Chemical Control Research Articles

Research on the prevention and control of plant diseases by antagonistic microorganisms

Plant diseases, often caused by bacterial infections, pose significant challenges to human society due to their widespread and harmful consequences, resulting in substantial losses. Although traditional chemical prevention and control methods have shown effectiveness, they still pose serious environmental and other risks. Therefore, developing biological control is crucial for future plant disease prevention and management. In this study, we investigated the efficacy of antagonistic microorganisms. We conducted four related experiments and eventually reaffirmed the substantial inhibitory effect of antagonistic microorganisms on the growth of plant pathogens. Our findings are of great significance for further expanding the application scope and popularization of antagonistic bacteria and also enriching the specific application of antagonistic microorganisms for specific plant control.

Ecology and management of the coffee berry borer (Hypothenemus hampei): the potential of biological control

AbstractCoffee is an important commodity in Latin America that is grown by smallholder farmers and large-scale coffee producers. The coffee berry borer, Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae) is a major pest of coffee that originates from West Africa and has invaded all coffee-producing regions. With climate change, the problems that this beetle poses to coffee production are expected to increase. Controlling this pest is a true challenge and chemical insecticides still are one of the main tools used, despite the environmental and human-health issues associated with this approach. To find sustainable alternatives for chemical control of the coffee berry borer, classical biological control, augmentative biological control, and integrated pest management have received extensive attention. Parasitoids, predators, entomopathogenic fungi, and nematodes have been identified and studied for their potential to manage the infestations of this major coffee pest. Conservation biological control has recently gained more attention, but its development is still in its infancy. In this review, we examine strategies for the control of the coffee berry borer in Latin America. We identify knowledge gaps for developing sustainable biological control programs, including conservation biological control within the context of farming systems, land use in the surrounding landscape, as well as the vision of coffee growers.

Comparative analysis of Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae) corn and rice strains microbiota revealed minor changes across life cycle and strain endosymbiont association.

Spodoptera frugiperda (FAW) is a pest that poses a significant threat to corn production worldwide, causing millions of dollars in losses. The species has evolved into two strains (corn and rice) that differ in their genetics, reproductive isolation, and resistance to insecticides and Bacillus thuringiensis endotoxins. The microbiota plays an important role in insects' physiology, nutrient acquisition, and response to chemical and biological controls. Several studies have been carried out on FAW microbiota from larvae guts using laboratory or field samples and a couple of studies have analyzed the corn strain microbiota across its life cycle. This investigation reveals the first comparison between corn strain (CS) and rice strain (RS) of FAW during different developmental insect stages and, more importantly, endosymbiont detection in both strains, highlighting the importance of studying both FAW populations and samples from different stages. The composition of microbiota during the life cycle of the FAW corn and rice strains was analyzed through high-throughput sequencing of the bacterial 16S rRNA gene using the MiSeq system. Additionally, culture-dependent techniques were used to isolate gut bacteria and the Transcribed Internal Spacer-ITS, 16S rRNA, and gyrB genes were examined to enhance bacterial identification. Richness, diversity, and bacterial composition changed significantly across the life cycle of FAW. Most diversity was observed in eggs and males. Differences in gut microbiota diversity between CS and RS were minor. However, Leuconostoc, A2, Klebsiella, Lachnoclostridium, Spiroplasma, and Mucispirilum were mainly associated with RS and Colidextribacter, Pelomonas, Weissella, and Arsenophonus to CS, suggesting that FAW strains differ in several genera according to the host plant. Firmicutes and Proteobacteria were the dominant phyla during FAW metamorphosis. Illeobacterium, Ralstonia, and Burkholderia exhibited similar abundancies in both strains. Enterococcus was identified as a conserved taxon across the entire FAW life cycle. Microbiota core communities mainly consisted of Enterococcus and Illeobacterium. A positive correlation was found between Spiroplasma with RS (sampled from eggs, larvae, pupae, and adults) and Arsenophonus (sampled from eggs, larvae, and adults) with CS. Enterococcus mundtii was predominant in all developmental stages. Previous studies have suggested its importance in FAW response to B. thuringensis. Our results are relevant for the characterization of FAW corn and rice strains microbiota to develop new strategies for their control. Detection of Arsenophonus in CS and Spiroplasma in RS are promising for the improvement of this pest management, as these bacteria induce male killing and larvae fitness reduction in other Lepidoptera species.

Apivectoring: Harnessing pollinators for sustainable crop protection and pollination

Apivectoring, or Pollinator Biocontrol Vector Technology, employs bees to distribute biological control agents, offering a sustainable solution for managing plant diseases and insect pests while enhancing crop yield and quality. The most commonly used vectors in apivectoring are honey bees and bumble bees, though there’s potential to explore other pollinator species. Commercial dispensers like BeeTreat Dispenser®, BVT Inoculum Dispenser® and Flying Doctors® have been developed in countries like Finland, Belgium, and Canada, respectively. Though initially pioneered in North America, Australia, and Europe, this method is now being evaluated in India. The technology is a promising alternative to chemical pest control, reducing pesticide usage and ensuring crop pollination, although challenges remain in regions deprived of local rearing and/or research facilities.

Development and characterization of microsatellite markers for population genetics of the cocoa pod borer Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillaridae).

The cocoa pod borer (CPB) Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillaridae) is one of the major constraints for cocoa production in South East Asia. In addition to cultural and chemical control methods, autocidal control tactics such as the Sterile Insect Technique (SIT) could be an efficient addition to the currently control strategy, however SIT implementation will depend on the population genetics of the targeted pest. The aim of the present work was to search for suitable microsatellite loci in the genome of CPB that is partially sequenced. Twelve microsatellites were initially selected and used to analyze moths collected from Indonesia, Malaysia, and the Philippines. A quality control verification process was carried out and seven microsatellites found to be suitable and efficient to distinguish differences between CPB populations from different locations. The selected microsatellites were also tested against a closely related species, i.e. the lychee fruit borer Conopomorpha sinensis (LFB) from Vietnam and eight loci were found to be suitable. The availability of these novel microsatellite loci will provide useful tools for the analysis of the population genetics and gene flow of these pests, to select suitable CPB strains to implement the SIT.

Biological strategies to control caterpillars in soybean, cotton and maize in the main producing regions of Brazil

Soybean, cotton and maize crops represent some of the main agricultural commodities grown during the hot season in Brazil. In order to provide more effective control options to producers, it is essential to deepen studies on management strategies using biological insecticides. This study aims to evaluate the effectiveness of the application of the bioinsecticide Ocimum basilicum, in controlling the caterpillar complex, notably the looper (Chrysodeixis includens) in soybeans, the fall armyworm (Spodoptera frugiperda) in maize and the cotton leafworm caterpillar (Alabama argillacea) in cotton, as a control alternative aimed at mitigating damage and contributing to more sustainable agricultural practices. Experiments were carried out in each culture in various environments in the states of MT, MS, SP and PR in Brazil. A randomized block design with four replications was used in all the experiments. Agronomic traits, insect pest incidence and insecticide efficiency were evaluated for each of the crops. The data were subjected to after being subjected to stratified analysis of variance for each experimental phase. The interaction significant interactions were broken down to simple effects using Tukey's multiple comparison test of means at 5% probability. Subsequently, Scott-Knott mean grouping was used at 5% probability. Management using 1L per hectare of basil extract (Ocimum basilicum L) demonstrated satisfactory efficacy in controlling the caterpillar complex, approaching the results obtained with traditional chemical control.

Inclusion of Anti-Tick Vaccines into an Integrated Tick Management Program in Mexico: A Public Policy Challenge

Acaricides are the most widely used method to control the cattle tick Rhipicephalus microplus. However, its use increases production costs, contaminates food and the environment, and directly affects animal and human health. The intensive use of chemical control has resulted in the selection of genes associated with resistance to acaricides, and consumers are increasingly less tolerant of food contamination. This scenario has increased the interest of different research groups around the world for anti-tick vaccine development, in order to reduce the environmental impact, the presence of residues in food, and the harmful effects on animal and human health. There is enough evidence that vaccination with tick antigens induces protection against tick infestations, reducing tick populations and acaricide treatments. Despite the need for an anti-tick vaccine in Mexico, vaccination against ticks has been limited to one vaccine that is used in some regions. The aim of this review is to contribute to the discussion on tick control issues and provide a reference for readers interested in the importance of using anti-tick vaccines encouraging concerted action on the part of Mexican animal health authorities, livestock organizations, cattle producers, and academics. Therefore, it is suggested that an anti-tick vaccine should be included as a part of an integrated tick management program in Mexico.

The Evaluation of Sweetcorn (Zea mays saccharata Sturt.) Infestation of Barnyardgrass (Echinochloa crus-galli) Depending on Weather Conditions and Crop Rotation

This paper focuses on the weed species Echinochloa crus-galli, commonly known as barnyardgrass, which is a persistent threat to crop yield and quality, especially in maize (Zea mays) cultivation. It is one of the most problematic weeds in agricultural fields due to its aggressive growth, adaptability to different environmental conditions and prolific seed production. The incidence of Echinochloa crus-galli in maize fields has increased in recent years. This study aims to provide a comprehensive understanding of the characteristics and behavior of Echinochloa crus-galli, and to suggest effective measures to control it. This research on sweetcorn was conducted from 1992 to 2019 at the Research and Education Center Gorzyń, Złotniki branch, which belongs to the Poznań University of Life Sciences. The evaluation of weed infestation was carried out in experiments focusing on chemical weed control in maize. The experiments were designed as a one-factor randomised block design with four field replications. The condition and the degree of weed infestation (number of weeds and fresh weight of weeds) in the control plots was assessed on an annual basis at the end of June and in July. The aim of the study was to evaluate the dynamic changes in the status and extent of barnyardgrass (Echinochloa crus-galli) infestation in maize grown after various other crops in the Wielkopolska region, with a focus on the weather conditions. The study found that barnyardgrass was most likely to occur when maize was sown after winter wheat in a dry and warm year, and least likely when maize was grown in rotation after winter wheat in a cold year with average rainfall. The proportion of barnyardgrass weed mass in the total weed mass was significantly lower after winter rye than after winter wheat, winter oilseed rape and winter triticale. Further research into the biology and ecology of barnyardgrass is key to effectively controlling this weed and safeguarding sweetcorn yields.

Farmer Perceptions on the Effects of Termites in Kwa Vonza Location, Kitui County, Kenya

Aims: This study aimed to assess (i) the perception of Kwa Vonza farmers regarding the presence of termites in their land, (ii) the perceived importance of termites, and (iii) how they control termites in their properties. Study Design:  This study is based on responses to a questionnaire sent to farmers. Place and Duration of Study: The study took place in Kwa Vonza Location, Yatta Sub County, Kitui County, Kenya, between April and November 2017. Methodology: 60 questionnaires, each comprising 20 multiple-choice questions, were sent out to farmers. Out of these, 54 responses were received. Where the response did not require a Yes or No answer, it elicited a response from a standardized five-point scale to demonstrate agreement with the provided proposition. Data analysis was done using descriptive statistics, in which percentages were tabulated, and frequency tables were generated using Microsoft Excel. Results: 73% of farmers perceived their land as infertile, with the causes ranging from soil erosion, drought, and mono-cropping. 87% of farmers acknowledged termite infestation in their farms but perceived them as destructive. Termite infestation was attributed to deforestation, drought, and flooding. Chemical control was the method of choice to manage termites. Conclusion: Kwa Vonza farmers do not perceive termites as of any agronomic significance but view them as destructive agents. Further research to address the complex issue of soil management at the farm-scale level that involves farmers is necessary to fill gaps in scientific knowledge and produce advice for practical use.

Review on novel approaches for controlling aflatoxin B1: Harnessing nature's defenses against food toxins

Aflatoxin B1 is the most harmful food toxin for humans and animals. According to the International Agency for Research on Cancer, it is ranked as one of the most carcinogenic substances in the world, directly connected to hepatocarcinoma in both humans and animals. Aflatoxin B1 is also involved in the occurrence of pathologies, and aflatoxicoses. Aflatoxin B1 can be produced by fungi from the genus Aspergillus section Flavi in a variety of foods during storage. Once aflatoxins are present, food processing cannot eradicate them. The damage and lack of complete elimination of aflatoxins from foodstuffs make them the most monitored and controlled substances in the world. Given the high-risk of Aflatoxin B1 on both animal and human health, it is important to study their worldwide distribution and existing control methods through a systematic review. Articles published from 1945 to 2022 found on several databases as Scopus, PubMed, Dimensions, Google Scholar and an extraction sieve was used to select the relevant articles. Of the two hundred and twenty-eight (228) French and English scientific articles on aflatoxins identified, forty of the most relevant original articles were selected for inclusion in this review following a rigorous selection process. Several genes are involved in the synthesis of aflatoxin B1. Moreover, certain environmental conditions, in particular oxidative stress are propitious for fungus by over-expressing aflatoxins. However, the fungi defences can be controlled by several methods. Articles showed efficiency of various of them. Good cultural practices and awareness raising are part of the preventive control. Synthetic chemicals such as insecticides and fungicides are chronically used in chemical control of fungal growth and prevent aflatoxins from being produced. Biological control is based on allelic recombination between toxic and atoxic strains. The use of microbial competition is focused on the natural predators of aflatoxic molds, most often lactic acid bacteria, and the natural control relies on the use of natural plant substances. Natural substances like aqueous or organic plant extracts that contain proteins, polyphenols, tannins, antioxidants, flavonoids, terpenes, and chelating ion as well as caffeic acid, gallic acid and ascorbic acid can be used to control fungal contamination currently. These molecules interfere with free radicals to slow down or even inhibit the production of reactive oxygen species significantly reducing the production of aflatoxins making them inactive. Implementation of the means of controlling fungal growth and producing aflatoxins will help make agriculture globally competitive and ensure food security. Key words: Natural substances, Aflatoxin B1, food poisoning, alternative control, biocontrol

Recent advances in the biosensors application for reviving infectious disease management in silkworm model: a new way to combat microbial pathogens.

Silkworms are an essential economic insect but are susceptible to diseases during rearing, leading to yearly losses in cocoon production. While chemical control is currently the primary method to reduce disease incidences, its frequent use can result in loss of susceptibility to pathogens and, ultimately, antibiotic resistance. To effectively prevent or control disease, growers must accurately, sensitively, and quickly detect causal pathogens to determine the best management strategies. Accurate recognition of diseased silkworms can prevent pathogen transmission and reduce cocoon loss. Different pathogen detection methods have been developed to achieve this objective, but they need more precision, specificity, consistency, and promptness and are generally unsuitable for in-situ analysis. Therefore, detecting silkworm diseases under rearing conditions is still an unsolved problem. As a consequence of this, there is an enormous interest in the development of biosensing systems for the early and precise identification of pathogens. There is also significant room for improvement in translating novel biosensor techniques to identify silkworm pathogens. This study explores the types of silkworm diseases, their symptoms, and their causal microorganisms. Moreover, we compare the traditional approaches used in silkworm disease diagnostics along with the latest sensing technologies, with a precise emphasis on lateral flow assay-based biosensors that can detect and manage silkworm pathogens.

Non‐chemical weed management for sustainable rice production in the Ebro Delta

AbstractWeed control is one of the major challenges in rice cultivation, and the use of agrochemicals for this crop is severely restricted under the new European agricultural policy. Therefore, new effective non‐chemical weed control techniques are the key to sustain European rice production. We investigated four non‐chemical weed management strategies in the Ebro Delta in north‐eastern Spain, two in dry‐seeded rice fields and two in water‐seeded rice fields. In addition, two controls per sowing condition were included: a positive control consisting of chemical herbicides treatment and a negative control consisting of no weeding and no seeding. Mechanical weeding using a rotary harrow placed in front of the seeder was the best weeding technique for dry seeding, while ‘stale seed bed’ and transplanting was the best performing technique for wet seeding. Both techniques were as effective as the chemical weeding control, reducing the density of weeds and the supplementary manual weeding time needed for those weed species more abundant in Ebro Delta rice fields (i.e., Echinochloa oryzoides, Echinochloa crus‐galli, Bolboschoenus maritimus and Heteranthera reniformis). Thus, non‐chemical weeding alternatives have been proven effective for both, transplanting and dry seeding field management strategies.

Effective application of operator training simulator in experiential education

AbstractConnecting the chemical industry with the academic environment has created a unique opportunity to apply experiential learning in many areas of teaching. A new approach of using the existing operator training simulator, which is basically a digital twin of a new dicyclopentadiene plant, was used to educate and train students from technical universities. Using this simulator, students can gain adequate knowledge for control, process optimization, and problem solving under nonstandard operating conditions. Simulating a dynamic process in the Aspen HYSYS interface along with elements of a real industrial control system and control interface, and especially the online visualization of the results, helps students understand the physicochemical principles through their own intervention and experience of the consequences. The training simulator's ability to accurately reflect ongoing processes can be verified by students during a guided tour of a production plant. The experience with student learning so far shows that this is a very attractive and, above all, effective tool for extending the teaching of chemical engineering, control, and automation of chemical processes.

Machine learning meets process control: Unveiling the potential of LSTMc

AbstractIn the past three decades, proportional‐integral/PI‐differential (PI/PID) controllers and model predictive controller (MPCs) have predominantly governed complex chemical process control. Despite their advancements, these approaches have limitations, with PI/PID controllers requiring scenario‐specific tuning and MPC being computationally demanding. To tackle these issues, we introduce the long‐short‐term‐memory (LSTM)‐controller (LSTMc), a model‐free, data‐driven framework leveraging LSTM networks' robust time‐series prediction capabilities. The LSTMc predicts subsequent manipulated inputs by evaluating state evolution and error dynamics from both the current and previous time‐steps, which proved effective in our dextrose batch crystallization case study. Remarkably, the achieves less than 2% set‐point deviation, three times better than MPCs, and retains robustness even with 10%–15% sensor noise. With these results, LSTMc emerges as a promising alternative for process control, adeptly adjusting to changing process conditions and set‐points, providing efficient computation for an optimal input profile, and effectively filtering out common industrial process noise.

Impact of Climate Change on Pest Biology, Behaviour and Their Distributions

Increased temperatures, rising CO2 levels, and changing precipitation patterns are influencing agricultural production. These changes can lead to the expansion of insect pests geographic distribution, increased survival during overwintering, more generations per year, altered synchrony with plants, changed interspecific interactions, higher risk of invasion by migratory pests, increased incidence of insect-transmitted plant diseases, and reduced effectiveness of biological control. There is a serious risk of economic losses in crop production. Human food security is challenged due to potential disruptions in agricultural systems. Climate change necessitates adaptive management strategies to address evolving pest dynamics. Future research should focus on developing modified integrated pest management tactics to cope with changing pest statuses. Monitoring climate and pest populations is crucial for understanding and predicting the impact of climate change on insect pests. This review examines the climate change effect on insect pest biology and behavior and explores the potential use of modern pest monitoring technologies, modeling prediction tools can aid in forecasting and planning for potential pest outbreaks. Integrated pest management (IPM) approaches should be adapted to incorporate the changing dynamics influenced by climate change. This may involve a combination of chemical, biological, cultural, and mechanical control methods.

Engineering MgHPO4·3H2O/Mg(OH)2 composite for boosting NH3 adsorption properties

The emission of ammonia gas (NH3) in agricultural composting not only leads to a decrease in fertilizer efficiency, but also causes environmental pollution. Here, an alkaline, insoluble composites was prepared and its adsorption performance for NH3 was explored. The results indicate that the material synthesized using a one-pot method with magnesium hydroxide (Mg(OH)2) and phosphoric acid (H3PO4) consists of a mixture of MgHPO4·3H2O and Mg(OH)2 (M1). TEM images reveal the adhesion of the two materials together, with Raman spectroscopy indicating that MgHPO4·3H2O is located on the outer surface of Mg(OH)2. The microenvironment formed by the adhesive construction of MgHPO4·3H2O and Mg(OH)2 mixture not only provides sufficient magnesium salts and phosphate for the growth of struvite but also creates alkaline conditions conducive to struvite formation. The kinetic results show that the NH3 adsorption of M1 follows pseudo second-order adsorption kinetics and belongs to surface chemical reaction control. Compared with a simple mixture of MgHPO4·3H2O and Mg(OH)2, M1 has a 4.5 fold increase in NH3 adsorption rate and a 3.15 fold increase in equilibrium adsorption capacity. Preliminary on-site tests demonstrated the potential application of the M1 adsorbent for NH3 adsorption in composting.

Technology Focus: Completions (April 2024)

To start a text for high-level readers with a cliché is always a risk, but I will take it: “Data is the new oil.” When British mathematician Clive Humby coined this clever sentence in 2006, the thought-provoking idea behind it was that both oil and data need to be refined and processed to have value. Time and repetition eventually shaped the new, more common-sense meaning that data is as valuable as oil. And when the data refers to oil exploration and production, Humby’s statement becomes resounding, especially in its original meaning. The oil and gas industry, notably the completion activity, with its distributed sensors, optical fibers, permanent downhole gauges, sealed-wellbore pressure monitoring (SWPM), and microseismic, has generated a fantastic amount of data, which has increasingly been properly refined and processed, producing more information—and more oil. A quick search of OnePetro shows the number of papers that deal with the use of artificial intelligence with massive amounts of data that are being made available in the cloud to solve everything from the most prosaic completion decisions to the automatic design of stimulations in naturally fractured reservoirs. A good example of the use of data is shown in paper SPE 212922, which provides an in-depth analysis of interventions in the UK sector of the North Sea. Most of the conclusions, although mostly based on the UK Stewardship Survey, can be easily extrapolated to other regions of the world. And one of them puts its finger on the wound: the fear of asset managers of conducting interventions, even though they appear to be highly effective and economically viable. Paper SPE 212367 discusses the automation of SWPM data analysis for automatic volume-to-first-response matching, a great evolution in the design of refractures in the legendary Eagle Ford shales. And, if the evolution of completing unconventionals led the US to its historic production record in 2023, with more than 16 million BOE/D, in Argentina, shale gas has been a driver of development. The evolution of completions in the most famous unconventional prospect, Vaca Muerta, can be followed in paper SPE 212574. All of these great readings prove the cliché that “data is the new oil.” To complement the reading, a paper that will bring a discreet smile to a generation that breathlessly watched spaceships and even planets being destroyed by lasers, paper SPE 215016, details the industrial use of lasers in perforation. The future has finally arrived. To close the selections, two papers present current and important topics: completion options for carbon capture, use, and storage (SPE 216187) and innovations in autonomous inflow control devices, with the ingenious activation of the apparatus with chemical devices (SPE 216041). Recommended additional reading at OnePetro: www.onepetro.org. SPE 215016 First Industrial High-Power Laser Perforation Deployment by Sameeh I. Batarseh, Saudi Aramco, et al. SPE 216187 Improving Injection Efficiency in CCUS Wells: A Comparative Analysis of Different Completion Designs by Prakasa Bona, Halliburton, et al. SPE 216041Configurable Adaptive Chemical Inflow Control Device Eliminates Intervention by P. Asthana, Saudi Aramco, et al.

Molecular mechanisms for selective action of afidopyropen to Myzus persicae and Coccinella septempunctata.

Afidopyropen is a novel insecticide with high selectivity between sucking insects such as the peach aphids Myzus persicae and natural enemies like the seven-spotted lady beetle Coccinella septempunctata. However, the mechanisms of selective action for afidopyropen remain unknown. The LC50 values of afidopyropen to the 1st-4th instar larvae and adult C. septempunctata were 372- to more than 7267-fold higher than that to adult M. persicae. Though the activity of cytochrome P450s in M. persicae was 6.1- to 7.5-fold higher than that in C. septempunctata, the latter has much higher activities of carboxylesterase (CarEs) and glutathione S-transferases (GSTs), and the crude enzyme of C. septempunctata and M. persicae showed similar metabolism efficiency to afidopyropen. Molecular docking results demonstrated that afdopyropen showed higher binding affinity to the vanilloid-type transient receptor potential (TRPV) channel of M. persicae (-9.1 kcal/mol) than to that of C. septempunctata (-8.2 kcal/mol). And the EC50 value of afdopyropen to the TRPV channel of C. septempunctata (41 360 nM) was 19 885-fold higher than that in M. persicae (2.08 nM). Our results demonstrated that the significantly different sensitivity of M. persicae and C. septempunctata TRPV channel to afidopyropen play a key role in the high selectivity of afidopyropen. These findings provide new insights into the selective mechanisms of afidopyropen against insect pests and natural enemies as well as the theory support for coordinated application of chemical control and biological control. © 2024 Society of Chemical Industry.

Rapid Bioassay for Detection of Insecticide Resistance in Aphis gossypii Glover, 1877 (Hemiptera: Aphididae)

Cotton aphid, Aphis gossypii Glover, 1877 (Hemiptera: Aphididae) is one of the most economically important polyphagous pests that shows rapid resistance to chemical control. Determination of resistance levels is important within resistance management. The insecticide activities of Acetamiprid, Dimethoate, Imidacloprid, L-cyalothrin were investigated on different aphid populations to develop a faster and more economical bioassay method. Resistance levels were compared by making bioassays with insecticides using the leaf dipping method for 72 hours, 120 minutes and different doses. Resistance rates varying between 1-10 times were observed in both methods. The rapid application of 120 minutes is more advantageous in terms of speed, application time and economy of the method in the detection of resistance against Acetamiprid, Dimethoate, Imidacloprid, L-cyalothrin insecticides, and will contribute to the detection of resistance and the development of bioassay method.

Resistance to natural tick infestation varies with age and coat and hair traits in a tropically adapted beef cattle breed

Rhipicephalus (Boophilus) microplus causes considerable livestock production losses. Knowledge of the traits that influence tick resistance contributes to the development of breeding strategies designed to improve herd productivity. Within this context, this study evaluated the resistance of Caracu, a tropically adapted cattle breed, to R. microplus. Tick count, hair length, coat thickness, and coat color were evaluated in 202 naturally tick-infested females (cows and heifers) over a period of 18 months. Blood samples were collected from all animals during the winter season for hematological analysis. Data were analyzed using Pearson correlations, generalized linear models, and principal component analysis. Correlation coefficients of tick count with coat color, coat thickness, and hair length were estimated within each season. Hematological parameters were only included in the winter season analysis and were analyzed by the restricted maximum likelihood method using log-transformed data. No differences in blood parameters were observed between animals with and without ticks. However, tick count was negatively correlated with erythrocytes (−0.29) and hematocrit (−0.24) and positively correlated with mean corpuscular hemoglobin (0.21) and mean corpuscular hemoglobin concentration (0.25). These findings suggest that higher tick counts lead to a decrease in erythrocytes but also to an increase in the amount of hemoglobin per erythrocyte, which could reduce the damage caused by low erythrocyte levels due to tick hematophagy, delaying or preventing anemia. Although tick infestation on pasture was demonstrated by the infestation of all staff members during herd management, none of the animals exhibited high tick counts, providing evidence of resistance of Caracu animals to R. microplus. Tick infestation was influenced by age class (cows > heifers), season (spring and summer > fall and winter), coat thickness (>1.5 mm > <1.5 mm), and hair length (>6 mm > <6 mm). Three components were extracted by principal component analysis, which accounted for 69.46% of data variance. The findings of this study will contribute to the development of efficient strategies aimed at reducing economic losses due to tick infestation and could be applied in animal breeding to select for tick resistance traits, reducing chemical control strategies and consequently improving sustainable livestock production.