Use Of Chemical Insecticides Research Articles

Physical and biochemical characteristics of cereal grains affect population growth parameters of Sitophilus oryzae (L.) (Coleoptera: Curculionidae)

The rice weevil, Sitophilus oryzae L. (Coleoptera: Curculionidae), is a significant pest of rice and other cereal grains. In this research, the effects of various grain species, including barley, maize, millet, rice, sorghum, and wheat, were assessed on biological properties and life history variables of S. oryzae under laboratory conditions. Data were analyzed based on the age-stage, two-sex life table method. Furthermore, various physicochemical properties of cereal grains, including protein content, starch content, humidity content, and seed hardness, were investigated to explore their correlation with the studied parameters of S. oryzae. The longest development time was observed on millet and sorghum hosts, while the shortest was on maize seed. The beetles reared on rice and millet species showed the maximum fecundity, whereas those reared on sorghum and millet grains showed the lowest. Maize grain had the highest intrinsic rate of increase (r), whereas millet and sorghum grains had the lowest. According to the correlation analysis, overall, seed protein content was negatively correlated with insect fecundity, R0 and r, but positively correlated with development time. Furthermore, starch content was positively correlated with insect fecundity, R0 and r, and negatively correlated with development time. The cluster results demonstrated that whereas sorghum and millet were comparatively resistant hosts for the growth of S. oryzae, maize and rice were relatively susceptible seeds. This information can be helpful in the development or improvement of integrated pest management (IPM) strategies against rice weevil. The findings of this research will also be helpful in introducing unsuitable hosts for the development of transgenic grains resistant to S. oryzae. The pest-resistant cereal grains identified in this study can potentially be utilized in combination with other pest control strategies for sustainable management of S. oryzae, which may help reduce the excessive use of chemical insecticides.

Potential of zodia (Evodia suaveolens) as natural repellents for Culex sp

Background: Adult Culex sp mosquitoes as disease vector also cause discomfort around humans. Various efforts have been made to prevent the transmission of diseases carried by mosquitoes, including the use of mosquito nets and the use of chemical insecticides in the larval and adult stages. Objectives: This Reserach aim to investigates the potential of Zodia (Evodia suaveolens) as natural repellents. Materials and Methods: An experimental study was conducted to test the effectiveness of Zodia extract at concentrations of 1%, 2%, and 3% against Culex sp. mosquitoes. The tests were conducted under controlled conditions in the Laboratory of Parasitology, University of Binawan. The effectiveness was measured by the percentage of mosquitoes repelled after exposure. Results: The effectiveness of Zodia repellent increased with concentration, showing 76.4% effectiveness at 1%, 81.3% at 2%, and 91.05% at 3%. These results indicate a concentration-dependent increase in repellency, with the highest concentration approaching typical efficacy rates of synthetic repellents. Conclusions: The Zodia repellent (Evodia suaveolens) with a concentration of 1%, 2% and 3% has been demonstrated to be effective as a natural repellent against Culex sp. mosquitoes.

The Effectiveness of Essential Oils as Vegetable Pheromones Against Cocoa Pests Using The Trap Method

Cocoa plants are one of the important commodities in plantation crops. The decreasing cocoa production is caused by several factors, one of which is pest attacks. There are several main pests in cocoa plants, namely, fruit borer pests, fruit sucking pests and lice. Currently, the use of chemical insecticides has been widely studied, causing many residues that can pollute the environment and disrupt the stability of the agro-ecosystem. One alternative that can be used is the use of attractants, namely pheromones derived from plant extracts containing essential oils. The use of pheromones with the trap method is one of the insect trapping techniques that has been widely used in control. The purpose of this study was to obtain the best combination of essential oils as vegetable pheromones to control pests in cocoa plants. This study consisted of six treatments and three replications. Treatment consists of use of vegetable pheromones derived from patchouli oil, cinnamon oil, oil nutmeg, clove oil, control (water) and combination (all treatments).

Deterrent Effects of Clary Sage Oil and Two Major Constituents against Drosophila suzukii (Diptera: Drosophilidae).

Drosophila suzukii (Diptera: Drosophilidae), spotted-wing drosophila, poses a significant threat to soft-skinned fruit crops in the Americas, Europe, Africa, and Oceania, as well as in Asia. The application of chemical insecticides is the primary control strategy for D. suzukii; however, resistance has developed with the indiscriminate use of chemical insecticides. Essential oils, considered potential alternatives to pesticidal strategies, exhibit potent toxic and sublethal behavioral effects against numerous pests, including D. suzukii. Clary sage oil repels a variety of agricultural and household pests; however, whether it has a repellent effect against D. suzukii remains unknown. Here, we found that clary sage oil exhibited dose-dependent repellency against D. suzukii adults in a T-maze assay, a two-choice assay and a two-choice attraction assay. Also, clary sage oil showed a significant repellent effect against D. suzukii larvae. Next, we explored the chemical constituents of clary sage oil by GC-MS and identified two major constituents, linalyl acetate (40.03%) and linalool (23.02%). Furthermore, the behavioral assays of linalyl acetate and linalool showed that both compounds conferred comparable repellency against D. suzukii adults and larvae. Finally, we found clary sage oil, linalyl acetate, and linalool elicited EAG responses in D. suzukii, especially clary sage oil, suggesting the repellency was mediated by the olfactory system. These findings indicate that D. suzukii shows olfactory-based behavioral avoidance of clary sage oil, linalyl acetate, and linalool. Clary sage oil and its major constituents may be possible alternatives in the management of D. suzukii.

Biochemical and toxicological characteristics of polyphenol oxidase from red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Red palm weevil (RPW) Rhynchophorus ferrugineus is the most destructive insect pests of numerous palm species in the world. The introduction of botanical extract(s) as integral part of an integrated pest management (IPM) programs against RPW will reduce the use of chemical insecticides. Polyphenol oxidase (PPO) is one of the RPW innate immune mechanisms and inhibition of such enzyme could result in a disorder of the insect's immune system. A one single PO isoenzyme has been purified from the hemolymph of the 12th instar larvae of RPW. Using L-DOPA as substrate, R. ferrugineus PPO exhibited specific activity 428 Units/mg proteins with 8.3-fold purification, optimum pH and temperature for activity at 7.5 and 40 °C, respectively and is enhanced by Cu2+ with 1.76-fold. The rank order for oxidizing R. ferrugineus PPO different substrates is catechol > pyrogallol > L-DOPA > pyrocatechuic acid and not tyrosine. The kinetic parameters Km, Vmax and Vmax/Km for L-DOPA are 3.3 mM, 1.3 μmol/ml/min, and 0.39, respectively. The catalytic efficiency of the enzyme towards catechol is 5.3-fold higher than that for L-DOPA. The enzyme completely inhibited by thiourea, ascorbic acid, dithiothreitol, and SDS. R. ferrugineus PPO is a catechol oxidase di-phenol: O2 oxidoreductase. Based on the toxicological studies of various botanical extracts, the IC50 ranged from 20 to 90 mg/ml. The enzyme completely inhibited by 50 mg/ml Cinnamomum camphora. Gallic acid, the major phenolic compound, has IC50 0.8 mM and competitively inhibited the enzyme with Ki 0.54 mM. C. camphora could be a useful natural RPW-controlling agent and used as integral part in IPM programs. This interpretation can be validated in future through an in vivo investigation.

Analysis of Essential Oils Extracted from Algerian Medicinal Plants and Their Aphicidal Effect Against the Melon Aphid Aphis Gossypii Glover (Homoptera: Aphididae)

Chemical insecticides are decisive in controlling insect pests, but they harm the environment. Reducing the use of chemical insecticides has become the main goal for ensuring healthy produce. However, research focusing on plant-based compounds has recently increased. The present study was carried out to analyze essential oils extracted from Algerian medicinal plants by gas chromatography coupled with mass spectrometry (GC-MS) to determine the insecticidal activity of essential oils from Juniperus phoenicea, Rosmarinus officinalis, Lavandula stoechas, Mentha pulegium and Pinus sylvestris, against Aphis gossypii Glover The main components constituting each essential oil were: α-pinene, β-Pinene 1,8- cineol, Linalool, Linalyl acetate, Fenchone, Pulegone, and Camphor. The toxicity of tested essential oils against Aphis gossypii was different and dependent on the concentration used (1000, 10000, and 100000 ppm), the duration of exposure (24, 48, and 72 h), and the chemical composition of the oil. The highest toxicity was for J. phoenicea, M. pulegium, and L. stoechas which were toxic as Actara® insecticide.

Effectiveness and biochemical impact of ozone gas and silica nanoparticles on Culex pipiens (Diptera: Culicidae)

Culex pipiens (Diptera: Culicidae) is a vector of many serious human diseases, and its control by the heavy use of chemical insecticides has led to the evolution of insecticide resistance and high environmental risks. Many safe alternatives, such as ozone gas (O3) and silica nanoparticles (silica NPs) can reduce these risks. Therefore, O3 and silica NPs were applied to 3rd larval instars of Cx. pipiens at different concentrations (100, 200, and 400 ppm) for different exposure times (1, 2, 3, and 5 min for O3 and 24, 48, and 72 h for silica NPs). The activity of some vital antioxidant enzymes as well as scanning electron microscopy of the body surface were also investigated. A positive correlation was observed between larval mortality % and the tested concentrations of O3 and silica NPs. O3 was more effective than silica NPs, it resulted in 92% mortality at 400 ppm for a short exposure time (5 min). O3-exposed larvae exhibited a significant increase in glutathione peroxidase, glutathione S-transferase, and catalase activities as well as the total antioxidant capacity. Scanning electron microscopy showing disruptive effects on the body surface morphology of ozone and silica NPs treated larvae. These results provide evidence that O3 and silica NPs have the potential for use as alternative vector control tools against Cx. pipiens.

Selection of Aphis craccivora (Hemiptera: Aphididae) for Resistance to Thiamethoxam Insecticide under Laboratory Conditions1

Abstract The cowpea aphid, Aphis craccivora Koch (Hemiptera: Aphididae), is a polyphagous pest that causes yield losses in a variety of crops worldwide. Its management relies mainly on the use of chemical insecticides. This study followed the development of resistance to thiamethoxam in A. craccivora under laboratory conditions for 24 generations. The initial median lethal concentration (LC50) of thiamethoxam in a susceptible laboratory population of A. craccivora was 2.62 ppm. Exposure of surviving aphids in each generation to thiamethoxam caused an increase in the LC50 with each successive generation. After 24 generations, the LC50 had increased to 225.83 ppm, an 86.2-fold increase over the initial LC50. Resistance, as indicated by the increasing LC50, appeared as early as the second generation with a 1.4-fold increase over the initial generation. By the 14th generation, the LC50 had increased by 29-fold, and by the 16th generation, it had quickly increased by 69.4-fold. Our results indicate that A. craccivora populations repeatedly exposed to thiamethoxam in a cropping system can lead to rapid development of resistance to the insecticide. Any overuse or other misuse of the pesticide may lead to an even more rapid development of high levels of resistance to thiamethoxam within a short period of time. Elevated levels of the detoxifying enzymes, carboxylesterase, glutathione-S-transferase, and mixed function oxidases, in aphids exhibiting resistance as compared with the initial susceptible population indicated that the detoxifying enzymes, especially the carboxylesterases, are likely involved in facilitating the development of resistance to thiamethoxam in A. craccivora.

Variation in Grain Yield Losses Due to Fall Armyworm Infestation among Elite Open-Pollinated Maize Varieties under Different Levels of Insecticide Application

Maize is an important food and industrial cereal crop that serves as the main source of energy for millions of low-income people in sub-Saharan Africa (SSA), but its production and productivity are constrained by many constraints, among which the fall armyworm (FAW) is the major one. The use of insecticides is the most effective control measure for the FAW. However, excessive use of chemical insecticides has environmental and health implications, and it can be expensive for resource-poor farmers. The objective of this study was to evaluate the extent of variation in yield losses due to the FAW among some elite maize open-pollinated varieties (OPVs) under two levels of insecticide application and control (0 application). In a two-year field study, 10 elite maize OPVs were evaluated under two levels of emamectin benzoate (5% WDG) applications and the control: 75 and 150 mL of spray solution per 20 L of water. The experimental design was a randomized complete block with three replications. The data were collected on grain yield (GY) and FAW leaf damage rating (LDR). The LDR was conducted on a 1–9 scale and used to categorize the maize varieties as resistant (1–4), moderately resistant (4–6), and susceptible (6–9). Significant varietal differences were obtained for GY and LDRs. The GY of the varieties under control (0 mL), 75 and 150 mL insecticide applications ranged from 3.3 t ha−1 (DTSTR-Y SYN-13) to 4.6 t ha−1 (PVA SYN-3), from 4.5 t ha−1 (DTSTR-Y SYN-13) to 6.4 t ha−1 (PVA SYN-13), and from 4.2 t ha−1 (DTSTR-Y SYN-13) to 6 t ha−1 (DTSTR-Y SYN-14), respectively. No significant differences in GY were found between the application of 75 and 150 mL of insecticide application. The relative loss in GY among the varieties under control (0 mL) differed with an increase in the level of insecticide application. The relative GY loss at the 75 mL insecticide application ranged from 18% (PVA SYN-3) to 38% (DTSTR-Y SYN-15) with a mean of 27%, whereas at the 150 mL insecticide application, it varied from 13% (PVA SYN-3) to 42% (DTSTR-Y SYN-15), with a mean of 26%. All the varieties exhibited moderate resistance to FAW, except DTSTR-Y SYN-14, which was susceptible. The varieties PVA SYN-3 and PVA SYN-13 were the most consistent in GY across the three insecticide treatment levels. The mean performance of the varieties for FAW leaf damage ranged from 4.0 (SAMMAZ-15) to 6.2 (DTSTR-Y SYN-14), from 4.5 (SAMMAZ-15) to 6.3 (PVA SYN-6), from 4.5 (SAMMAZ-15) to 6.3 (DTSTR-Y SYN-14), and from 3.5 (SAMMAZ-15) to 5 (DTSTR-Y SYN-14) for LDR 1, LDR 2, LDR 3, and LDR 4, respectively. The use of moderately resistant varieties, combined with timely spraying of emamectin benzoate at 75 mL provided adequate management for the FAW infestation and sustained high maize grain yield.

Insecticides may compromise the benefits of tree-crop diversification on arthropod biodiversity in cocoa agroforestry smallholdings

ABSTRACT Arthropods play vital roles in ecosystem functions, yet their distribution is subjected to environmental factors. Hence, this study investigates the impact of habitat features on arthropod communities within cocoa smallholdings under different farming practices: agroforestry and monoculture systems. We conducted arthropod sampling using yellow sticky traps and assessed the habitat features at each plantation twice to capture temporal variations in arthropod populations. The study recorded 2945 individual arthropods belonging to eight different functional groups. The most abundant functional group was saprophagous, followed by phytophagous, parasitoid, predator, mycetophagous, frugivorous, palynivore, and nectarivorous group. Using Generalized Linear Mixed Models (GLMMs), we found that the abundance of phytophagous and predatory arthropods increases with leaf litter, while it decreases with saprophagous arthropods. Our findings suggest that tree-crop diversification within cocoa smallholdings can play a significant role in preserving higher arthropod biodiversity, particularly when these smallholdings remain free from chemical insecticide use. Canopy cover was also found to positively affect the variability of arthropods indicating that it is a crucial factor affecting arthropod biodiversity. This study underscores the significance of integrating agroforestry systems into cocoa production landscapes, particularly those utilizing agrochemicals, to support diverse arthropod communities and promote sustainable cocoa production.

Workers knowledge and anticipation in reducing adverse impacts of climate change

Climate change has become a global environmental issue that impacts all sectors of life, including agriculture. This study aims to determine workers’ knowledge of climate change in Karang Anyar Village Hamlet VII A Beringin Sub-district and workers’ anticipation strategies in reducing the adverse effects of climate change. This study used a qualitative approach. Informants were selected based on the criteria of wet-rice workers who have been farming for ten years by implementing semi-organic farming. Data were collected through interview techniques and literature study. Data analysis was conducted using the descriptive analysis method. The study results showed that workers know about climate change limited to seeing natural signs. Adverse impacts of climate change include a decrease in rice productivity. Workers anticipate reducing the adverse impacts of climate change by using rice varieties that are resistant to climate change, reducing the use of chemical insecticides and vegetable pesticides, and implementing a sustainable agricultural system.

The performance and physiological responses of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) to different sorghum cultivars

Utilizing pest-resistant cultivars is a highly effective and environmentally-friendly approach for managing crop infestations by pests. In the present study, the differences in the resistance of eight cultivars of Sorghum bicolor (L.) Moench (Kimia, Payam, Pegah, Sepideh, Spidfid, KGS23, KFS2, and KFS18) against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), a polyphagous pest of stored products, were evaluated based on demographic parameters, nutritional indices, and digestive enzymatic activities within the pest. The results revealed that the development time of R. dominica was the shortest when reared on Kimia, Spidfid, and KFS2, while the longest was recorded in those fed on Payam and Pegah. The fecundity of R. dominica was the lowest on Pegah. Furthermore, Kimia and Sepideh showed the highest intrinsic rate of increase (r) and finite rate of increase (λ), whereas the lowest values for these parameters were observed on Pegah and KGS23. The highest relative growth rate (RGR) of R. dominica was achieved on Sepideh, whereas the lowest RGR was observed on KGS23. The highest level of digestive proteolytic activity in R. dominica was observed on Sepideh, whereas the lowest level was found on KGS23. The amylolytic activity in R. dominica was the highest on Sepideh, and the lowest on Pegah and KGS23. The findings showed significant negative correlations between fecundity, intrinsic rate of increase, and amylolytic activity of the pest with the total phenolic content of the studied sorghum cultivars. Furthermore, the results obtained from cluster analysis revealed that Sepideh, Kimia, and KFS2 were the susceptible cultivars for population growth of R. dominica, while Payam, Pegah, and KGS23 were the partially resistant hosts for this pest. The pest-resistant sorghum cultivars identified in this study can potentially be utilized in combination with other pest control strategies for sustainable management of R. dominica, which may help reduce the excessive use of chemical insecticides.

Antenna-Biased Odorant Receptor PstrOR17 Mediates Attraction of Phyllotreta striolata to (S)-Cis-Verbenol and (-)-Verbenone.

Phyllotreta striolata, the striped flea beetle, is one of the most destructive pests in Brassicaceae plants worldwide. Given the drawbacks associated with long-term use of chemical insecticides, green strategies based on chemical ecology are an effective alternative for beetle control. However, the lack of information on beetle ecology has hindered the development of effective biocontrol strategies. In this report, we identified two odorants, (S)-cis-verbenol and (-)-verbenone, which displayed significant attraction for P. striolata (p < 0.05), indicating their great potential for P. striolata management. Using the Drosophila "empty neuron" system, an antenna-biased odorant receptor, PstrOR17, was identified as responsible for the detection of (-)-verbenone and (S)-cis-verbenol. Furthermore, the interactions between PstrOR17 and (-)-verbenone or (S)-cis-verbenol were predicted via modeling and molecular docking. Finally, we used RNAi to confirm that PstrOR17 is essential for the detection of (-)-verbenone and (S)-cis-verbenol to elicit an attraction effect. Our results not only lay a foundation for the development of new and effective nonchemical insecticide strategies based on (S)-cis-verbenol and (-)-verbenone, but also provide new insight into the molecular basis of odorant recognition in P. striolata.

Laboratory evaluation of a bio-insecticide candidate from tangerine peel extracts against Trialeurodes vaporariorum (Homoptera: Aleyrodidae).

The excessive use of synthetic insecticides in modern agriculture has led to environmental contamination and the development of insect resistance. Also, the prolonged use of chemical insecticides in producing flowers and tomatoes in greenhouses has caused health problems for workers and their offspring. In this study, we analyzed the efficacy of mandarin peel (Citrus reticulata L.) essential oil (EO) as a natural insecticide against greenhouse whitefly (Trieurodes vaporariorum W., Homoptera: Aleyrodidae), a common pest in greenhouse production of different crops. Petroleum ether (PET) and n-hexane (HEX) were used as solvents to extract essential oil (EO) from tangerine peels. The yield of EO was 1.59% and 2.00% (m/m) for PET and HEX, respectively. Additionally, the insect-killing power of EO was tested by checking how many greenhouse whiteflies died at different times. The results showed that PET and HEX extracts of tangerine EO effectively controlled greenhouse whiteflies. Furthermore, with both solvents, a 12.5% (v/v) application was as practical as the commercial insecticide imidacloprid. Further characterization tests with the polarimeter, FTIR, HPLC-RP, and GC-MS showed that the essential oil (EO) contained about 41% (v/v) of d-limonene and that this compound may be responsible for the observed insecticidal properties. Therefore, tangerine peel essential oil is an excellent botanical insecticide candidate for controlling greenhouse whiteflies.

Biocontrol potential of entomopathogenic nematodes against the grey maize weevil Tanymecus dilaticollis (Coleoptera: Curculionidae) adults.

The grey maize weevil, Tanymecus dilaticollis, is a polyphagous species, which is among the most important pests of maize in Southeastern Europe. The efficacy of commercial products with two species of entomopathogenic nematodes (EPNs), Steinernema carpocapsae and Heterorhabditis bacteriophora, was investigated against adults of the grey maize weevil under laboratory conditions. Nemastar®, containing S. carpocapsae was more effective on T. dilaticollis adults than Nematop® containing H. bacteriophora, when applied uniformly to the surface of the soil, on Petri dishes containing T. dilaticollis adults. Results showed that S. carpocapsae rates of 83-333 infective juveniles/adult caused > 94% mortality in T. dilaticollis adults, whereas H. bacteriophora caused 27-61%, adult mortality, after exposure of insects to the commercial products of EPNs for 15days. The infection rates of EPNs increased with concentration applied and ranged from 70-83% and 19-64% for Nemastar® and Nematop®, respectively. Subsequent field and semi-field tests were conducted with Nemastar® (application rate of 50 million S. carpocapsae per 100m2) in maize crops with biological (mycoinsecticide Naturalis®, biofungicides and fertilizers) and chemical seed treatment (Gaucho® FS 600; active ingredient: imidacloprid) in Knezha, Bulgaria. Nematodes were found only in the dead specimens, in open plots and cages sprayed with the commercial nematode product. Nematode sprayings contributed for higher maize yields in the open maize plots in the fields with different seed treatments. We suggest that the use of powder formulation of S. carpocapsae in combination with biologically treated maize seeds can contribute to minimize the use of chemical insecticides against the grey maize weevil. The results obtained can be used as a base to further tests to ascertain the efficacy of EPNs products before they can be recommended for use in the integrated approach to T. dilaticollis management.

Effectiveness of Citronella and Basil Essential Oil Spray as Repellents against Aedes aegypti Mosquitoes

Background: In 2023, Dengue Fever cases in Indonesia reached 35,694 cases from January to May. Dengue Fever is caused by the bite of Aedes aegypti mosquitoes. Mosquito control efforts have been widely conducted, including the use of chemical insecticides. The use of chemical insecticides can lead to environmental contamination and cause skin irritation. An alternative approach that can be taken is to use natural insecticides. One of the natural insecticides that can be used as a repellent is citronella and basil essential oils. Citronella and basil essential oils contain geraniol and citronellal, which can cause mortality in mosquitoes. This study intends to evaluate the effectiveness of a spray mixture of basil leaves and citronella essential oil as a mosquito repellent. Materials and Methods: Aedes aegypti mosquitoes, basil leaf essential oil, citronella essential oil, propylene glycol, glycerin, butylated hydroxytoluena and etanol 96% v/v. Subsequently, an evaluation of physical properties was conducted, including organoleptic testing, pH, and viscosity evaluation, as well as irritation and repellent activity test. Results: The spray formulations in the control and F1 are clear in color, while F2 and F3 are clear with a slightly yellowish hue. The scent produced has the characteristic smell of citronella. The pH and viscosity tests resulted in pH values consistent with the skin's pH range of 4.5-7 and viscosity within the range of 1-1000 Cp. The spray formulation did not irritate after 48 hours of observation. The results of the effectiveness test indicate that F2 can protect against mosquito bites for 1 hour, while F3 can protect for 3 hours. Conclusion: Citronella essential oil and basil leaves are effective as a repellent for the Aedes aegypti mosquito for 3 hours of use in concentration 15%.

Defense Responses of Different Rice Varieties Affect Growth Performance and Food Utilization of Cnaphalocrocis medinalis Larvae

Rice leaf folder, Cnaphalocrocis medinalis (Guenée), is one of the most serious pests on rice. At present, chemical control is the main method for controlling this pest. However, the indiscriminate use of chemical insecticides has non-target effects and may cause environmental pollution. Besides, leaf curling behavior by C. medinalis may indirectly reduce the efficacy of chemical spray. Therefore, it is crucial to cultivate efficient rice varieties resistant to this pest. Previous studies have found that three different rice varieties, Zhongzao39 (ZZ39), Xiushui134 (XS134), and Yongyou1540 (YY1540), had varying degrees of infestation by C. medinalis. However, it is currently unclear whether the reason for this difference is related to the difference in defense ability of the three rice varieties against the infestation of C. medinalis. To explore this issue, the current study investigated the effects of three rice varieties on the growth performance and food utilization capability of the 4th instar C. medinalis. Further, it elucidated the differences in defense responses among different rice varieties based on the differences in leaf physiological and biochemical indicators and their impact on population occurrence. The results showed that the larval survival rate was the lowest, and the development period was significantly prolonged after feeding on YY1540. This was not related to the differences in leaf wax, pigments, and nutritional components among the three rice varieties nor to the feeding preferences of the larvae. The rate of superoxide anion production, hydrogen peroxide content, and the activity of three protective enzymes were negatively correlated with larval survival rate, and they all showed the highest in YY1540 leaves. Compared to other tested varieties, although the larvae feeding on YY1540 had higher conversion efficiency of ingested food and lower relative consumption rate, their relative growth was faster, indicating stronger food utilization capability. However, they had a lower accumulation of protein. This suggests that different rice varieties had different levels of oxidative stress after infestation by C. medinalis. The defense response of YY1540 was more intense, which was not conducive to the development of the larvae population. These results will provide new insights into the interaction mechanism between different rice varieties and C. medinalis and provide a theoretical basis for cultivating rice varieties resistant to this pest.

Efficacy of plant products in controlling disease vector mosquitoes, a review

AbstractMosquitoes pose a severe threat to the environment as vectors of numerous harmful diseases affecting humans and animals. Mosquitoes transmit pathogens that cause dengue, chikungunya, malaria, zika, yellow fever, Japanese encephalitis, and filariasis. Today's mosquito control strategies heavily rely on the use of chemical insecticides such as N,N‐diethyl‐meta‐toluamide (DEET), N,N‐diethyl mandelic acid amide (DEM), and dimethyl phthalate (DMP). However, the widespread use of chemical insecticides has resulted in pollution, bio‐magnification, and other health and environmental issues. It has also become ineffective because of the mosquitoes' aptitude to develop resistance, emphasizing the urgent need for safe, effective, and long‐lasting strategies. An alternative and promising approach to circumventing these obstacles involves the implementation of insecticides made from natural compounds found in plants. Therefore, the scientific community has shifted its focus towards plant‐based phytochemicals, oils, and extracts, as these are eco‐friendly, safe, and cost‐effective alternatives to conventional chemical insecticides. This review aims to provide details on current advances in plant‐based products (plant compounds, extracts, and essential oils), which are used to control all the life cycle stages (egg, larva, pupa, and adult) of the mosquito genera Aedes, Anopheles, and Culex. Hopefully, this review will pave the way to devise control strategies against these challenging pests.

Diverse Approaches to Insect Control: Utilizing Brassica carinata (A.) Braun and Camelina sativa (L.) Crantz Oil as Modern Bioinsecticides

The forest environment is exposed to a number of harmful factors that significantly reduce the resistance of forest stands, often leading to their extinction. In addition to abiotic and anthropogenic factors, biotic factors pose a significant threat to forests, among which insect pests are at the top of the list. Until now, the use of chemical insecticides has been considered the most effective method of pest control, resulting in pesticide residue in the environment. In an effort to minimize the harmful effects of insecticides, the European Union (EU), through EU Commission Implementing Regulations 2022/94, 2021/2081, 2021/795, and 2020/1643, has decided to withdraw from use a number of preparations containing compounds such as phosmet, indoxacarb, alpha-cypermethrin, and imidacloprid, among others. Botanical insecticides appear to be a promising alternative. Among them, plant oils and essential oils have become an innovative solution for controlling pests not only of forests but also of agricultural crops. The purpose of this literature review was to select oilseed plants with great biological potential. The rich chemical compositions of the seeds of Brassica carinata (A.) Braun and Camelina sativa (L.) Cranz predispose them to use as raw materials for the production of biopesticides with broad mechanisms of action. On the one hand, the oil will provide a physical action of covering pests feeding on a plant with a thin film, which will consequently lead to a reduction in gas exchange processes. On the other hand, the bioactive compounds in it or extracts of fat-insoluble compounds suspended in it and derived from the pomace fraction may have deterrent or lethal effects. This paper presents evidence of the potential action of these raw materials. Preparations based on these oils will not pose a threat to living beings and will not negatively affect the environment, thus allowing them to gain social acceptance.

A shot in the foot: Could chemical control of malaria vectors threaten food security?

Overwhelmingly, contemporary malaria vector control equals the use of chemical pesticides (through insecticide-treated bednets or indoor residual spraying). Gradually, but surely, we have become enslaved to thinking that controlling malaria mosquitoes equals the use of chemical insecticides, and much of the vector control field today is dominated by scientists, lobbyists, chemical companies, funding agencies and (global) institutions that endlessly repeat this dogmatic belief. Although chemical control has undoubtedly saved millions of lives, which, morally speaking would immediately justify its continued use, it has many sides that may ultimately cost more lives than it saves. Not only the cyclical problems with insecticide resistance, but also our increased understanding of the human and environmental health impacts of these chemicals, continue to raise red flags. Furthermore, the millions of kilogrammes of annual bednet waste (polyethylene, polypropylene) and bednet packaging material cannot be ignored. In recent years, an abundance of evidence that the use of chemical pesticides is a prime cause for the global decline in insect biodiversity and abundance has surfaced. The rate at which this decline is happening is frightening and may sooner rather than later threaten food production on a global scale. Should we opt for saving lives in the short term by using chemicals and face devastating and irrevocable long-term consequences or become wise(r) in the way we control malaria mosquitoes?