Control Of Insect Pests Research Articles

Environmental Influences on the Entomopathogenic Nematodes Used in the Biological Control of Insect Pests: Review

The importance of this appraisal is on the utilization and possible of entomopathogenic roundworms (EPNs) as biotic regulator factors in maintainable nutrition manufacture transversely an extensive variety of agronomic and extra supplies. To help by the consideration of the possibility of EPNs in supportable nutriment construction, this evaluation to offers impressions on EPN biology and environmental science, conglomerate manufacture and implementation expertise, and communications through additional organization gears. Primary find out in the 1920s, their trade as biopesticides in the 1980s was attended and pursued via exponential development in investigate on their implementation, biology, and ecosystem sought via a more increase in extra rudimentary investigate regions then the middle-2000s. This assessment précises important advancement completes in the study and implementation of EPN in insect pest administration in significant nutrition yields inclusive groves, minor fruitiness, corn, vegetative, corm yields, glasshouses, and bourgeons. Noteworthy agents impacting the achievement of EPN caramelization are similarly argued. An increasing benefit in substitutes to artificial insecticides and in biological cultivation unbolts chances intended for EPNs, nonetheless, EPNs will necessity to be additionally enhanced by a concern to effectiveness, decreased charges, and facility of utilizing. Furthermore, they're probable to reprocess harbor inhabitants and seduce them to be more invested for an extended period of pest repression.

Low Concentrations of Eucalyptus Essential Oil Induce Age, Sex, and Mating Status-Dependent Stimulatory Responses in Drosophila suzukii

Plant-extracted essential oils are generally suggested as potential sources for alternatives to synthetic insecticides in insect pest control strategies. The increased interest in the use of essential oils derives from the generalized perception of their safety for the environment, human health, and non-target organisms as well as a lower risk of resistance development. However, studies on essential oils have largely focused on their activity on targeted insect pests while overlooking their potential unintended effects on insect biological and reproductive traits, especially with sublethal exposures. Here, we first determined the toxicity of Eucalyptus globulus essential oil to adults of Drosophila suzukii and assessed the effects of low concentrations (i.e., LC5 and LC20) in old (5–7 days) and mated flies. Subsequently, we assessed longevity and fecundity in newly emerged virgin flies from four couples’ combinations: unexposed couples, exposed females, exposed males, and exposed couples to the low concentration LC20. Our results show that eucalyptus essential oil has good insecticidal activity against adults of D. suzukii. However, compared to untreated flies, the exposure to low concentrations enhanced the females’ fecundity only when both old and mated female and male flies were exposed, while the females’ but not males’ life span was extended only in couples where newly emerged virgin females were exposed. Our findings suggest that although the eucalyptus essential oil may be a good control alternative for adult D. suzukii, its age-, sex-, and mating status-dependent stimulatory responses mediated by exposure to low concentrations need to be considered and further investigated.

Genetic improvement of some microorganisms to increase the effect of bio-control on the potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

BackgroundDuring the last five decades, chemical synthetic pesticides have been used extensively to control pests and protect crops. Use of synthetic pesticide has caused some unfortunate consequences like environmental pollution, pest resistance and toxicity to other non-target organisms. Due to the hazardous effects of their chemical residues to human and animal health, several studies have been carried out to determine effective alternative control methods. One of methods is the usage of entomopathogens such as bacteria, virus and fungi. Entomopathogenic bacteria have unique insecticidal properties mainly due to the production of larvicidal proteins that accumulate as parasporal crystalline inclusions within the cell. The bio-insecticidal bacterium Bacillus thuringiensis (Bt) has been widely used in agriculture for the control of pest insects which attack crops.ResultsThirteen genetically stable fusants strains were obtained as a result of protoplast fusion technique between a local Bacillus thuringiensis (Bt) and each of B. subtilis subsp. subtilis strain (Bs1), Bacillus licheniformis strain (Bl) or B. subtilis subsp. spizizeniie (Bs2). Thirteen fusants were obtained, including three fusants (group B) from Bt::Bs1 fusion, six fusants (group C) from Bt::Bl fusion and four fusants (group D) from Bt::Bs2 fusion. All fusants were chosen for bioassay treatments against the potato tuber moth (PTM) Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) which recorded a high mortality percentage of PTM ranged from 75 to 80% in F1 and F2 of first attempt B (Bt::Bs1). The accumulative larval mortality was notation the highest percentage reached to 90% in case of treatment by fusants F4 followed by F7, F8 and F9 which gave 75, 70 and 80% larval mortality, respectively, for second attempt C (Bt::Bl). The third attempt D (Bt::Bs2) fusants F10, F11, F13 achieved the highest mortality percentage up to 60, 60 and 70%, respectively. Expression of apoptosis-related encoding genes in PTM was determined in three fusants B (Bt::Bs1), C (Bt::Bl) and D (Bt::Bs2) and compared with A (Bt) and Control. The results showed a high expression of gene apoptosis to fusants D (Bt::Bs2) to Caspase-16 gene, Dronc and Dredd genes in tissues of the (PTM) treated with different biological pesticides.ConclusionsThe study used protoplast fusion technique between a local Bacillus thuringiensis (Bt) and B. subtilis subsp. subtilis strain (Bs1), B. licheniformis strain (Bl) and B. subtilis subsp. spizizeniie (Bs2). Thirteen fusants were chosen for bioassay treatments against PTM. Bacterial fusant, F1, F2, F4, F7, F9 and F13, achieved the highest mortality rates against PTM ranged 75–90% under laboratory conditions. The highest expression of gene apoptosis to fusants D (Bt::Bs2) to Caspase-16 gene, Dronc and Dredd genes was recorded in insect tissues treated with different bio-insecticides. As a result of the effected on the genes responsible for expression the vital processes (genes of apoptosis) in the insect as a result of treatment with bacteria, this led to deformities and death of PTM.

Core–Shell Polymeric Nanostructures with Intracellular ATP-Fueled dsRNA Delivery toward Genetic Control of Insect Pests

Transgenic RNA interference (RNAi) represents a burgeoning and promising alternative avenue to manage plant diseases and insect pests in plants. Nonviral nanostructured dsRNA carriers have been demonstrated to possess great potential to facilitate the application of RNAi. However, it remains a critical challenge to achieve the targeted and effective release of dsRNA into the pest cells, limiting the efficiency of the biological control of pests and diseases in practical applications. In this study, we designed and constructed a new type of core-shell polymeric nanostructure (CSPN) with controllable structure, eco-friendliness, and good biocompatibility, on which dsRNA can be efficiently loaded. Once loaded into CSPNs, the dsRNA can be effectively prevented from nonsense degradation by enzymes before entering cells, and it shows targeted and image-guided release triggered by intracellular ATP, which significantly increases the efficiency of gene transfection. Significantly, the in vivo study of the typical lepidoptera silkworm after oral feeding demonstrates the potential of dsCHT10 in CSPNs for a much better knockdown efficiency than that of naked dsCHT10. This innovation enables the nanotechnology developed for the disease microenvironment-triggered release of therapeutic genes for application in sustainable crop protection.

The impact of curcumin on livestock and poultry animal's performance and management of insect pests.

Plant-based natural products are alternative to antibiotics that can be employed as growth promoters in livestock and poultry production and attractive alternatives to synthetic chemical insecticides for insect pest management. Curcumin is a natural polyphenol compound from the rhizomes of turmeric (Curcuma spp.) and has been suggested to have a number of therapeutic benefits in the treatment of human diseases. It is also credited for its nutritional and pesticide properties improving livestock and poultry production performances and controlling insect pests. Recent studies reported that curcumin is an excellent feed additive contributing to poultry and livestock animal growth and disease resistance. Also, they detailed the curcumin's growth-inhibiting and insecticidal activity for reducing agricultural insect pests and insect vector-borne human diseases. This review aims to highlight the role of curcumin in increasing the growth and development of poultry and livestock animals and in controlling insect pests. We also discuss the challenges and knowledge gaps concerning curcumin use and commercialization as a feed additive and insect repellent.

The Impact of Various IPM Modules on the Management of Major Insect Pests of Sesame in Madhya Pradesh's Bundhelkhand Zone

The All India Coordinated Research Project Sesame Centre, College of Agriculture, JNKVV, Tikamgarh (M.P.) conducted a field experiment in 2017 kharif season using a Randomised block design to examine the effects of several IPM modules on the control of the main sesame insect pest. The experiment was set up using a Randomized Block Design with three replications, six treatments, and 21.6 M2 plots for each, using the sesame variety modrate resistant TKG -22 as the test variety. All of the plots' seeds were treated with imidacloprid 600 (5g/kg seed), and all plots except for the control were intercropping with black gram (3:3) and yellow sticky trap (1 trap/plot). Profenofos 50EC (2ml/L), NSKE5% (T1 and T2), two sprays of NSKE5% + NSKE 5%, Profenofos 0.1% (2ml/l)+ NSKE 5%, and Profenofos 0.1% were used as the treatment, with the untreated control side receiving no treatment. The results showed that treated areas with insecticides outperformed untreated areas by a significant margin. Of the treatments, treatment T5 (imidacloprid 600FS (5g/kg seed) foliar spray of NSKE5% at 30 & profenofos 0.11% (2ml/l)45 DAS) was the most effective and recorded the lowest population of Antigashtra (0.17) larvae/5plant). Bud flies were greatly diminished, and the populations of the three main sucking pests—mirid bugs (0.24 bugs per three leaves/plant), white flies (0.48 Nymphs per three leaves/plant were at their lowest. In T5 (imidacloprid 600FS (5g/kg seeds + intercropping with black gram 3:3) foliar srpray of NSKE5% at 30, & profenofos 0.1% (2ml/l), the seed equivalent yield was also greatly increased. 45 DAS had the highest seed equivalent yield of 1176 kg/ha, the highest net profit of Rs. 78667, and the highest B:C ratio (6.11); T4 had the highest seed equivalent yield of 1075 kg/ha, the net profit of Rs.70297, and the highest B:C ratio (5.48).

Special issue: Relationship between insect vectors and plant pathogens

Special issue: Relationship between insect vectors and plant pathogens

Assessment of Farmers' Attitudes Toward Pest Control Services Provided by Birds

Sustainable, conservation-oriented agricultural practices like pest regulation by insectivorous birds can decrease agrochemical use and enhance efforts on maximizing biodiversity. Previous research has shown that attracting insect-eating bird species can improve pest control in fruit crops and have a positive impact on fruit yield. We conducted a survey among fruit farmers to analyze the determinants of the potential adoption of biological pest control (BPC) provided by insectivorous birds on their farms. Quantitative analysis showed that their willingness to implement the innovative practice, favoring farmland wildlife, is influenced by both economic and noneconomic factors. Farmers’ overall interest in attracting birds to their farms was related to a variety of factors, including their understanding of the beneficial role of insectivorous birds in biodiversity, their desire to reduce production costs, and their personal characteristics. These factors influencing farmers’ motivations for participation in biological pest control should be taken into account to clarify the barriers that prevent, and the incentives that might draw them into adoption of an eco-friendly approach for insect pest control.
 Keywords: environmental benefits, innovative practice favoring farmland wildlife, farmers’ perceptions

INFLUENCE OF HOST PLANTS ON THE AGE-SPECIFICLIFE HISTORY TRAITS OF PARASITOID TRICHOGRAMMA CHILONIS (ISHII) A BIO-CONTROL AGENT OF THE LEPIDOPTERAN PEST HELICOVERPA ARMIGERA (LEPIDOPTERA: NOCTUIDAE) EGG DENSITIES

The pod borer, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is considered to be the most important pest in several crops such as chick pea (Cicer arietinum L.), Pigeon pea (Cajanus cajan L.) and Tomato (Lycopersicum esculentum L.) in North-East Uttar Pradesh, India. Extensive and indiscriminate use of chemical insecticides against pest caused severe effect on both soil health and environment, therefore effective bio-control agent (BCA), is generally perceived as providing both long-lasting insect pest control and negligible damage to the environment and non-target organisms. The aim of the present study is to control the pest population of H. armigera at Gorakhpur district by using effective bio-control agent. The age-specific life-table statistics of the parasitoid were observed at five different host densities (10, 25, 50, 100 and 200 eggs/female/day). It was found that the values of age-specific survival rate (lx) of T. chilonis increased progressively when more and more host eggs exposed to the female parasitoid throughout their life-span. It was highest at 200 host-density for all the host plants. The age-specific net fecundity rate (mx) was found to be host densities dependent. It appears that at low host density egg laying tendency of the female compel her to lay eggs in a previously parasitised egg. The longevity of the female were significantly (P < 0.001) correlated with host density. The data obtained from the present study will used in the development of management strategies for the control of H. armigera on host crops.

The Metagenomic Analysis of Viral Diversity in Colorado Potato Beetle Public NGS Data.

The Colorado potato beetle (CPB) is one of the most serious insect pests due to its high ecological plasticity and ability to rapidly develop resistance to insecticides. The use of biological insecticides based on viruses is a promising approach to control insect pests, but the information on viruses which infect leaf feeding beetles is scarce. We performed a metagenomic analysis of 297 CPB genomic and transcriptomic samples from the public National Center for Biotechnology Information Sequence Read Archive (NCBI SRA) database. The reads that were not aligned to the reference genome were assembled with metaSPAdes, and 13314 selected contigs were analyzed with BLAST tools. The contigs and non-aligned reads were also analyzed with Kraken2 software. A total of 3137 virus-positive contigs were attributed to different viruses belonging to 6 types, 17 orders, and 32 families, matching over 97 viral species. The annotated sequences can be divided into several groups: those that are homologous to genetic sequences of insect viruses (Adintoviridae, Ascoviridae, Baculoviridae, Dicistroviridae, Chuviridae, Hytrosaviridae, Iflaviridae, Iridoviridae, Nimaviridae, Nudiviridae, Phasmaviridae, Picornaviridae, Polydnaviriformidae, Xinmoviridae etc.), plant viruses (Betaflexiviridae, Bromoviridae, Kitaviridae, Potyviridae), and endogenous retroviral elements (Retroviridae, Metaviridae). Additionally, the full-length genomes and near-full length genome sequences of several viruses were assembled. We also found sequences belonging to Bracoviriform viruses and, for the first time, experimentally validated the presence of bracoviral genetic fragments in the CPB genome. Our work represents the first attempt to discover the viral genetic material in CPB samples, and we hope that further studies will help to identify new viruses to extend the arsenal of biopesticides against CPB.

A Review of Entomopathogenic Fungi of Iraq

Insect pest management has been dominated by the use of synthetic pesticides since early 1950s. However, lately this control method is not widely accepted due to an increase in environmental awareness, food safety concerns and the increasing number of insecticide-resistant species. In Iraq, the chemical insect pest control is still a dominant control method regardless of the increased pressure to replace it gradually with environment friendly alternatives such as predators, parasitoids, nematodes and entomopathogenic fungi. In Iraq, there is an increasing volume of research that has used different genus and species of entomopathogenic fungi for controlling several agricultural pests. However, these efforts are not yet reflected in the industry. In this short review article, a detailed summary of the research that has been done with entomopathogenic fungi in Iraq since 2000 is given and a brief discussion of the potential of using entomopathogenic fungi on a large scale in Iraq, its challenges, and recommendations is presented.

Horizontally transferred genes as RNA interference targets for aphid and whitefly control.

RNA interference (RNAi)-based technologies are starting to be commercialized as a new approach for agricultural pest control. Horizontally transferred genes (HTGs), which have been transferred into insect genomes from viruses, bacteria, fungi or plants, are attractive targets for RNAi-mediated pest control. HTGs are often unique to a specific insect family or even genus, making it unlikely that RNAi constructs targeting such genes will have negative effects on ladybugs, lacewings and other beneficial predatory insect species. In this study, we sequenced the genome of a red, tobacco-adapted isolate of Myzus persicae (green peach aphid) and bioinformatically identified 30 HTGs. We then used plant-mediated virus-induced gene silencing (VIGS) to show that several HTGs of bacterial and plant origin are important for aphid growth and/or survival. Silencing the expression of fungal-origin HTGs did not affect aphid survivorship but decreased aphid reproduction. Importantly, although there was uptake of plant-expressed RNA by Coccinella septempunctata (seven-spotted ladybugs) via the aphids that they consumed, we did not observe negative effects on ladybugs from aphid-targeted VIGS constructs. To demonstrate that this approach is more broadly applicable, we also targeted five Bemisia tabaci (whitefly) HTGs using VIGS and demonstrated that knockdown of some of these genes affected whitefly survival. As functional HTGs have been identified in the genomes of numerous pest species, we propose that these HTGs should be explored further as efficient and safe targets for control of insect pests using plant-mediated RNA interference.

Phylogenetic analysis and biocontrol potential of entomopathogenic fungi against Tropinota (=Epicometis) hirta (Poda) (Coleoptera: Cetoniidae) and the apple scab disease Ventura inaequalis

BackgroundEntomopathogenic fungi have long been used as a biopeptide in the biological control of insect pests in agriculture, forestry and veterinary. At the same time, it is known that these fungi have positive effects on plant growth, health, and the antagonist effect against various plant pathogens. Entomopathogenic fungal isolation was performed from soil samples collected from apple orchards and Tropinota (=Epicometis) hirta (Poda) (Coleoptera: Cetoniidae) adults which is an important pest of fruit trees. The isolated fungi were identified at the species level by phylogenetic analysis based on multi-locus sequence approach using various gene sequences (ITS, rpb1, bloc, EF1-α and β-tubulin). The fungi obtained were tested against T. hirta and the apple scab disease, Ventura inaequalis under laboratory conditions.ResultsThree (Bz isolates) and 15 (AK isolates) entomopathogenic fungi (EPF) were isolated from T. hirta adults and 48 soil samples, respectively. The isolated fungi were identified as Beauveria bassiana (Bz-1, Bz-2, AK-10, AK-14, AK-17, and AK-18), Metarhizium robertsii (Bz-3, AK-4, AK-5, AK-6, AK-7, AK-8, AK-9, AK-11, AK-13, AK-15, and AK-16) and Metarhizium sp. (AK-12). All isolated fungi were tested against T. hirta adults, causing the same mortality but different mycosis values. In addition, the antagonistic effects of fungal isolates against V. inaequalis, the important apple pathogen, were determined and the highest effect was obtained from B. bassiana AK-10 with 69.3%.ConclusionThis is the first study to determine the effectiveness of EPF against T. hirta and V. inaequalis, and the results obtained are thought to be useful for the biological control of both pests.

Mitochondrial genomes of soft scales (Hemiptera: Coccidae): features, structures and significance

BackgroundSoft scales (Hemiptera: Coccidae), including important agricultural and forestry pests, are difficult to identify directly by morphological characters. Mitochondrial genomes (mitogenomes) have been widely used in species identification and phylogenetic research. However, only three complete mitogenomes, and very few mitochondrial genes of scale insects (Hemiptera: Coccoidea) can be searched in GenBank. Mitogenome comparisons between scale insects or between scale insects and other hemipteran species have not yet been reported.ResultsIn this study, detailed annotation of three new mitogenomes and comparative analysis of scale insects were completed, as well as comparative analysis of the gene composition, gene arrangement, codon usage and evolutionary forces between scale insects and 488 other hemipteran species for the first time. We found that high A + T content, gene rearrangement and truncated tRNAs are common phenomena in soft scales. The average A + T content and codon usage bias of scale insects are higher and stronger than those of other hemipteran insects, respectively. The atp8 gene of Hemiptera and nine other protein-coding genes of scale insects are under positive selection with higher evolutionary rates.ConclusionsThe study revealed the particularity of the scale insect mitogenomes, which will provide a good reference for future research on insect phylogenetic relationships, insect pest control, biogeography and identification.

A Review of Insect Pest Management in Vegetable Crop Production in Nigeria.

Insect pest infestations and damage can limit the production of vegetables in the farming systems in Nigeria. This review looks at integrated insect pest management as a possible panacea for resolving insect pest issues in vegetable crops. The main vegetable crops which include okra, tomatoes, chilli peppers, cucumbers, green amaranth, carrots and onions are highlighted. The major insect pests of the various vegetables which include foliage beetles, caterpillars, aphids, fruit flies, stink bugs, and grasshoppers are also mentioned. The various control measures that have been empirically verified for the mitigation of the impact of these insect pests, including the application of synthetic insecticides, modification of agronomic practices, use of resistant varieties, application of botanicals, biological and mechanical controls, are discussed. Studies which have been carried out attempting to integrate two or more of the control strategies for better insect pest control are also reviewed. Strategies that can be put in place for the integrated pest management of vegetable insect pests in Nigeria are considered. Among the IPM (Integrated Pest Management) practices instituted for the mitigation of pest infestations on vegetable crops in Nigeria, intercropping of suitable vegetables in combination with the application of aqueous extracts of Azadirachta indica and Piper guineense seeds under good farm hygiene and sanitation proved to be most successful.

Steinernema carpocapsae

Steinernema and Heterorhabditis are not closely related phylogenetically but they share many characteristics via convergent evolution. Over 100 species of Steinernema have been described. Here we focus on Steinernema carpocapsae. All entomopathogenic nematode (EPN) species are symbiotically associated with entomopathogenic bacteria: S. carpocapsae retains Xenorhabdus nematophila. The bacteria kill the insect host along with EPN-produced factors, provide nutrition for the EPNs, and produce metabolites that protect the infection by inhibiting opportunistic colonization by other soil organisms. S. carpocapsae is a common species isolated from soil from every continent except Antarctica and was the first EPN-produced in vitro and commercially developed for pest control. To date, 12 species of EPNs have been commercialized for biological control of soil insect pests for agriculture, municipalities, and homeowners.

The complete genome assemblies of 19 insect pests of worldwide importance to agriculture

There are many insect pests worldwide that damage agricultural crop and reduce yield either by direct feeding or by the transmission of plant diseases. To date, control of pest insects has been achieved largely by applying synthetic insecticides. However, insecticide use can be seriously impacted by legislation that limits their use or by the evolution of resistance in the target pest. Thus, there is a move towards less use of insecticides and increased adoption of integrated pest management strategies using a wide range of non-chemical and chemical control methods. For good pest control there is a need to understand the mode of action and selectivity of insecticides, the life cycles of the pests and their biology and behaviours, all of which can benefit from good quality genome data. Here we present the complete assembled (chromosome level) genomes (incl. mtDNA) of 19 insect pests, Agriotes lineatus (click beetle/wireworm), Aphis gossypii (melon/cotton aphid), Bemisia tabaci (cotton whitefly), Brassicogethes aeneus (pollen beetle), Ceutorhynchus obstrictus (seedpod weevil), Chilo suppressalis (striped rice stem borer), Chrysodeixis includens (soybean looper), Diabrotica balteata (cucumber beetle), Diatraea saccharalis (sugar cane borer), Nezara viridula (green stink bug), Nilaparvata lugens (brown plant hopper), Phaedon cochleariae (mustard beetle), Phyllotreta striolata (striped flea beetle), Psylliodes chrysocephala (cabbage stem flea beetle), Spodoptera exigua (beet army worm), Spodoptera littoralis (cotton leaf worm), Diabrotica virgifera (western corn root worm), Euschistus heros (brown stink bug) and Phyllotreta cruciferae (crucifer flea beetle). For the first 15 of these we also present the annotation of genes encoding potential xenobiotic detoxification enzymes. This public resource will aid in the elucidation and monitoring of resistance mechanisms, the development of highly selective chemistry and potential techniques to disrupt behaviour in a way that limits the effect of the pests.

Lepidopteran pheromones as potential tools for pest insect control in the Arecaceae family

Lepidoptera is the second larger order of Insecta Class. Lepidopteran which feed of species of the Arecaceae family are notorious for the damage they cause, attacking a range from seedlings to the fruit. There are several control methods used against these pest insets, and among them, chemical pesticides are the most explored. Biological and mechanical control are also relevant, but they require a large number of trained workers. Behaviour modulation through chemical communication, using pheromones, stands out with a great potential to sustainably control insect populations. Pheromones have already been identified in lepidopteran pest which infest Arecaceae plants, they are mainly female-produced compounds, and belong to the sexual and contact types. The majority of pheromone compounds identified to this date are classified as Types I and II (unsaturated C10–C18 alcohols and their derivatives; and unsaturated C17–C25 hydrocarbons and their epoxides, respectively) with rare occurrences of Types 0 (short-chain secondary alcohols) and 3 (methyl-branched structures). Considering the vast quantity of lepidopteran species that attack this family and the economic impacts they generate, the present work aggregates the current knowledge on pheromones used the Integrated Pest Management of lepidopteran insects that damage palm plant species, and discusses both the compounds already applied in the field and the promising one that must yet to be tested.

Assessment of Resistance Mechanisms to Fall Armyworm, Spodoptera frugiperda in Tropical Maize Inbred Lines

The fall armyworm (FAW), Spodoptera frugiperda, a pest of maize native to the Americas first reported in West and Central Africa in 2016, severely threatens maize production and food security in Sub-Saharan Africa. Native genetic resistance is one of the best methods of control of insect pests as it is contained in the seed making it more amenable for use by farmers compared to other interventions and it is also compatible with other integrated pest management (IPM) options. An intensive screening against FAW was carried out by artificial infestation in greenhouse conditions in Kenya between 2017 and 2018 on about 3000 inbred lines available in the germplasm collection of the International Maize and Wheat Improvement Center (CIMMYT). Among these lines, only four showed to be resistant to FAW, but the mechanisms of resistance are not yet known. The objective of this study was to determine the resistance mechanisms specifically non-preference and antibiosis to S. frugiperda in these four selected resistant inbred lines. The studies were conducted under laboratory and net house conditions in Kenya from April 2020 to November 2021. Non-preference was assessed estimating the feeding preference by counting the number of FAW neonates found on each leaf portion, silk portion and grain using binary and multiple choice methods under laboratory conditions, while antibiosis was assessed through the relative growth rate (RGR) and developmental time of FAW larvae on leaves, silks and grains under both laboratory and net house conditions. Among the four resistant maize inbred lines tested, two, namely CML71 and CKSBL10008, exhibited the highest level of antibiosis resistance on leaves. Under laboratory conditions, the larval RGR reduced from 13 mg/d on the most susceptible line to 8 mg/d on CML71. CML71 also showed a good non-preference on leaves compared to other tested lines. Only 6% of neonates choose to feed on CML71 whereas more than 10% choose to feed on the other lines (and 15% on the most susceptible) in multiple choice tests. The non-preference for feeding and lower RGR of larvae on CML71 suggest a biochemical involvement resistance to FAW. Through this study, CML71 is revealed as a highly promising line for use in breeding for native genetic resistance to FAW in tropical maize.

Insights into insecticide-resistance mechanisms in invasive species: Challenges and control strategies.

Threatening the global community is a wide variety of potential threats, most notably invasive pest species. Invasive pest species are non-native organisms that humans have either accidentally or intentionally spread to new regions. One of the most effective and first lines of control strategies for controlling pests is the application of insecticides. These toxic chemicals are employed to get rid of pests, but they pose great risks to people, animals, and plants. Pesticides are heavily used in managing invasive pests in the current era. Due to the overuse of synthetic chemicals, numerous invasive species have already developed resistance. The resistance development is the main reason for the failure to manage the invasive species. Developing pesticide resistance management techniques necessitates a thorough understanding of the mechanisms through which insects acquire insecticide resistance. Insects use a variety of behavioral, biochemical, physiological, genetic, and metabolic methods to deal with toxic chemicals, which can lead to resistance through continuous overexpression of detoxifying enzymes. An overabundance of enzymes causes metabolic resistance, detoxifying pesticides and rendering them ineffective against pests. A key factor in the development of metabolic resistance is the amplification of certain metabolic enzymes, specifically esterases, Glutathione S-transferase, Cytochromes p450 monooxygenase, and hydrolyses. Additionally, insect guts offer unique habitats for microbial colonization, and gut bacteria may serve their hosts a variety of useful services. Most importantly, the detoxification of insecticides leads to resistance development. The complete knowledge of invasive pest species and their mechanisms of resistance development could be very helpful in coping with the challenges and effectively developing effective strategies for the control of invasive species. Integrated Pest Management is particularly effective at lowering the risk of chemical and environmental contaminants and the resulting health issues, and it may also offer the most effective ways to control insect pests.