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Abstract. Plant resistance is considered as an important pillar of Integrated Pest Management (IPM), being a highly targeted method since is a less harmful method to the environment, if compared to other tactics such as chemical control. Abiotic factors are those related to the environment and have a direct influence on the dynamics of interaction between insects and plants. The abiotic factors such as altitude, temperature, humidity, luminosity, wind and soil fertility, among others, do not act alone, but in a complex net that leads insect population dynamics in agroecosystems. How the variations of these factors can be studied in the same context? First, it is important to consider how each abiotic factors act separately and then in a coexistence influence over the populations dynamics of insects and plants. In this study, the literature about the influence of abiotic factors on insect herbivory has been reviewed, focusing mainly on the mechanisms in which the plants use in the defense against insects.Influência de fatores abióticos na resistência de plantas a insetos Resumo. A resistência de plantas é considerada um importante pilar no contexto do Manejo Integrado de Pragas (MIP), sendo um método bastante visado por ser menos nocivo ao meio ambiente, quando comparado a outras táticas como o controle químico. Os fatores abióticos são aqueles relacionados ao ambiente e têm influência direta na dinâmica de interação entre insetos e plantas. Os fatores abióticos como altitude, temperatura, umidade, luminosidade, ventos e fertilidade do solo, por exemplo, não atuam sozinhos, mais sim em um complexo de fatores coexistentes que regem as dinâmicas populacionais nos diversos agroecosistemas. Como as variações destes fatores podem ser estudadas em um mesmo contexto? Primeiramente, é importante conhecer como cada uma atua individualmente para então contextualizar em uma situação de coexistência sobre as dinâmicas populacionais de insetos e plantas. Neste artigo, a literatura sobre a influência de fatores abióticos na herbivoria de insetos foi revisada, focando principalmente nos mecanismos em que as plantas utilizam na defesa contra insetos.

Immature endoparasitoids develop inside their hosts. Consequently, endoparasitoids need to circumvent the action of the immune system and reprogram the physiology of their hosts to develop successfully. For this, parasitoids release host regulationrelated molecules into their host's hemolymph produced by the parasitoid itself or expressed in specific host cells infected by parasitoid symbiotic viruses. In addition to their roles in host regulation, these molecules may also present biotechnological potentials, such as for insecticidal purposes in crop protection. We performed a survey for the biotechnological potential of compounds present in the hemolymph serum with and without circulating cell contents of Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) parasitized by Cotesia flavipes Cameron (Hymenoptera: Braconidae) as insecticides in feeding assays. Hemolymph serum from D. saccharalis larvae at 6 days after the start of the parasitism with and without circulating cell contents were collected and spread over artificial diet or over sugarcane leaves for feeding assays with D. saccharalis neonates. Hemolymph serum with or without circulating cell contents from non-parasitized D. saccharalis larvae at the same age were used as controls. Subsequently, hemolymph serum plus circulating cell contents was fractioned using molecular filters and fractions with different molecular weight range were used for feeding assays with D. saccharalis neonates. Feeding larvae with leaf disks amended with hemolymph serum plus circulating cell contents from parasitized hosts resulted in an increase of ca. 30% in the mortality of D. saccharalis neonates.After fractioning hemolymph serum plus circulating cell contents, feeding assays with the >100 or 3-10 kDa fractions did not result in the previously observed increase in larval mortality, but resulted in a reduction of leaf consumption by neonates. Finally, we selected a parasitism-specific protein band observed in the hemolymph >100 kDa fraction for mass spectrometry identification. This parasitism-specific protein was similar to hymenopteran apolipophorins-I. We conclude that there is an insecticidal potential in the hemolymph serum plus circulating cell contents of D. saccharalis larvae parasitized by C. flavipes and further investigations will be performed to identify, characterize, and uncover the biotechnological application of these molecules.

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.

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A cultura da soja é atacada por diversos insetos-praga, divididos principalmente em mastigadores e sugadores. O percevejo-marrom-da-soja (Euschistus heros) tem se destacado como uma das principais pragas sugadoras por causar danos, principalmente, no estágio reprodutivo da cultura. Neste trabalho objetivou-se avaliar o efeito de inseticidas utilizados para pragas mastigadoras da soja sobre ovos, ninfas e adultos de Euschistus heros. Foi avaliada a mortalidade de ovos, ninfas e adultos, além do efeito sub-letal sobre a fecundidade dos adultos. Foram realizados ao total 5 tratamentos, na máxima dosagem registrada para soja: tiametoxam+lambda-cialotrina, flubendiamida, diflubenzurom e lufenurom. Os resultados indicam que flubendiamida e lufenurom apresentaram efeito sobre ninfas de E. heros, apesar de serem utilizados apenas para o controle de lepidópteros. Além disso, os inseticidas testados não apresentaram efeitos negativos sobre ovos e na fecundidade das fêmeas.

Teratocytes are specialized cells released by parasitoid wasps into their hosts. They are known for producing regulatory molecules that aid the development of immature parasitoids. We have recently reported the primary structures of cystine-rich peptides, including some containing inhibitor cystine knot (ICK) motifs, produced by teratocytes of the parasitoid Cotesia flavipes (Hymenoptera: Braconidae). ICKs are known for their stability and diverse biological functions. In this study, we produced four putative ICK peptides from the teratocytes of C. flavipes using solid-phase peptide synthesis or recombinant expression in E. coli, and investigated their functions on host immune modulation as well their potential to impair the development of two lepidopterans after ingestion of the peptides. In addition, the peptides were assayed against pathogens and human cells. The peptides did not influence total hemocyte count but suppressed cellular immunity, detectable as a reduction of hemocyte encapsulation (CftICK-I, CftICK-II, CftICK-III) and spread indexes (CftICK-IV) in the host. None of the peptides influenced the activities of prophenoloxidase and phenoloxidase in the hemolymph of larval Diatraea saccharalis (Lepidoptera: Crambidae). CftICK-I and CftICK-II with previously unknown function showed antifungal activity against Candida albicans but were non-toxic to human cells. CftICK-I, CftICK-II, and CftICK-III increased larval mortality and reduced leaf consumption of D. saccharalis, a permissive host for C. flavipes. The CftICK-III also increased larval mortality and reduced leaf consumption of Spodoptera frugiperda (Lepidoptera: Noctuidae), a non-permissive host for C. flavipes. This study highlights biological functions and biotechnological potential of ICK peptides from the teratocytes of C. flavipes.