Broad-spectrum Pesticide Research Articles

Identification, isolation, characterization, and synthesis of impurities of pesticide spirotetramat

Research work featured in this article describes the impurity profile of spirotetramat, a widely used broad-spectrum pesticide targeting acetyl-CoA carboxylase. Technical grade spirotetramat from four different sources were analyzed and compared with commercial Movento using UPLC-MS. Seven potential impurities were detected and six of them except for the trans-isomer of spirotetramat were subsequently isolated using preparative HPLC. All impurities were characterized mainly by MS and NMR spectroscopy and their structures were further confirmed by chemical synthesis. The formation of the impurities was described in this report as well.

Effects of pesticide application and plant sexual identity on leaf physiological traits and phyllosphere bacterial communities

AbstractPesticides are widely used to enhance food production on a global scale. However, little information is available on the effects of pesticide application on leaf physiology and phyllosphere bacterial communities of dioecious plants. Therefore, this study aimed to assess the impact of λ-cyhalothrin, a broad-spectrum pesticide, on leaf physiology and phyllosphere bacterial communities in the dioecious Populus cathayana. Physiological leaf traits such as photosynthetic apparatus (net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration (E)) of males were significantly higher than those of females, independent of pesticide use. In contrast, pesticide application significantly reduced the photosynthetic apparatus for both sexes, and the reduction was greater in males relative to females. Also, pesticide application significantly increased peroxidase (POD) activity and malondialdehyde (MDA) content and maintained superoxide dismutase (SOD) activity and total chlorophyll content in leaves of males. The phyllosphere bacteria showed some conserved characteristics, in which, Simpson and Shannon diversity indices were not affected by sex or pesticide application. Phyllosphere bacterial community composition differed between females and males, indicating that intrinsic sex significantly shapes the phyllosphere bacterial community. However, pesticide application significantly increased the relative abundance of Actinobacteria but reduced the relative abundance of Proteobacteria. Principal component analysis showed associations between leaf physiology and specific bacterial taxa. For instance, Proteobacteria negatively correlated with leaf SOD activity and MDA content, while Actinobacteria showed an opposite pattern. Our study highlights sex-specific phyllosphere bacterial community composition and leaf physiological traits in dioecious plants.

Histopathological Alterations in Liver and Kidney Tissues of Banded Gourami (Trichogaster fasciata) Exposed to Thiamethoxam

Thiamethoxam is a broad-spectrum pesticide used in Bangladesh to protect crops from pests. In several ways, this pesticide ends up in aquatic ecosystems. Researchers have detected its existence in waterbodies. However, the harmful effects on non-target aquatic residents are not well studied and reported. As a result, the study sought to investigate the effect of thiamethoxam on the liver and kidney tissues of banded gourami (Trichogaster fasciata) using histopathological observations. Fish were exposed to five sub-lethal concentrations (in triplicates) of thiamethoxam (9.37, 18.75, 37.5, 75, and 150 mg/L) and 0 mg/L (control) for 90 days. Fish livers and kidneys were sampled on days 30, 60, and 90 of thiamethoxam exposure. The histopathological changes observed in thiamethoxam exposed fish were autolysis, acute cellular swelling, vacuolation, necrosis, and fatty change in the liver, whereas irregular renal corpuscle and cellular degradation of tissue were also observed in the kidney. The present study reveals that thiamethoxam can affect the livers and kidneys of Banded Gourami; therefore, the usage of this insecticide in agriculture should be applied carefully and monitored to avoid entry into water bodies.

Biotechnological Approaches for Host Plant Resistance to Insect Pests.

Annually, the cost of insect pest control in agriculture crosses billions of dollars around the world. Until recently, broad-spectrum synthetic pesticides were considered as the most effective means of pest control in agriculture. However, over the years, the overreliance on pesticides has caused adverse effects on beneficial insects, human health and the environment, and has led to the development of pesticide resistant insects. There is a critical need for the development of alternative pest management strategies aiming for minimum use of pesticides and conservation of natural enemies for maintaining the ecological balance of the environment. Host plant resistance plays a vital role in integrated pest management but the development of insect-resistant varieties through conventional ways of host plant resistance takes time, and is challenging as it involves many quantitative traits positioned at various loci. Biotechnological approaches such as gene editing, gene transformation, marker-assisted selection etc. in this direction have recently opened up a new era of insect control options. These could contribute towards about exploring a much wider array of novel insecticidal genes that would otherwise be beyond the scope of conventional breeding. Biotechnological interventions can alter the gene expression level and pattern as well as the development of transgenic varieties with insecticidal genes and can improve pest management by providing access to novel molecules. This review will discuss the emerging biotechnological tools available to develop insect-resistant engineered crop genotypes with a better ability to resist the attack of insect pests.

The Antimicrobial Potential of the Neem Tree Azadirachta indica

Azadirachta indica (A. Juss), also known as the neem tree, has been used for millennia as a traditional remedy for a multitude of human ailments. Also recognized around the world as a broad-spectrum pesticide and fertilizer, neem has applications in agriculture and beyond. Currently, the extensive antimicrobial activities of A. indica are being explored through research in the fields of dentistry, food safety, bacteriology, mycology, virology, and parasitology. Herein, some of the most recent studies that demonstrate the potential of neem as a previously untapped source of novel therapeutics are summarized as they relate to the aforementioned research topics. Additionally, the capacity of neem extracts and compounds to act against drug-resistant and biofilm-forming organisms, both of which represent large groups of pathogens for which there are limited treatment options, are highlighted. Updated information on the phytochemistry and safety of neem-derived products are discussed as well. Although there is a growing body of exciting evidence that supports the use of A. indica as an antimicrobial, additional studies are clearly needed to determine the specific mechanisms of action, clinical efficacy, and in vivo safety of neem as a treatment for human pathogens of interest. Moreover, the various ongoing studies and the diverse properties of neem discussed herein may serve as a guide for the discovery of new antimicrobials that may exist in other herbal panaceas across the globe.

Agrochemical bioaccumulation in pitaya cacti (Stenocereus queretaroensis) and its effect on bat interaction and yield

Abstract Bats are among the most valuable pollinators of economically important crops in Mexico including agaves and columnar cacti. High demand for the agricultural products of these crops has resulted in increasing use of agrochemicals, including pesticides and fertilizers, to increase yield and decrease pest damage. However, these compounds can negatively affect crop mutualists such as pollinating bats. In this study, we investigated: (i) how the application of the broad-spectrum pesticide carbamate and/or synthetic fertilizers affect crop yield of the pitaya cacti (Stenocereus queretaroensis); (ii) whether carbamate bioaccumulates in pitaya nectar and fruits; and (iii) whether the application of these agrochemicals affects visitation rates of the pitaya’s most efficient pollinators, nectarivorous bats of the genus Leptonycteris. We designed an experiment consisting of four treatments (pesticide, nutrients, both, or neither) applied to pitaya plants. We estimated the effect of each treatment by quantifying pitaya reproductive structures (flower buds and flowers) and fruit yield and quality, performed trace analysis to detect the pesticide in the nectar and fruits, and estimated bat flower visitation rates using camera traps to determine whether the addition of agrochemicals influenced pitaya–bat interactions. We found that none of the treatments increased yield or fruit sweetness, and they did not affect bat visitation rates. Fruit pulp and floral nectar contained pesticide concentrations above those permitted by international environmental agencies. Thus, our results show that adding these agrochemicals to pitaya crops does not improve yield but could negatively affect their crop pollinators, especially since bats apparently do not avoid visiting flowers containing pesticide residues.

Selenium Heals the Chlorpyrifos-Induced Oxidative Damage and Antioxidant Enzyme Levels in the Rat Tissues.

Chlorpyrifos (CPF), mainly exposed by oral, dermal, or inhalation, is a broad-spectrum organophosphate pesticide used in pest control, increasing agricultural productivity, and being considered toxic to living things. Selenium (Se), an essential component of selenoenzymes and selenoproteins, is an essential element that protects cells from oxidative stress and has antioxidant properties. The study aimed to examine the oxidative stress caused by different doses of CPF exposure in brain, liver, and kidney tissues while observing the healing effect of Se application on tissue damage and antioxidant levels. A total of 56 rats were divided into seven different groups: 1st group control (water); 2nd group sham (corn oil); the 3rd group was CPF-L (5.4mg/kg CPF); the 4th group was CPF-H (13.5mg/kg CPF); the 5th group was Se (3mg/kg Se); 6th group was CPF-L + Se (5.4mg/kg CPF + 3mg/kg Se); the 7th group was CPF-H + Se (13.5mg/kg CPF + 3mg/kg Se). The brain, liver, and kidney tissues were obtained from rats sacrificed 6weeks later. Acetylcholinesterase (AChE), oxidant, and antioxidant parameters were examined in the tissues. The results suggest that CPF causes neurotoxicity, hepatotoxicity, and renal toxicity by altering AChE levels, inducing lipid peroxidation, and decreasing antioxidant systems. Se treatment increased the activities of AChE and, antioxidant defense system and reduced the malondialdehyde (MDA) levels in the brain, liver, and kidney tissues of rats. Se was found to heal and also protect these tissues against these changes resulting from CPF exposure.

Correlation of use of pesticides with incidence of cervical erosion in women of reproductive age in Republic of Dagestan

This paper presents practical and literary material. The literary material is compiled from data from various urban and territorial medical and preventive organizations of the Ministry of Health of the Republic of Dagestan. The practical material was a survey of 200 women who were assessed for quality of life, endotoxicosis, lipoperioxidation processes, and the functional state of the blood hemostasis system. It has been established that a large number of heterogeneous and broad-spectrum pesticides, such as organochlorine, copper-containing, organomercury, etc., are used in different territories of the Republic of Dagestan. Despite the fact that the pesticide load is decreasing in the Republic of Dagestan, the level of drugs used remained above the norm by 4–8 times (p = 0.01). This is due to several factors: the shelf life of most pesticides is expired; productive companies will convert expired ones into new products; the period of pesticide treatment is not evaluated by specialists, but, by eye, which is not determined by experts, which leads to a decrease in the biological impact of these substances, and an increase in their consumption. It has been established that the pesticide load of ecological zones spreads in different ways across the territory of Dagestan. At the same time, the ability of self-purification is recorded to a large extent in the mountainous regions and less in the flat and foothill areas. However, the residual concentration of pesticides in food in these areas remains at a high level. It was revealed that the incidence of cervical erosion has a significant tendency to increase under the influence of toxic chemicals, to a lesser extent with a separate type of application, and to the greatest extent with combined and total. It was found that women living in an area with increased use of pesticides had a decrease in physical and emotional activity, chronic endogenous intoxication, activation of lipoperioxidation processes, hypercoagulation of the blood hemostasis system.

Population ecology and economic thresholds-based time series for climate smart pest management of Spilosoma obliqua Walker (Lepidoptera: Arctiidae) on three sesame cultivars

BackgroundSesame (Sesamum indicum L.) is a widely used oil seed crop throughout the world but its productivity is extremely low due to use of low yielding cultivars as well as biotic stress for the major pest Spilosoma obliqua Walker. But even today, farmers generally use broad-spectrum synthetic pesticides for their management injudiciously without considering any economic threshold (ET) limit and creates ecosystem crisis. So, time-based ecologically sustainable management of the said pest and selection of a superior cultivar of sesame was studied by stage-specific two-sex pooled life table and nutritional ecology of S. obliqua on three sesame cultivars (Rama, Shubhra and Amrit) along with their economic thresholds (ETs) in 2019.ResultsThe nutritional ecology and population dynamics of S. obliqua were significantly affected by the host phytoconstituents in terms of host suitability or susceptibility (Rama > Shubhra > Amrit). The mean EIL and ETL for S obliqua was 36.316 ± 3.911 and 33.243 ± 2.734 pests/m2, respectively on cv. Rama that were significantly (F2,6 = 5.421–5.435; P ≤ 0.042) lower than Shubhra and Amrit. For a single pest per m2 (30 ± 2 plants/m2) the possible time that can be taken to reach EIL (Ti) and ETL (Tt) were 39.132 ± 3.969 and 38.132 ± 3.969 days, respectively on cv. Rama which were also significantly (F2,6 = 26.551; P = 0.001) lower than the other cultivars. The seed yield and benefit cost ratio (BCR) were 857.099 ± 0.000 (Kg/ha) and 0.607 ± 0.000, respectively for cv. Rama that were significantly (P < 0.05) lower than the others.ConclusionsIt will enable growers to find the most preferred cultivar (Rama > Shubhra > Amrit) based on BCR values irrespective of their biotic resistance (Rama < Shubhra < Amrit) due to host antibiosis. Even, the ETs-based time series for judicious management of the pest along with carbon sequestration efficiency (CSE) will also support superiority of the cultivars (Rama > Shubhra > Amrit) towards climate smart pest management (CSPM) of sesame and or other such crops in near future.

Nectar Water - A Bio-Pesticide

Crop protection has depended significantly on synthetic chemical pesticides for the last 60 years. Inadequate use of broad-spectrum chemical pesticides to improve agricultural productivity has resulted in a number of negative consequences, including the development of resistance in target pests, the killing of beneficial organisms, the presence of harmful residues in food, feed, and fodder, and a hazardous impact on human health. The growing public awareness about the possible negative effects of synthetic agrochemicals encourages a quest for technology and products that are less harmful to the environment. As a result, different eco-friendly pest management strategies are required. Pest management agents based on live microorganisms or natural items are known as bio-pesticides. They have demonstrated pest management capability and are utilised all around the world. Bio-pesticides are formulations derived from naturally occurring compounds that control pests through non-toxic and environmentally acceptable techniques. The use of bio-pesticides has the potential to significantly assist agricultural and public health initiatives.

Phytochemical and Synergism of Plant and Microbial Insecticides to Eliminate Earias Vittella Gut Epithelial Cells

The spotted bollwom, Earias vittella is a very serious and polyphagous pest that attacks many plants of Malvaceae family. Such as Lady’s finger (Abelmoschus esculentus Moench), which attacks growing points of the plant. The intensive use of highly toxic and broad-spectrum pesticides threatens the sustainability of vegetable production, mainly due to the development of pest resistance. Consequently, it becomes more difficult to manage key pests and secondary pests, which assume major status due to the elimination of natural enemies from the eco system. In the present study, evaluation of the larvicidal, quantitative food utilization and histological activity of Manihot esculenta, Azadirachtin (AZA), Bacillus thuringiensis var. kurstaki (Btk), and synergistic effects, was carried out against Earias vittella. The GC-MS analysis of M. esculenta was estimated and seventeen different phytoactive compounds were identified. Larvicidal activity of M. esculenta, AZA, and Btk provided significant mortality against E. vittella. The lowest LC50 of individual treatment was from AZA, the LC50 being as follows: 0.122%, 0.131%, 0.150%, 0.157%, and 0.168%, and the LC50 of synergistic treatment was 1.434ppm, 1.469ppm, 1.531ppm, 1.701ppm, and 1.908ppm for I, II, III, IV, and V instars, respectively. The food utilization result showed that, the food intake of E. vittella was significantly reduced after the treatment. Here, synergistic effects controls the food intake, which is highly reduced, and fecal pallet egestion considerably reduces the amount of food consumed. Histological studies state that, after the treatment, the gut of E. vittella is drastically damaged by the biopesticides. M. esculenta, AZA and Btk and their synergism are very effective against the immature stage of E. vittella. Gut region of the insect finely eradicated by the biopesticide. Overall, this study concludes that the taken botanical insecticides are ecofriendly, harmless to mammals and other non-target animals.

Isolation, Identification, and Biocontrol Potential of Entomopathogenic Nematodes and Associated Bacteria against Virachola livia (Lepidoptera: Lycaenidae) and Ectomyelois ceratoniae (Lepidoptera: Pyralidae).

Simple SummaryFor sustainable agriculture, there is a need to identify and evaluate more biocontrol agents, including entomopathogenic nematodes (EPNs). In this study, EPNs and their associated entomopathogenic bacteria symbionts (EPBs) were isolated and identified from 320 soil samples collected in Taif, Saudi Arabia. The biocontrol efficacy of EPNs and EPBs was also evaluated against third instar larvae of the pomegranate butterfly, Virachola livia, and the carob moth, Ectomyelois ceratoniae, two important insect pests of pomegranate, under laboratory conditions. Our results show that the EPNs Steinernema spp. were more virulent than Heterorhabditis spp. against the two pomegranate insects. In addition, the EPB Stenotrophomonas maltophilia CQ1, isolated from Steinernema spp., surpassed Pseudomonas mosselii SJ10, associated with Heterorhabditis spp., in their ability to kill V. livia or E. ceratoniae larvae. We conclude that either application of EPNs’ infective juveniles (IJs) or their associated EPBs could serve as potential biocontrol agents for V. livia and E. ceratoniae.Virachola livia (Lepidoptera: Lycaenidae) and Ectomyelois ceratoniae (Lepidoptera: Pyralidae) are the key pests of pomegranates in Saudi Arabia that are managed mainly using broad-spectrum pesticides. Interactions between the entomopathogenic nematodes (EPNs) Steinernematids, and Heterorhabditids, and their entomopathogenic bacterial symbionts (EPBs) have long been considered monoxenic 2-partner associations responsible for killing insects and, therefore, are widely used in insect pest biocontrol. However, there are limited reports identifying such organisms in Taif, Saudi Arabia. The current study aimed to identify the EPNs and their associated bacteria isolated from Taif, Saudi Arabia, and evaluate their biocontrol potential on third instar larvae of V. livia and E. ceratoniae under laboratory conditions. A total of 35 EPN isolates belonging to Steinernema (20) and Heterorhabditis (15) were recovered from 320 soil samples. Twenty-six isolates of symbiotic or associated bacteria were isolated from EPNs and molecularly identified as Xenorhabdus (6 isolates), Photorhabdus (4 isolates), Pseudomonas (7), or Stenotrophomonas (9). A pathogenicity assay revealed that Steinernema spp. were more virulent than Heterorhabditis spp. against the two pomegranate insects, with LC50 values of 18.5 and 13.6 infective juveniles (IJs)/larva of V. livia for Steinernema spp. and 52 and 32.4 IJs/larva of V. livia for Heterorhabditis spp. at 48 and 72 h post-treatment, respectively. Moreover, LC50 values of 9 and 6.6 IJs/larva (Steinernema spp.) and 34.4 and 26.6 IJs/larva (Heterorhabditis spp.) were recorded for E. ceratoniae larvae at 48 and 72 h post-treatment. In addition, the EPB Stenotrophomonas maltophilia CQ1, isolated from Steinernema spp., surpassed Pseudomonas mosselii SJ10, associated with Heterorhabditis spp., in their ability to kill V. livia or E. ceratoniae larvae within 6 h post-application, resulting in 100% mortality in both insects after 24 and 48 h of exposure. We conclude that either application of EPNs’ IJs or their associated EPBs could serve as potential biocontrol agents for V. livia and E. ceratoniae.

Advancement of Agricultural Technology in Farming of India

Background: Agricultural technology is an innovated, invented and discovered material that assists people and the country for improving production and productivity. Conventional agricultural technologies were practiced in the country in sustainable agriculture. A large number of inventions from several research and development projects were evolved and discovered that help in boosting transformation of sustainable agriculture into modern agriculture. Methods: The agriculture technology is currently utilized in the dairy farming, poultry farming and organic farming. The working principles of agriculture technology were glanced from the dairy farming, poultry farming and organic farming and collected from the Andhra Pradesh, Karnataka, Maharashtra, Punjab and Gujarat. Result: The control of fly, milking parlours, calf care, young stock housing, hygiene, milk testing technologies etc are currently utilized into the dairy farming in rural India. The robots carries out ding dirty work, flock protection using drones and use of sensors for monitoring and management are applied in the poultry animals. The Information and Communication Technology (ICT) contributes at production and management in dairy farming and poultry farming. It imposes crop development and management and sprays adequate organic chemicals in the crop field. The effective and less expensive technologies like neem based preparations, concentrated organic manure, organic formulations for seed treatment and plant protection, broad-spectrum botanical pesticides and many more have been developed that promote organic agriculture.

Cholinesterase activity as a potential biomarker for neurotoxicity induced by pesticides in vivo exposed Oreochromis niloticus (Nile tilapia): assessment tool for organophosphates and synthetic pyrethroids

ABSTRACT Organophosphates (OPs) and synthetic pyrethroids (SPs) are the most popular broad spectrum pesticides, used in agriculture as they have a strong pesticidal activity while also being biodegradable in the environment. The present study aimed to demonstrate the effects of these pesticides on the Acetylcholinesterase (AChE) activity in brain, gills and body muscles of Oreochromis niloticus – an important enzyme for the assessment and biomonitoring pollution caused by neurotoxins in the environment. The fish were exposed for 24 and 48 h to the LC0 concentrations of the malathion (1.425 mg/L), the chlorpyrifos (0.125 mg/L) and the λ-cyhalothrin (0.0039 mg/L), respectively. The activity of the AChE was significantly increased (p < 0.05) at 24 h and decreased at 48 h (except for the chlorpyrifos-treated brain and gills while tissues had shown no activity at 48 h’s exposure) in all pesticides-treated tissues. The maximum increase in the activity and inhibition in the AChE activity were recorded as +92% and −52% in the chlorpyrifos and the lambda-cyhalothrin exposed brain tissues, respectively. Thus, the alterations in the AChE activities indicated that the applied pesticides are highly neurotoxic to fish and the enzyme (AChE) could be used as a useful biomarker for estimation of water pollution.

Presence of pesticide residues in cannabis products

The literature addressing the cannabis use for medical purposes provides scientific evidence that both cannabis and cannabinoids have potential therapeutic effects. The Cannabis plant has gained substantial attention in recent years due to the growing number of countries that legalize cannabis for medicinal and recreational use. Smoking is the most common method of administering cannabis. Broad-spectrum pesticides are widely used in plant crops to control insects, weeds, and other pests. This prevention strategy is also used on Cannabis plants, currently cultivated in significant areas to produce food supplements and pharmaceuticals. Pesticides used in Cannabis crops can be insecticides, acaricides and fungicides that can accumulate in the environment and can be found in the final product, thus reaching the human body. The use of pesticides in Cannabis plants is not regulated in most countries. In countries where Cannabis use is legalized, either for medical or recreational use, there are not always guidelines for pesticide use, so sample analysis is not a priority. When the maximum permitted limits are exceeded, these substances may cause undesirable potential dangerous effects. We cannot ignore the idea that standardized testing should be considered mandatory in countries where consumption is already legal, which will help also other countries that are in the process of legalization.

Evaluation of the Effect of Fungatol and Gamma-T-ol on the Emergence and Adult Parasitoid Survival of Mummies of Cotton Aphids Parasitized by Aphidius colemani.

Simple SummaryBiological control can be used as an alternative control measure to reduce pesticide resistance. Unfortunately, many biological control agents, such as natural enemies of pests, are susceptible to a broad spectrum of pesticides. This creates a potential problem when these two components are utilized together. Therefore, it is necessary to find alternatives that are not harmful to natural enemies but also have the potential to replace synthetic pesticides. Essential oils (EOs) are widely used in crop protection and organic agriculture. The EO formulations evaluated in this study are new botanical pesticides that play an important role in agriculture. EOs are available as an alternative to synthetic pesticides. Two blends (Fungatol and Gamma-T-ol) are mostly composed of Alpha Tops, and Gamma Tops were assessed for their effects on the aphid parasitoid Aphidius colemani in laboratory and glasshouse trials. According to the International Organization for Biological Control (IOBC) classification, they were found to be safe or only slightly toxic, making them potential candidates for introduction into an integrated pest control program for aphids.Beneficial insects play a major role in controlling pest populations. In sustainable agricultural production systems, control methods compatible with integrated pest management (IPM) are preferred over broad-spectrum pesticides. EOs from aromatic plants may provide a new and safe alternative to synthetic chemicals. In this research, the efficacy of Fungatol, Gamma-T-ol, Fungatol plus neem, and Gamma-T-ol plus neem was evaluated against Aphidius colemani Viereck (Hymenoptera: Braconidae; Aphidiidae), the parasitoid of the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae). Under laboratory and greenhouse conditions, five different concentrations of each formulation were applied to parasitized mummies and adult parasitoids. Results for parasitoid emergence from aphid mummies sprayed with different concentrations of Fungatol, Gamma-T-ol, Fungatol plus neem, and Gamma-T-ol plus neem in the laboratory and glasshouse showed that the formulations did not adversely affect adult emergence as rates above 60% were observed. For residual toxicity tests done by exposing adult parasitoids to a fresh, dry biopesticide film sprayed on glass plates, less than 20% mortality was observed after 48 h of exposure. Adult longevity tests revealed that the highest concentrations of some of the formulations evaluated were slightly toxic to A. colemani. According to the IOBC rating, our results indicated that most of the tested concentrations for each formulation were harmless to A. colemani. Based on the above results, it may be proposed that the formulations evaluated in this study are potential botanical pesticide candidates for incorporation into an IPM program.

Control Potentials of Three Entomopathogenic Bacterial Isolates for the Carob Moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae) in Pomegranates

Ectomyelois ceratoniae (Lepidoptera: Pyralidae) is the primary pest of pomegranates in Saudi Arabia and is mostly controlled using broad-spectrum pesticides. Providing environmentally sound choices to limit reliance on chemical management is a major challenge in the control of E. ceratoniae and, as a consequence, in the protection of pomegranate crops from its invasion. Entomopathogenic bacteria (EPB) symbiotically associated with entomopathogenic nematodes (EPNs) are well-known biocontrol agents of soil-dwelling or aerial pests. The bacterium symbiont (EPB) is the real insect-killing biocontrol agent, while the nematode (EPN) serves as a vector. We wondered whether the EPB vector, which is extremely vulnerable to adverse environmental conditions, like drought, high temperatures, and repellent soil microorganisms, could be omitted. We intended to evaluate the biocontrol potential of directly applied EPB cells and cell-free culture media (CFCM) on the larval instar E. ceratoniae. Xenorhabdus budapestensis DSM 16342 (EMA), X. szentirmaii DSM 16338 (EMC), and Photorhabdus luminescens ssp. laumondi (TT01) strains were used. After three days of exposure, the cells of EMA, EMC, and TT01 strains resulted in 100%, 88%, and 79.3% larval mortality rates, respectively. The applied EMA CFCM resulted in 53.7% larval mortality, indicating the presences of (at least) one extremely strong component produced by EMA. We concluded that the direct application of either the EPB cells or the CFCM must be a prospective alternative biocontrol of E. ceratoniae, especially to protect the important fruit (pomegranate, Punica granatum) cultivars. Especially, newly identified local EPB isolates could be applied as bio-pesticides for integrated management practices or organic pomegranate production.

Insecticidal, Repellent and Antifeedant Activity of Essential Oils from Blepharocalyx cruckshanksii (Hook. & Arn.) Nied. Leaves and Pilgerodendron uviferum (D. Don) Florin Heartwood against Horn Flies, Haematobia irritans (Diptera: Muscidae).

Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC50 values for B. cruckchanksii essential oil of 3.58 µL L−1 air at 4 h, and for P. uviferum essential oil of 9.41 µL L−1 air and 1.02 µL L−1 air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.

Regioselective hydroxylation of carbendazim by mammalian cytochrome P450: A combined experimental and computational study

Carbendazim (CBZ), a broad-spectrum pesticide frequently detected in fruits and vegetables, could trigger potential toxic risks to mammals. To facilitate the assessment of health risks, this study aimed to characterize the cytochrome P450 (CYPs)-mediated metabolism profiles of CBZ by a combined experimental and computational study. Our results demonstrated that CYPs-mediated region-selective hydroxylation was a major metabolism pathway for CBZ in liver microsomes from various species including rat, mouse, minipig, dog, rabbit, guinea pig, monkey, cow and human, and the metabolite was biosynthesized and well-characterized as 6-OH-CBZ. CYP1A displayed a predominant role in the region-selective hydroxylation of CBZ that could attenuate its toxicity through converting it into a less toxic metabolite. Meanwhile, five other common pesticides including chlorpyrifos-methyl, prochloraz, chlorfenapyr, chlorpyrifos, and chlorothalonil could significantly inhibit the region-selective hydroxylation of CBZ, and consequently remarkably increased CBZ exposure in vivo. Furthermore, computational study clarified the important contribution of the key amino acid residues Ser122, and Asp313 in CYP1A1, as well as Asp320 in CYP1A2 to the hydroxylation of CBZ through hydrogen bonds. These results would provide some useful information for the metabolic profiles of CBZ by mammalian CYPs, and shed new insights into CYP1A-mediated metabolic detoxification of CBZ and its health risk assessment.

Chemical and biological studies of natural and synthetic products for the highly selective control of pest insect species.

Tanacetum cinerariifolium was known to produce pyrethrins, but the mechanism of pyrethrin biosynthesis was largely unclear. The author showed that the nonmevalonate and oxylipin pathways underlie biosynthesis of the acid and alcohol moieties, respectively, and a GDSL lipase joins the products of these pathways. A blend of the green leaf volatiles and (E)-β-farnesene mediates the induction of wounding responses to neighboring intact conspecies by enhancing pyrethrin biosynthesis. Plants fight against herbivores underground as well as aboveground, and, in soy pulps, some fungi produce compounds selectively modulating ion channels in insect nervous system. The author proposed that indirect defense of plants occurs where microorganisms produce defense substances in the rhizosphere. Broad-spectrum pesticides, including neonicotinoids, may affect nontarget organisms. The author discovered cofactors enabling functional expression of insect nicotinic acetylcholine receptors (nAChRs). This led to understanding the mechanism of insect nAChR-neonicotinoid interactions, thus paving new avenues for controlling crop pests and disease vectors.