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Nuclear receptors are important targets in the research for the discovery of brand-new insecticides, and the ecdysteroid receptor is one of the most important targets nowadays. In this study, nine organocalcogenic compounds analogs of dibenzoylhydrazine were tested in a screening system, that presented at least 80% of compatibility in at least one of the three micromolar concentrations tested. We optimized in embryonic cell lines of the order Lepidoptera (SF9) and Diptera (S2), and these cell lines were transfected with a specific reporter plasmid. The nine compounds tested did not present agonist activity in both cell lines tested. In S2 cells the DAF-2 molecule inhibited the ECR-USP luminescence in 29.91%, and the DAF-4 molecule significantly inhibited the nuclear receptor luminescence in 51 to 55% compared to 20-Hydroxyecdysone (control). In SF9 cells, DAF-2 inhibited ECR-USP luminescence in 19.62%, and DAF-4 inhibited the receptor luminescence by 35.14% compared to 20-Hydroxyecdysone (control). In silico analysis of the Drosophila melanogaster receptor with the compound, DAF-2 showed inhibition of amino acids THR467 and MET-508 and with compound DAF-4 inhibition of ARG-511. For the of Heliothis virescens receptor for dendritic compounds, DAF-2 promoted inhibition of amino acids THR-343 and ARG-387 and DAF-4 inhibited ASN-504 and ARG-387

Use of pesticides in agroecosystems is considered a major cause of bees diversity losses in the Neotropics, where Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) (Hymenoptera: Apidae: Meliponini) are wild pollinators of native and crop plants. The aim of this study was to know the acute lethal toxicity of acetamiprid, malathion, phosmet and spinosad insecticides on P. emerina and T. fiebrigi. We obtained the mean concentration and mean lethal dose (LC50 and LD50) and the mean survival of workers after oral and topical exposure to insecticides, respectively. The LC50 values (ng a.i./μl of diet) and the decreasing order of toxicity for P. emerina was spinosad (4.96) > malathion (18.75) > phosmet (97.33) > acetamiprid (4204.06), and for T. fiebrigi also was spinosad (5.65) > malathion (8.39) > phosmet (53.91) > acetamiprid (9841.32), when orally exposed. The LD50 values (ng a.i./bee) and the decreasing order of toxicity for P. emerina was spinosad (1.90) > malathion (10.90) > phosmet (19.54) > acetamiprid (6216.55) and for T. fiebrigi was malathion (29.29) ≥ spinosad (29.79) > phosmet (41.95) > acetamiprid (1421.23), when topically exposed. The mean survival (hours) of contaminated bees by malathion, phosmet, and spinosad, was 11.81, 7.20, and 12.32 for P. emerina and 8.55, 7.20, and 13.34 for T. fiebrigi when orally exposed; and was 4.87, 9.87 and 11.17 for P. emerina, and 4.87, 4.76, and 19.05 for T. fiebrigi when topically exposed. Malathion, phosmet, and spinosad were highly toxic, while acetamiprid was moderately toxic. Our results indicated that the insecticides tested, mainly malathion, phosmet, and spinosad may be harmful to P. emerina and T. fiebrigi, making it essential to propose measures to minimize their impact on wild pollinators.

Insecticidal gene silencing by RNA interference (RNAi) involves a post-transcriptional mechanism with great potential for insect control. Here, we aim to summarize the progress on RNAi research toward control of insect pests in the Neotropical region and discuss factors determining its efficacy and prospects for pest management. We include an overview of the available RNAi information for Neotropical pests in the Lepidoptera, Coleoptera, Diptera, and Hemiptera orders. Emphasis is put on significant findings in the use of RNAi against relevant Neotropical pests, including diamondback moth (Plutella xylostella L.), Asian citrus psyllid (Diaphorina citri Kuwayama), and the cotton boll weevil (Anthonomus grandis Boheman). We also examine the main factors involved in insecticidal RNAi efficiency and major advances to improve screening of lethal genes, formulation, and delivery. Few studies detail resistance mechanisms to RNAi, demonstrating a need for more research. Advances in formulation, delivery, and resistance management tools for insecticidal RNAi in the Neotropics can provide a basis for efficient field application.

Strawberry cultivation under semi-hydroponic conditions has increased in the Southern region of Brazil since it facilitates management, besides avoiding weather adversities, pests and diseases. However, protected environment can hamper the access of pollinator insects, essential for crop productivity. This work aimed to know the entomofauna associated with strawberry cultivar Albion cultivated under semi-hydroponic conditions and to identify potential species of native pollinating bees. Insects were captured at different times of the day (9:30 a.m., 12:30 p.m. and 3:30 p.m.) in three commercial crops located in Bento Gonçalves and Farroupilha, Rio Grande do Sul. In each study area, three days of sampling were carried out during January 2017. The flowers were visited by 47 species of insects. Apis mellifera (Hymenoptera: Apidae) was the most abundant, constant, dominant and frequent species. Twelve species of native bees were identified: Tetragonisca fiebrigi, Tetrapedia sp., Trigona spinipes, Schwarziana quadripunctata, Plebeia emerina, P. remota, Bombus pauloensis (Hymenoptera: Apidae), Dialictus sp.1, Dialictus sp.2, Augochloropsis sp.1, Augochloropsis sp.2, and Augochlora sp.1 (Hymenoptera: Halictidae). All these species are potential pollinators of the crop. The native species T. fiebrigi, P. emerina and P. remota present potential for directed pollination of the strawberry under protected cultivation due to abundance and ease of management. RESUMO O cultivo do morangueiro no sistema semi-hidropônico tem aumentado na região Sul do Brasil por facilitar o manejo, além de evitar adversidades climáticas, pragas e doenças. Contudo, nesse sistema, o ambiente protegido pode dificultar o acesso de insetos polinizadores, fundamentais para a produtividade da cultura. Assim, este trabalho teve como objetivo conhecer a entomofauna associada ao morangueiro da cultivar Albion cultivado no sistema semi-hidropônico e identificar potenciais espécies de abelhas nativas polinizadoras. Os insetos foram capturados em diferentes períodos do dia (9h30min, 12h30min e 15h30min) em três cultivos comerciais localizados nos municípios de Bento Gonçalves e Farroupilha, Rio Grande do Sul. Em cada área de estudo foram realizados três dias de amostragens durante janeiro de 2017. As flores foram visitadas por 47 espécies de insetos. Apis mellifera (Hymenoptera: Apidae) foi a espécie mais abundante, constante, dominante e frequente. Doze espécies de abelhas nativas foram identificadas: Tetragonisca fiebrigi, Tetrapedia sp., Trigona spinipes, Schwarziana quadripunctata, Plebeia emerina, P. remota, Bombus pauloensis (Hymenoptera: Apidae), Dialictus sp.1, Dialictus sp.2, Augochloropsis sp.1, Augochloropsis sp.2 e Augochlora sp.1 (Hymenoptera: Halictidae). Todas essas espécies são potenciais polinizadoras da cultura. As espécies nativas T. fiebrigi, P. emerina e P. remota apresentam potencial para polinização dirigida do morangueiro em cultivo protegido devido a abundância e facilidade de manejo.

Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) primarily attack the pods and seeds of soybean plants, causing severe economic losses in Neotropical Region, and chemical control is essential to avoid these losses. Thus, insecticides more effective against this pest and less toxic to Telenomus podisi Ashmead (Hymenoptera: Platygastridae) - the main biological control agent of E. heros - should be used. In this report, we studied the differential acute impacts of pesticides used in Brazilian soybean against E. heros and T. podisi and evaluated their sublethal effects on the parasitoid to identify effective pesticides towards the pest with less harmful effect to the natural enemy. The LC50 of the insecticides to E. heros ranged from 1.20 to 533.74 ng a.i./cm2; the order of toxicity was thiamethoxam + lambda-cyhalothrin > acetamiprid + fenpropathrin > zeta-cypermethrin > acephate > imidacloprid. All pesticides were classified as slightly to moderately toxic to T. podisi based on the risk quotient. The exposure of T. podisi females to imidacloprid and the insecticide pre-formulated mixtures reduced the emergence of the offspring parasitoids by up to 40% whereas zeta-cypermethrin and the insecticides pre-formulated mixtures reduced offspring survival. The preferred order of choice of insecticides for the management of E. heros according to agronomic, toxicological, and environmental feasibility was the following: thiamethoxam + lambda-cyhalothrin > zeta-cypermethrin > acetamiprid + fenpropathrin > acephate > imidacloprid. Our study provides important and pioneer information to select insecticides for effective control of E. heros with lower impacts on T. podisi.

Of the different approaches to pest control, use of juvenile hormone analogs (e.g. methoprene), molting hormone (20-hydroxyecdysone) analogs (e.g. tebufenozide) and chitin synthesis inhibitors (e.g. diflubenzuron) has dominated this field. Since they adversely interfere with the normal growth and development in one way or another, they have been collectively called as 'insect growth regulators' or IGRs. A lesser known fact is that they all have deleterious effects on reproduction as well as act as ovicides. The raison d'être for this review is to summarize what we have learnt during the last 3-4 decades in the use of these IGRs, how they affect insect reproduction and how we can apply this knowledge to control pest insects. Finally, we present, information on the state of the art use of molecular technologies such as RNAi and CRISPR/Cas9 applications for pest management targeting insect reproduction.

The use of pesticides is considered one of the most important threats to pollinators, especially since they are widely used in agriculture for pest control. In the last years, several studies have reported severe secondary effects on various bee species, including exotic and native bees. In this study, lethal (mortality) and sublethal (locomotor activity) effects of insecticides and acaricides used in strawberries in Brazil (abamectin, novaluron, spinetoram, and thiamethoxam) were evaluated on the native stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi. The results showed that the effects varied significantly according to the pesticide, type of exposure (oral or topical), and bee species. Through oral exposure, M. quadrifasciata was more susceptible to all insecticides except for abamectin, while in topical exposure, T. fiebrigi was more sensitive. Thiamethoxam followed by spinetoram and abamectin were the most lethal, regardless of species or exposure route; novaluron was not harmful at the highest tested dose. The locomotor activity of bees was altered in the presence of sublethal doses (LC10 and LC50) of all insecticides. Spinetoram and abamectin can be as much as toxic as thiamethoxam against M. quadrifasciata and T. fiebrigi in laboratory experiments. These findings should be confirmed in field experiments to define possibilities to combine pest control and pollinator management. In crops like strawberries, the selectivity of native pollinators should be considered.

Over the past few years, the use of RNA interference (RNAi) for insect pest management has attracted considerable interest in academia and industry as a pest-specific and environment-friendly strategy for pest control. For the success of this technique, the presence of core RNAi genes and a functional silencing machinery is essential. Therefore, the aim of this study was to test whether the Neotropical brown stinkbug Euschistus heros has the main RNAi core genes and whether the supply of dsRNA could generate an efficient gene silencing response. To do this, total mRNA of all developmental stages was sequenced on an Illumina platform, followed by a de novo assembly, gene annotation and RNAi-related gene identification. Once RNAi-related genes were identified, nuclease activities in hemolymph were investigated through an ex vivo assay. To test the functionality of the siRNA machinery, E. heros adults were microinjected with ~28 ng per mg of insect of a dsRNA targeting the V-ATPase-A gene. Mortality, relative transcript levels of V-ATPase-A, and the expression of the genes involved in the siRNA machinery, Dicer-2 (DCR-2) and Argonaute 2 (AGO-2), were analyzed. Transcriptome sequencing generated more than 126 million sequenced reads, and these were annotated in approximately 80,000 contigs. The search of RNAi-related genes resulted in 47 genes involved in the three major RNAi pathways, with the absence of sid-like homologous. Although ex vivo incubation of dsRNA in E. heros hemolymph showed rapid degradation, there was 35% mortality at 4 days after treatment and a significant reduction in V-ATPase-A gene expression. These results indicated that although sid-like genes are lacking, the dsRNA uptake mechanism was very efficient. Also, 2-fold and 4-fold overexpression of DCR-2 and AGO-2, respectively, after dsRNA supply indicated the activation of the siRNA machinery. Consequently, E. heros has proven to be sensitive to RNAi upon injection of dsRNA into its hemocoel. We believe that this finding together with a publically available transcriptome and the validation of a responsive RNAi machinery provide a starting point for future field applications against one of the most important soybean pests in South America.

Several fruit fly species are invasive pests that damage quality fruits in horticultural crops and cause significant value losses. The management of fruit flies is challenging due to their biology, adaptation to various regions and wide range of hosts. We assessed the historical and current approaches of fruit fly management research worldwide, and we established the current knowledge of fruit flies by systematically reviewing research on monitoring and control tactics, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We performed a systematic review of research outputs from 1952 to 2017, by developing an a priori defined set of criteria for subsequent replication of the review process. This review showed 4900 publications, of which 533 publications matched the criteria. The selected research studies were conducted in 41 countries for 43 fruit fly species of economic importance. Although 46% of the studies were from countries of North America, analysis of the control tactics and studied species showed a wide geographical distribution. Biological control was the most commonly studied control tactic (29%), followed by chemical control (20%), behavioral control, including SIT (18%), and quarantine treatments (17%). Studies on fruit flies continue to be published and provide useful knowledge in the areas of monitoring and control tactics. The limitations and prospects for fruit fly management were analyzed, and we highlight recommendations that will improve future studies.

Scientists have made significant progress in understanding and unraveling several aspects of double-stranded RNA (dsRNA)-mediated gene silencing during the last two decades. Now that the RNA interference (RNAi) mechanism is well understood, it is time to consider how to apply the acquired knowledge to agriculture and crop protection. Some RNAi-based products are already available for farmers and more are expected to reach the market soon. Tailor-made dsRNA as an active ingredient for biopesticide formulations is considered a raw material that can be used for diverse purposes, from pest control and bee protection against viruses to pesticide resistance management. The RNAi mechanism works at the messenger RNA (mRNA) level, exploiting a sequence-dependent mode of action, which makes it unique in potency and selectivity compared with conventional agrochemicals. Furthermore, the use of RNAi in crop protection can be achieved by employing plant-incorporated protectants through plant transformation, but also by non-transformative strategies such as the use of formulations of sprayable RNAs as direct control agents, resistance factor repressors or developmental disruptors. In this review, RNAi is presented in an agricultural context (discussing products that have been launched on the market or will soon be available), and we go beyond the classical presentation of successful examples of RNAi in pest-insect control and comprehensively explore its potential for the control of plant pathogens, nematodes and mites, and to fight against diseases and parasites in beneficial insects. Moreover, we also discuss its use as a repressor for the management of pesticide-resistant weeds and insects. Finally, this review reports on the advances in non-transformative dsRNA delivery and the production costs of dsRNA, and discusses environmental considerations. © 2017 Society of Chemical Industry.

Understanding the biology of insect pests is an important step towards developing appropriate control strategies. In this study, a CRISPR/Cas9 gene knockout work flow was established for the first time and was together with RNAi used as tools to study gene functions in the Neotropical stink bug, Euschistus heros. RNAi was first employed to study the function of three genes, abnormal wing disc (awd), tyrosine hydroxylase (th) and yellow (yel). Targeting awd and th resulted in distinct malformed phenotypes such as a deformed wing or a lighter cuticle pigmentation/defects in cuticle sclerotization, respectively. However, no distinct phenotype was observed for yel. To further investigate the function of yel, a CRISPR/Cas9 gene editing protocol was developed for E. heros. A total of 719 eggs were microinjected with single-guide (sgRNA) and Cas9 and total of six insects hatched. Out of these six nymphs, one insect showed mutation in yel but no clear phenotype was visible. Although, we were unable to generate insects with a distinct phenotype for yel, a successful gene editing workflow was established to complement RNAi for future functional gene studies in E. heros. Additionally, we provided recommendations to improve the established gene editing workflow. The Neotropical brown stink bug, Euschistus heros, is one of the most important stink bug pests in leguminous plants in South America. RNAi and CRISPR/Cas9 are important and useful tools in functional genomics, as well as in the future development of new integrated pest management strategies. Here, we explore the use of these technologies as complementing functional genomic tools in E. heros. Three genes, abnormal wing disc (awd), tyrosine hydroxylase (th) and yellow (yel), known to be involved in wing development (awd) and the melanin pathway (th and yel) in other insects, were chosen to be evaluated using RNAi and CRISPR/Cas9 as tools. First, the genes were functionally characterized using RNAi knockdown technology. The expected phenotype of either deformed wing or lighter cuticle pigmentation/defects in cuticle sclerotization was observed for awd and th, respectively. However, for yel, no obvious phenotype was observed. Based on this, yel was selected as a target for the development of a CRISPR/Cas9 workflow to study gene knockout in E. heros. A total of 719 eggs were injected with the Cas9 nuclease (300 ng/mu L) together with the sgRNA (300 ng/mu L) targeting yel. A total of six insects successfully hatched from the injected eggs and one of the insects showed mutation in the target region, however, the phenotype was still not obvious. Overall, this study for the first time provides a useful CRISPR/Cas9 gene editing methodology to complement RNAi for functional genomic studies in one of the most important and economically relevant stink bug species.

Since the discovery of RNA interference (RNAi), scientists have made significant progress towards the development of this unique technology for crop protection. The RNAi mechanism works at the mRNA level by exploiting a sequence-dependent mode of action with high target specificity due to the design of complementary dsRNA molecules, allowing growers to target pests more precisely compared to conventional agrochemicals. The delivery of RNAi through transgenic plants is now a reality with some products currently in the market. Conversely, it is also expected that more RNA-based products reach the market as non-transformative alternatives. For instance, topically applied dsRNA/siRNA (SIGS – Spray Induced Gene Silencing) has attracted attention due to its feasibility and low cost compared to transgenic plants. Once on the leaf surface, dsRNAs can move directly to target pest cells (e.g., insects or pathogens) or can be taken up indirectly by plant cells to then be transferred into the pest cells. Water-soluble formulations containing pesticidal dsRNA provide alternatives, especially in some cases where plant transformation is not possible or takes years and cost millions to be developed (e.g., perennial crops). The ever-growing understanding of the RNAi mechanism and its limitations has allowed scientists to develop non-transgenic approaches such as trunk injection, soaking, and irrigation. While the technology has been considered promising for pest management, some issues such as RNAi efficiency, dsRNA degradation, environmental risk assessments, and resistance evolution still need to be addressed. Here, our main goal is to review some possible strategies for non-transgenic delivery systems, addressing important issues related to the use of this technology.

RNA interference (RNAi) technology has been used in the development of approaches for pest control. The presence of some essential genes, the so-called “core genes,” in the RNAi machinery is crucial for its efficiency and robust response in gene silencing. Thus, our study was designed to examine whether the RNAi machinery is functional in the South American (SA) fruit fly Anastrepha fraterculus (Diptera: Tephritidae) and whether the sensitivity to the uptake of double-stranded RNA (dsRNA) could generate an RNAi response in this fruit fly species. To prepare a transcriptome database of the SA fruit fly, total RNA was extracted from all the life stages for later cDNA synthesis and Illumina sequencing. After the de novo transcriptome assembly and gene annotation, the transcriptome was screened for RNAi pathway genes, as well as the duplication or loss of genes and novel target genes to dsRNA delivery bioassays. The dsRNA delivery assay by soaking was performed in larvae to evaluate the gene-silencing of V-ATPase, and the upregulation of Dicer-2 and Argonaute-2 after dsRNA delivery was analyzed to verify the activation of siRNAi machinery. We tested the stability of dsRNA using dsGFP with an in vitro incubation of larvae body fluid (hemolymph). We identified 55 genes related to the RNAi machinery with duplication and loss for some genes and selected 143 different target genes related to biological processes involved in post-embryonic growth/development and reproduction of A. fraterculus. Larvae soaked in dsRNA (dsV-ATPase) solution showed a strong knockdown of V-ATPase after 48 h, and the expression of Dicer-2 and Argonaute-2 responded with an increase upon the exposure to dsRNA. Our data demonstrated the existence of a functional RNAi machinery in the SA fruit fly, and we present an easy and robust physiological bioassay with the larval stages that can further be used for screening of target genes at in vivo organisms’ level for RNAi-based control of fruit fly pests. This is the first study that provides evidence of a functional siRNA machinery in the SA fruit fly.

Toxic bait formulations have been one of the main strategies used in apple orchards in southern Brazil for the control of South American fruit fly. However, its effects on the stingless bees Plebeia emerina (Friese) and Tetragonisca fiebrigi (Schwarz) are unknown. This study aimed to assess the toxicity, attraction and repellency of food lures and toxic baits on P. emerina and T. fiebrigi. We evaluated the food lures Anamed® (pure), Biofruit® (3%), Flyral® (1.25%), Sugarcane molasses (7%) and Samarita Tradicional® (3%), in toxic baits formulations associated with spinosad (Tracer® 480SC) and malathion (Malathion® 1000EC), and the ready-to-use toxic baits Success® 0.02CB and Gelsura®. We obtained the mean lethal concentration (LC50) and the mean survival of workers after exposure to toxic bait formulations. In the field, we carried out attraction and repellency tests of toxic baits to foraging. The food lures associated with malathion and spinosad showed different levels of toxicity to P. emerina and T. fiebrigi. Sugarcane molasses and Samarita Tradicional® associated with spinosad showed high toxicity, with LC50 values of 6.92 and 10.61 ng/μL diet to P. emerina, and of 4.37 and 15.48 ng/μL diet to T. fiebrigi, respectively. Gelsura® and food lures with malathion caused rapid workers mortality, with mean survival less than 3 h after exposure. No toxic bait formulation was attractive to P. emerina foragers in the field. Anamed®, Gelsura®, and Success® were repellent to P. emerina foragers.

In insects, the identity of body segments is controlled by homeotic genes and the knockdown of these genes during embryogenesis can lead to an abnormal development and/or atypical phenotypes. The main goal of this study was to investigate the involvement of labial (lab), deformed (dfd), sex comb reduced (scr), extradenticle (exd) and proboscipedia (pb) in rostrum development in the Neotropical brown stink bug Euschistus heros, using parental RNAi (pRNAi). To achieve this objective, 10-days-old adult females were first microinjected with double-stranded RNAs (dsRNA) targeting these five genes. Then, the number of eggs laid per female, the percentage of hatched nymphs with normal or abnormal phenotype and target gene silencing were evaluated. Except for the dsDfd-treatment, the number of eggs laid per female per day was not affected by the different dsRNA-treatments compared to the control (dsGFP). However, treatment with either dsLab, dsDfd, dsScr or dsExd caused a strong reduction in egg hatching. The dsExd-treatment caused no apparent change in phenotype in the nymphs while hatched nymphs from the dsDfd, dsScr and dsPb-treatment showed abnormalities in the rostrum. Particularly for the dsPb-treatment, 91% of the offspring displayed a bifurcated rostrum with a leg-like structure. Overall, these results indicate that these five genes are involved in E. heros embryonic development and that the knockdown of dfd, scr and pb leads to an abnormal development of the rostrum. Additionally, this study demonstrates the efficiency of pRNAi in studying genes involved in embryogenesis in E. heros, with clear phenotypes and a strong target gene silencing in the next generation, after treatment of the parent female adult with gene-specific dsRNA.

Made available in DSpace on 2021-07-14T10:33:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-11-25. Added 1 bitstream(s) on 2021-07-14T11:32:55Z : No. of bitstreams: 1 S1808-16572019000100409.pdf: 231587 bytes, checksum: 1c9dd257749cb3b3edf77d26772394df (MD5) O receptor de ecdisona, naturalmente ativado por hormônios esteroidais, é uma proteína-chave nos processos de muda e reprodução de insetos. A ativação artificial desse receptor por meio de pesticidas específicos induz um processo de ecdise anômala, levando o inseto à morte por dessecação e inanição. Neste trabalho, foi estabelecido um protocolo para a triagem de moléculas agonistas em relação ao receptor de ecdisona nas linhagens celulares responsivas S2 (Diptera) e Sf9 (Lepidoptera), transfectadas com o plasmídeo repórter ere.b.act.luc. Para tanto, curvas de dose-resposta foram estabelecidas com o ecdisteroide 20-hidroxiecdisona, o fitoecdisteroide ponasterona-A e tebufenozida, um pesticida pertencente à classe das diacilhidrazinas. Em ambas linhagens celulares, os valores médios de concentração efetiva para indução gênica (EC50) ponasterona-A foram menores, significando que este é o agonista mais potente. Em células Sf9, a tebufenozida apresentou EC50 menor que a 20-hidroxiecdisona, indicando uma alta atividade agonista e especificidade deste inseticida a lepidópteros. O protocolo estabelecido neste trabalho pode ser utilizado para uma rápida triagem e busca racional de pesticidas de alvo bioquímico específico. The ecdysone receptor, naturally activated by steroidal hormones, is a key protein for molting and reproduction processes of insects. Artificial activation of such receptor by specific pesticides induces an anomalous process of ecdysis, causing death of insects by desiccation and starvation. In this paper, we established a protocol for screening agonistic molecules towards ecdysone receptor of insect cells line S2 (Diptera) and Sf9 (Lepidoptera), transfected with the reporter plasmid ere.b.act.luc. Therefore, we set dose-response curves with the ecdysteroid 20-hydroxyecdysone, the phytoecdysteroid ponasterone-A, and tebufenozide, a pesticide belonging to the class of diacylhydrazines. In both cell lines, the median effective concentration values on reporter gene induction (EC50) of ponasterone-A was the smallest, meaning the most active agonist molecule. In Sf9 cells, tebufenozide had as smaller EC50 than 20-hydroxyecdysone, indicating the high agonistic capability and lepidopteran specificity. The protocol established in this study can be useful for a quick screening and rational research of site-specific pesticides. Universidade Estadual Paulista “Júlio de Mesquita Filho” Universidade Federal de Pelotas Universidade Estadual Paulista “Júlio de Mesquita Filho”

Limited oral bioavailability has hindered the widespread use of flavonoids as bioactive substances. Several studies have been performed to evaluate the transport characteristics of flavonoids in the intestines using cell models, such as Caco-2 cells, but information regarding the key structural features of flavonoids that influence intestinal uptake is still limited to date. In this study, quantitative structure–permeability relationship (QSPR) models were developed to study the permeability of 36 flavonoids through Caco-2 cells using both 2D and 3D approaches. For the 2D model, stepwise multiple linear regression (SMLR) and partial least squares regression (PLSR) resulted in good internal (R SMLR 2 = 0.8, R PLSR 2 = 0.93) and external (R SMLR 2 = 0.93, R PLSR 2 = 0.90) predictability using a set of 409 molecular descriptors. The high cross-validated (leave-one-out) R 2 values (Q 2) for both 2D models (Q SMLR 2 = 0.77, Q PLSR 2 = 0.67) suggest that the models are robust and predictive. A pharmacophore (GALAHAD)-based COMSIA analysis was used to generate the 3D QSPR model, which yielded a predictive and robust model (R training 2 = 0.96, R test 2 = 0.95, Q 2 = 0.625) composed of hydrogen bond acceptor and donor fields. According to the contour plots, the locations of hydrogen bond acceptors and donors play a crucial role in determining Caco-2 permeability of flavonoids. The models provide deeper insight into the QSPR of flavonoids on intestinal absorption using Caco-2 cell models and could be useful for the high-throughput screening of flavonoids and/or flavonoid-like drugs with health-promoting activities.

In this study, 22 phenolic compounds were investigated to inhibit the angiotensin-converting enzyme (ACE). Tannic acid showed the highest activity (IC50 = 230 μM). The IC50 values obtained for phenolic acids and flavonoids ranged between 0.41 and 9.3 mM. QSAR analysis confirmed that the numbers of hydroxyl groups on the benzene ring play an important role for activity of phenolic compounds and that substitution of hydroxyl groups by methoxy groups decreased activity. Docking studies indicated that phenolic acids and flavonoids inhibit ACE via interaction with the zinc ion and this interaction is stabilized by other interactions with amino acids in the active site. Other compounds, such as resveratrol and pyrogallol, may inhibit ACE via interactions with amino acids at the active site, thereby blocking the catalytic activity of ACE. These structure-function relationships are useful for designing new ACE inhibitors and potential blood-pressure-lowering compounds based on phenolic compounds.

Las abejas sin aguijón (Hymenoptera: Apidae, Meloponini) hacen parte fundamental del ecosistema, ofreciendo el servicio de polinización y diversificación genética de las especies, además de proporcionar miel y cera para los seres humanos. Tetragonisca angustula y Scaptotrigona xanthotricha son especies que han sido usadas en la meliponicultura por tiempos ancestrales. En la actualidad ellas, junto con otras especies, han estado expuestas a las prácticas agronómicas entre las cuales se destaca la protección de cultivos. El objetivo de este trabajo fue evaluar la toxicidad de tiametoxam y fipronil, insecticidas usados en la agricultura de varios países de la franja tropical y subtropical, a fin de establecer el riesgo que pueden representar para la supervivencia de estas dos especies. Se obtuvo por medio del análisis Probit las DL50 para la exposición oral y tópica de los dos insecticidas. Se realizaron comparaciones con la DL50 de otras especies de abejas sin aguijón y Apis mellifera. Aunque se requieren más estudios para calcular el riesgo real de los dos compuestos, se evidenció la susceptibilidad de las dos especies y el riesgo para su supervivencia. Se concluyó que es fundamental el uso de herramientas y prácticas que disminuyan el riesgo que corren estas especies, además de la realización de evaluaciones toxicológicas sobre las abejas sin aguijón a la hora de aprobar el uso de nuevos y existentes pesticidas. Stingless bees (Hymenoptera: Apidae, Meliponini) have crucial roles in the ecosystem, offering pollination service and contributing to genetic diversity of species, and also providing honey and wax to humankind. Tetragonisca angustula and Scaptotrigona xanthotricha are species that have been used since ancient times for beekeeping. Currently these and other species have been exposed to agronomic practices, among which the use of synthetic pesticides used for crop protection stands out. The aim of this study was to evaluate the toxicity of the insecticides thiamethoxam and fipronil, which are used in agriculture in several countries in the tropical and subtropical belt in order to establish the risk that these products represent to the survival of these two species. The oral and topical LD50 was obtained by Probit analysis. Comparisons with the LD50s of other stingless bees and Apis mellifera were realized. Although further studies are required to calculate the real risk of the two compounds, the results showed an evident susceptibility of both species. We concluded that it is essential to use tools and practices that reduce the risk, and perform toxicological evaluations of new and existing pesticides on stingless bees. © 2017, Universidad Nacional de Colombia1. All rights reserved.

The comprehensive knowledge that the delayed systemic and reproduction side effects can be even more deleterious than acute toxicity, has caused a shift in focus toward sublethal effects assessment on physiology and behavior of beneficial insects. In this study, we assessed the risks posed by some insecticides with different mode of action through lethal and delayed systemic sublethal effects on the pupation, adult emergence, and reproduction of the chrysopid Chrysoperla externa (Hagen, 1861; Neuroptera: Chrysopidae), an important predator in pest biological control. The maximum field recommended dose (MFRD) and twice (2×MFRD) for chlorantraniliprole, tebufenozide, and pyriproxyfen were harmless to C. externa. In contrast, all the tested chitin synthesis inhibitors (CSIs) were highly detrimental to the predator, despite of their lack of acute lethal toxicity. Therefore, the safety assumed by using IGRs toward beneficial insects is not valid for chrysopids. Dose–response data showed that although all CSIs have a similar mechanism of action, the relative extent of toxicity may differ (novaluron > lufenuron > teflubenzuron). For CSIs, the delayed systemic effects became obvious at adult emergence, where the predicted no observable effect dose (NOED) was 1/2 048 of the MFRD for novaluron (0.085 ng/insect), and 1/256 of the MFRD for both lufenuron (0.25 ng/insect) and teflubenzuron (0.6 ng/insect). Finally, this work emphasized the significance of performing toxicity risk assessments with an adequate posttreatment period to avoid underestimating the toxicities of insecticides, as the acute lethal toxicity assays may not provide accurate information regarding the long-range effects of hazardous compounds.

Ecdysteroids play a crucial role in regulating molting in the phylum of Arthropoda and much is known with members of the subphylum of Hexapoda including the Insecta. However, this is still unclear in key pests as spider mites belonging to the subphylum of Chelicerata that originated earlier in the Cambrian period. In this study, we investigated 14 key genes of ecdysteroid biosynthesis and signaling and their expression over the different developmental stages in the citrus red mite, Panonychus citri (Acari: Stigmaeidae). P. citri is an economically important and widespread pest of citrus crops and it has five developmental stages of egg, larva, protonymph, deutonymph and adult. Typically, the expression of the ecdysteroid-synthesizing Halloween gene Spook (PcSpo) followed a positive zigzag-like pattern with a peak in the first half of each developmental stage and a drop in the second half prior to the molting to the next stage. Similar to PcSpo, PcDib, PcSad, PcRXR2, PcE75 and PcHR38 showed a positive zigzag-like expression pattern, while that of PcE78, PcHR3 and PcFTZ-F1 was opposite that we called a negative zigzag-like pattern. Silencing of the PcSpo gene by RNAi showed that molting was inhibited. Interestingly, we could rescue these RNAi effects by supplementing ponasterone A (PonA) and not by 20E, which is indicative that mites use PonA rather than 20E as ecdysteroid hormone. Modeling of the ecdysteroid receptor (PcEcR) hormone binding cavity also predicted binding of PonA, but showed a steric hindrance for 20E. We believe our data provide insight into the evolution and expression patterns of key ecdysteroid biosynthesis and signaling genes in a distant, non-insect species, and can become a foundation to develop new targets for controlling important agricultural pests such as spider mites.

In recent years, the research on the potential of using RNA interference (RNAi) to suppress crop pests has made an outstanding growth. However, given the variability of RNAi efficiency that is observed in many insects, the development of novel approaches towards insect pest management using RNAi requires first to unravel factors behind the efficiency of dsRNA-mediated gene silencing. In this review, we explore essential implications and possibilities to increase RNAi efficiency by delivery of dsRNA through non-transformative methods. We discuss factors influencing the RNAi mechanism in insects and systemic properties of dsRNA. Finally, novel strategies to deliver dsRNA are discussed, including delivery by symbionts, plant viruses, trunk injections, root soaking, and transplastomic plants.

BACKGROUND Dibenzoylhydrazine (DBH) compounds have been applied successfully as environmentally safe insecticides against lepidopteran larvae and ground-dwelling coleopterans, but their potential to combat mosquito larvae is largely unknown. Here, toxicity tests of three commercial DBHs (tebufenozide, methoxyfenozide and halofenozide) and one experimental DBH (KU-106) against larvae of Anopheles gambiae, the major vector for human malaria, are reported. RESULTS Based on calculated median larvicidal concentration (LC50) values at 5 days of treatment, KU-106 (760 nM) showed an activity against Anopheles larvae similar to that of commercial halofenozide. Induction of the early-late gene hr3 and docking studies of DBHs in the ligand-binding pocket of the modelled Anopheles ecdysone receptor indicated that toxicity is caused by the activation of the ecdysone regulatory cascade causing a premature lethal moult. CONCLUSIONS As a result of the similar toxicity exhibited by the experimental compound KU-106 to that shown by commercial products, the present study demonstrated that the use of DBH compounds to combat harmful dipteran insects, such as mosquitoes, remains unexplored and invites further systematic toxicity tests using other derivatives of the DBH class of compounds.© 2012 Society of Chemical Industry

Understanding how variations in genetic sequences are conveyed into structural and biochemical properties is of increasing interest in the field of molecular evolution. In order to gain insight into this process, we studied the ecdysone receptor (EcR), a transcription factor that controls moulting and metamorphosis in arthropods. Using an in silico homology model, we identified a region in the lepidopteran EcR that has no direct interaction with the natural hormone but is under strong evolutionary constraint. This region causes a small indentation in the three-dimensional structure of the protein which facilitates the binding of tebufenozide. Non-Mecopterida are considered much older, evolutionarily, than Lepidoptera and they do not have this extended cavity. This location shows differences in evolutionary constraint between Lepidoptera and other insects, where a much lower constraint is observed compared with the Lepidoptera. It is possible that the higher flexibility seen in the EcR of Lepidoptera is an entirely new trait and the higher constraint could then be an indication that this region does have another important function. Finally, we suggest that Try123, which is evolutionarily constrained and is up to now exclusively present in Lepidoptera EcRs, could play a critical role in discriminating between steroidal and non-steroidal ligands.

RESUMO O objetivo do presente trabalho foi avaliar a seletividade dos inseticidas utilizados na cultura do milho sobre Doru lineare. Foi avaliada a seletividade de inseticidas utilizados na cultura do milho para D. lineare, seguindo metodologia proposta pela IOBC/WPRS em condições de laboratório. Adultos foram expostos aos resíduos dos inseticidas por meio de contato com placas de vidros e pelo consumo de ovos de Spodoptera frugiperda contaminados com os inseticidas. A porcentagem de mortalidade dos insetos em contato residual foi utilizada para classificar os inseticidas como inócuo (< 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). A mortalidade de adultos após consumo de ovos contaminados foi comparada com a testemunha. Para adultos deD. lineare mediante contato residual, nas 360 HAIE (horas após o início da exposição), os inseticidas Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR, Match EC, Neem Azal e Sevin 480 SC foram nocivos ao predador. Certero, Fastac 100 SC e Tracer foram moderadamente nocivos. Intrepid 240 SC e Mimic 240 SC foram inócuos. A mortalidade de adultos após o consumo de ovos contaminados foi significativa para os inseticidas Certero, Dimilin, Tracer, Engeo Pleno, Lorsban 480 BR, Sevin 480 SC.

RESUMO O objetivo do trabalho foi avaliar a seletividade de inseticidas usados na cultura do milho para o controle de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) sobre ninfas de primeiro ínstar e ovos do predador Doru lineare (Scudder, 1876) (Dermaptera: Forficulidae). Para os bioensaios foi utilizada a metodologia padronizada da IOBC/WPRS, em condições de laboratório, com temperatura de 25 ± 1º C, umidade relativa de 70 ± 10% e fotofase de 14 horas. No bioensaio com ninfas para contato residual, a aplicação dos inseticidas foi realizada com um equipamento pressurizado a CO2, pressão de 50 psi. Para aplicação dos inseticidas sobre os ovos foi utilizada torre de Potter, com pressão de 10 psi. Em ambas as formas de aplicação o depósito foi de 1,75 ± 0,25 mg de calda cm-2 conforme metodologia da IOBC/WPRS. A mortalidade de ninfas foi utilizada para classificar os inseticidas como inócuo (< 30%), levemente nocivo (30-79%), moderadamente nocivo (80-99%) e nocivo (> 99%). Os dados de viabilidade de ovos e sobrevivência de ninfas que eclodiram deles foram comparados com os dados das testemunhas positiva (Sevin 480 SC) e negativa (água). Certero, Dimilin, Engeo Pleno, Karate Zeon 250 SC, Lorsban 480 BR, Match EC e Sevin 480 SC reduziram a viabilidade de ovos. A sobrevivência de ninfas provenientes dos ovos tratados teve redução para os inseticidas: Decis 25 EC, Dimilin, Engeo Pleno, Karate Zeon 250 CS, Lorsban 480 BR e Sevin 480 SC. Para ninfas de D. lineare em contato residual, todos os inseticidas foram nocivos em 96 horas após a exposição.

O objetivo do trabalho foi estudar a biologia de populações de Spodoptera frugiperda (J.E. Smith) em folhas de milho e arroz irrigado. Foram coletadas lagartas de quatro populações no Rio Grande do Sul: em áreas isoladas (distanciadas em mais de 300 km), municípios de Santa Rosa (M/SR) e Uruguaiana (A/U), tradicionalmente produtores de milho e arroz irrigado, respectivamente; e, em áreas adjacentes, município de Pelotas, que produz milho (M/P) e arroz irrigado (A/P) lado a lado. Individualizaram-se 150 lagartas em tubos de vidro contendo folhas do híbrido de milho Pioneer 30F33 e do cultivar de arroz irrigado Pelota, em condições controladas de temperatura (25 ± 1ºC), umidade relativa (70 ± 10%) e fotofase (14h). Por ocasião da emergência dos adultos, 20 casais foram individualizados em gaiolas cilíndricas de PVC revestidas internamente com papel jornal, e alimentados com solução aquosa de mel a 10%. As populações de S. frugiperda originárias do milho e arroz, independente do local de coleta, apresentaram necessidades fisiológicas intrínsecas e que são evidenciadas nos diferentes parâmetros biológicos avaliados. As populações M/SR e M/P (cultura do milho) e A/U e A/P (cultura do arroz irrigado), não apresentaram diferenças fisiológicas. Diante dos resultados, conclui-se que ambos biótipos "milho" e "arroz" de S. frugiperda ocorrem no Rio Grande do Sul. The objective of this work was to analyze the biology of Spodoptera frugiperda (J.E. Smith) populations in corn and irrigated rice leaves. Caterpillars from four populations from Rio Grande do Sul state were collected from isolated areas (distant more than 300 km apart), from the counties of Santa Rosa (M/SR) and Uruguaiana (A/U), traditional areas of corn and irrigated rice production, respectively, and in adjacent areas in Pelotas county, where corn (M/P) and rice (A/P) are grown side by side. In the laboratory, 150 caterpillars were individualized in glass vials containing leaves of the Pioneer 30F33 corn hybrid and the cultivar of the irrigated rice Pelota, under controlled temperature (25 ± 1ºC), relative humidity (70 ± 10%) and photophase (14h). After adult emergence, 20 couples were individualized in cylindrical PVC cages, covered inside with paper towels, and fed with a 10% honey aqueous solution. All populations of S. frugiperda collected from corn and rice, regardless their place of origin, showed unique physiological needs, as evidenced by the different biological parameters evaluated. The Populations M/SR and M/P (maize) and A/U and A/P (irrigated rice), did not differ physiologically. Based on the results, both "corn" and "rice" S. frugiperda biotypes are present in Rio Grande do Sul.

O objetivo deste trabalho foi avaliar o efeito da temperatura sobre a biologia dos biótipos "milho" e "arroz" de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) e estimar o número de gerações por ano em laboratório e campo. Foram coletadas lagartas de quatro populações de S. frugiperda no Estado do Rio Grande do Sul, identificadas eletroforeticamente como os biótipos "milho" e "arroz", em áreas isoladas, distanciadas entre si em mais de 300 km, produtoras de milho e arroz irrigado e em áreas adjacentes, que produzem milho e arroz irrigado lado a lado. A temperatura mais adequada para o desenvolvimento dos dois biótipos foi 25ºC. Em laboratório, podem ser obtidas 11,0 e 11,3 gerações ano-1 do biótipo "milho" proveniente de áreas isoladas e adjacentes, respectivamente. Foram estimadas 12,1 gerações ano-1 do biótipo "arroz" quando proveniente de áreas isoladas e 12,2 gerações ano-1 quando proveniente de áreas adjacentes. Em campo, estimou-se a ocorrência de 8,3 e 6,1 gerações ano-1 do biótipo "milho", respectivamente, em áreas isoladas e áreas adjacentes e 8,4 e 7,0 gerações ano-1 do biótipo "arroz", respectivamente, em áreas isoladas e áreas adjacentes. Em áreas adjacentes, o biótipo "arroz" apresenta uma geração a mais ao longo de um ano em relação ao biótipo "milho". The objective of this work was to evaluate the effect of the temperature on the biology of the biotypes "corn" and "rice" of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) and to estimate the number of generations per year in laboratory and field. Caterpillars of four populations of S. frugiperda were collected in Rio Grande do Sul State, Brazil, identified by electrophoresis as the biotypes "corn" and "rice" in isolated areas (spaced for more than 300 km), areas of corn and irrigated rice production, as well as in adjacent areas that produces corn and rice irrigated side by side. The most appropriate temperature for the development of the two biotypes was 25ºC. In laboratory, a number between 11.0 and 11.3 generations year-1 for the biotype "corn" can be obtained, originating from isolated and adjacent areas, respectively, and, for the biotype "rice", 12.1 and 12.2 generations year-1 when originating from isolated and adjacent areas, respectively. In the field, the occurrence of 8.3 and 6.1 generations year-1 for the biotype "corn" was estimated, respectively, in isolated and adjacent areas and 8.4 and 7.0 generations year-1 for the "rice" biotype, respectively, in isolated and adjacent areas. In adjacent areas, the "rice" biotype presents an extra generation per year in relation to the "corn" biotype.

The time has passed for us to wonder whether RNA interference (RNAi) effectively controls pest insects or protects beneficial insects from diseases. The RNAi era in insect science began with studies of gene function and genetics that paved the way for the development of novel and highly specific approaches for the management of pest insects and, more recently, for the treatment and prevention of diseases in beneficial insects. The slight differences in components of RNAi pathways are sufficient to provide a high degree of variation in responsiveness among insects. The current framework to assess the negative effects of genetically modified (GM) plants on human health is adequate for RNAi-based GM plants. Because of the mode of action of RNAi and the lack of genomic data for most exposed non-target organisms, it becomes difficult to determine the environmental risks posed by RNAi-based technologies and the benefits provided for the protection of crops. A better understanding of the mechanisms that determine the variability in the sensitivity of insects would accelerate the worldwide release of commercial RNAi-based approaches.

Flavonoids are a group of polyphenols that provide health-promoting benefits upon consumption. However, poor bioavailability has been a major hurdle in their use as drugs or nutraceuticals. Low bioavailability has been associated with flavonoid interactions at various stages of the digestion, absorption and distribution process, which is strongly affected by their molecular structure. In this review, we use structure-activity/property relationship to discuss various flavonoid interactions with food matrices, digestive enzymes, intestinal transporters and blood proteins. This approach reveals specific bioactive properties of flavonoids in the gastrointestinal tract as well as various barriers for their bioavailability. In the last part of this review, we use these insights to determine the effect of different structural characteristics on the overall bioavailability of flavonoids. Such information is crucial when flavonoid or flavonoid derivatives are used as active ingredients in foods or drugs.

Despite their fundamental importance for growth, the mechanisms that regulate food intake are poorly understood. Our previous work demonstrated that insect sulfakinin (SK) signaling is involved in inhibiting feeding in an important model and pest insect, the red flour beetle Tribolium castaneum. Because the interaction of SK peptide and SK receptors (SKR) initiates the SK signaling, we have special interest on the structural factors that influence the SK-SKR interaction. First, the three-dimensional structures of the two T. castaneum SKRs (TcSKR1 and TcSKR2) were generated from molecular modeling and they displayed significance in terms of the outer opening of the cavity and protein flexibility. TcSKR1 contained a larger outer opening of the cavity than that in TcSKR2, which allows ligands a deep access into the cavity through cell membrane. Second, normal mode analysis revealed that TcSKR1 was more flexible than TcSKR2 during receptor-ligand interaction. Third, the sulfated SK (sSK) and sSK-related peptides were more potent than the nonsulfated SK, suggesting the importance of the sulfate moiety.

Com o objetivo de conhecer a diversidade e riqueza de gastropodes terrestres em ambientes com diferentes graus de perturbacao, foram realizadas amostragens no municipio de Juarez, Chiapas - Mexico durante os meses de Fevereiro e Marco de 2013. Utilizando amostragens aleatorias simples e coletas manuais que foram peneiradas e analizadas em laboratorio. Foram coletados 778 organismos, identificando 20 especies, duas subclasses, quarto ordens, 16 familias e 16 generos. Noventa por cento dos representantes foram da subclasse Pulmonata e os 10% restantes da subordem Prosobranchia. As unicas especies de selva foram Averilliaco actiliata, Helicinia (Tristramina) tenuis, Spiraxis sp2 y Streptosthyla meridana. Os ambientes com maior similaridade foram a selva e floresta madura com uma similaridade de 72%.

Ecdysteroid signal transduction is a key process in insect development and therefore an important target for insecticide development. We employed an in vitro cell-based reporter bioassay for the screening of potential ecdysone receptor (EcR) agonistic and antagonistic compounds. Natural ecdysteroids were assayed with ecdysteroid-responsive cell line cultures that were transiently transfected with the reporter plasmid ERE-b.act.luc. We used the dipteran Schneider S2 cells of Drosophila melanogaster and the lepidopteran Bm5 cells of Bombyx mori , representing important pest insects in medicine and agriculture. Measurements showed an EcR agonistic activity only for cyasterone both in S2 (EC 50 = 3.3 μM) and Bm5 cells (EC 50 = 5.3 μM), which was low compared to that of the commercial dibenzoylhydrazine-based insecticide tebufenozide (EC 50 = 0.71 μM and 0.00089 μM, respectively). Interestingly, a strong antagonistic activity was found for castasterone in S2 cells with an IC 50 of 0.039 μM; in Bm5 cells this effect only became visible at much higher concentrations (IC 50 = 18 μM). To gain more insight in the EcR interaction, three-dimensional modeling of dipteran and lepidopteran EcR-LBD was performed. In conclusion, we showed that the EcR cell-based reporter bioassay tested here is a useful and practical tool for the screening of candidate EcR agonists and antagonists. The docking experiments as well as the normal mode analysis provided evidence that the antagonist activity of castasterone may be through direct binding with the receptor with specific changes in protein flexibility. The search for new ecdysteroid-like compounds may be particularly relevant for dipterans because the activity of dibenzoylhydrazines appears to be correlated with an extension of the EcR-LBD binding pocket that is prominent in lepidopteran receptors but less so in the modeled dipteran structure.

The insect sulfakinins (SKs) constitute a family of neuropeptides that display both structural and functional similarities to the mammalian hormones gastrin and cholecystokinin (CCK). As a multifunctional neuropeptide, SKs are involved in muscle contractions as well as food intake regulation in many insects. In the red flour beetle Tribolium castaneum, the action on food intake by a series of synthetic SK analogs and one putative antagonist was investigated by injection in beetle adults. The most remarkable result was that both sulfated and non-sulfated SKs [FDDY(SO3H)GHMRFamide] inhibited food intake by about 70%. Strong activity observed for SK analogs featuring a residue that mimics the acidic nature of Tyr(SO3H) but lack the phenyl ring of Tyr, indicate that aromaticity is not a critical characteristic for this position of the peptide. SK demonstrated considerable tolerance to Ser and Ala substitution in position 8 (basic Arg), as analogs featuring these uncharged substitutions retained almost all of the food intake inhibitory activity. Also, the Phe in position 1 could be replaced by Ser without complete loss of activity. Conversely, substitution of Met by Nle in position 7 led to inactive compounds. Finally, the Caenorhabditis elegans sulfated neuropeptide-like protein-12 (NLP-12), that shares some sequence similarities with the SKs but features a Gln-Phe-amide rather than an Arg-Phe-amide at the C-terminus, elicited increased food intake in T. castaneum, which may indicate an antagonist activity. Co-injection of NLP-12 with nsSK blocked the food intake inhibitory effects of nsSK.

A seletividade de dezesseis agrotóxicos utilizados na produção integrada e convencional de pêssego foi avaliada sobre a fase adulta de Chrysoperla externa através de bioensaios de exposição residual conduzidos em laboratório (temperatura de 25±1ºC, umidade relativa 70±10% e fotofase 14 horas), utilizando-se de metodologia prescrita pela "International Organization for Biological Control" (IOBC). Os agrotóxicos (% de ingrediente ativo na calda) azoxystrobina (0,016), captana (0,192), dodina (0,126), folpete (0,200), mancozebe (0,256), mancozebe + oxicloreto de cobre (0,140 + 0,096), tebuconazole (0,320), abamectina (0,002), óleo mineral 1 (2,420), óleo mineral 2 (1,920), dicloreto de paraquate (0,300) e glifosato (1,440) foram inócuos; deltametrina (0,002) foi levemente nocivo e dimetoato (0,160), fosmete (0,160) e malationa (0,240) foram nocivos a adultos de C. externa.

The objective of this work was to evaluate the susceptibility of caterpillars of the biotypes corn and rice of Spodoptera frugiperda, to insecticides with different action manners. The insects were collected in corn and in irrigated rice in the lowland, county of Pelotas, area that produces corn and irrigated rice (side by side). The experiments were conducted, in controlled conditions of temperature (25 ± 1°C), relative humidity (70 ± 10%) and photophase (14 hours), with leaves of the corn hybrid Pionner 30F33 (40 days after the emergency). The leaves were powdered in Potter tower gauged for application of a volume of 1.7 ± 0.305mg cm-2, they were put in containers of plastics with cover, and individualized 25 caterpillars of 3rd instar of each biotype of S. frugiperda. The insecticides and concentrations evaluated were: chlorpyrifos [Lorsban 480 BR, 0.960g a.i. L-1 (Chlorophosphate)], lambda-cyhalothrin [Karate Zeon 50 CE, 0.003g a.i. L-1 (synthetic Piretroid)], lufenuron [Match CE, 0.006g a.i. L-1 (Acilureis)], methoxyfenozide [Intrepid 240 SC, 0.158g a.i. L-1 (Diacylhydrazine)] and spinosad [Tracer, 0.960g a.i. L-1 (Naturalyte)]. The evaluation of the mortality was accomplished 24, 48, 72, 96 and 120 hours after the treatment. The biotype corn of S. frugiperda was less susceptible to the insecticides lambda-cyhalothrin, lufenuron and methoxyfenozide. The insecticides chlorpyrifos and spinosad were efficient in the control of the caterpillars of the biotypes corn and rice of S. frugiperda.

The use of pesticides is considered one of the most important threats to pollinators, especially since they are widely used in agriculture for pest control. In the last years, several studies have reported severe secondary effects on various bee species, including exotic and native bees. In this study, lethal (mortality) and sublethal (locomotor activity) effects of insecticides and acaricides used in strawberries in Brazil (abamectin, novaluron, spinetoram, and thiamethoxam) were evaluated on the native stingless bees Melipona quadrifasciata and Tetragonisca fiebrigi. The results showed that the effects varied significantly according to the pesticide, type of exposure (oral or topical), and bee species. Through oral exposure, M. quadrifasciata was more susceptible to all insecticides except for abamectin, while in topical exposure, T. fiebrigi was more sensitive. Thiamethoxam followed by spinetoram and abamectin were the most lethal, regardless of species or exposure route; novaluron was not harmful at the highest tested dose. The locomotor activity of bees was altered in the presence of sublethal doses (LC10 and LC50) of all insecticides. Spinetoram and abamectin can be as much as toxic as thiamethoxam against M. quadrifasciata and T. fiebrigi in laboratory experiments. These findings should be confirmed in field experiments to define possibilities to combine pest control and pollinator management. In crops like strawberries, the selectivity of native pollinators should be considered. Keywords: Acute toxicity; Behavior effects; Fragaria x ananassa Duch; Native bees; Pesticides; Selectivity. Made available in DSpace on 2020-11-21T09:13:08Z (GMT). No. of bitstreams: 1 Piovesan2020-Article-EffectsOfInsecticidesUsedInStr.pdf: 901659 bytes, checksum: d72a3cce8475710016c555cd6f5112cc (MD5) Previous issue date: 2020

Made available in DSpace on 2019-02-01T23:38:44Z (GMT). No. of bitstreams: 1 Dori5.CropProtection.pdf: 1205724 bytes, checksum: a644067d9106b02bd3920a1ea2bb5067 (MD5) Previous issue date: 2019-01-30

Foi avaliada a seletividade dos principais inseticidas utilizados na cultura do milho ao predador Doru lineare (Eschscholtz, 1822) (Dermaptera: Forficulidae) seguindo metodologia da IOBC/WPRS em condições de semi-campo. Ninfas e adultos provenientes da criação de laboratório foram colocadas no interior do cartucho de plantas de milho. Logo após foi realizada a pulverização dos inseticidas com um equipamento costal pressurizado com CO2 pressão de 50psi. Após a pulverização as plantas de milho foram cobertas com tecido em recipiente adequado. Avaliando-se as mortalidades para adultos e ninfas, após 72 horas, verificou-se que: Certero, Intrepid 240 SC e Mimic 240 SC são inócuos (classe 1), Dimilin e Karate Zeon 250 CS são levemente nocivos (classe 2) e Engeo Pleno é moderadamente nocivo (classe 3); Decis 25 EC, Fastac 100 SC, Match EC e Neem Azal são, inócuos (classe 1) e levemente nocivos ( classe 2), respectivamente para adultos e ninfas. Lorsban 480 BR e Sevin 480 SC são moderadamente nocivos (classe 3) e nocivos (classe 4), respectivamente; inseticida Tracer é levemente nocivo (classe 2) e moderadamente nocivo (classe 3), para adultos e ninfas, respectivamente.