA has promising insecticidal efficiency against S. oryzae. In addition, the usage of PPA with a food attractant carob extract in bait traps can be recommended as a new biorational formulation in S. oryzae management.

Entomotoxic effects of synthesized aluminum oxide nanoparticles against Sitophilus oryzae and their toxicological effects on albino rats.

Recently, nanoparticles are emerging as a potential alternative to synthetic pesticides for protection against stored-product insect pests, such as the rice weevil Sitophilus oryzae; however, the toxic effects of nanoparticles on nontarget organisms are not yet understood. Therefore, we investigated the insecticidal effects of synthesized aluminum oxide nanoparticles (Al2O3-NPs) on S. oryzae, as well as their potential toxicity in albino rats. S. oryzae mortality increased as the period of Al2O3-NP exposure increased; 100% mortality was reached at 8000 mg Al2O3-NPs/kg of wheat grain after 7 days of exposure. After 60 days of exposure, all tested Al2O3-NPs concentrations (1000, 2000, 4000, and 8000 mg/kg grain) significantly reduced the number of S. oryzae offspring in a dose-dependent manner. In albino rats, exposure to the LC90 of Al2O3-NPs in a treated diet caused a significant decrease in total body weight and an increase in liver weight in a subacute toxicity test. Moreover, Al2O3-NP treatment elevated the levels of alanine aminotransferase, aspartate aminotransferase, and creatinine in exposed rats relative to control rats, while the uric acid levels of treated rats decreased. Histopathological analysis also revealed various hepatic and renal lesions in treated rats. In summary, although Al2O3-NPs have insecticidal effects, they also have hazardous toxicological effects on rats. Therefore, if Al2O3-NPs are used in the current powder form to protect stored products, they may cause adverse effects to workers and consumers. Further research will be required to develop new nanoformulations with increased safety and potency before these nanoparticles can be used in stored-product pest control.

Bacterial chitinase biochemical properties, immobilization on zinc oxide (ZnO) nanoparticle and its effect on Sitophilus zeamais as a potential insecticide.

It has been planned to minimize the yield and quality impairment of the seed corn, which is strategically important in the world, by pests under storage conditions with a biological product produced with a biotechnological approach. In this context, the present study aimed to control the maize weevil Sitophilus zeamais, known as a warehouse pest, using a nanoformulation. In the study, the chitinase enzyme from Lactobacillus coryniformis was purified first using ammonium sulfate precipitation and then by using the HiTrap Capto DEAE column, and the molecular mass of the purified enzyme was determined to be ~ 33 kDa, and the optimum pH and the values as pH 6.0 and 65-75 °C, respectively. Five different doses of nanoformulation (2, 4, 6, 8 and 10 mg/L) were applied to corn grains by the spraying method with three repetitions so that the insect can ingest the formulation through feeding. The effects of the applications on the death rate and mean time of death of Sitophilus zeamais were determined. According to these findings, it was concluded that the best practice was nanoformulation with 6 mg/L, considering both the mortality rate (100%) and the average death time (2.4 days). Chitinase from L. coryniformis is a promising candidate for corn lice control and management.

Clove Buds Essential Oil: The Impact of Grinding on the Chemical Composition and Its Biological Activities Involved in Consumer's Health Security.

This study is aimed at identifying the chemical composition of the essential oil extracted from the Syzygium aromaticum seeds, as well as investigating its biological activities, insecticide effect, and allelopathic properties. The extraction yield was about 14.3 and 7.14% for grounded and ungrounded seeds, respectively. The GC-MS analysis allowed the identification of 17 heterogeneous compounds, including eugenol (68.7-87.4%), as major compound, cyperene (20.5-7.2%), phenethyl isovalerate (6.4-3.6%), and cis-thujopsene (1.9-0.8%), respectively, for grounded and ungrounded seeds. Concerning the antibacterial activity, the diameter of the inhibition zone reached 35 mm when the essential oil extracted from grounded seeds was applied against Escherichia coli. Regarding the antioxidant activity via the DPPH radical scavenging test, the IC50 varied from 1.2 ± 0.1 to 2.8 ± 0.5 µg/mL. With respect to reducing power, the efficient concentration EC50 ranged from 32 to 50 µg/mL. The essential oil exhibited also an allelopathic effect against seeds of Hyoscyamus niger, as well as an insecticide effect against Sitophilus oryzae with a DL50 value of 252.4 µL/L air. These findings enhance the use of this spice as a natural food preservative and encourage its use in several fields, including pharmaceutical, cosmetics, agriculture, and therapy, that could be a strategic way to guarantee the consumer's health.

Intergenerational Transmission of Resistance of Callosobruchus maculatus to Essential Oil Treatment.

Due to the rise of numerous legal restrictions as well as the increasing emergence of resistant populations, the number of available pesticides is decreasing significantly. One of the potential alternatives often described in the literature are essential oils (EOs). However, there is a lack of research addressing the potential emergence of resistance to this group of substances. In this paper, we investigated the multi-generational effects of sublethal concentrations of rosemary oil (Rosmarinus officinalis) on physiological and biochemical parameters of the cowpea weevil (Callosobruchus maculatus) such as egg laying, hatchability, oxygen consumption and acetylcholinesterase activity. Imago, which as larvae were exposed to EO at concentrations equivalent to LC25, showed significantly lower mortality. The results obtained indicate the potential development of resistance in insects exposed to EO in concentrations corresponding to LC25. In addition, in the case of the group treated with an EO concentration corresponding to LC3.12, a stimulation effect of the above-mentioned parameters was observed, which may indicate the occurrence of a hormesis effect. The obtained results may be an important reference for the development of future guidelines and EO-based insecticides.

Synthesis and Insecticidal Evaluation of Chiral Neonicotinoids Analogs: The Laurel Wilt Case.

Xyleborus sp beetles are types of ambrosia beetles invasive to the United States and recently also to Mexico. The beetle can carry a fungus responsible for the Laurel Wilt, a vascular lethal disease that can host over 300 tree species, including redbay and avocado. This problem has a great economic and environmental impact. Indeed, synthetic chemists have recently attempted to develop new neonicotinoids. This is also due to severe drug resistance to "classic" insecticides. In this research, a series of neonicotinoids analogs were synthesized, characterized, and evaluated against Xyleborus sp. Most of the target compounds showed good to excellent insecticidal activity. Generally, the cyclic compounds also showed better activity in comparison with open-chain compounds. Compounds R-13, 23, S-29, and 43 showed a mortality percent of up to 73% after 12 h of exposure. These results highlight the enantioenriched compounds with absolute R configuration. The docking results correlated with experimental data which showed both cation-π interactions in relation to the aromatic ring and hydrogen bonds between the search cavity 3C79 and the novel molecules. The results suggest that these sorts of interactions are responsible for high insecticidal activity.

Repellent Effects of Selected Organic Leaf Extracts of Tithonia diversifolia (Hemsl.) A. Gray and Vernonia lasiopus (O. Hoffman) against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae).

INTRODUCTION: Sitophilus zeamais infestation is among the major setbacks to sustainable maize farming and availability. It causes an estimated annual loss of 5-10% and 20-30% of the total maize grains loss in the temperate and tropical zones, respectively. Although synthetic pesticides are quick and effective in managing crop pests, their overuse and misuse is discouraged due to their detrimental effects on human and environment. Natural pesticidal products that are extracted from plants are particularly gaining importance as an alternative to synthetic pesticides. They are available, easily biodegraded and have low toxicity to nontarget organisms. Most botanical pesticides act on insects by repelling them away from the crops in the field or in the stores. Therefore, this study aimed to determine repellency potential of organic leaf extracts of Tithonia diversifolia and Vernonia lasiopus on S. zeamais. Materials and methods. The phytochemical profile of T. diversifolia and V. lasiopus was determined using GC-MS. Laboratory-based experiments were carried out using area preference method to assess the efficacy of the extracts against weevils for a test period of 5 h. Six groups of experiments were set up with ten S. zeamais in each test: positive control (Actellic), negative control (solvent only), and four different experimental extract concentrations (25, 50, 75, and 100%). RESULTS: The results indicated that T. diversifolia and V. lasiopus leaf extracts possess potent repellency effect on weevils. All the extracts simply discouraged S. zeamais from the treated areas recording significantly good levels of repellent activities between 26 and 96%. Furthermore, the GC-MS analysis manifested the presence of bioactive compound in the extracts which are associated with the repellency effects. CONCLUSION: The study scientifically confirms the traditional use of the T. diversifolia and V. lasiopus and provides important platform for further study on the extracts as bioresource of botanical repellent.