It is commonly thought that blow flies are nocturnally inactive. Blowflies are often important in helping to estimate post mortem intervals (PMI) for corpses found at death scenes. If blow flies oviposit during nocturnal hours, there could possibly be up to 12-hour discrepancies for estimates of PMI. Two blow fly species, Phaenicia eximia (Wiedemann) and Cochliomyia macellaria (F.), oviposited nocturnally on ground beef baits in 2003, during the onset of low-atmospheric pressure (an air mass with lower atmospheric pressure than that of the air surrounding it) at rural study sites near Snook (Burleson County), Texas, under artificial lighting of at least 1500 footcandles when temperatures were at 26?C or higher. Trials conducted under similar conditions during the same year without a low-pressure system moving into the area resulted in no nocturnal blow fly oviposition. Nocturnal blow fly oviposition went undetected once low-atmospheric pressure systems settled into the study area, irrespective of temperature and lighting conditions. Thus, this study illustrates that there is a connection between the onset of low-atmospheric pressure and nocturnal blow fly oviposition on baits under artificial lighting of 1500 footcandles or more when temperatures are 26 ?C or above. After concluding 2003 experiments, statistical analyses supplied evidence that woodland habitat was more favorable for blow fly oviposition than prairieland habitat throughout the 2003 study, irrespective of species or time of year. Furthermore, statistical analyses conducted on nocturnal and diurnal temperature ranges furnished evidence to support the hypothesis that 2003 nocturnal temperatures had more of an effect on daily ovipositing than diurnal temperatures for P. eximia and Cynomyopsis cadaverina (Robineau-Desvoidy).

The invasive cactus moth, Cactoblastis cactorum, poses a threat to opunitoid cacti species of North America. The following work contains four separate studies investigating C. cactorum host plant preference and performance, predation and parastitism of C. cactorum, effects of C. cactorum on local Opuntia populations, and associational effects of host and non-host plants on C. cactorum and native Opuntia-feeding herbivores. We found that, among southwestern and Mexican opuntioid taxa, moths preferred O. engelmannii var. linguiformis and var. engelmannii for oviposition, while Consolea rubescens and O. streptacantha were superior larval hosts. Oviposition was best predicted by number of cladodes and degree of spininess; epidermal toughness was a significant predictor of most larval fitness parameters. In general, oviposition preference was not correlated with larval performance. A lack of co-evolutionary history between C. cactorum and North American opuntioid species may help explain this disconnect. We placed irradiated C. cactorum eggsticks and pupae on Opuntia plants in the field to test for predation. We found evidence of predation, most likely from ants, on ~16% of eggsticks and ~18% of pupae. Predation rates, ant abundance, and cladode growth were higher, and C. cactorum damage lower, on Opuntia located near the extrafloral nectar-producing legume Chamaecrista fasciculata. We attribute these associational effects to the ability of C. fasciculata to attract ants to its extrafloral nectar. Over the course of six years, ~78% of nearly 600 tagged Opuntia were attacked by C. cactorum at least once and ~76% of the plants survived. Two separate studies found that Opuntia stricta was more likely to be attacked by C. cactorum than O. humifusa; we also found that O. stricta was more likely to die following an attack. A plant's odds of survival decreased as C. cactorum attack frequency increased, but plants that did survive had positive growth rates, regardless of attack status. We did not find significant evidence of associational effects for O. humifusa and O. stricta, either for C. cactorum or native Opuntia-feeding herbivores. It could be that present herbivore densities are low enough, and host plants plentiful enough, to avoid mechanisms that usually lead to associational resistance or susceptibility. Overall, our results suggest that the presence and spread of C. cactorum should be taken seriously, especially for rare opuntioids and the Opuntia-rich deserts of North America. However, for more common opuntioid host species, there may be enough resistant or tolerant individuals, and sufficient top down control through ant predation, for populations to persist at current C. cactorum densities. We acknowledge that information on Opuntia reproduction and recruitment rates are needed to confirm this suggestion, and see this as an excellent opportunity for future research

The salamander family Sirenidae is composed of two extant genera, Siren and Pseudobranchus, each with two known species. Several questions regarding Sirenidae life history persist, and much of the available life history data for Pseudobranchus are attributed to studies of P. axanthus in northern Florida. Information on the reproductive biology of P. axanthus is limited, and historical references often suggest contradictory results. This study was undertaken to clarify information and expand on the limited data regarding P. axanthus reproductive biology, specifically for southern Florida populations. The study population was most likely the P. a. belli subspecies. P. axanthus in southern Florida exhibited year round, continuous reproduction with oviposition documented in nine months. Potential clutch size was positively correlated to female size. The largest observed potential clutch was a female with 58 pre-ovulatory oocytes. The largest observed bout was a female with 15 oviductal eggs. Female P. axanthus in southern Florida oviposited eggs singly and at total densities of 3-4 eggs/m2. Developmental time to egg hatching lasted about 30 days, larvae hatched at 16mm TL, and minimum size at female sexual maturity was 115mm TL and 72mm SVL. The reproductive biology of P. axanthus was distinctly contrasting to other members of the family Sirenidae, S. intermedia and S. lacertina, that occupy the same habitat at the same study location.

Wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a key pest of wheat, Triticum aestivum L. (Poaceae), in the Canadian Prairies. The larvae destroy wheat kernels, resulting in reduction of quality and quantity of wheat. Deployment of antixenotic wheat lines, which suppress oviposition of wheat midge, can reduce damage in wheat fields. The objectives of this thesis were to explore the interactions between wheat midge and spring wheat with emphasis on oviposition behavior and to explore the antixenosis of wheat to oviposition from the point of view of genetics and crop breeding. In this research, a doubled-haploid spring wheat population was studied, which was the progeny of a cross between a susceptible wheat cultivar ‘Roblin’ and a resistant (antixenotic and antibiotic) wheat line ‘Key 10’. Oviposition of wheat midge on wheat spikes in the laboratory was affected by visual and chemical cues. The visual contrast between wheat spikes and the background color in the laboratory was important in modifying oviposition of wheat midge on wheat spikes. Low contrast resulted in low egg density on wheat spikes in the laboratory. The egg density on wheat spikes in the laboratory decreased when the background color of the spikes was red or black; while yellow and blue backgrounds did not decrease egg density on the spikes. The laboratory study provided evidence that wheat midge oviposition was affected by volatiles emitted by wheat spikes. The volatiles of spikes of a post-anthesis susceptible wheat cultivar, ‘Roblin’, and a pre-anthesis resistant wheat line, ‘Key 10’, significantly suppressed the oviposition of wheat midge in the laboratory. It is hypothesized that these volatiles might be a factor in antixenosis of wheat against wheat midge in the doubled-haploid population studied. It is suggested that the differences of oviposition behavior in susceptible and antixenotic wheats, which was observed in the laboratory, might be due to volatiles emitted by wheat spikes. However, other factors such as tactile cues might also be involved. The observation of oviposition behavior in the laboratory on the susceptible wheat cultivar ‘Roblin’ showed that wheat midge started ovipositing sooner, stayed longer, laid more eggs and left the spike sooner after the last oviposition than on the antixenotic line ‘Key 10’. However, the time required for laying one egg was similar when wheat midge was on the susceptible or resistant wheat. The observed antennation behavior of wheat midge while probing the wheat spike might indicate that wheat midge probed for chemical cues emitted by the host plant. The observed ovipositor tapping and dragging on the wheat spike surface while probing the spike suggested that there might be receptors at the tip of the ovipositor which receive tactile cues from the plant surface, guiding oviposition. The correlations between morphological traits of bread wheat spikes and antixenosis in the laboratory were not high enough to conclude that those traits were associated with antixenosis. However, more research on fine scale morphological traits of the spike may reveal relationships with antixenosis. Based on data from a laboratory trial and trials in the field over two field seasons, it was concluded that the antixenosis to wheat midge in the doubled-haploid population was probably conferred by two genes with complementary interactions among genes, and a heritability of 67%. In the two field seasons, the least preferred line received 13% and 11% as many eggs as on ‘Roblin’; ‘Key 10’ received 57% and 20% as may eggs as on ‘Roblin’. Our study did not provide evidence for linkage between antixenosis genes and the antibiosis gene, Sm1, which is associated with death of larvae of wheat midge. The antixenosis of spring wheat against wheat midge can be considered as a promising mechanism for suppressing wheat midge oviposition in the field. More research is required to reveal additional genetic information which would help crop breeders in production of cultivars antixenotic to wheat midge.

Wheat bulb fly (WBF) (Delia coarctata, Fallén, Diptera: Anthomyiidae) is a pest of commercial importance in cereal crops. Control is dependent on organophosphates some of which are restricted in the UK, while current oviposition monitoring techniques are labour intensive and subjective. Eggs are not laid in association with a host-plant, therefore, prompt location of a suitable host is critical to the survival of the newly hatched larvae. Wheat bulb fly larvae have been shown to exhibit a positive chemotactic response to wheat and other host-plant seedlings and their root exudates. The objective of this study was to improve the control and population monitoring methodology associated with WBF, by investigating the ecology and specifically the chemical ecology of the WBF. Bioassays were used to investigate the behavioural response of WBF to known chemical constituents of host-plant exudates. Four secondary metabolites were found to be attractive while CO2 was found to alter the behaviour of larvae. Wheat bulb fly oviposition was assessed in field situations to describe egg laying spatially and through time. Geostatistical and ecological techniques were used to observe the spatial dependence and dispersion of oviposition and construct contour maps or scale-sized dot graphs of oviposition density. The traditional single line transect sampling pattern was compared against a more intensive sampling regime. Oviposition monitoring was conducted over a three year period to ascertain the time of peak egg density of this fly. A molecular based diagnostic test to assess WBF egg populations for damage forecasting was developed. A real time polymerase chain reaction (PCR) protocol was produced to estimate field populations of WBF eggs through the quantification of eggs from field samples. In addition endpoint PCR was used to identify the presence or absence of eggs from samples. This study gives the potential to advance current control methodology by providing the basis for the development of a lure and kill or confusion/disruption strategy, while offering a more accurate sampling system and a molecular diagnostic test, for improvement of the management of WBF.

Wheat midge, Sitodiplosis mosellana (Géhin) (Diptera: Cecidomyiidae), is a key pest of wheat, Triticum aestivum L. (Poaceae), in the Canadian Prairies. The larvae destroy wheat kernels, resulting in reduction of quality and quantity of wheat. Deployment of antixenotic wheat lines, which suppress oviposition of wheat midge, can reduce damage in wheat fields. The objectives of this thesis were to explore the interactions between wheat midge and spring wheat with emphasis on oviposition behavior and to explore the antixenosis of wheat to oviposition from the point of view of genetics and crop breeding. In this research, a doubled-haploid spring wheat population was studied, which was the progeny of a cross between a susceptible wheat cultivar ‘Roblin’ and a resistant (antixenotic and antibiotic) wheat line ‘Key 10’. Oviposition of wheat midge on wheat spikes in the laboratory was affected by visual and chemical cues. The visual contrast between wheat spikes and the background color in the laboratory was important in modifying oviposition of wheat midge on wheat spikes. Low contrast resulted in low egg density on wheat spikes in the laboratory. The egg density on wheat spikes in the laboratory decreased when the background color of the spikes was red or black; while yellow and blue backgrounds did not decrease egg density on the spikes. The laboratory study provided evidence that wheat midge oviposition was affected by volatiles emitted by wheat spikes. The volatiles of spikes of a post-anthesis susceptible wheat cultivar, ‘Roblin’, and a pre-anthesis resistant wheat line, ‘Key 10’, significantly suppressed the oviposition of wheat midge in the laboratory. It is hypothesized that these volatiles might be a factor in antixenosis of wheat against wheat midge in the doubled-haploid population studied. It is suggested that the differences of oviposition behavior in susceptible and antixenotic wheats, which was observed in the laboratory, might be due to volatiles emitted by wheat spikes. However, other factors such as tactile cues might also be involved. The observation of oviposition behavior in the laboratory on the susceptible wheat cultivar ‘Roblin’ showed that wheat midge started ovipositing sooner, stayed longer, laid more eggs and left the spike sooner after the last oviposition than on the antixenotic line ‘Key 10’. However, the time required for laying one egg was similar when wheat midge was on the susceptible or resistant wheat. The observed antennation behavior of wheat midge while probing the wheat spike might indicate that wheat midge probed for chemical cues emitted by the host plant. The observed ovipositor tapping and dragging on the wheat spike surface while probing the spike suggested that there might be receptors at the tip of the ovipositor which receive tactile cues from the plant surface, guiding oviposition. The correlations between morphological traits of bread wheat spikes and antixenosis in the laboratory were not high enough to conclude that those traits were associated with antixenosis. However, more research on fine scale morphological traits of the spike may reveal relationships with antixenosis. Based on data from a laboratory trial and trials in the field over two field seasons, it was concluded that the antixenosis to wheat midge in the doubled-haploid population was probably conferred by two genes with complementary interactions among genes, and a heritability of 67%. In the two field seasons, the least preferred line received 13% and 11% as many eggs as on ‘Roblin’; ‘Key 10’ received 57% and 20% as may eggs as on ‘Roblin’. Our study did not provide evidence for linkage between antixenosis genes and the antibiosis gene, Sm1, which is associated with death of larvae of wheat midge. The antixenosis of spring wheat against wheat midge can be considered as a promising mechanism for suppressing wheat midge oviposition in the field. More research is required to reveal additional genetic information which would help crop breeders in production of cultivars antixenotic to wheat midge.

Terpenes are important specialised metabolites produced by all organisms. Plants produce the greatest diversity of terpenoid compounds, which function in a variety of crucial processes including regulation of growth and development, energy production and plant-insect communication, including pollinator attraction and prevention of herbivore damage. Isopentenyl diphosphate (IPP), the building block for all terpenoid compounds, is synthesised in plants via two unique terpene synthesis pathways located in the plastids and the cytosol, and the regulation of these pathways is still not well understood. The aim of this research was to (1) modify and study the regulation of floral volatile production in Nicotiana tabacum (tobacco) by altering the expression of various enzymes in the terpene biosynthesis pathway and (2) determine the role of specific volatile compounds in floral odour blends in feeding and oviposition behaviours of Helicoverpa armigera, a polyphagous moth of widespread agricultural importance. Expression levels of several enzymes in the terpene biosynthetic pathway were altered by genetic modification in order to modify terpene volatile emissions produced by flowers of N. tabacum. Genes chosen for overexpression were cloned from several species and RNAi hairpins were constructed from gene fragments amplified from tobacco flower cDNA. Transgenic plants were produced by Agrobacterium-mediated transformation, and lines with high levels of transgene expression selected for analysis. The flower-specific Antirrhinum majus chalcone synthase promoter was chosen to control gene expression in transgenic lines in order to avoid the potentially deleterious effects of widespread disruption to terpene biosynthesis. Floral volatiles were sampled using two methods; solid phase microextraction, a highly sensitive technique able to detect even trace levels of volatile compounds in headspace samples, and Tenax sampling, a robust and replicable method to quantify volatile emissions. All floral headspace samples were analysed by gas chromatography-mass spectrometry. Floral volatile analysis determined that wild type Ti68 tobacco flowers emit a simple blend of floral volatiles, with only linalool, a monoterpene, and β-caryophyllene, a sesquiterpene, detected by both sampling methods. Volatile emissions were not subject to temporal regulation, but changes in the floral odour blend were detected during flower development. Overexpression of the plastidic terpene biosynthesis genes 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) and geranyl diphosphate synthase did not affect volatile production, however increased farnesyl diphosphate synthase expression in the cytosol surprisingly caused an increase in linalool emissions, synthesised in the plastids. Downregulation of DXR resulted in an albino phenotype affecting all young leaves, the upper stem and the sepals in the most severely affected lines. A significant three-fold decrease in floral linalool emissions, and a nine-fold reduction of both linalool and β-caryophyllene retained within floral tissues was observed in the transgenic lines. In feeding behaviour tests, male and virgin female H. armigera moths did not discriminate between wild type and DXR knockdown flowers at close-range, despite the significant difference in linalool emissions. Expression of an (E)-β-ocimene synthase gene controlled by the CHS promoter did not result in any transgenic plants emitting the novel monoterpene, (E)-β-ocimene. Significant problems with seed germination suggested that (E)-β-ocimene may cause embryo lethality in these lines. However, overexpression of a heterologous (S)-linalool synthase under control of the constitutive cauliflower mosaic virus 35S promoter resulted in a significant two-fold increase in volatile linalool, and β-glycosidase assays confirmed sequestration of a glycosylated linalool derivative in floral tissues. Oviposition preference tests with mated female H. armigera moths indicated a significant preference for egg-laying on wild type flowers compared to flowers with increased linalool production. The results of this research, and previous studies of volatile production in transgenic tobacco, indicate that IPP precursor exchange occurs predominantly in one direction from the cytosol to the plastids, at least under the stress caused by alterations in pathway flux. Regulation of the cytosolic terpene biosynthetic pathway upstream of IPP synthesis appears to be less strictly controlled than the plastidic pathway. Insect behavioural assays support the findings of recent studies in other moth species, and suggest that close-range feeding attraction of H. armigera may be more strongly influenced by visual cues, whereas odour cues, including contact chemoreception, play a more important role in oviposition preferences. The increase in knowledge of the olfactory contribution toward insect-plant communication demonstrated here, and from future work, will lead to improved management of pest species in agricultural and ecological settings.

Diss. (sammanfattning) Alnarp : Sveriges lantbruksuniversitet, 2004. / Härtill 5 uppsatser.

Mosquito-borne viral tropical diseases represent a great threat to the global public health. Diseases transmitted by mosquitoes are usually endemic, and millions of people throughout the world are infected by mosquitoes of the Family Culicidae. The mosquito Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Diptera: Culicidae) is the main vector of the dengue viruses and the urban yellow fever. The great proliferation of the different mosquitoes species is not only due to the high number of the breeding sites in the urban areas, but also due to the development of the resistance of the mosquitoes to the insecticide, such as the chlorinated organic compounds, organophosphates, carbamates, as well as the biological insecticide. With respect to the environment, the Laboratory of Synthesis and Isolation of the Pheromones (LaSIF) has been studying in the last years more ecological alternatives of control and surveillance of mosquito-borne vector of tropical diseases. Therefore, studies related to the breeding sites of the mosquito Ae. aegypti were accomplished as a form of obtaining data on how to control the populations of this vector. A study of the selection of specific oviposition breeding sites of the Ae. aegypti female mosquito was accomplished with different aqueous samples collected from artificial and natural breeding sites. Among all the different aqueous samples studied at the laboratory, the Aloe vera (Liliaceae) infusion was considered greater stimulant of the oviposition behavior of the Ae. Aegypti female. The Aloe vera infusion was also bioassayed the field and compared with the traditional attractive infusion used in programs of control and surveillance of the mosquito Ae. aegypti. Sample preparation methods solid phase extraction (SPE), stir-bar sorptive extration (SBSE), and liquid-liquid extraction (LLE), were accomplished to isolate the organic compounds present in the Aloe vera infusion. The extracts obtained by the extraction techniques were analyzed in relation to the stimulating potential of oviposition behavior of the female of the mosquito Ae. Aegypti. The separation of the organic substances contained in the extracts was accomplished through gas chromatography (GC). The identification of isolated substances was accomplished through to the use of high resolution gas chromatography coupled the mass spectrometry (CG-MS), and the active components in the extracts were located by coupled high resolution gas chromatography-electrophysiology (GC-EAG). / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Mosquitos hematófagos vetores de doenças tropicais representam uma grande ameaça à saúde pública global. Doenças transmitidas por mosquitos são normalmente endêmicas, e milhões de pessoas no mundo todo são infectados por mosquitos da Família Culicidae. O mosquito Aedes (Stegomyia) aegypti (Linnaeus, 1762) (Diptera: Culicidae) é o principal vetor do vírus da dengue e da febre amarela urbana. A grande proliferação de diferentes espécies de mosquitos é não somente devido ao alto número de criadouros aquáticos nas grandes áreas urbanas, mas também devido ao desenvolvimento da resistência dos mosquitos aos inseticidas tais como os organoclorados, organofosfatos, carbamatos e também aos inseticidas biológicos. Assim, em respeito ao meio ambiente, o Laboratório de Síntese e Isolamento de Feromônios (LaSIF) tem estudado nos últimos anos formas alternativas ecologicamente corretas, de controle e de vigilância de mosquitos hematófagos vetores de doenças tropicais. Portanto, estudos relacionados com os criadouros potenciais do mosquito Ae. aegypti foram realizados como uma forma de obter dados de como controlar as populações deste vetor. Primeiramente, foi realizado um estudo comportamental da seleção de sítios específicos de oviposição da fêmea do mosquito Ae. aegypti com diferentes amostras aquosas provenientes de criadouros artificiais e naturais. Dentre todas as diferentes amostras aquosas estudadas em laboratório, a infusão de Aloe vera (Liliaceae) foi considerada a mais estimulante do comportamento de oviposição da fêmea do mosquito Ae. aegypti. A amostra aquosa foi também testada em campo e comparada com a tradicional infusão atraente utilizada em programas de controle e vigilância do mosquito Ae. aegypti. Métodos de preparação de amostras tais como extração em fase sólida (SPE), extração por sorção com magneto de agitação (SBSE), assim como extração líquido-líquido (LLE) foram realizados para isolar os constituintes orgânicos presentes na infusão de Aloe vera. Os extratos obtidos pelas técnicas de extração também foram analisados em relação ao potencial estimulante de oviposição da fêmea do mosquito Ae. aegypti. A separação das substâncias orgânicas contidas nos extratos foi realizada através da cromatografia gasosa (GC). A identificação das substâncias isoladas foi realizada através do uso da cromatografia gasosa acoplada ao espectrômetro de massa de alta resolução (CG-MS), e a localização das substâncias eletrofisologicamente ativas foi possível através da cromatografia gasosa acoplada à eletroantenografia (GC-EAG).

Áreas verdes urbanas são ambientes que podem oferecem oportunidade de interação entre reservatórios e vetores dos meios urbano e silvestre, potencializando o risco de transmissão de doenças e de mudanças em seu perfil epidemiológico. Entender como as alterações da paisagem interferem na composição da fauna de culicídeos e conhecer quais espécies de vetores ocorrem nessas áreas, pode auxiliar na predição da distribuição espacial das espécies frente à urbanização, fornecendo importantes ferramentas para o controle de endemias e planejamento urbano. O objetivo desse estudo foi verificar a ocorrência de espécies de mosquitos vetores e avaliar a relação entre os diferentes tipos de uso e cobertura do solo e a composição da fauna de culicídeos. As coletas ocorreram quinzenalmente entre outubro de 2012 a março de 2013 com a utilização de armadilhas de oviposição instaladas em oito áreas verdes com diferentes características de paisagem do município de Porto Alegre, sul do Brasil. Foram coletados 4179 culicídeos de pelo menos 10 espécies. Destas, Aedes albopictus e Limatus durhami foram eudominante/dominantes, juntos representando 90% do total de indivíduos. Esse estudo foi o primeiro registro de ocorrência de Sabethes albiprivus e Li. durhami em Porto Alegre. As espécies de culicídeos demonstraram responder de maneira diversa aos tipos de uso e cobertura do solo, indicando que as afinidades mais evidentes se mantém nas três escalas avaliadas. A abundância relativa de Ae. albopictus foi relacionada às áreas verdes mais urbanizadas, enquanto a de Li. durhami, Haemagogus leucocelaenus e Toxorhynchites sp., à presença da mata nativa. A ocorrência de Aedes aegypti não demonstrou ser influenciada pelo tipo de uso e cobertura do solo. Foram coletadas três espécies relacionadas à transmissão de febre amarela, febre chikungunya e dengue, Ae. albopictus, Hg. leucocelaenus e Ae. aegypti e verificada a ocorrência simultânea dessas em algumas áreas, o que pode representar a oportunidade para o surgimento de surtos epidêmicos e a mudança do perfil epidemiológico dessas doenças. / Urban green areas can offer opportunity for interactions between reservoirs and vectors of urban and wild environments, increasing the risk of disease transition and changes in their epidemiological profile. The understanding of how changes in the landscape affect the composition of culicid fauna and which vector species occur in these areas may help and prediction the spatial distribution of the species along urbanized areas, providing important tools to control endemic disease. This study aimed to verify the occurrence of mosquito vector species and to evaluate the relationship between different types of land cover and land use with the composition of Culicidae fauna. Sampling occurred biweekly, from October 2012 to March 2013, where oviposition traps were installed in eight green areas with different landscape traits, in Porto Alegre, Southern Brazil. 4179 mosquitoes belonging to et least ten species were sampled. Aedes albopictus and Limatus durhami were eudominants/dominant representing together 90% of total individuals. This is the first report of Sabethes albiprivus and Li. durhami occurrence in Porto Alegre. The mosquitos species responded differently to types of land use cover and land use, indicating that the most obvious affinities are maintained in three scales evaluated. The relative abundance of Ae. albopictus was related to the more urbanized green area, while the abundance of Li. durhami , Haemagogus leucocelaenus and Toxorhynchites sp., was related to the presence of preserved areas. The occurrence of Aedes aegypti was not influenced by land use and land cover. Three species related to dengue, chikungunya and yellow fever transmission were sampled, Ae. albopictus, Hg. leucocelaenus and Ae. aegypti. We also verified the simultaneous occurrence of these species, which may represent an opportunity of changes in the epidemiologic of these diseases.