The 96-hr LC50 of cyfluthrin in Pimephales promelas ata temperature of 23*C and a pH of 8 was 1.08 g/L. The toxicity of cyfluthrin was inversely related to temperature and pH. A temperature of 10*C and a pH of 6 significantly decreased the 96-hr LC50 to 0.009 gg/L. Likewise, sublethal exposures to cyfluthrin significantly affected the fathead minnow's ability to tolerate high and low temperatures. Cyfluthrin compromised the fathead minnow's lower temperature tolerance (CTMin) by 60C and the upper temperature tolerance (CTMax) by 20C. Although cyfluthrin may not be present in the environment in large amounts due to its physical and chemical properties, small concentrations ( g/L) may adversely affect fish populations.

A behavioral model for acute responses in bivalves, was developed using time series analysis for use in a real-time biomonitoring unit. Stressed bivalves closed their shell and waited for the stressful conditions to pass. Baseline data showed that group behavior of fifteen bivalves was periodic, however, individuals behaved independently. Group behavior did not change over a period of 20 minutes more than 30 percent, however, following toxic exposures the group behavior changed by more than 30 percent within 20 minutes. Behavior was mathematically modeled using autoregression to compare current and past behavior. A logical alarm applied to the behavior model determined when organisms were stressed. The ability to disseminate data collected in real time via the Internet was demonstrated.

Graduation date: 2002

Made available in DSpace on 2014-06-11T19:22:59Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-04-25Bitstream added on 2014-06-13T20:10:19Z : No. of bitstreams: 1 jacob_cro_me_rcla.pdf: 1789232 bytes, checksum: 4d1aeb62cf1a6763869b8890da8b652a (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Recentemente as abelhas têm sido devidamente valorizadas como importantes polinizadoras de flores silvestres e cultivadas. A densidade populacional de muitos polinizadores tem diminuído devido, principalmente, à intensificação agrícola e ao uso de pesticidas, prejudicando os serviços de polinização. A metodologia clássica para estimar a toxicidade dos produtos químicos para insetos é determinar a dose letal média (DL50) ou a concentração letal média (CL50), podendo então estabelecer doses que sejam mais seguras aos organismos não-alvo ou benéficos. Além dos efeitos de toxicidade aguda, levando a morte das abelhas, doses subletais dos inseticidas podem provocar alterações comportamentais e fisiológicas nos indivíduos, que ao longo do tempo acarretarão em sérios prejuízos na manutenção da colônia. Um dos inseticidas amplamente utilizado é o fipronil, este atua ligando-se aos receptores do ácido gama-aminobutírico (GABA), interrompendo os canais de cloro, resultando na perda de sinalização inibitória neural. Na literatura pode-se encontrar diversos trabalhos que utilizam como modelo principal a abelha Apis mellifera, porém, é importante ressaltar a diversidade existente entre as abelhas nativas no Brasil, os meliponíneos, e sua participação na conservação da biodiversidade, assim como na polinização de áreas de cultivo, o que torna extremamente importante estudos com essa abelha. Com a finalidade de entender como o fipronil interfere morfo e fisiologicamente em abelhas sem ferrão, a região de interesse deste estudo foram os corpos pedunculados, já que estes são centros cerebrais complexos e tidos como local de convergência multisensorial. Para auxiliar no mapeamento metabólico, utilizou-se como marcador a enzima citocromo oxidase e a enzima caspase-3, técnicas utilizadas na observação de atividade neural... / A few decades the bees are considered an important indicator of high environmental sensitivity, and appreciated as important pollinators of wildflowers and cultivated. The population density of many pollinators have declined to harmful levels to pollination services manly due to agricultural intensification and the use of pesticides. The classic methodology of estimating the effects of chemicals for insects is to determine the median lethal dose (LD50) or median lethal concentration (LC50) that can then establish doses that do not harm non-target organisms or beneficial. Besides the effects of acute toxicity, leading to death bees, sublethal doses of insecticides can cause physiological and behavior changes of individuals over time, resulting in serious harm to maintain the colony. One of the widely used insecticides is fipronil, its acts by binding to gamma-aminobutyric acid (GABA) disrupting chloride channels, resulting in loss of inhibitory neural signaling. In the literature one can find several works using as main bee model Apis mellifera, however, it is important to highlight the diversity of Brazilian native bees, the stingless bees, and their participation in biodiversity conversation, as well as in the pollination of cultivated land. In order to understand how fipronil affect morpho and physiologically the stingless bee S. postica, the region of interest in this study were the mushroom bodies, since these are complex brain centers and used as a place of multisensory convergence. This work established the contact LD50 and Ingestion LC50 to the fipronil insecticide for foragers workers stingless bee Scaptotrigona postica in 0.54ng/bee and 0.24ng/μL of the food after 24 hours, respectively, confirming the high toxicity of this phenylpyrazole, in the groups submitted to contact contamination, were identify morphological... (Complete abstract click electronic access below)

In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).

Resumo: Recentemente as abelhas têm sido devidamente valorizadas como importantes polinizadoras de flores silvestres e cultivadas. A densidade populacional de muitos polinizadores tem diminuído devido, principalmente, à intensificação agrícola e ao uso de pesticidas, prejudicando os serviços de polinização. A metodologia clássica para estimar a toxicidade dos produtos químicos para insetos é determinar a dose letal média (DL50) ou a concentração letal média (CL50), podendo então estabelecer doses que sejam mais seguras aos organismos não-alvo ou benéficos. Além dos efeitos de toxicidade aguda, levando a morte das abelhas, doses subletais dos inseticidas podem provocar alterações comportamentais e fisiológicas nos indivíduos, que ao longo do tempo acarretarão em sérios prejuízos na manutenção da colônia. Um dos inseticidas amplamente utilizado é o fipronil, este atua ligando-se aos receptores do ácido gama-aminobutírico (GABA), interrompendo os canais de cloro, resultando na perda de sinalização inibitória neural. Na literatura pode-se encontrar diversos trabalhos que utilizam como modelo principal a abelha Apis mellifera, porém, é importante ressaltar a diversidade existente entre as abelhas nativas no Brasil, os meliponíneos, e sua participação na conservação da biodiversidade, assim como na polinização de áreas de cultivo, o que torna extremamente importante estudos com essa abelha. Com a finalidade de entender como o fipronil interfere morfo e fisiologicamente em abelhas sem ferrão, a região de interesse deste estudo foram os corpos pedunculados, já que estes são centros cerebrais complexos e tidos como local de convergência multisensorial. Para auxiliar no mapeamento metabólico, utilizou-se como marcador a enzima citocromo oxidase e a enzima caspase-3, técnicas utilizadas na observação de atividade neural... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A few decades the bees are considered an important indicator of high environmental sensitivity, and appreciated as important pollinators of wildflowers and cultivated. The population density of many pollinators have declined to harmful levels to pollination services manly due to agricultural intensification and the use of pesticides. The classic methodology of estimating the effects of chemicals for insects is to determine the median lethal dose (LD50) or median lethal concentration (LC50) that can then establish doses that do not harm non-target organisms or beneficial. Besides the effects of acute toxicity, leading to death bees, sublethal doses of insecticides can cause physiological and behavior changes of individuals over time, resulting in serious harm to maintain the colony. One of the widely used insecticides is fipronil, its acts by binding to gamma-aminobutyric acid (GABA) disrupting chloride channels, resulting in loss of inhibitory neural signaling. In the literature one can find several works using as main bee model Apis mellifera, however, it is important to highlight the diversity of Brazilian native bees, the stingless bees, and their participation in biodiversity conversation, as well as in the pollination of cultivated land. In order to understand how fipronil affect morpho and physiologically the stingless bee S. postica, the region of interest in this study were the mushroom bodies, since these are complex brain centers and used as a place of multisensory convergence. This work established the contact LD50 and Ingestion LC50 to the fipronil insecticide for foragers workers stingless bee Scaptotrigona postica in 0.54ng/bee and 0.24ng/μL of the food after 24 hours, respectively, confirming the high toxicity of this phenylpyrazole, in the groups submitted to contact contamination, were identify morphological... (Complete abstract click electronic access below) / Orientador: Osmar Malaspina / Coorientador: Roberta Cornélio Ferreira Nocelli / Banca: Elaine Cristina Mathias da Silva Zacarin / Banca: Thaisa Cristina Roat / Mestre