979 resultados para insect pest


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Aiming to contribute to a rearing methodology for the brown stink bug, Euschistus heros, in the laboratory, we evaluated oviposition on artificial substrates of different colors. During six days, oviposition was evaluated daily, by counting the total number of eggs, number of clutches, and eggs/clutch. Females laid 12,463 eggs, in 1,677 clutches, resulting in an average of 7.28 ± 0.44 eggs/clutch. Black, brown, and green felt had the most eggs and clutches. The results demonstrated that many colors are suitable as oviposition substrate for E. heros, providing information for the mass rearing of this insect.

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Occurrence and damages of Danothrips trifasciatus (Thysanoptera: Thripidae) on Calophyllum brasiliense (Clusiaceae) in Brazil. Danothrips trifasciatus Sakimura, 1975 (Thysanoptera, Thripidae) is recorded for the first time in Brazil, in the municipality of Garça, São Paulo state. Individuals were collected in April 2011 damaging young leaves of guanandi, Calophyllum brasiliense Cambess. (Clusiaceae), forest species of increasing importance in Brazil. Future studies involving aspects on biology and population dynamics of the thrips in this plant species need to be carried out, in order to establish its potential economic importance to guanandi.

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This study reports for the first time the occurrence of Hypatropis inermis on upland rice crops (variety Cambará), in Novo Progresso, state of Pará, Brazil (7°07'45.71"S 55°23'21.13"W). The inventory of insect pests was conducted between November 2010 and March 2011 with entomological sweep nets and visual search on stems of rice plants. This record indicates that rice crops may represent important feeding and mating sites for this species.

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Includes vital information on the Alfalfa Weevil including description, life cycle, damage that it does to alfalfa, how to find and identify and the recommended controls and management of the insect pest

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Includes vital information on the Alfalfa Weevil including description, life cycle, damage that it does to alfalfa, how to find and identify and the recommended controls and management of the insect pest

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As we initiate entomological research on potato (Solanum tuberosum L.) in Uganda, there is need to understand farmers’ knowledge of existing insect pest problems and their management practices. Such information is important for designing a suitable intervention and successful integrated pest management (IPM) strategy. A farm household survey using a structured questionnaire was conducted among 204 potato farmers in six districts of Uganda (i.e., Kabale, Kisoro, Mbale, Kapchorwa, Mubende, and Kyegegwa) during August and September 2013. Diseases, insect pests, price fluctuations, and low market prices were the four highest ranked constraints in potato production, in order of decreasing importance. Cutworms (Agrotis spp.), aphids (Myzus persicae (Sulzer)), and potato tuber moth (Phthorimaea operculella (Zeller)) were the three most severe insect pests. Ants (Dorylis orantalis Westwood), whiteflies (Bemisia tabaci (Gennadius)), and leafminer flies (Liriomyza huidobrensis (Blanchard)) were pests of moderate importance. Major yield losses are predominantly due to late blight (Phytophthora infestans (Mont.) de Bary) and reached 100% without chemical control in the districts of Kabale, Kisoro, Mbale, and Kapchorwa. On average, farmers had little to moderate knowledge about pest characteristics. The predominant control methods were use of fungicides (72% of respondents) and insecticides (62% of respondents). On average, only 5% of the 204 farmers knew about insect pests and their natural enemies. This lack of knowledge calls for training of both farmers and extension workers in insect pest identification, their biology, and control. Empowering farmers with knowledge about insect pests is essential for the reduction of pesticide misuse and uptake of more environmentally friendly approaches like IPM. Field surveys would need follow-up in order to assess the actual field infestation rates and intensities of each insect pest and compare the results with the responses received from farmers.

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Biosecurity is a great challenge to policy-makers globally. Biosecurity policies aim to either prevent invasions before they occur or to eradicate and/or effectively manage the invasive species and diseases once an invasion has occurred. Such policies have traditionally been directed towards professional producers in natural resource based sectors, including agriculture. Given the wide scope of issues threatened by invasive species and diseases, it is important to account for several types of stakeholders that are involved. We investigate the problem of an invasive insect pest feeding on an agricultural crop with heterogeneous producers: profit-oriented professional farmers and utility-oriented hobby farmers. We start from an ecological-economic model conceptually similar to the one developed by Eiswerth and Johnson [Eiswerth, M.E. and Johnson, W.S., 2002. Managing nonindigenous invasive species: insights from dynamic analysis. Environmental and Resource Economics 23, 319-342.] and extend it in three ways. First, we make explicit the relationship between the invaded state carrying capacity and farmers' planting decisions. Second, we add another producer type into the framework and hence account for the existence of both professional and hobby fanners. Third, we provide a theoretical contribution by discussing two alternative types of equilibria. We also apply the model to an empirical case to extract a number of stylised facts and in particular to assess: a) under which circumstances the invasion is likely to be not controllable; and b) how extending control policies to hobby farmers could affect both types of producers. (C) 2008 Elsevier B.V. All rights reserved.

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Susceptibility of late instar vine weevil Otiorhynchus sulcatus larvae and pupae to four species entomopathogenic nematodes were tested. Bioassays on production and infectivity to larvae and pupae were compared for two steinernematids and two heterorhabditis such as Steinernema carpocapsae, S. feltiae, Heterorhabditis indica and H. bacteriophora. Nematodes production of all species was determined by the number infective juveniles (IJs) established in vine weevil larvae and pupae O. sulcatus using sand and filter paper bioassay. S. feltiae produced the maximum number in larvae and pupae at 20°C as compared to other nematodes but production of H. indica, was better at 25°C in larvae and pupae followed by H. bacteriophora, S. carpocapsae and Infectivity test of larvae and pupae was also done in sand media. Infective juveniles recovered from larvae and pupae when infected with S. feltiae produced maximum infective juveniles at 20°C temperatures than all other isolates. H. bacteriophora produced higher number of IJs in larvae and pupae than all other nematode isolates at 25°C. This paper indicates the application of nematodes with the knowledge of insect pest biology represents a possible new strategy for O. sulcatus larvae and pupae.

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The Entomopathogenic bacterium Pseudomonas putida from Steinernema abbasi and its metabolic secretions were lethal to the Galleria mellonella larvae. Different laboratory experiments on time interval, substrate, moisture, temperature, dose, penetration of cells, stored and dried metabolites were conducted in sand and filter paper bioassays. It was concluded that death was probably due to the toxic metabolites. This bacterium and its metabolites were found very effective at 30 degree C. Penetration of bacterium was rapid after application on G. mellonella larvae. P. putida cells were recovered from the haemocoele when suspensions containing bacterial cells were applied to the G. mellonella indicating that bacterial symbionts do have a free-living existence and can enter the haemocoele in the absence of nematode vector. Stored metabolite and dried metabolites were found persistent for long time. This bacterium or its toxic secretions can be used for insect control that can be important component of integrated pest management against different insect pests. P. putida and its secretions are suggested as the most appropriate suspension to apply against insect pest control program in tropical ecological regions.

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Biocontrol agents such as Xeiwrhabduf, nemalophilci and X. nematophila ssp. bovienii and their cell-free protein toxin complexes were lethal to larvae of O. sulcatus when applied to potting compost in the absence of plants. Similarly, strawberry plants infected with 0. sulcaitfi larvae were protected from damage by applications of both cell suspensions of the bacteria and solutions of their cell-free toxic metabolites, indicating that it is the protein toxins, which are responsible for the lethal effects observed. These toxic metabolites were found more effective against 0. sulccitus larvae when treated in soil microflora. Insect mortality is increased by increasing temperature and bacterial concentration. The toxins remained pathogenic for several months when stored in potting soil either at 15 or 20°C, however, bacterial cells were not as persistent as the toxins. It is therefore suggested that these bacteria and their toxic metabolites can he applied in soil for insect pest control.

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1. Determining the functional significance of species diversity in natural enemy assemblages is a key step towards prediction of the likely impact of biodiversity loss on natural pest control processes. While the biological control literature contains examples in which increased natural enemy diversity hinders pest control, other studies have highlighted mechanisms where pest suppression is promoted by increased enemy diversity. 2. This study aimed to test whether increased predator species diversity results in higher rates of predation on two key, but contrasting, insect pest species commonly found in the rice ecosystems of south-east Asia. 3. Glasshouse experiments were undertaken in which four life stages of a planthopper (Nilaparvata lugens) and a moth (Marasmia patnalis) were caged with single or three-species combinations of generalist predators. 4. Generally, predation rates of the three-species assemblages exceeded expectation when attacking M. patnalis, but not when attacking N. lugens. In addition, a positive effect of increased predator species richness on overall predation rate was found with M. patnalis but not with N. lugens. 5. The results are consistent with theoretical predictions that morphological and behavioural differentiation among prey life stages promotes functional complementarity among predator species. This indicates that emergent species diversity effects in natural enemy assemblages are context dependent; they depend not only on the characteristics of the predators species, but on the identity of the species on which they prey.

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The parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) has been used successfully for the control of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae). The development of UV-blocking plastic films has added a new component to future integrated pest management systems by disrupting insect pest infestation when UV light is excluded. Because both T. vaporariorum and E. formosa are reported to have similar spectral efficiency, there was a need to identify the impact of UV-blocking films on the dispersal behavior of both the pest and the natural enemy. In field studies, using choice-chamber experiments, E. formosa showed some preference to disperse into compartments where less UV light was blocked. However, further studies indicated that the effect was primarily attributable to the different light diffusion properties of the films tested. Thus, unlike its whitefly host, when the UV-absorbing properties of the films were similar, but the light diffusion properties differed, E.formosa adults preferred to disperse into compartments clad with films that had high light diffusion properties. When the plastic films differed most in their UV-absorbing capacity and had no light-diffusion capability, the initial dispersal of E. formosa between treatments was similar, although a small preference toward the environment with UV light was observed over time. When parasitoid dispersal was measured 3 h after release, more parasitoids were found on plants, suggesting that the parasitoids would search plants for whitefly hosts, even in a UV-blocked light environment. The potential for the integration of UV-blocking films with E. formosa in an advanced whitefly management system is discussed.

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Arthropods that have a direct impact on crop production (i.e. pests, natural enemies and pollinators) can be influenced by both local farm management and the context within which the fields occur in the wider landscape. However, the contributions and spatial scales at which these drivers operate and interact are not fully understood, particularly in the developing world. The impact of both local management and landscape context on insect pollinators and natural enemy communities and on their capacity to deliver related ecosystem services to an economically important tropical crop, pigeonpea was investigated. The study was conducted in nine paired farms across a gradient of increasing distance to semi-native vegetation in Kibwezi, Kenya. Results show that proximity of fields to semi-native habitats negatively affected pollinator and chewing insect abundance. Within fields, pesticide use was a key negative predictor of pollinator, pest and foliar active predator abundance. On the contrary, fertilizer application significantly enhanced pollinator and both chewing and sucking insect pest abundance. At a 1 km spatial scale of fields, there were significant negative effects of the number of semi-native habitat patches within fields dominated by mass flowering pigeonpea on pollinators abundance. For service provision, a significant decline in fruit set when insects were excluded from flowers was recorded. This study reveals the interconnections of pollinators, predators and pests with pigeonpea crop. For sustainable yields and to conserve high densities of both pollinators and predators of pests within pigeonpea landscapes, it is crucial to target the adoption of less disruptive farm management practices such as reducing pesticide and fertilizer inputs.

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Annual losses of cocoa in Ghana to mirids are significant. Therefore, accurate timing of insecticide application is critical to enhance yields. However, cocoa farmers often lack information on the expected mirid population for each season to enable them to optimise pesticide use. This study assessed farmers’ knowledge and perceptions of mirid control and their willingness to use forecasting systems informing them of expected mirid peaks and time of application of pesticides. A total of 280 farmers were interviewed in the Eastern and Ashanti regions of Ghana with a structured open and closed ended questionnaire. Most farmers (87%) considered mirids as the most important insect pest on cocoa with 47% of them attributing 30-40% annual crop loss to mirid damage. There was wide variation in the timing of insecticide application as a result of farmers using different sources of information to guide the start of application. The majority of farmers (56%) do not have access to information on the type, frequency and timing of insecticides to use. However, respondents who are members of farmer groups had better access to such information. Extension officers were the preferred channel for information transfer to farmers with 72% of farmers preferring them to other available methods of communication. Almost all the respondents (99%) saw the need for a comprehensive forecasting system to help farmers manage cocoa mirids. The importance of accurate timing for mirid control based on forecasted information to farmer groups and extension officers was discussed.

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The characterization and identification of proteolytic bacteria from the gut of the velvetbean caterpillar (Anticarsia gemmatalis) were the objectives of this study. Twelve aerobic and anaerobic isolates of proteolytic bacteria were obtained from the caterpillar gut in calcium caseinate agar. The number of colony forming units (CFUs) of proteolytic bacteria was higher when the bacteria were extracted from caterpillars reared on artificial diet rather than on soybean leaves (1.73 +/- 0.35 X 10(3) and 0.55 +/- 0.22 X 10(3) CFU/mg gut, respectively). The isolated bacteria were divided into five distinct groups, according to their polymerase chain reaction restriction fragment-length polymorphism profiles. After molecular analysis, biochemical tests and fatty acid profile determination, the bacteria were identified as Bacillus subtilis, Bacillus cereus, Enterococcus gallinarum, Enterococcus mundtii, and Staphylococcus xylosus. Bacterial proteolytic activity was assessed through in vitro colorimetric assays for (general) proteases, serine proteases, and cysteine proteases. The isolated bacteria were able of hydrolyzing all tested substrates, except Staphylococcus xylosus, which did not exhibit serine protease activity. This study provides support for the hypothesis that gut proteases from velvetbean caterpillar are not exclusively secreted by the insect cells but also by their symbiotic gut bacteria. The proteolytic activity from gut symbionts of the velvetbean caterpillar is suggestive of their potential role minimizing the potentially harmful consequences of protease inhibitors from some of this insect host plants, such as soybean, with implications for the management of this insect pest species.