Alternative Control Methods Research Articles

Management of Myzus persicae with leaves of Jatropha curcas and Ricinus communis in different vegetative stages

Although chemical insecticides are successfully used in agriculture, several problems may be related to their indiscriminate use. This has encouraged the development of alternative methods for pest insect control and societal pressure for pesticide-free products. The jatropha (J. curcas) and castor bean (Ricinus communis) are plants that have shown insecticidal potential. Thus, the objective of this work was to study the effects of leaves of R. communis and J. curcas of different ages on the cabbage aphid (Myzus persicae). Five solution concentrations and five leaf types were used. Each treatment consisted of ten individuals M. persicae, kept in Petri dishes (10.0 x 1.2 cm), about kale leaf discs. Each Petri dish was considered a repeat, totaling ten. An airbrush connected to a compressor calibrated at constant pressure and 5 mL of solution per repetition was used for direct application. The cabbage discs were immersed in the different treatments for five seconds and offered to aphids in the indirect application. For both tests, evaluations were performed 72 hours after application. Data were submitted to linear regression analysis and means test. There was an interaction between the application type, leaf type, and concentrations for both plants. We argue that at their different ages, jatropha and castor bean leaves have insecticidal potential in the management of M. persicae.

Chemistry and Bioactivities of Six Tunisian Eucalyptus Species.

The complex taxonomy of Eucalyptus genus, the renewed interest in natural compounds able to combat microbial strains, the overuse of synthetic pesticides, the consequent request for alternative control methods were the reasons for this research. The essential oils (Eos) of Eucalyptus bosistoana, Eucalyptus melliodora, Eucalyptus odorata, Eucalyptus paniculata, Eucalyptus salmonopholia, and Eucalyptus transcontinentalis were analyzed by GC/MS and their potential phytotoxic activity was evaluated against the germination and radicle elongation of Sinapis arvensis, Raphanus sativus and Lolium multiflorum. The antibiofilm activity was assayed against both Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Acinetobacter baumannii) bacteria. Monoterpenoids were the most representative constituents in all EOs and eucalyptol was the dominant component except in E. melliodora EO, in which p-cymene was the most abundant. In phytotoxic assays, the EOs from E. odorata and E. paniculata were the most active against germination and radical elongation of the tested seeds. Finally, the Eucalyptus EOs proved their capacity to effectively inhibit the adhesion process of all five pathogen strains, with percentages often reaching and exceeding 90%. These Eucalytpus EOs could have possible employments in the food, health and agricultural fields.

The Fight against Plant-Parasitic Nematodes: Current Status of Bacterial and Fungal Biocontrol Agents.

Plant-parasitic nematodes (PPNs) are among the most notorious and underrated threats to food security and plant health worldwide, compromising crop yields and causing billions of dollars of losses annually. Chemical control strategies rely heavily on synthetic chemical nematicides to reduce PPN population densities, but their use is being progressively restricted due to environmental and human health concerns, so alternative control methods are urgently needed. Here, we review the potential of bacterial and fungal agents to suppress the most important PPNs, namely Aphelenchoides besseyi, Bursaphelenchus xylophilus, Ditylenchus dipsaci, Globodera spp., Heterodera spp., Meloidogyne spp., Nacobbus aberrans, Pratylenchus spp., Radopholus similis, Rotylenchulus reniformis, and Xiphinema index.

Genetic parameters for resistance to gastrointestinal nematodes in sheep: a meta-analysis

Gastrointestinal nematodes (GINs) are damaging parasites of global sheep populations. The key weapons in fighting GINs have been anthelmintic drugs, but the emergence of drug-resistant parasites has meant that alternative control methods are needed. One of these alternatives is to breed for enhanced host resistance to GINs, and decades of research have estimated the genetic contribution to different measures of resistance to GINs and their genetic correlations with other desirable performance traits. It is clear that parasite resistance is a heritable trait that can be selected for. Despite this consensus, estimates of both heritability of resistance and genetic correlations with other traits vary widely between studies, and the reasons for this variation have not been examined. This study provides a comprehensive and quantitative meta-analysis of genetic parameters for resistance to GINs in sheep, including measures of worm burden (faecal egg counts, FECs), anti-parasite immunity (GIN-specific antibodies), and parasite-induced pathology (FAMACHA© scores). Analysis of 591 heritability estimates from 121 studies revealed a global heritability estimate for resistance to GINs of 0.25 (95% confidence interval (CI) = 0.22–0.27) that was stable across breeds, ages, geographical location and analytical methods. Meanwhile, analysis of 559 genetic correlations from 54 studies revealed that resistance to GINs overall has a positive genetic correlation of +0.10 (95% CI = 0.02–0.19) with performance traits, and that this was consistent across breeds, ages, sexes and analytical methods. Importantly, the direction of the genetic correlation varied with the resistance trait measured: while FECs and FAMACHA© scores were favourably correlated with performance traits, adaptive immune markers were unfavourably correlated, suggesting that selection for enhanced immune responses to GINs could reduce animal performance. Overall, the results suggest that breeding for resistance to GINs should continue to form part of integrated management programs to reduce the impact of parasites on health and performance, but that selection for enhanced immune responses should be avoided.

Effect of mechanical weeding on soil erosion and earthworm abundance in sugar beet (Beta vulgaris L.)

The use of herbicides for weed control in plant production is widely criticized because of their potential aquatic and terrestrial toxicity. However, the environmental risks of mechanical weed control as an alternative control method in row crops have not yet been studied in Europe. Field trials in Southern Lower Saxony were carried out over three years on five sugar beet fields to assess the effect of weeding by hoeing on earthworm abundance, runoff, and soil erosion. Treatments were hoeing (H), herbicide spraying (S) and combined hoeing-spraying (HS), tested in four replicates at each field. The abundance of adult and juvenile earthworms of anecic and endogeic groups was determined in autumn using formalin expulsion 4 months after the final weed control operation. Runoff and soil erosion in mechanically and chemically weeded plots were measured by means of rainfall simulation on 2-m2 subplots after weed control. The experiment was organized in completely randomized block design. The abundance of adult and juvenile earthworms of anecic and endogeic groups was not affected by the weed control treatment. Cumulative runoff and soil loss were significantly reduced by mechanical weed control by a factor of six and eight, respectively, but only if the soil was crusted before weed control. In the absence of a soil crust before weed control there was no difference in runoff and erosion between mechanical and chemical weed control. Measured runoff and soil loss were used to calculate the curve number (CN) and the soil loss ratio (SLR) which are the empirical parameters for the prediction of runoff and soil erosion with the Curve Number SCS method and the Revised Universal Soil Loss Equation, respectively. CN was significantly increased and SLR tended (p =0.08) to be increased if the soil was crusted before weed control. Mechanical weed control reduced CN and SLR in crusted soils but had no effect in non-crusted soils. Therefore, for correct runoff and soil erosion prediction the effect of crusting and mechanical weeding on CN and SLR must be considered. In conclusion, mechanical weeding was revealed to be particularly beneficial for crusted soil by simultaneously reducing toxicological and erosional risks.

A potential role of nitric oxide in postharvest pest control: A review

Novel methods of stored-product pest control are essential to greater success against a wide variety of pest species worldwide, especially in tropical regions. Modern methods such as ozonation and organic pesticides have ensured grain preservation without loss of quality and without the accumulation of residues; these properties are considered fundamental to food safety. Thereby, nitric oxide (NO) is a newly discovered fumigant that has shown the potential to control stored product pests. It has also been described as a substitute for phosphine and sulfuryl fluoride. In this regard, NO has the potential to become an alternative method of postharvest pest control, primarily due to its high pest mortality rate from a broader range of pests and products. However, research is needed to reduce the impact of NO on food quality due to the high reactive power of NO. Potentially toxic residues, such as the primary forms of NO oxidation, NO2− and NO3−, can accumulate in treated products and damage consumers' health. Further research is needed into the possible use of NO fumigation as an alternative practice in controlling stored grain pests.

SEAN 2.0: Formalizing and Generating Social Situations for Robot Navigation

We present SEAN 2.0, an open-source system designed to advance social navigation via the training and benchmarking of navigation policies in varied social contexts. A key limitation of current social navigation research is that policies are often trained and evaluated considering only a few social contexts, which are fragmented across prior work. Inspired by work in psychology, we describe navigation context based on social situations, which encompass the robot task and environmental factors, and propose logic-based classifiers for five common examples. SEAN 2.0 allows a robot to experience these social situations via different methods for specifying and generating pedestrian motion, including a novel Behavior Graph method. Our experiments show that when data collected using the Behavior Graph method is used to learn a robot navigation policy, that policy outperforms others trained using alternative methods for pedestrian control. Also, social situations were found to be useful for understanding performance across social contexts. Other components of SEAN 2.0 include vision and depth sensors, several physical environments, different means of specifying robot tasks, and a range of evaluation metrics for social robot navigation. User feedback for SEAN 2.0 indicated that the system was “easier to navigate and more user friendly” than SEAN 1.0.

Evaluation of the use of alternative control methods of coffee tree diseases in the tropical Amazon

The present study aimed to evaluate the effect of alternative products on the control of coffee brown-eye spot and coffee rust. The experiment was carried out in two conilon coffee plantations, in the following agroforestry system models: a) continuous system (SM-1) and b) mixed system (SC-2). The following treatments were used: i) aqueous plant extract of Himatanthus sucuuba (2%) - SUC, ii) Bordeaux mixture (2%) - CB and iii) control (water). Four monthly samplings of the temporal progress of the diseases were carried out, during the period from October/2019 to January/2020, evaluating the symptoms in three leaves per plant, one from each of the upper, middle and lower thirds of the plant. Incidence percentages were determined according to the number of leaves with symptoms in relation to the total number of leaves sampled. In order to estimate severity, diagrammatic scales were used for each disease evaluated. The obtained data were submitted to routine statistical analysis in R programming with a significance of 5%. Interaction effects were not significant according to the ANOVA test. Significant differences were observed among the treatments studied for the two diseases with the following results: percent reduction of rust incidence: (SUC - 50%, CB - 80% and TEST - 95%) and percent reduction of brown-eye spot: (SUC - 30%, CB - 60 % and TEST - 80%). SUC treatment was more effective in reducing disease severity with the following results: (SUC - 0.26%, CB - 0.40% and TEST - 0.83%) and (SUC - 0.35%, CB - 0.41% and TEST - 0.99%) for rust and brown-eye spot diseases, respectively. The treatment (SUC) proved to be a promising alternative product for the management of brown-eye spot and rust diseases.

Larvicidal, antioxidant and biotoxicity assessment of (2-(((2-ethyl-2 methylhexyl)oxy)carbonyl)benzoic acid isolated from Bacillus pumilus against Aedes aegypti, Anopheles stephensi and Culex quinquefasciatus.

Mosquitoes are a vector for many dreadful diseases known for their public health concern. The continued use of synthetic insecticides against vector control has led to serious environmental impacts, human health problems, and the development of insect resistance. Hence, alternative mosquito control methods are needed to protect the environment and human health. In the present study, the bioefficacy of (2-(((2-ethyl-2 methylhexyl)oxy)carbonyl) benzoic acid isolated from Bacillus pumilus were tested against Aedes aegypti, Culex quinquefasciatus and Anopheles stephensi. The isolated bioactive compound was characterized through thin layer chromatography (TLC), UV-visible spectroscopy (UV), Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and gas chromatography-mass spectrometry analysis. The pure compound caused a high percent mortality rate in a dose-dependent manner, the obtained values were 96, 82, 69, 50 and 34%; 86, 72, 56, 43, and 44%; 100, 90, 83, 70 and 56% against Ae. aegypti, Cx. quinquefasciatus, and An. stephensi respectively. The effective lethal concentration values (LC50) were 13.65, 14.90 and 9.64ppm against Ae. aegypti, Cx. quinquefasciatus, An. Stephensi, respectively. The effect of (2-(((2-ethyl-2 methylhexyl)oxy)carbonyl) benzoic acid significantly increased the superoxide dismutase, catalase, α, β esterase and Glutathione-S-transferase level after 24h of the treatment period. The comet assay confirmed that isolated compound causes DNA damage in all tested insects. Histopathological examinations of treated larvae showed shrunken body posture, damaged epithelial cells and microvillus as compared to control organisms. The biosafety of the isolated compound was assessed against G. affinis and did not produce mortality which confirmed that the activity of the isolated compound is species specific. The current study concludes that the critical success factors of new insecticidal agent development are based on the eco-compatibility and alternative tools for the pesticide producing industry.

Effects of stabilized hypochlorous acid on oral biofilm bacteria

BackgroundCaries and periodontitis are amongst the most prevalent diseases worldwide, leading to pain and loss of oral function for those affected. Prevention relies heavily on mechanical removal of dental plaque biofilms but for populations where this is not achievable, alternative plaque control methods are required. With concerns over undesirable side-effects and potential bacterial resistance due to the use of chlorhexidine gluconate (CHX), new antimicrobial substances for oral use are greatly needed. Here we have investigated the antimicrobial effect of hypochlorous acid (HOCl), stabilized with acetic acid (HAc), on oral biofilms and compared it to that of CHX. Possible adverse effects of stabilized HOCl on hydroxyapatite surfaces were also examined.MethodsSingle- and mixed-species biofilms of six common oral bacteria (Streptococcus mutans, Streptococcus gordonii, Actinomyces odontolyticus, Veillonella parvula, Parvimonas micra and Porphyromonas gingivalis) within a flow-cell model were exposed to HOCl stabilized with 0.14% or 2% HAc, pH 4.6, as well as HOCl or HAc alone. Biofilm viability was assessed in situ using confocal laser scanning microscopy following LIVE/DEAD® BacLight™ staining. In-situ quartz crystal microbalance with dissipation (QCM-D) was used to study erosion of hydroxyapatite (HA) surfaces by stabilized HOCl.ResultsLow concentrations of HOCl (5 ppm), stabilized with 0.14% or 2% HAc, significantly reduced viability in multi-species biofilms representing supra- and sub-gingival oral communities, after 5 min, without causing erosion of HA surfaces. No equivalent antimicrobial effect was seen for CHX. Gram-positive and Gram-negative bacteria showed no significant differential suceptibility to stabilized HOCl.ConclusionsAt low concentrations and with exposure times which could be achieved through oral rinsing, HOCl stabilized with HAc had a robust antimicrobial activity on oral biofilms, without causing erosion of HA surfaces or affecting viability of oral keratinocytes. This substance thus appears to offer potential for prevention and/or treatment of oral biofilm-mediated diseases.

Silicon and boron on cauliflower induce attractiveness and mortality in Plutella xylostella.

Boron (B) and silicon (Si) are fundamental for brassica nutrition, and in some cases, they have potential as an insecticide. Plutella xylostella (L.) (Lepidoptera: Plutellidae), one of the most economically important agricultural pests, is difficult to control due to the resistance to insecticides and the absence of alternative control methods. Cauliflower leaves sprayed with Si and B showed a higher concentration of the beneficial element and micronutrient, respectively. When evaluating the firmness of the cauliflower leaves, it was found that the plants with leaf sprayings of Si and B did not differ statistically from each other. However, they showed an increase in firmness, in relation to the plants of the control treatment. Leaf spraying of Si and B on cauliflower did not influence the number of eggs/female. The attractiveness index showed that both Si and B applications stimulated the presence of second instar larvae, being more stimulating in relation to the control treatment. However, the use of Si and B in isolation showed a positive result, since it caused high mortality in diamondback moth larvae compared to the control treatment. The application of both foliar fertilizers positively affects the attractiveness index of the larvae, being attractive; however, both Si and B caused high mortality (~80%). The results showed that Si and B have the potential to control P. xylostella and serve as a basis for alternative pest management in brassica crops. © 2022 Society of Chemical Industry.

Experimental vaccination in rabbits using the peptide RmS-17 antigen reduces the performance of a Mexican Rhipicephalus microplus tick strain

The tick vector Rhipicephalus microplus is considered one of the main problems in cattle production in tropical and subtropical regions. Anti-tick vaccines may form an alternative tick control method to the use of acaricides, and tick salivary proteins, such as Serpins, may be valuable as target antigens for developing anti-tick vaccines. In this study, we synthesized a recombinant peptide derived from Serpin RmS-17 protein using an Escherichia coli expression system and characterized the efficacy of the peptide RmS-17 for the control of R. microplus females infesting rabbits. Twelve New Zealand white rabbits were assigned to three experimental groups and vaccinated with three subcutaneous doses of the peptide RmS-17, recombinant R. microplus Bm86 antigen, and adjuvant/saline alone. The tick challenge was conducted with 120 R. microplus adults (60 females and 60 males) per animal, with the ticks placed inside a cotton sleeve glued to the back of the rabbit. Serum antibody levels (IgG) were assessed by ELISA and confirmed by Western blot; also, the reproductive performance of R. microplus was determined. The results showed that experimental vaccination in rabbits using the peptide RmS-17 antigen had a vaccine efficacy of 79% based on reductions in adult tick number, oviposition, and egg fertility compared to control animals. The peptide RmS-17 vaccinated rabbits developed a strong humoral immune response expressed by high anti-pRmS-17 IgG levels, and the Western blot analysis confirmed that it is immunogenic. The efficacy for the Bm86 vaccine was 62%, which is within the range of efficacy reported previously for Bm86 vaccine. The negative correlation between antibody levels and reduction in tick number strongly suggests that the effect of the vaccine was the result of the antibody response in vaccinated rabbits. In conclusion, this is the first study to evaluate the efficacy of the peptide RmS-17 against R. microplus tick infestation and show it to be immunogenic and protective in a rabbit model.

Evaluation of Tetrofosmin Cold Kit Fractionation Using Alternative New Method of Quality Control for Testing Radiochemical Purity

Objective The aim of this study is to establish a method for the fractionation of tetrofosmin cold kit under different storage conditions and to optimize an alternate chromatography method from the reference method to test radiochemical purity (RCP). Materials and Methods Tetrofosmin cold kit vial was fractionated aseptically in six equal fractions and stored in vials and syringes. To test the stability of the reconstituted solution for a longer duration, the mother vials and syringes were stored at two different temperatures, that is, at 4°C and at -20°C till further used. Radiolabeling of fractionated tetrofosmin was performed as per the standard labeling protocol. Radionuclide purity, radioassay, and pH were tested. Radiolabeling efficiency and RCP were determined by paper chromatography. Results Radionuclide purity of eluate was greater than 99.9%. The pH of technetium-99m (Tc-99m) eluate and Tc-99m tetrofosmin was between 4.5-7.5 and 7.5-9.5, respectively. The deviation in the radioactivity during all measurements was less than 1%. The kits fractioned in glass vials resulted in higher radiolabeling yield and RCP as compared with kits fractionated in syringes. The RCP of glass vial versus syringe was observed to be greater than 95 versus 90% and 95 versus 80% at -20°C and 4°C, respectively. Conclusion Tetrofosmin kit can be used in a cost-effective manner by fractionation. One tetrofosmin vial can be used in six fractions for up to 15 days when stored at -20°C and 4°C freezer temperature. The alternative method to check the RCP of Tc-99m tetrofosmin is safer and less time consuming as compared with the reference method.

Phytopathogenic fungi as potential biocontrol agents against an invasive weed, Asystasia gangetica, at Sakambangan rubber plantation in Garut, West Java, Indonesia

Abstract. Yulia E, Mahmudah AI, Rahayu A, Nasahi C, Maharani Y, Suganda T, Widayat D. 2022. Phytopathogenic fungi as potential biocontrol agents against an invasive weed, Asystasia gangetica, at Sakambangan rubber plantation in Garut, West Java, Indonesia. Biodiversitas 23: 4532-4538. Many weeds are invasive species causing both economic and ecological losses. Asystasia gangetica is one of invasive species from the Acanthaceae family and has now been established as one of the most important weeds of rubber plantation. Mechanical control of A. gangetica is ineffective, while chemical control is harmful to the environment. Thus, it is imperative to explore alternative control methods. This study aimed to carry out an inventory of pathogenic fungi isolated from A. gangetica and test their pathogenicity to A. gangetica and rubber seedlings. This research was conducted from November 2021 to February 2022. The methods used were field observation and laboratory test conducted at the Sakambangan rubber plantation, Garut District, West Java and the Phytopathology Laboratory, Department of Plant Pests and Diseases, Faculty of Agriculture, Universitas Padjadjaran. Pathogenicity test was carried out using water-culture method to grow the tested plants without soil. Fungi isolated from A. gangetica identified as Fusarium sp., Pestalotiopsis sp., Colletotrichum sp. and Cercospora sp. were tested to be pathogenic to A. gangetica, and deemed potential biocontrol agents. However, Pestalotiopsis sp. and Cercospora sp. were also pathogenic to rubber seedlings which make them ineligible as biocontrol agents for A. gangetica in rubber plantations.

Bioaccessibility and oral immunization efficacy of a chimeric protein vaccine against Ascaris suum

Human ascariasis has been characterized as the most prevalent neglected tropical disease worldwide. There is an urgent need for search to alternative prevention and control methods for ascariasis. Here we aimed to establish a protocol of oral immunization with a previously described chimera protein capable of resist through digestion and induce mucous protection against Ascaris suum infection. Mice were oral immunized with seven doses with one day interval and challenged with A. suum ten days after the last dose. In vitro digestion showed that 64% of chimeric protein was bioaccessible for absorption after digestion. Immunized mice display 66,2% reduction of larval burden in lungs compared to control group. In conclusion we demonstrated that oral immunization with chimera protein protects the host against A. suum larval migration leading to less pronounced histopathological lesions.

Reduction of Weed Growth under the Influence of Extracts and Metabolites Isolated from Miconia spp.

Weeds pose a problem, infesting areas and imposing competition and harvesting difficulties in agricultural systems. Studies that provide the use of alternative methods for weed control, in order to minimize negative impacts on the environment, have intensified. Native flora represents a source of unexplored metabolites with multiple applications, such as bioherbicides. Therefore, we aimed to carry out a preliminary phytochemical analysis of crude extracts and fractions of Miconia auricoma and M. ligustroides and to evaluate these and the isolated metabolites phytotoxicity on the growth of the target species. The growth bioassays were conducted with Petri dishes with lettuce, morning glory, and sourgrass seeds incubated in germination chambers. Phytochemical analysis revealed the presence of flavonoids, isolated myricetin, and a mixture of quercetin and myricetin. The results showed that seedling growth was affected in a dose-dependent manner, with the root most affected and the seedlings of the lettuce, morning glory, and sourgrass as the most sensitive species, respectively. Chloroform fractions and myricetin were the most inhibitory bioassays evaluated. The seedlings showed structural changes, such as yellowing, nonexpanded cotyledons, and less branched roots. These results indicate the phytotoxic potential of Miconia allelochemicals, since there was the appearance of abnormal seedlings and growth reduction.

Electrolyzer array alternate control strategy considering wind power prediction

Non grid connected wind power hydrogen production technology is of great significance for the large-scale comprehensive utilization of hydrogen energy and accelerating the development of clean energy. In this paper, an electrolyzer power allocation and alternate control method for non grid connected wind power hydrogen production is proposed, and the optimized control strategy are combined to predict the maximum wind power of certain time interval. While retaining the required data characteristics, the instantaneous fluctuation of some wind power data is eliminated, which provides a reliable basis for power distribution in the alternation control strategy of electrolyzer array. The case simulation verifies the effectiveness of the electrolyzer array control principle and the prediction of the maximum wind power. While ensuring the absorption effect and hydrogen production rate, the service life and operation safety of the electrolyzer array are effectively improved by balancing the working state of each electrolyzer.

State observer-based fuzzy echo state network sliding mode control for uncertain strict-feedback chaotic systems without backstepping

To control uncertain strict-feedback chaotic systems, the adaptive backstepping technique is a popular method, yet this method requires repeatedly differentiating virtual control inputs, which will result in the “explosion of complexity” problem. In this paper, an alternative control method for uncertain strict-feedback chaotic systems without using backstepping technique is presented. We first translate the uncertain strict-feedback chaotic system into a new straightforward normative system whose states are unmeasurable, and then, an observer is designed to estimate the unknown states of the transformed system. A new recurrent neural network, namely fuzzy echo state network (FESN), is constructed to approximate the lumped uncertainty of the normative system. The semi-globally stability of the closed-loop system can be guaranteed by the FESN sliding mode controller that only uses one FESN and one adaptation law. Comparative simulations are put forward to verify the derived theoretical results.

Exploring Potential Mechanisms of Fludioxonil Resistance in Fusarium oxysporum f. sp. melonis.

Melon Fusarium wilt (MFW), which is caused by Fusarium oxysporum f. sp. melonis (FOM), is a soil-borne disease that commonly impacts melon cultivation worldwide. In the absence of any disease-resistant melon cultivars, the control of MFW relies heavily on the application of chemical fungicides. Fludioxonil, a phenylpyrrole fungicide, has been shown to have broad-spectrum activity against many crop pathogens. Sensitivity analysis experiments suggest that fludioxonil has a strong inhibitory effect on the mycelial growth of FOM isolates. Five fludioxonil-resistant FOM mutants were successfully generated by repeated exposure to fludioxonil under laboratory conditions. Although the mutants exhibited significantly reduced mycelial growth in the presence of the fungicide, there initially appeared to be little fitness cost, with no significant difference (p < 0.05) in the growth rates of the mutants and wild-type isolates. However, further investigation revealed that the sporulation of the fludioxonil-resistant mutants was affected, and mutants exhibited significantly (p < 0.05) reduced growth rates in response to KCl, NaCl, glucose, and mannitol. Meanwhile, molecular analysis of the mutants strongly suggested that the observed fludioxonil resistance was related to changes in the sequence and expression of the FoOs1 gene. In addition, the current study found no evidence of cross-resistance between fludioxonil and any of the other fungicides tested. These results indicate that fludioxonil has great potential as an alternative method of control for FOM in melon crops.

Morphological description and population dynamic of Spodoptera littoralis (Boisduval, 1833) (Lepidoptera: Noctuidae)’s parasitoid on cabbage in South Côte d’Ivoire

The Egyptian cotton leafworm Spodoptera littoralis Boisduval (Lepidoptera: Noctuidae) is among the serious cabbage pests in tropical countries. It can lead an intensive chemical insecticides use in market gardening perimeters. Alternative control methods such as biological control are necessary for the integrated management of this pest. The laboratory rearing of S. littoralis larvae sampled in […]