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Melanagromyza sojae, the soybean stem fly (Zehntner) (Diptera: Agromyzidae), is a new pest in soybean and chickpea crops in South America. The objective of this study was to determine population fluctuations of M. sojae in both crops using adults caught in yellow sticky traps and by sampling injured plants. Additionally, an update of its geographical distribution in Argentina is provided. Adults of this species were collected for multiple years and during the cycles of both soybean and chickpea crops, on volunteer soybean plants, and during periods when the crops were not present. Injuries caused by M. sojae occurred throughout the growing period of chickpea and the reproductive stages of soybean. The highest infestation level was registered in chickpea crops. Regarding the distribution of M. sojae, we have reported Medicago sativa, Vigna radiata, Mellilothus sp., Helianthus annuus, Carthamus tinctorius, Heliotropium sp., Glandularia sp., and Parthenium sp. for the first time as new host plants in Argentina. The presence of M. sojae in Chaco province (Argentina) was also reported for the first time. Finally, the highest percentage of infestation registered in chickpea crops shows that M. sojae is a pest in chickpea-growing areas in Argentina where this pest is widely distributed. It is of vital importance to develop effective control methods, to research and recommend efficient management strategies and control methods for M. sojae in chickpea.

The objective of this work was to produce an herbicide by submerged fermentation in a stirred-tank bioreactor and to assess the potential herbicidal in pre-emergence, post-emergence, and in a detached leaves of Cucumis sativus var species. wisconsin (cucumber) and Sorghum bicolor (sorghum) species. Fermentations were carried out in a stirred-tank bioreactor with useful volume of 3L. Stirring rate (40, 50, and 60 rpm) and aeration (1, 2 and 3 vvm) were the variables studied for bioherbicide production. Fermented broth was fractioned with different solvents to identify the molecules produced by the fungus in a multi-dimensional gas chromatograph system. Bioherbicide showed 100% inhibition of germination of both species in the pre-emergence tests. From detached leaves tests were verified yellowish lesions in Cucumis sativus and necrotic lesions on leaves of Sorghum bicolor . Post-emergence test presented variation of the phytotoxicity from 25 to 66% for the species C. sativus and from 32 to 58% by S. bicolor . The metabolites produced by submerged fermentation of Phoma sp. presented activity in pre-emergence, post-emergence, and detached leaves of C. sativus and S. bicolor and it could be an alternative in the future for weed control.

The lesser mealworm, Alphitobius diaperinus (Panzer, 1797) (Coleoptera:Tenebrionidae), is considered the primary insect pest in broiler farms in Brazil. In this study, we characterized the susceptibility of A. diaperinus populations from broiler farms of southern Brazil to cypermethrin and chlorpyrifos. Larvae and adults of A. diaperinus were exposed to these technical insecticides diluted in acetone in residual bioassays. A geographic variation in the susceptibility of larvae and adults of A. diaperinus to both insecticides was detected.The larval LC50 for cypermethrin ranged from 0.43 to 7.33 µg a.i./cm2. Two populations from Santa Catarina state presented higher resistance ratios of 13.6- and 17-fold. When adults were exposed to cypermethrin, the LC50 ranged from 0.46 to 4.93 µg a.i./cm2, with population SC-3 from Santa Catarina having lower susceptibility (resistance ratio of 10.7-fold). When exposed to chlorpyrifos, A. diaperinus larvae present LC50 values ranging from 0.21 to 4.30 µg a.i./cm2. Larvae from Paraná and Santa Catarina (SC-1 population) presented the highest resistance ratios, ranging from 10- to 20-fold. In adults, the LC50 of chlorpyrifos ranged from 0.17 to 5.30 µg a.i./cm2, showing a maximum resistance ratio of 31-fold in a population from Paraná state. Based on LC99 values, candidate diagnostic concentrations of 15 and 12 µg a.i./cm2 of cypermethrin and chlorpyrifos, respectively, were also estimated for the resistance monitoring of A. diaperinus in Brazil. The implications of these results in Insect Resistance Management are discussed.

Chrysodeixis includens (Walker, [1858]) is one of the most important defoliator of soybean in Brazil because of its extensive geographical distribution and high tolerance to insecticides compared with other species of caterpillars. Because of this, we conducted bioassays to evaluate the efficacy of pyrethroid λ-cyhalothrin on a C. includens resistant strain (MS) and a susceptible (LAB) laboratory strain. High throughput RNA sequencing (RNA-seq) of larval head and body tissues were performed to identify potential molecular mechanisms underlying pyrethroid resistance. Insecticide bioassays showed that MS larvae exhibit 28.9-fold resistance to pyrethroid λ-cyhalothrin relative to LAB larvae. RNA-seq identified evidence of metabolic resistance in the head and body tissues: 15 cytochrome P450 transcripts of Cyp6, Cyp9, Cyp4, Cyp304, Cyp307, Cyp337, Cyp321 families, 7 glutathione-S-transferase (Gst) genes, 7 α-esterase genes from intracellular and secreted catalytic classes, and 8 UDP-glucuronosyltransferase (Ugt) were overexpressed in MS as compared with LAB larvae. We also identified overexpression of GPCR genes (CiGPCR64-like and CiGPCRMth2) in the head tissue. To validate RNA-seq results, we performed RT-qPCR to assay selected metabolic genes and confirmed their expression profiles. Specifically, CiCYP9a101v1, CiCYP6ae149, CiCYP6ae106v2, CiGSTe13, CiCOE47, and CiUGT33F21 exhibited significant overexpression in resistant MS larvae. In summary, our findings detailed potential mechanisms of metabolic detoxification underlying pyrethroid resistance in C. includens.

The sugarcane borer, Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) and the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), are important pests of corn in Brazil and have not been successfully managed, because of the difficulty of managing them with pesticides. The objective of this study was to evaluate the effect of Bt corn MON810, transformed with a gene from Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) insecticide seed treatment, and foliar insecticide spray using treatments developed for control of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), which is the major pest of corn. The experiments were done under field conditions in early- and late-planted corn in the state of Rio Grande do Sul, Brazil, and in the laboratory. The MON810 corn reduced infestations and damage by D. saccharalis and H. zea. The insecticides used in seed treatments or foliar sprays did not affect D. saccharalis and H. zea infestations or damage levels. The exception was the insecticide seed treatment in non-transformed corn, which reduced early infestations of D. saccharalis. The MON810 corn, therefore, can be used for managing these two pest species, especially D. saccharalis.

Tuta absoluta is one of the most devastating pests of fresh market and processing tomatoes. Native to South America, its detection was confined to that continent until 2006 when it was identified in Spain. It has now spread to almost every continent, threatening countries whose economies rely heavily on tomatoes. This insect causes damage to all developmental stages of its host plant, leading to crop losses as high as 80–100%. Although T. absoluta has yet to be found in the USA and China, which makes up a large portion of the tomato production in the world, computer models project a high likelihood of invasion. To halt the continued spread of T. absoluta and limit economic loss associated with tomato supply chain, it is necessary to develop accurate and efficient methods to identify T. absoluta and strengthen surveillance programs. Current identification of T. absoluta relies on examination of morphology and assessment of host plant damage, which are difficult to differentiate from that of native tomato pests. To address this need, we sequenced the genomes of T. absoluta and two closely related Gelechiidae, Keiferia lycopersicella and Phthorimaea operculella , and developed a bioinformatic pipeline to design a panel of 21-SNP markers for species identification. The accuracy of the SNP panel was validated in a multiplex format using the iPLEX chemistry of Agena MassARRAY system. Finally, the new T. absoluta genomic resources we generated can be leveraged to study T. absoluta biology and develop species-specific management strategies.

Soybean looper (SBL), Chrysodeixis includens (Walker) (Lepidoptera: Noctuidae), is an important pest of soybean and cotton in Brazil. The use of insecticides is one of the main control tactics against this pest. To support Integrated Pest Management (IPM) and Insect Resistance Management (IRM) programs, we characterized the susceptibility of Brazilian populations of SBL to insecticides. Field populations were collected from soybean fields during the 2016–2017 and 2017–2018 crop seasons. In the laboratory, late L2/early L3 larvae were exposed to insecticides in diet-overlay or topical bioassays. Field populations of SBL showed high susceptibility to spinetoram (LC50 = 0.074–0.25 μg a.i. per cm2), indoxacarb (LC50 = 0.46–0.94 μg a.i. per cm2), thiodicarb (LC50 = 9.14–36.61 μg a.i. per cm2), chlorantraniliprole (LC50 = 0.15–0.57 μg a.i. per cm2), flubendiamide (LC50 = 0.45–2.01 μg a.i. per cm2), and chlorfenapyr (LC50 = 0.15–0.25 μg a.i. per cm2); the resistance ratios were less than 16-fold. In contrast, SBL populations have reduced susceptibility to lambda-cyhalothrin (LC50 = 3.71–9.54 μg a.i./cm2), methoxyfenozide (LC50 = 0.67–4.23 μg a.i. per cm2), novaluron (LC50 = 27.52–77.63 μg a.i. per cm2), and teflubenzuron (LC50 = 13.41–73.02 μg a.i. per cm2). The resistance ratios relative to a Lab population (susceptible of reference) was up to 38-, 63-, 1,553-, and 5,215-fold, respectively. These high resistance ratios can be associated with resistance evolution. Implications of these findings to IPM and IRM programs are discussed.

Production of a bioherbicide for biological control of weeds requires a series of steps, from selection of a suitable microbial strain to final formulation. Thus, this study aimed to select fungi for production of secondary metabolites with herbicidal activity using biological resources of the Brazilian Pampa biome. Phytopathogenic fungi were isolated from infected tissues of weeds in the Pampa biome. A liquid synthetic culture medium was used for production of metabolites. The phytotoxicity of fungal metabolites was assessed via biological tests using the plant Cucumis sativus L., and the most promising strain was identified by molecular analysis. Thirty-nine fungi were isolated, and 28 presented some phytotoxic symptoms against the target plant. Fungus VP51 belonging to the genus Diaporthe showed the most pronounced herbicidal activity. The Brazilian Pampa biome is a potential resource for the development of new and sustainable chemical compounds for modern agriculture.

The occurrence of insect pests in crops directly affects the yield of plants and grains. This scenario led to the mass investigation of chemical products that overcome these adversities and provide control potential. Nonetheless, over the years, this strategy resulted in high production costs, generation of waste harmful to the environment, and resistance of target insects. The adoption of alternative practices, such as the formulation and production of products of microbial origin, emerges as an encouraging tool compared to control alternatives, indicating a sustainability bias, and allowing a reduction in the risks of human and animal contamination. The purpose of this study was to perform bioprospecting for microbial agents with potential insecticidal effects. The isolated microorganisms were submitted to submerged fermentation, at 28 °C and 120 rpm, for seven days. The fermented broth was filtered using a vacuum pump and centrifuged at 3200× g and 10 °C for 10 min. Initially, 163 microbial agents were collected. Subsequently, a pre-selection of the 50 most promising bioagents was conducted, based on the mortality rates (%) of the applied isolates to target pests. Furthermore, a global mathematical modeling design was created, indicating the best potential microorganisms. Moreover, to stipulate the difference between treatments, dilutions of the fermented broths of each microorganism were conducted (n × 10−5–n × 10−8). Mortality was maximum (100%) for Helicoverpa zea and Euschistus heros. Other encouraging results were indicated in the control of Anticarsia gemmatalis and Chrysodeixis includens (up to 87.5%) and Elasmopalpus lignosellus (up to approximately 83.5%). Fungal isolates were identified as Talaromyces piceae. Among the bacteria, based on sequencing of the 16S ribosomal gene, the isolates were identified as Lysinibacillus fusiformis, Paenibacillus ottowii, and Clostridium sphenoides. The results obtained are relevant to the scientific community and, especially, are interesting for companies that are operating in this field in the agricultural sector.

This study focused on obtaining a spray-dried powder containing chitinase and β-1,3-glucanase as active ingredients for the control of agricultural pests. Different carriers were tested in the spray drying of these enzymes. The effectiveness of the application of the enzymes was evaluated against Ceratitis capitata (Diptera: Tephritidae). The combination of maltodextrin (2.5% w/v), gum Arabic (2.5% w/v), and soluble starch (5.0% w/v) as carriers showed the best result of residual activity of β-1,3-glucanase (88.36%) and chitinase (69.82%), with a powder recovery of 45.49%. The optimum conditions for the operational parameters of the spray drying process were: inlet air temperature of 120 °C, drying airflow rate of 1.1 m3/min, feed flow rate of 5.8 mL/min, and nozzle air pressure of 0.4 MPa. The powder produced showed 65.6% efficiency for the control of the fly. These results demonstrated the possibility of using the spray drying process to obtain an enzymatic potential product for biological pest control.