Due to concerns with synthetic neurotoxic insecticides used in insect pest management, alternative control methods are sought. Methoprene is a juvenile hormone analogue, which is well-known for its lethal effects on immature insects, and is registered as a stored-grain insecticide in the U.S.A. and Australia. However, less is known about its sub-lethal effects. Experiments were conducted to investigate the effects of methoprene (Diacon II) on heat tolerance, cold tolerance and progeny production of Tribolium castaneum (Herbst) when late-instar larvae or adults were exposed to wheat treated with methoprene. Methoprene at 3.33 ppm or higher, reduced heat tolerance of adults at 46ºC. In contrast, methoprene did not affect the heat tolerance of larvae. Cold tolerance and cold acclimation of both adults and larvae was not affected by methoprene. Exposure of larvae to 0.001 or 0.0165 ppm of methoprene on wheat had 37 and 72% reduction in adult emergence, respectively. The surviving adults had normal movement, but their progeny production was reduced by 71%. Males were affected more than females. Exposure of adults to methoprene (66.6 ppm) did not reduce progeny production. Methoprene is used as a surface treatment to control insects in empty grain bins, processing facilities and warehouses. Experiments were conducted to assess the effect of surface material, temperature and cleaning practices on methoprene residual efficacy. A bioassay with late-instar larvae at 30ºC until adult emergence was used to measure methoprene residual efficacy. Methoprene applied at the label rate (0.0003 mg/cm2) on varnished wood, held at 20, 30 or 35ºC for 24 weeks, prevented all development of larvae into adults. Conversely, concrete surfaces allowed 22% adult emergence after 8 weeks and 69% after 24 weeks. Temperatures, 20, 30 or 35ºC, that the concrete surfaces were held before the bioassay, did not affect this decline in efficacy. Presence of flour or repeated removal of flour (cleaning) reduced the efficacy of methoprene on concrete surfaces, but not on varnished wood. Maintaining concrete surfaces at 65ºC for 48 hours did not reduce efficacy. The implications of these results are discussed in the context of controlling stored-product insects, as well as insect physiology.

Due to concerns with synthetic neurotoxic insecticides used in insect pest management, alternative control methods are sought. Methoprene is a juvenile hormone analogue, which is well-known for its lethal effects on immature insects, and is registered as a stored-grain insecticide in the U.S.A. and Australia. However, less is known about its sub-lethal effects. Experiments were conducted to investigate the effects of methoprene (Diacon II) on heat tolerance, cold tolerance and progeny production of Tribolium castaneum (Herbst) when late-instar larvae or adults were exposed to wheat treated with methoprene. Methoprene at 3.33 ppm or higher, reduced heat tolerance of adults at 46ºC. In contrast, methoprene did not affect the heat tolerance of larvae. Cold tolerance and cold acclimation of both adults and larvae was not affected by methoprene. Exposure of larvae to 0.001 or 0.0165 ppm of methoprene on wheat had 37 and 72% reduction in adult emergence, respectively. The surviving adults had normal movement, but their progeny production was reduced by 71%. Males were affected more than females. Exposure of adults to methoprene (66.6 ppm) did not reduce progeny production. Methoprene is used as a surface treatment to control insects in empty grain bins, processing facilities and warehouses. Experiments were conducted to assess the effect of surface material, temperature and cleaning practices on methoprene residual efficacy. A bioassay with late-instar larvae at 30ºC until adult emergence was used to measure methoprene residual efficacy. Methoprene applied at the label rate (0.0003 mg/cm2) on varnished wood, held at 20, 30 or 35ºC for 24 weeks, prevented all development of larvae into adults. Conversely, concrete surfaces allowed 22% adult emergence after 8 weeks and 69% after 24 weeks. Temperatures, 20, 30 or 35ºC, that the concrete surfaces were held before the bioassay, did not affect this decline in efficacy. Presence of flour or repeated removal of flour (cleaning) reduced the efficacy of methoprene on concrete surfaces, but not on varnished wood. Maintaining concrete surfaces at 65ºC for 48 hours did not reduce efficacy. The implications of these results are discussed in the context of controlling stored-product insects, as well as insect physiology.

No abstract.

No description available.

Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-05-17T14:57:52Z No. of bitstreams: 1 Amaury Soares de Brito.pdf: 1041809 bytes, checksum: 74b076dde16ba738e59a5ac81be89a70 (MD5) / Made available in DSpace on 2017-05-17T14:57:52Z (GMT). No. of bitstreams: 1 Amaury Soares de Brito.pdf: 1041809 bytes, checksum: 74b076dde16ba738e59a5ac81be89a70 (MD5) Previous issue date: 2015-03-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Tribolium castaneum is a secondary pest that causes quantitative and qualitative losses in grain stocks of various cereals and derivatives. Your control is performed with several applications of insecticides and the consequence of this practice is the environmental contamination of people and the selection of resistant insects populations. New methods of control, such as the use of essential oils are gaining strength to mitigate negative impacts. Following this line of reasoning the objective of this study was to evaluate the fumigant action, contact and repellent of essential oils in control of T. castaneum. Were used essential oils of plants Eucalyptus citriodora Hook (Myrtaceae), Foeniculum vulgare Mill (Lamiaceae), Cymbopogon winterianus Jowitt (Poaceae), Citrus sinensis (L) Osbeck (Rutaceae), Citrus aurantium, Croton helitropiifolius Kunth, Croton blanchetianus Baill and Croton pulegiodorus Baill (Euphorbiaceae). In fumigation different concentrations of test oils were applied on filter paper strips attached on the bottom of the fumigation chamber cover (0.5 L), which contained 20 grams of food substrate and 20 adults of T. castaneum unsexed. The insect mortality was recorded after 120 hours of exposure in B.O.D kiln incubator, at 30 °C and RH 70±5%. For the contact test, different concentrations of the oils were diluted in acetone and applied to filter paper disks (9 cm ∅) and the control was applied only acetone. After evaporation of the solvent, the disks were placed in petri dishes and 20 adult insects released unsexed, and the mortality was assessed after 24 hours of exposure in BOD. The repellency tests were performed in arenas composed of two pots connected to a central box. In a pot of one end moistened feed substrate was mixed deposited with concentrations of the essential oil diluted in acetone, in the other pot (control) was deposited only food; Twenty insects do not sexed adult were released in the central box, being exposed for 48 hours to evaluate the preference. Was used a completely randomized design with four replications; data fumigation tests were submitted to regression analysis, and the contact tests submitted to probit analysis. The repellent rate was calculated by the formula IR=2*(G+P) and the percentage of repellency (PR) by the formula [PR=(NC-NT)/(NC+NT)*100]. In fumigation tests C. aurantium oil showed 100% mortality at a concentration of 490 μL/L air, and F. vulgare 93% mortality at the concentration of 900 μL/L air. In contact tests for E. citriodora were obtained LC50 =0.5035 μL/cm2 and CL99 = 0.8478 μL/cm2. For C. winterianus were estimated LC50 = 0.9760 and 5.1983 CL99 = μL/cm2. F.vulgare got the lowest concentrations with LC50 = 0.0157 and CL99 = 0,0216 μL/cm2. The oils of E. citriodora and C. winterianus showed repellent effect and C. winterianus and F. vulgare reduced adult emergence. / Tribolium castaneum é uma praga secundária que causa perdas quantitativas e qualitativas nos estoques de grãos de diversos cereais e seus derivados. O seu controle é realizado com diversas aplicações de inseticidas e a consequência dessa prática é a contaminação ambiental, das pessoas e a seleção de populações de insetos resistentes. Novos métodos de controle, como o uso de óleos essenciais estão adquirindo força por mitigar impactos negativos. Seguindo esta linha de raciocínio o objetivo deste trabalho foi avaliar o efeito fumigante, de contato e repelente de óleos essenciais no controle do T. castaneum. Foram usados óleos essenciais das plantas Eucalyptus citriodora Hook (Myrtaceae), Foeniculum vulgare Mill (Lamiaceae), Cymbopogon winterianus Jowitt (Poaceae), Citrus sinensis (L) Osbeck (Rutaceae), Citrus aurantium L., Croton helitropiifolius Kunth, Croton blanchetianus Baill e Croton pulegiodorus Baill (Euphorbiaceae). Nos testes de fumigação diferentes concentrações dos óleos foram aplicadas em tiras de papel filtro presas na parte inferior da tampa da câmara de fumigação (0,5L), na qual continha 20 gramas de substrato alimentar e 20 insetos adultos de T. castaneum não sexados. A mortalidade dos insetos foi avaliada após 120 horas de exposição em estufa incubadora tipo B.O.D, a 30ºC e 70 % UR. Para os testes de contato, diferentes concentrações dos óleos foram diluídas em acetona e aplicados em discos de papel filtro (9 cm Ø), e na testemunha foi aplicado apenas acetona P.A. Após a evaporação do solvente os discos foram colocados em placas de Petri e liberados 20 insetos adultos não sexados, e a mortalidade avaliada após 24 horas de exposição, em estufa incubadora tipo B.O.D. Os testes de repelência foram efetuados em arenas compostas por dois potes ligados a uma caixa central. Em um pote de uma extremidade foi depositado substrato alimentar umedecido com concentrações do óleo essencial diluído em acetona, e no pote da outra extremidade (testemunha) foi depositado apenas alimento; vinte insetos adultos não sexados foram liberados na caixa central, ficando expostos por 48 horas para avaliação da preferência. Utilizou-se o delineamento inteiramente casualizado com quatro repetições; os dados dos testes de fumigação foram submetidos à análise de regressão, e os dos testes de contato submetidos à análise de probit. O índice de repelência foi calculado pela formula IR=2*G(G+P) e a porcentagem de repelência (PR) pela formula [PR=(NCNT)/(NC+NT)*100]. Nos testes de fumigação o óleo de C. aurantium apresentou 100% de mortalidade na concentração de 490 μL/L ar e F. vulgare 93% de mortalidade com a concentração de 900 μL/L. ar. Nos testes de contato para E. citriodora foram obtidas CL50=0,5035 μL/cm2 e CL99=0,8478 μL/cm2. Para C. winterianus foram estimadas CL50=0,9760 e CL99= 5,1983 μL/cm2. F. vulgare obteve as menores concentrações com CL50=0,0157 e CL99= 0,0216μL/cm2. Os óleos de E. citriodora C. winterianus apresentaram efeito repelente e C. winterianus e F. vulgare reduziram a emergência de adultos.

Doctor of Philosophy / Department of Entomology / James F. Campbell / James R. Nechols / Theoretical and empirical ecological research has emphasized the need for understanding how animals perceive and respond to landscape structure and the importance of integrating both behavioral and landscape approaches when studying movement behavior. Knowledge of insect movement behavior is essential for understanding and modeling dispersal and population structure and developing biologically-based integrated pest management programs. My dissertation research addresses questions concerning how insects respond to landscape structure by examining movement behavior of an important stored-product pest, red flour beetle (Tribolium castaneum), in experimental landscapes. Results show that beetles modify movement behavior depending on landscape structure. Edge effects and interpatch distances may influence landscape viscosity, or the degree to which landscape structure facilitates or impedes movement, resulting in significant differences in velocity and tortuosity (amount of turning) of movement pathways, as well as retention time in landscapes with different levels of habitat abundance and aggregation. Perceptual range, or the distance from which habitat is detected, appears to be limited while beetles are moving in a landscape as they did not respond to a flour resource before physical encounter. Beetles showed differential responses to patches with various characteristics, entering covered patches more quickly than uncovered patches with more resource or the same amount of resource. Permeability of patches changed with subsequent encounters suggesting that full evaluation of patch quality may only occur after entering a patch. Beetles responded to landscape structure differently depending on the activity in which they were engaged. Distribution of movement pathways was similar to that of the habitat, but distribution of oviposition sites were significantly more aggregated than pathways and habitat. Oviposition site choice may be influenced by a complex set of factors which include previous visitation, amount of resource, travel costs, and edge effects. Insights were gained concerning how red flour beetle perceives resources, modifies search strategies, responds to boundaries, and chooses reproductive sites in patchy landscapes. This research provides new information regarding how red flour beetle interacts with landscape structure that has implications in the areas of behavioral and landscape ecology and applications in stored-product insect ecology.

Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-07-13T13:51:37Z No. of bitstreams: 1 texto completo.PDF: 406966 bytes, checksum: abd8716c362cf52ad877eda05b8eaefc (MD5) / Made available in DSpace on 2017-07-13T13:51:37Z (GMT). No. of bitstreams: 1 texto completo.PDF: 406966 bytes, checksum: abd8716c362cf52ad877eda05b8eaefc (MD5) Previous issue date: 2001-03-30 / Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Atualmente, têm-se encontrado grandes entraves no controle de pragas em unidades armazenadoras e processadoras de grãos. A necessidade de formas de controle rápidas, de baixo custo e com menor impacto ambiental tem induzido a geração de novas tecnologias e o melhor manejo das já existentes. A futura saída do brometo de metila do mercado gera a necessidade de se estudarem tecnologias que permitam um controle efetivo de pragas de grãos armazenados em período inferior a 24 h, especialmente em unidades processadoras de grãos. O trabalho desenvolvido teve por objetivo estudar a interação da utilização de fosfina (PH3) e dióxido de carbono (CO2) no controle de Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) em diferentes temperaturas. Foram utilizados 40 adultos de T. castaneum em três repetições. Os tratamentos testados constituíram -se de uma atmosfera contendo 1 g m^-3 de fosfina (PH3) associada a 5% de CO2, nas temperaturas de 20, 25, 30, 35 e 40ºC. Em cada temperatura, foram avaliados cinco diferentes períodos de exposição, de acordo com os dados obtidos em testes preliminares. Os testes foram realizados em três câmaras metálicas, acondicionadas no interior de uma câmara climática, com controle de temperatura e umidade relativa. Após a avaliação de mortalidade em cada tratamento, realizou-se uma análise de próbite dos dados para determinar os tempos letais (TL) para controlar 50 e 95% da população de T. castaneum em cada temperatura estudada. Através de análise de regressão, obtiveram-se equações para determinar os TL50 e TL95 em função da temperatura. Ao utilizar-se a temperatura de 40ºC, verificou- se que é possível controlar 95% da população do inseto testado em aproximadamente 23 h. De acordo com os resultados obtidos, efetuou-se uma análise da viabilidade econômica da tecnologia proposta: considerando um aquecimento da estrutura a ser tratada, a tecnologia mostrou-se viável a 40ºC, em volumes superiores a 1.447 m³. / The control of stored grains and processing unities pests is going through great difficulties. The need of rapid, low cost and environmentally safe ways of controlling such pests induces the generation of new technologies and a better handling of the existing ones. The phasing out of methyl bromide is sparking the search for possible alternatives for effective pest control within a 24 hours period, especially for grain processing units. The accomplished work aimed to study the combination of phosphine (PH3) with carbon dioxide (CO2) in different temperatures on the control of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Forty adults of T. castaneum were used in three replicates, and the treatments were modified atmospheres with 1 g m^-3 of phosphine combined with 5% of CO2 in the temperatures of 20, 25, 30, 35 and 40ºC. Five exposure periods for each temperature were used, according to results obtained in preliminary tests. The experiment was carried out in metallic chambers placed inside a climatic chamber with air temperature and relative humidity control. After the mortality evaluation of each treatment, probit analyses were carried out in order to determine the lethal times (LT) values to control 50 and 95% of T. castaneum population for each studied temperature. Afterwards, a regression analysis was used to obtain the equations of the LT50 and LT95 as a function of the temperature. For the temperature of 40ºC, it was possible to control 95% of the insect population with the proposed treatment in 23.2 hours. An analysis of the economical viability was then made using the results obtained on the research, comparing the proposed technology with two other one available, an increasing of the environment temperature was also studied. In the economical analysis, the treatment of 40ºC was better than the available one when the facilities to be treated are greater than 1447 m³.

No description available.

Master of Science / Department of Entomology / Frank H. Arthur / Kun Yan Zhu / Experiments were conducted to assess the effects of direct and indirect exposure scenarios, different degrees of residual flour, open and obstructed positions, and seasonal temperature variations on the efficacy of synergized pyrethrin against the red flour beetle, Tribolium castaneum (Herbst) and the confused flour beetle, Tribolium confusum Jacquelin du Val. To evaluate effects of direct and indirect exposures of T. castaneum and T. confusum eggs, larvae, pupae, or eggs to the insecticide aerosol within a flour mill, the following treatments were made to each life stage: insects treated with aerosol and transferred to treated or untreated flour, untreated insects transferred to treated flour, and insects and flour combined and treated together. Different degrees of harborage or sanitation levels were created by exposing T. confusum larvae, pupae, and adults to pyrethrin aerosol in Petri dishes containing 0, 0.1, 1, 5, and 10 g of wheat flour. Effects of pyrethrin dispersal in open and obstructed positions and seasonal temperature variations were assessed by exposing T. confusum pupae and adults in open positions and inside wooden boxes (1 m long, 20 cm wide, and 5, 10, or 20 cm high) inside experimental sheds maintained at target temperatures of 22, 27, and 32 °C. Results showed that when T. castaneum and T. confusum were directly exposed to aerosol without the flour source, or with a low amount of flour at open exposed areas, the aerosol provided good control against all life stages of T. castaneum and T. confusum. However, when insects were indirectly exposed (treated together with flour or untreated insects were transferred to treated flour), or treated together with deeper flour amounts, and exposed inside the boxes, the efficacy was greatly reduced. Eggs and pupae of both the species were more susceptible compared to larvae and adults. Additionally, the moribund adults initially observed in indirect exposure treatments, or at the deeper flour depth and exposure positions insides the boxes, were better able to recover. Generally, temperatures in the range of 22-32 °C had no significant effects on overall efficacy of pyrethrin aerosol.

Master of Science / Department of Entomology / Yoonseong Park / Neuropeptides are diffusible signal molecules mediating vital physiological processes. We have been interested in a group of neuropeptides and their receptors involved in osmoregulatory neuroendocrine system which has been suggested as a possible target for development of new biopesticides. Since the genome sequence of the T. castaneum has recently been completed, we were able to identify the respective genes encoding three peptide hormones from T. castaneum that were characterized for their diuretic activities in other insects: one calcitonin-like (CT-like DH31) and two corticotropin releasing factor-like (CRF-like DH37 and DH47, the numbers indicates the number of amino acid residues). This peptide is expressed at all developmental stages and in the central nervous system (CNS), Malpighian tubules (MT) and gut. The synthetic peptide TricaDH31 also has been show to be biologically active, inducing significant excretions in adults beetles. When Tcdh31 was silenced using RNAi, adults had deformed wings and abnormal body shape. Mortality in adults was high, the number of eggs laid was reduced as well as the hatchability of the eggs. The two biologically active CRF-like peptides in T. castaneum, are encoded by one gene which undergoes alternative splicing. When Tcdh47 was knocked down, high mortality occurred as well as low oviposition and egg hatchability. Similar effects were observed with silencing of both CRF-like genes. However, RNAi of Tcdh37 transcripts had similar, but less severe effects. Adults also had deformed wings when both CRF-like genes were silenced, but not when just one of them was knocked down. These results indicate that CRF-like genes could have additional biological functions to their roles in dieresis. We tested the in vivo activity of these peptides. TenmoDH47 induced high excretions in adults, whereas TenmoDH37 induces smaller excretions. We identified the respective genes encoding two putative receptors for TricaDH31 as Glean_13321 and Glean_02694 (Trica-ctr1 and Trica-ctr2, respectively) and two receptors for CRF-like peptide as Glean_12799 and Glean_07104 (Trica-crfr1 and Trica-crfr2, respectively). The CT-like receptors are expressed at all developmental stages, in the CNS and MT. RNAi of the receptors revealed that only Trica-ctr2 silencing caused significant mortality and reduction in the number of eggs laid. The CRF-like receptors are expressed at all developmental stages. Adults also had deformed wings and laid fewer eggs after RNAi of Trica-crfr1. RNAi of Trica-crf2 also caused significant mortality. These peptides and receptors seem to fine tune the beetle physiology and may have functions not yet known.