Insecticide use remains controversial, and subjected to increasing environmental and health concerns, even when recent insecticide groups are considered. Neonicotinoids and even bioinsecticides are in the forefront of discussions regarding their nontarget safety. The ubiquitous focus on the lethal effects of insecticides on nontarget species has been expanding to sublethal effects, as sublethal exposure extends for a longer time and affects a broader range of (nontarget) species. Here we explored the lethal and sublethal effects of a lambda-cyhalothrin + thiamethoxan mixture, the neonicotinoid imidacloprid, and the bioinsecticide azadirachtin on the egg parasitoid Telenomus podisi Ashmead, an important parasitoid of stink bug Euschistus heros (F.), a key soybean pest in neotropical America. Contact with dry insecticide residue on glass surface and (parasitized and healthy) host egg immersion exposure bioassays were performed, assessing their acute lethal effects, and their potential sublethal impairment of parasitism, adult emergence, and fertility of the egg parasitoid. Both imidacloprid and the insecticide mixture exhibited high acute lethal activity toward the parasitoid under contact with dry insecticide residue. These insecticides compromised parasitism and wasp emergence when exposure took place before parasitism. In contrast, azadirachtin did not affect adult survival. However, this bioinsecticide compromised parasitism and progeny production, impairing the female parasitoid reproductive potential. Our results indicate strong negative effects of imidacloprid, and specially of the mixture lambda-cyhalthrin + thiamethoxan. However, even azadirachtin, which exhibited low acute lethality, exhibited significant negative sublethal effects on parasitism and population growth of egg parasitoid, cautioning against their use and the need of semifield and field assessments to confirm such an impact.

No abstract

This research aimed to evaluate the insecticide potential of the leaves extract of Piper aduncum (L.) (Piperaceae) on development of brown stink bug, Euschistus heros (F.), major pest in soybean crop in Mato Grosso

Plant essential oils have been recognized as significant natural resources for insecticides. Herein, we have assessed the toxicity of the essential oil of Piper aduncum (Piperaceae) against Euschistus heros (F.) (Hemiptera: Pentatomidae), a key soybean pest in Neotropical America. In addition, we have assessed its effect on the performance of egg parasitoids. The essential oil was obtained from the leaves of P. aduncum via hydrodistillation. Subsequently, bioassays of the concentration response to eggs (contact and immersion methods), nymphs, and adults (topical application) were conducted, to assess the lethal effects on the stink bug. We also evaluated the performance of parasitism and adult emergence of egg parasitoids, when the host eggs were treated with essential oil. In the egg bioassay, both exposure methods were efficient for unviable eggs (immersion LC = 15.64 mg mL; contact LC = 21.29 mg mL), with the highlight on the immersion method. The bioassay with nymphs indicated a higher toxicity of essential oil, with lower concentrations (LC = 11.37 mg mL) being required to cause the death of insects. For adults, a reduction in survival of insects was observed, and consequently, there was a reduction in the number of individuals in the next generation. Although the essential oil was toxic to E. heros, it exhibited lower toxicity for egg parasitoids, as there was no effect on parasitism and the emergence of wasps. We discuss likely explanations for such selectivity. In summary, we found that the essential oil was promising for the control of E. heros, because it caused deleterious effects at all development stages of the stink bug and had no effect on parasitism and emergence of the egg parasitoids, which suggested compatibility with biological control.

RESUMO: O percevejo marrom, Euschistus heros (Hemiptera:Pentatomidae), é um inseto praga na cultura da soja no estado do Mato Grosso, Brasil. Nesta região, inseticidas sintéticos são frequentemente utilizados ao controle de insetos. Uma alternativa para o uso indiscriminado de inseticidas é o controle biológico com parasitoides. Assim, o objetivo deste estudo foi realizar o levantamento dos parasitoides que utilizam adultos de E. heros como hospedeiros. Para isso, amostras aleatórias foram conduzidas durante as safras de 2009/10 e 2010/11, em duas fazendas produtoras de soja (sistema convencional) em Tangará da Serra, Mato Grosso, Brasil. O número total de E. heros coletados foi: 297 (Área 1) e 293 (Área 2) em 2009/10 e 295 (Área 1) e 376 (Área 2) em 2010/11. Destes percevejos 1,50 (Área 1) e 13,99% (Área 2) encontravam-se parasitados em 2009/10 e 8,47 (Área 1) e 7,45% (Área 2) em 2010/11. Nas duas áreas, o parasitoide encontrado foi Hexacladia smithii Ashmead (Hymenoptera: Encyrtidae). Este é o primeiro registro de parasitismo em adultos de E. heros no estado do Mato Grosso, Brasil.

The resistance of pests to insecticides and the high costs of pest control have prompted a search for less harmful alternatives to the environment. Phytoinsecticides can be a promising option in the control of pests. The insecticidal properties of the essential oil of Piper aduncum L. (Piperaceae) have been demonstrated by several authors. This study was aimed at evaluating the insecticidal activity of P. aduncum essential oil on caterpillars of the soybean looper, Chrysodeixis includens Walker. Two bioassays were conducted: The first was based on the ingestion of treated leaves, while the second, on direct contact. Chromatography was performed, and the resulting oil was used to treat larvae fed cotton leaves at the concentrations of 0.5, 1.0, 2.0, 4.0, and 8.0%. The controls consisted of water and acetone. The first assessment was carried out 24 h after the application. The main compounds identified by chromatography were dillapiole, myristicin, and Z-carpacin. In the ingestion bioassay, mortality reached 90% for the highest concentration in the first 24 h after application. For the topical application of P. aduncum essential oil, no significant differences were observed until the end of the life cycle of C. includens. This study demonstrates the insecticidal activity essential oil of P. aduncum on C. includens and its potential in the control of this insect by ingestion.

This study evaluated the occurrence of lepidopteran pests on millet cultivated in off-season in the state of Mato Grosso, Brazil. Larvae were collected from May to July 2013 in an area of 145 hectares located in Tangará da Serra, MT. After being collected, caterpillars were kept in the laboratory and fed an artificial diet until the pupal stage. After emergence, adults were dry mounted, identified, and deposited in the entomological collection of Embrapa Cerrados, Planaltina, Distrito Federal, Brazil. Adults obtained from 117 caterpillars were identified as Mocis latipes (Guenée), Spodoptera frugiperda (J.E. Smith), Helicoverpa armigera (Hübner), H. zea (Boddie), Mythimna (Pseudaletia) sequax Franclemont, Urbanus proteus (Linnaeus), and Leucania latiuscula Herrich-Schäffer. This study describes the first record of lepidopteran pests on millet plants in the state of Mato Grosso, and the incidence of lepidopterans in the system that uses millet as cover crop represents a risk of the occurrence of insect pests on subsequent crops on the straw of this grass.

IV Exigências térmicas de INTRODUÇÃODiversas espécies de insetos danificam a cultura do milho desde a semeadura até a fase da formação dos grãos (VIANA, 2004). Entre as mais prejudiciais, encontra-se a lagarta-do-cartucho do milho Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), cujo dano ocorre pela raspagem e perfuração das folhas já emitidas, bem como daquelas em formação no cartucho do milho, caracterizando o nome popular da espécie. Além disto, as lagartas podem ainda broquear a base da planta e atacar a espiga. Com o plantio do milho "safrinha", o ataque se intensificou, e as perdas oscilam entre 34 a 40% (FERNANDES, 2003).O controle da lagarta-do-cartucho tem sido realizado basicamente por agrotóxicos, mas algumas espécies da ordem Dermaptera, conhecidas como "tesourinhas", são relatadas como importantes predadoras da referida praga. Entre essas predadoras, a espécie Doru lineare (Eschs.) pode ser mencionada, por ser frequente na cultura do milho (ROMERO-SUELDO & CUEZZO, 2001). Também são registradas como entomófagos nas culturas da soja (LEITE & LARA, 1985), do algodão (SOARES et al., 1995;SOARES & BUSOLI, 2000) e do trigo (GASSEN,1986). Além desta, Doru luteipes (Scudder), também faz parte do complexo de inimigos naturais de S. frugiperda (REIS et al., 1988;CRUZ, 1991; CRUZ, 1994;GUERREIRO et al., 2003;PICANÇO et al., 2003;FIGUEIREDO et al., 2006), de Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) (CRUZ et al., 1995) e de Ascia monustes orseis (Goudart) (Lepidoptera: Pieridae) (PICANÇO et al., 2003).CRUZ (2007) menciona que D. luteipes é um dos inimigos naturais mais importantes na supressão de pragas na cultura do milho, pois as ninfas podem consumir diariamente cerca de 10 ovos e/ou lagartas de S. frugiperda, e os adultos podem consumir diariamente 20 lagartas de primeiro e segundo ínstar. Além de S. frugiperda, D. luteipes preda ovos e lagartas de H. zea (CRUZ, 2007), assim como ninfas e adultos do pulgão-verde do sorgo (Schizaphis graminum (Rondani) (Hemiptera: Aphididae)) (ALVARENGA et al., 1995a,b;ALVARENGA et al., 1996; CRUZ, 2007).Devido à relevância dessa espécie como agente de mortalidade biótica, estudos visando ao controle biológico por conservação, com a utilização de inseticidas seletivos, têm sido realizados (SIMÕES et al.,1998;PICANÇO et al., 2003). Entretanto, ainda que se reconheça a importância dos predadores na redução populacional de insetos-praga, dermápteros não vem sendo utilizados em programas de controle biológico aplicado, devido, principalmente, à falta de conhecimento das suas características biológicas (CÔNSOLI & PARRA, 1997;BERTI FILHO & CIOCIOLA, 2002). PASINI et al. (2007) demonstraram a possibilidade da criação de D. luteipes em laboratório; porém, há carência de estudos sobre a influência de fatores abióticos, como temperatura, no seu desenvolvimento. Segundo HAGEN et al. (1976), tal parâmetro é fundamental para o sucesso no uso de predadores em programas de controle biológico.O efeito da temperatura sobre o ciclo de vida e a determinação das exigência...