Effects Of Insecticides Research Articles

Ecofriendly synthesis of copper oxide-chitosan nanocomposites and their efficacy as nano-pesticide and nano-fertilizer

Chemical pesticides and fertilizers are a long time threat to human health and environment. One of the prime risks in pest management is the resistance to insecticide applied. There is demand for formulations which are eco-friendly, effective in small amounts, biodegradable and economically viable. The demand for organic formulations and nanomaterials to control the pests of economically important plants is rising every day. Mealy bugs and fruit flies are the major pests and their control has been a serious issue in pest management. The current research work was conducted to synthesize copper oxide nanoparticles (CuO NPs) from Eucalyptus leaves and nanocomposites comprising chitosan through a green way to evaluate the insecticidal efficacy of prepared nanomaterials. The nanomaterials were characterized by Fourier-transform infrared spectroscopy (FT-IR), UV–Visible spectroscopy, Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). CuO NPs showed crystalline monoclinic structure in XRD pattern. Different concentrations of nano-pesticides were tested against mealy bugs and fruit flies to find out % mortality and LC50 values. The LC50 values in mealy bugs for extract, CuO NPs, CuO-Chitosan nanocomposites (NCs) and CuO-Chitosan NCs with Cu layer were found to be 10.45 ppm, 6.96 ppm, 4.58 ppm and 3.29 ppm, respectively. Results showed that mortality enhanced with rising pesticides concentration, so plant extract, CuO NPs, CuO-Chitosan NCs and CuO-Chitosan NCs with Cu layer showed 50 %, 70 %, 80 % and 90 % mortality at the highest concentration (10 ppm). The synthesized nanomaterials significantly improved seeds germination, yield and growth parameters in maize whenever used as nano-fertilizers. The results showed that prepared nanomaterials have good insecticidal effects as well as the best fertilizer properties. So, the products having dual application as nano-pesticides and nano-fertilizers have promising future in agriculture.

Insecticidal Efficacy of Diatomaceous Earth and Botanical Powders against Pulse Beetle, Callosobruchus analis F. in Stored Mung Bean (Vigna radiata L.)

The pulse beetle is the most damaging insect pest of legumes causing huge economic losses. The experiment was conducted to find out the insecticidal effects of diatomaceous earth (DE) combined with three botanical powders in three different combinations of 25% plant powder with 75% DE, 50% plant powder with 50% DE and 75% plant powder with 25% DE. The results indicated that the least number of adult beetles settled on grains treated with T9 (75% GP + 25% DE and T3 (75% NP + 25% DE) whereas maximum number of adult beetles settled in T4 (25% TP + 75% DE). After 168 hours, all the treatments showed significant mortality (100%) of adult beetles compared to control (43%). All the treatments reduced the number of eggs (3.60 to 6.80 eggs per 20 grains) in comparison to control (17.00). The maximum (28.80) days to adult emergence were documented in T9 whereas; minimum (21.40) days were recorded in untreated grains. Among all the treatments, T9: showed minimum emergence (36.40) of adult beetles whereas; the maximum (125.20) adults emerged in control. The lowest grain damage (5.50%) was observed in T9 as related to the maximum grain damage (28.96%) in the untreated control. The minimum weight loss (3.49%) was recorded in T9. The maximum weight loss (21.08%) was recorded in untreated grains. The use of diatomaceous earth in combination with garlic powder is recommended for the management of pulse beetle under storage conditions.

Green purification of Acmella oleracea extract by wiped-film short path molecular distillation boosts the insecticidal activity on mosquito larvae

The development of insecticide resistance by mosquito vectors highlighted an urgent need for effective and sustainable botanical insecticides. Acmella oleracea R.K. Jansen (Asteraceae)-derived extracts and the major constituents N-alkylamides have already demonstrated their potential as insecticidal and acaricidal agents. Nowadays, the development of scalable green extraction and purification processes in the manufacture of biopesticides is a topic of great interest. In this context, supercritical fluid extraction and wiped-film short path molecular (WSM) distillation techniques were combined for the first time to obtain an eco-friendly N-alkylamides-enriched fraction (AEF) from A. oleracea. This was characterized by a notably higher content of spilanthol and N-alkylamides than the supercritical fluid extract (SFE), as determined by HPLC-DAD-MS analysis. The AEF also contained free fatty acids (e.g., palmitic, linoleic, and linolenic acids) as revealed by GC-FID analysis. The mosquito larvicidal activity of SFE, AEF, and pure spilanthol was assessed against 3rd instar larvae of Aedes albopictus Skuse, Anopheles stephensi Liston, and An. gambiae Giles. Results showed that AEF exhibited an insecticidal efficacy comparable with that of spilanthol, and higher than that of SFE. These products were tested against human keratinocytes (HaCaT) confirming their dermal safety. The present study paves the way for the utilization of WSM distillation in the agrochemical industry for the manufacture of botanical insecticides. Indeed, this technique allows to avoid the use of organic solvents related to conventional extraction and spilanthol isolation procedures and gives a product devoid of undesired pigments appealing to other industrial application as well.

Studying the effectiveness of Jatropha carcus L. Extract as a repellent, antifeedant, and toxic substance against red palm weevil (Rhynchophorus Ferrugineus) adult insects in Saudi Arabia

ObjectiveRed palm weevil (RPW), Rhynchophorus ferrugineus, is a highly harmful pest that causes severe damage to date palm trees. The detrimental influence of RPW on date palm trees cannot be ignored and must be addressed. Chemical insecticides are available for controlling RPW; however, the insect population has become resistant to these chemicals, leading to damage and spread to new areas. The present investigation examined the impacts of physic nut (Jatropha curcas L.) seeds essential oils (PNEO) on laboratory-reared RPWs adult insects reared in a controlled laboratory environment. MethodsThe insecticidal, repellent, and antifeedant potentials of different doses (10, 20, 30, 40, 50%) of PNEO were tested against RPW. The insecticidal activity of J. curcas seeds oil extracts was assessed using topical application and feeding methods. ResultsRPW showed a high mortality rate when J. curcas seeds oil was applied topically after 24 h (P < 0.05). The mortality (%) of insects was 8, 76, 92, 96, and 100 for 10 %, 20 %, 30 %, 40 %, and 50 % concentrations, respectively. The LC50 and LC90 were 16.50 %, and 28.14 %, respectively. Results from the feeding method demonstrated a significant increase in mortality with a 100 % mortality rate at higher concentrations of PNEO compared to 10 and 20 % concentrations (P < 0.0001). The LC50 and LC90 were 24.42 % and 31.30 %, respectively. There was no significant decrease in food consumption and the antifeedant index when 10 % and 20 % of J. curcas seeds oil were used on the 3rd and 6th day after application. All J. curcas oil concentrations showed a repellent effect significantly higher than the controls (P < 0.05). ConclusionJ. curcas seeds oil has shown potential insecticidal and repellent effects against RPW, and it could provide an eco-friendly tool for RPW pest management.

Insecticide Efficacy of Green Synthesis Silver Nanoparticles on Diaphorina citri Kuwayama (Hemiptera: Liviidae).

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of Liberibacter asiaticus Jagoueix et al. and Liberibacter americanus Teixeira et al., causal agents of the critical yellow dragon disease or Huanglongbing (HLB), which affects citrus production worldwide. Recently, green synthetic nanoparticles have emerged as a potential alternative to control of agricultural insect pests. The insecticide effect of silver nanoparticles (AgNPs) on 2nd instar nymphs of D. citri under laboratory and greenhouse conditions was evaluated. Mortality was recorded 24, 48, and 72 h after application on D. citri nymphs under both laboratory and greenhouse conditions. The laboratory results showed that AgNPs caused 97.84 and 100% mortality at 32 and 64 ppm, respectively, 72 h after treatment. In the greenhouse, AgNPs caused 78.69 and 80.14% mortality using 64 and 128 ppm 72 h after application. This research is the first to evaluate the green synthesis AgNPs on D. citri and are a promising strategy to control the pest.

Life Table Study of Liriomyza trifolii and Its Contribution to Thermotolerance: Responding to Long-Term Selection Pressure for Abamectin Resistance.

Liriomyza trifolii is a significant invasive pest that targets horticultural and vegetable crops, causing large-scale outbreaks characterized by pronounced thermotolerance and insecticide resistance. This study examined the impact of long-term selection for abamectin resistance during the larval stage of L. trifolii on its population dynamics and thermal tolerance. We conducted a comprehensive comparison between the abamectin-resistant strain (AB-R) and the susceptible strain (S), including age-stage, two-sex life table analysis, thermal preference (Tpref), critical thermal maximum (CTmax), heat knockdown times (HKDTs), eclosion and survival rates, and LtHsp expression under heat stress. Our results showed that while selection for abamectin resistance was detrimental to survival and reproduction, it activated self-defense mechanisms and rapid adaptive adjustments and conferred modest thermal tolerance, which suggests a dual nature of insecticide effects. The AB-R strain exhibited significantly higher thermal preference and CTmax values, along with a longer HKDT and improved survival. Additionally, there was a significant upregulation of LtHsp expression in the AB-R strain compared to the S strain. These findings indicate that the evolution of thermal adaptation was accompanied by abamectin resistance development, emphasizing the necessity of considering temperature effects when applying chemical control. Our study provides valuable insights into how physiological acclimation may help mitigate the toxic effects of insecticides and illustrate how insects respond to multiple environmental pressures.

Reduction of Colorado potato beetle damage by various organic mulches

IntroductionThe Colorado potato beetle (Leptinotarsa decemlineata) (CPB) is a major threat to potato crops in Europe, Asia, and America. In Europe, it is expected that climate change will cause the species to expand its range northwards and allow for an additional generation per year in regions where it is already established. The effectiveness of insecticides, a common method of control, is decreasing due to the emergence of resistance to several substances. Therefore, research into alternative measures is becoming increasingly necessary. One preventive measure that has already been shown to have great effects in past studies is the use of organic mulch. For organic mulching, conserved or freshly cut plant material is spread on the field usually when the potato emerges. Previous research has mainly used cereal straw for this purpose in plots that are relatively small compared to actual agricultural fields. Materials and methodsTo address the lack of large-scale field trials in the literature, a series of on-station and on-farm field trials were conducted in this study. Organic, legume-rich mulches were used primarily, which so far have not been extensively investigated. Over a period of four years and in a total of six field trials, CPB and larval infestations were assessed. Results and discussionOur results show effects on the initial infestation of young plants by adult CPB and on the emergence time of the first two larval stages. By the time of flowering, when the feeding effect of CPB on yield is known to be greatest, L3 and L4 larvae were reduced by about 30% in the on-station trials and by about 40% in the on-farm trials. In addition, when CPB larval stages were used to calculate a weighted daily leaf consumption per stage, total calculated leaf consumption was on average about 40% lower in the mulch treatments across all sampling dates and all trials. The recorded yields were equal or higher in the mulched treatments. In conclusion, organic mulching can effectively reduce CPB damage even on a large scale and can have a positive impact on yield. Further agronomic benefits of mulching, as well as drawbacks and putative mechanisms of action, are discussed.

INFLUENCE OF ALUMINUM OXIDE NANOPARTICLES ON BIOLOGICAL FEATURES AND HOST HEMOCYTES OF Galleria mellonella L. (Lepidoptera: Pyralidae) WITH ITS ENDOPARASITOID Pimpla turionellae L. (Hymenoptera: Ichneumonidae)

Nanoparticles (NPs) are released directly or indirectly into nature with increased production and consumption, and their effects on insects, which occupy a large place in the ecosystem, are of interest. There is also interest in the potentially toxic effects of NPs applied to hive pests on parasitoids, or honey bees, and host-parasitoid relationships. The influence of aluminum oxide (Al2O3) NPs on the biological features of the hive pest Galleria mellonella, total counts of hemocyte, and hemocyte types; as well as on the biological features of the endoparasitoid Pimpla turionellae were investigated. The data obtained revealed that Al2O3 NPs caused a decrease in the larval, pupal, and adult development time of G. mellonella. The immature developmental time of P. turionellae was reduced. It was also demonstrated that Al2O3 NPs decreased the total counts of hemocytes in G. mellonella larvae; granulocyte, spherulocyte, oenocytoid, and prohemocyte counts decreased at all NP concentrations, while plasmatocyte counts increased. The data showed that Al2O3 NPs affected the biological properties of the hive pest model organism G. mellonella and indirectly affected its endoparasitoid P. turionellae. In addition, NPs showed a suppressive effect on cellular immune system responses, decreasing hemocyte counts. Our study results suggest that especially honey bees, honeycomb pests, and parasitoids may be negatively affected by NPs, which have increased in recent years as environmental pollutants, and that NPs may have insecticidal effects.

Uniform plasmon enhanced luminescence of Eu-PMMA films for sensitive and single droplet detection of malachite green

The sensitively detection of malachite green (MG) is very important because it is a low-cost and effective fungicide and insecticide in the aquatic industry. In this study, the gold nanorods (Au NRs) are prepared and incorporated into Eu-poly(methylmethacrylate) (PMMA) films in a simple and convenient way. The Au NRs embedded Eu-PMMA films reveal a significant and uniform luminescence enhancement due to the LSPR effect of plasmonic nanostructures. Based on the enhanced luminescence, the sensitive and single droplet (<10 μL) detection of malachite green is achieved through the fluorescence resonance energy transfer between Eu and MG. The detected lowest concentration for MG is reduced from 0.01 mg L-1 to 0.001 mg L-1. Further more, the Au NRs embedded Eu-PMMA films as the platform exhibits the excellent recyclability and stability, which not only reduces waste but also enhances the platform’s environmental friendliness. This work not only provides an enhanced fluorescence for the detection of MG, but also provides a novel strategy for the design of fluorescent sensor toward different biomolecules.

Effect of drought and pine weevil damage on mechanically protected Norway spruce seedlings

Pine weevils (Hylobius abietis L.) pose a significant threat to conifer seedlings by feeding on the bark, thus damaging or killing seedlings. Historically, insecticides were used to suppress such damage, but were slowly phased out in Sweden due to environmental and health concerns. This study aimed to assess field performance of an alternative protection method: mechanical coating applied to the stem of planted Norway spruce (Picea abies) seedlings. Field trials were conducted on 14 sites in south Sweden, using four different types of mechanical protection (Cambiguard, Conniflex, Ekovax, Hylonox), standard insecticide (Merit Forest), and ambient control. Seven sites were established in the drought year of 2018 and seven more in 2019. This allowed for additional investigation of the effect of drought on seedling establishment and possible interaction with pine weevil damage. Seedlings were surveyed for survival and height after the first, second and fourth growing season. Results show drought as the main source of damage for seedlings planted in 2018, with no significant effect of insecticide or mechanical protection on survival of seedlings. However, mechanical protections performed equally well as insecticide and positively increased survival by 30 %, compared to untreated, four growing seasons after planting for seedlings planted in 2019. Seedling height was not significantly affected by planting year or any of the treatments, suggesting no adverse effects of coating application. However, a synergistic effect between pine weevil damage and drought was observed, where even low levels of pine weevil damage resulted in high mortality for seedlings planted in 2018, compared to those planted in 2019. Additionally, for seedlings planted in 2019, damage to the top of the stem did not result in significant mortality, until high damage levels were reached (40 % and above). The opposite was found for seedlings planted in a 2018 drought year, where both damage to the top and the bottom of the stem followed a linear response. In conclusion, we show that investigated mechanical protection methods can be considered a viable replacement for insecticides, but our results also highlight the importance of considering multiple environmental stressors such as drought and pest damage on seedling establishment.

Engineering a wolf spider A-family toxin towards increased antimicrobial activity but low toxicity

Spider-derived peptides with insecticidal, antimicrobial and/or cytolytic activities, also known as spider venom antimicrobial peptides (AMPs), can be found in the venoms of RTA-clade spiders. They show translational potential as therapeutic leads. A set of 52 AMPs has been described in the Chinese wolf spider (Lycosa shansia), and many have been shown to exhibit antibacterial effects. Here we explored the potential to enhance their antimicrobial activity using bioengineering. We generated a panel of artificial derivatives of an A-family peptide and screened their activity against selected microbial pathogens, vertebrate cells and insects. In several cases, we increased the antimicrobial activity of the derivatives while retaining the low cytotoxicity of the parental molecule. Furthermore, we injected the peptides into adult Drosophila suzukii and found no evidence of insecticidal effects, confirming the low levels of toxicity. Our data therefore suggest that spider venom linear peptides naturally defend the venom gland against microbial colonization and can be modified into more potent antimicrobial agents that could help to battle infectious diseases in the future.

Lethal and Sublethal Effects of Cyantraniliprole on the Biology and Metabolic Enzyme Activities of Two Lepidopteran Pests, Spodoptera littoralis and Agrotis ipsilon, and A Generalist Predator, Chrysoperla carnea (Neuroptera: Chrysopidae).

Cyantraniliprole is a novel anthranilic diamide insecticide registered for controlling chewing and sucking insect pests. Here, the lethal and sublethal effects of this insecticide on two destructive lepidopteran pests, Spodoptera littoralis Boisduval and Agrotis ipsilon Hufnagel, were evaluated. Because the effects of novel insecticides on beneficial and non-target arthropods must be considered, the impact of cyantraniliprole on a generalist biological control agent, Chrysoperla carnea [Stephens 1836], were also examined. Overall, our study revealed that cyantraniliprole was more toxic to A. ipsilon than to S. littoralis. Moreover, the LC15 and LC50 of the insecticide significantly prolonged the duration of the larval and pupal stages and induced enzymatic detoxification activity in both species. Treatment of the second-instar larvae of C. carnea with the recommended concentration of cyantraniliprole (0.75 mg/L) doubled the mortality rates and resulted in a slight negative effect on the biology and detoxification enzymes of C. carnea. Our results indicate that both sublethal and lethal concentrations of cyantraniliprole can successfully suppress S. littoralis and A. ipsilon populations. They also suggest that C. carnea, as a generalist predator, is compatible with cyantraniliprole under the modelled realistic field conditions. In future investigations, insights into the effects of cyantraniliprole on S. littoralis, A. ipsilon, and C. carnea under field conditions will be required to appropriately validate our results.

Biosynthesis and characterization of selenium and silver nanoparticles using Trichoderma viride filtrate and their impact on Culex pipiens

Abstract Some of the significant globally prevalent vector-borne illnesses are caused by Culex pipiens. Synthetic pesticides have been widely utilized to eradicate C. pipiens, which has led to a number of health risks for people, insect resistance, and environmental contamination. Alternative strategies are therefore vitally needed. In the current investigation, the Trichoderma viride fungal culture filtrate was used to create selenium and silver nanoparticles (SeNPs and AgNPs, respectively) and test them on C. pipiens larvae in their fourth instar stage. The death rate increased significantly when SeNP and AgNP concentrations increased, according to the results. SeNPs and AgNPs significantly affected the developmental and detoxification enzymes in fourth instar larvae of C. pipiens at 24 h after being treated with the sublethal concentration of the tested NPs. As a result of their insecticidal effect on C. pipiens larvae, SeNPs and AgNPs are considered effective and promising larvicidal agents.

Design, Synthesis and Bioactivities of Novel Pyridyl Containing Pyrazole Oxime Ether Derivatives.

In this research, with an aim to develop novel pyrazole oxime ether derivatives possessing potential biological activity, thirty-two pyrazole oxime ethers, including a substituted pyridine ring, have been synthesized and structurally identified through 1H NMR, 13C NMR, and HRMS. Bioassay data indicated that most of these compounds owned strong insecticidal properties against Mythimna separata, Tetranychus cinnabarinus, Plutella xylostella, and Aphis medicaginis at a dosage of 500 μg/mL, and some title compounds were active towards Nilaparvata lugens at 500 μg/mL. Furthermore, some of the designed compounds had potent insecticidal effects against M. separata, T. cinnabarinus, or A. medicaginis at 100 μg/mL, with the mortalities of compounds 8a, 8c, 8d, 8e, 8f, 8g, 8o, 8s, 8v, 8x, and 8z against A. medicaginis, in particular, all reaching 100%. Even when the dosage was lowered to 20 μg/mL, compound 8s also expressed 50% insecticidal activity against M. separata, and compounds 8a, 8e, 8f, 8o, 8v, and 8x displayed more than 60% inhibition rates against A. medicaginis. The current results provided a significant basis for the rational design of biologically active pyrazole oxime ethers in future.

Effects of Lightweight Rolling, Sand Topdressing, and Insecticide on the Rhodesgrass Mealybug (Hemiptera: Pseudococcidae) on Golf Course Putting Greens1

Abstract Rhodesgrass mealybug, Antonina graminis Maskell (Hemiptera: Pseudococcidae), is an important pest on golf course putting greens. Antonina graminis feeding causes extensive yellowing and browning that causes turfgrass mortality. Lightweight rolling and sand topdressing are standard cultural practices on the golf course; however, it is unclear whether they can reduce A. graminis densities and provide additional suppression when combined with insecticide. Thus, the objectives of the study were to determine the effects of (a) lightweight rolling and sand topdressing and (b) combining these practices with a systemic insecticide, thiamethoxam, on A. graminis densities on golf course putting greens. In 2021 and 2022, experiments were conducted in a split-plot design where lightweight rolling was the main plot treatment and sand topdressing, insecticide, sand topdressing + insecticide, and nontreated were subplot treatments. The numbers of A. graminis were not significantly affected by rolling treatment in the 2021 and 2022 experiments. Similarly, the sand topdressing alone had no significant effect on the A. graminis densities on the putting greens. The numbers of A. graminis were significantly lower for the insecticide (thiamethoxam) and combination of sand topdressing + insecticide treatment than for the nontreated subplot.

Physical and insecticidal durability of Interceptor®, Interceptor® G2, and PermaNet® 3.0 insecticide-treated nets in Burkina Faso: results of durability monitoring in three sites from 2019 to 2022

BackgroundNational Malaria Programmes (NMPs) monitor the durability of insecticide-treated nets (ITNs) to inform procurement and replacement decisions. This is crucial for new dual active ingredients (AI) ITNs, for which less data is available. Pyrethroid-only ITN (Interceptor®) and dual AI (Interceptor® G2, and PermaNet® 3.0) ITNs were assessed across three health districts over 36 months in southern Burkina Faso to estimate median ITN survival, insecticidal efficacy, and to identify factors contributing to field ITN longevity.MethodsDurability was monitored through a prospective study of a cohort of nets distributed during the 2019 mass campaign. Three health districts were selected for their similar pyrethroid-resistance, environmental, epidemiological, and population profiles. Households were recruited after the mass campaign, with annual household questionnaire follow-ups over three years. Each round, ITNs were withdrawn for bioassays and chemical residue testing. Key measures were the percentage of cohort ITNs in serviceable condition, insecticidal effectiveness, and chemical residue content against target dose. Cox proportional hazard models were used to identify determinants influencing ITN survival.ResultsAt endline, the median useful life was 3.2 (95% CI 2.5–4.0) years for PermaNet® 3.0 ITNs in Orodara, 2.6 (95% CI 1.9–3.2) years for Interceptor® G2 ITNs in Banfora and 2.4 (95% CI 1.9–2.9) years for Interceptor® ITNs in Gaoua. Factors associated with ITN survival included cohort ITNs from Orodara (adjusted hazard ratio (aHR) = 0.58, p = 0.026), households seeing less rodents (aHR = 0.66, p = 0.005), female-headed households (aHR = 0.66, p = 0.044), exposure to social behavior change (SBC) messages (aHR = 0.52, ≤ 0.001) and folding nets when not in use (aHR = 0.47, p < 0.001). At endline, PermaNet® 3.0 ITN recorded 24-h mortality of 26% against resistant mosquitos on roof panels, with an 84% reduction in PBO content. Interceptor® G2 ITN 72-h mortality was 51%, with a 67% reduction in chlorfenapyr content. Interceptor® ITN 24-h mortality was 71%, with an 84% reduction in alpha-cypermethrin content.ConclusionOnly PermaNet® 3.0 ITNs surpassed the standard three-year survival threshold. Identified protective factors should inform SBC messaging. Significant decreases in chemical content and resulting impact on bioefficacy warrant more research in other countries to better understand dual AI ITN insecticidal performance.

GABA-gated chloride channel mutation (Rdl) induces cholinergic physiological compensation resulting in cross resistance in Drosophila melanogaster

The Drosophila melanogaster MD-RR strain contains an Rdl mutation (A301S) resulting in resistance to several insecticide classes viz. phenyl pyrazoles (e.g., fipronil), cyclodienes (e.g., dieldrin), and chlorinated aliphatic hydrocarbons (e.g., lindane). Fitness costs are commonly observed with resistant insect populations as side effects of the genetic change conferring the resistant phenotype. Because of fitness costs, reversion from the resistant to susceptible genotype and phenotype is common. However, the Rdl genotype in D. melanogaster appears to allow the flies to maintain the resistant genotype/phenotype without selective pressure and with minimal fitness costs. We provide evidence that compensation for the Rdl mutation influences the cholinergic system, where an increase in acetylcholinesterase gene expression and enzyme activity results in neurophysiological changes and cross resistance to a carbamate insecticide (propoxur oral resistance ratio (RR) of 63) and an organophosphate insecticide (dichlorvos oral RR of 7). Such cross resistance was not previously reported with the initial collection and testing of this strain. In addition to acetylcholinesterase, the Rdl mutation influences the expression of the muscarinic acetylcholine receptor subtype-B, resulting in resistance to non-selective muscarinic compounds (pilocarpine and atropine). Collectively, these results indicate that the Rdl mutation (A301S) at GABA-gated ionophore complex influences the physiology of the cholinergic system, leading to resistance to established insecticide classes. Additionally, this mutation may impact the effectiveness of insecticides targeting novel sites, like muscarinic receptors.

Insecticidal, antifeedant, and repellent effect of Lavandula mairei var. antiatlantica essential oil and its major component carvacrol against Sitophilusoryzae

The genus Lavandula encompasses plants commonly known for their bioactivities and applications as insecticides. Despite this recognition, certain species such as Lavandula mairei Humbert have received no attention. For this reason, our study offers a close insight into the chemical profile, insecticidal (i.e. fumigant and contact toxicity), repellent, and antifeedant effect of Lavandula mairei var. antiatlantica (Maire) Maire essential oil (LMEO) against Sitophilus oryzae (L.), a major stored product insect. Additionally, the major compound of LMEO, i.e. carvacrol, was also tested for the aforementioned bioactivities. In the fumigant bioassays LMEO and carvacrol showed LC50 values of 69.5 and 69.3 μL/L of air, respectively, after 72 h while in the contact bioassays LC50 values of 0.14 and 0.117 μL/insect, respectively, after 24 h. In terms of antifeedant effect, carvacrol and LMEO significantly influenced the Feeding Deterrent Index (FDI) recording 83.2 and 55.0%, respectively, at a concentration of 3.2%. Furthermore, a notable reduction of 5.5 and 2.1-fold in Relative Consumption Rate (RCR) was observed for carvacrol and LMEO, respectively, compared to the control. Regarding the repellent effect, carvacrol and LMEO exhibited percentages of repellency (PR) of 94 and 82%, respectively, at 0.312 μL/cm2 after 24 h. In conclusion, our study underscores the significant insecticidal, feeding deterrent, and repellent effects of LMEO and its major compound against the rice weevil. Its cultivable potential and bioactivities confirmed through this study promote its use as sustainable pest control solution.

Chemical composition and pharmacological effects of Cinnamomum camphora chvar. borneol essential oil: a review

Cinnamomum camphora chvar. borneol, a rare camphor tree variant recently identified in China, is distinguished by its high concentration of D-borneol, also known as &quot; plant gold&quot; due to its significant value. The essential oil extracted from this variant,rich in monoterpenes and sesquiterpenes, demonstrates a broad spectrum of pharmacological activities, including analgesic, antiinflammatory, antioxidant, cognition-enhancing, anti-bacterial, and insecticidal effects. These properties, underscored by extensive research, highlight the oil's potential in the biomedical, chemical, and food sectors as a valuable commodity. Nonetheless, the safety profile of this valuable oil remains poorly characterized, with its chemical composition and therapeutic efficacy subject to variations in the factors like geographic origin, harvesting timing, part used for extraction, and processing techniques. Such variability poses challenges to its clinical application and hampers the efficient exploitation of this resource. This review synthesizes current studies on C. camphora chvar. borneol essential oil and provides a detailed examination of its chemical and pharmacological profiles. In this study, we discuss existing research gaps and propose strategies for advancing its clinical use and industrial application, aiming to provide a foundational reference for future investigations and the resolution of its commercial and therapeutic challenges.

Effect of chemical insecticides used for management of mulberry thrips on leaf yield of mulberry

Effect of chemical insecticides used for management of mulberry thrips on leaf yield of mulberry