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Search Results: 1 - 10 of 29508 matches for " biological control "
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Modeling and Control of pH in Pulp and Paper Wastewater Treatment Process  [PDF]
Jiayu KANG, Mengxiao WANG, Zhongjun XIAO
Journal of Water Resource and Protection (JWARP) , 2009, DOI: 10.4236/jwarp.2009.12016
Abstract: Pulp and paper industry is responsible for large discharge of highly polluted effluents, which often be treated by biological treatment process. For biological treatment system, pH is an important environmental factor that can influence the activity of microorganisms. In general, the optimal pH for aerobic processes is around neutral pH (7_7.8) and for the anaerobic process is between 6.8_7.2. The control of pH is a difficult link in the biological treatment system due to its nonlinearity and large time-delay. Aiming at the difficult point in the pH control of the biological wastewater treatment system, a mathematical model of pH control is estab-lished in the essay. On this basis, a traditional PID control and a cascade control are adopted to carry out simulation and comparison with MATLAB. The results show that the cascade control has better comprehen-sive effect in terms of response speed, stability and disturbance resistance.
Fungicide tolerance of Trichoderma asperelloides and T. harzianum strains  [PDF]
Adriana Paola Chaparro, Lilliana Hoyos Carvajal, Sergio Orduz
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.23040
Abstract: Tolerance in isolations of Trichoderma was developed by exposing two strains of T. harzianum and three of T. asperelloides to increasing concentrations of chemical fungicides. These isolation of Trichoderma were exposed to three fungicides: Captan, Thiabendazol and the mixture Captan-Carboxin. Some selected lines of these strains reached tolerance to Captan and partial tolerance to the mixture Captan-Carboxin. The biological and genetic changes in these tolerant lines were monitored by determining the relative growth rate of the fungus, inhibition of Fusarium and by analyzing the genomic changes through UP-PCR. The results show that the tolerance to fungicides can be developed without affecting the parameters of biological activity in these lines of Trichoderma (growth and parasitism against Fusarium). Chemical tolerance to the fungicide was verified by means of changes at the DNA level (UP-PCR), mainly in the lines tolerant to Captan. This suggests that Trichoderma survives in environments with remnants of fungicide molecules.
Harmonia axyridis Pallas (Coleoptera: Coccinellidae): Biological aspects and thermal requirements  [PDF]
Tatiana de Oliveira Ramos, Terezinha Monteiro dos Santos-Cividanes, Francisco Jorge Cividanes, Laís da Concei??o dos Santos
Advances in Entomology (AE) , 2014, DOI: 10.4236/ae.2014.21007
Abstract: The aim of this study was to determine the biological aspects and thermal requirements of Harmonia axyridis Pallas (Coleoptera: Coccinellidae) fed daily with Anagasta kuehniella (Zeller) (Lep-idoptera: Pyralidae) eggs. Under laboratory conditions, the experiment was carried out in acclimatized chambers set to 18°C, 21°C, 24°C, 27°C, and 30°C. Larvae of H. axyridis were separated, kept in a glass tube, and fed with A. kuehniella eggs. The Asiatic lady beetle adults were separated into 20 couples and kept in plastic cups receiving the same food as the larvae. The length of the larval, pupal, and total biological cycle (from egg to adult) stages declined significantly from 18°C to 27°C, but was stable between 27°C and 30°C. Survival was similar for larvae from the first to the fourth stadium when kept at 18°C, 21°C, and 24°C with a higher total biological cycle survival at 27°C. H. axyridis males presented higher longevity at 18°C and 21°C in comparison to females that had a longer life and a higher fecundity at 24°C and 27°C, respectively. The lower thermal limit for biological cycle development was 12.4°C, and the thermal constant was 243.9 degree-days.
Ocurrence of Entomopathogenic Fungus from Flea Ctenocephalides canis (Siphonaptera: Pulicidae)  [PDF]
Jonathan E. Ortega-Palomares, Hector G. Nu?ez-Palenius, Ana M. Cruz-Avalos, Aarón A. Hernández-Rangel, Roberto Lezama-Gutiérrez, César A. Angel-Sahagún
Open Journal of Veterinary Medicine (OJVM) , 2014, DOI: 10.4236/ojvm.2014.412034
Abstract: The objective of this study was to isolate entomopathogenic fungus from fleas (Ctenocephalides canis Curtis) collected from Cannis familiaris specimens. From 60 collected fleas, two dead insects presented white mycelia growth on the body surface, changing to a creamy color as time passed; the insects presented a mummified aspect, typical characteristic caused by entomopathogenic fungus. This fungus was identified as Beauveria bassiana (Balsamo-Crivelli) Vuillemin by their mycelia characteristics, macro- and micro-morphology. Up to our knowledge, this is the first report of entomopathogenic fungus isolated from adult C. canis fleas.
Mortality by Parasitization in the Association between Diachasmimorpha tryoni (Hymenoptera: Braconidae) and Ceratitis capitata (Diptera: Tephritidae) under Field-Cage Conditions  [PDF]
Patricia Albornoz Medina, Laura Patricia Bezdjian, Laura Patricia Bezdjian, Pablo Schliserman, Claudia Fidelis-Marinho, Sergio Marcelo Ovruski
Natural Science (NS) , 2014, DOI: 10.4236/ns.2014.617116
Abstract: Ceratitis capitata (Wiedemann) is one of the major pests currently affecting world fruit production. In Argentina’s northern Citrus-producing regions, C. capitata is actively multiplying in large exotic host fruits, such as Citrus paradisi Macfadyen (grapefruit), Citrus aurantium L. (sour orange) and Citrus sinensis L. (Osbeck) (sweet orange). Faced with this situation, the use of parasitoids as biocontrol agents is currently receiving renewed attention as a new biological tool for controlling pestiferous fruit flies within the Argentinean National Fruit Fly Control and Eradication Program (ProCEM). Consequently, a viable approach to controlling C. capitata involves the use of exotic parasitoids such as Diachasmimorpha tryoni (Cameron). In this study, the effectiveness of D. tryoni females to find and successfully parasitize C. capitata larvae infesting all Citrus species mentioned earlier was assessed. Parasitoids were allowed to forage for 8 h on grapefruits and oranges artificially infested with laboratory-reared C. capitata larvae under natural environmental conditions (field cage). Parasitoid emergence, parasitism, overall effectiveness, and sex ratio of parasitoid offspring were estimated as response variables. The higher effectiveness of D. tryoni females recorded from C. sinensis would be mainly a result of both increased host density per unit of fruit surface area and fruit physical features. The study provides evidence that D. tryoni contributed to C. capitata mortality in all Citrus species assessed. However, the mortality values recorded from C. sinensis, C. aurantium, and C. paradisi did not exceed 10%, 1.5%, and 1.7%, respectively. Nonetheless, D. tryoni might be selected to forage under both high and low host density conditions.
Controlling Dengue: Effectiveness of Biological Control and Vaccine in Reducing the Prevalence of Dengue Infection in Endemic Areas  [PDF]
Bryan Paul, Wai Liang Tham
Health (Health) , 2016, DOI: 10.4236/health.2016.81008
Abstract: With the increased prevalence of dengue infection in tropical countries, concerned members of the public are now pressing their local health ministries to act immediately and effectively in managing the rising numbers of reported cases. This includes reviews of the methodologies and the effectiveness of current combative systems to find other possible novel approaches that might yield better results. One of those novel approaches is the integration of a parasite into mosquito vector, manipulating the parasite-host interaction to reduce the transmission of dengue in endemic hotspots. Another alternative is by Sanofi-Pasteur’s dengue vaccine that showed over 60.8% success rate in reducing severe dengue infection in children aged 9 - 16 during its final clinical implementation phase. This report will compare and contrast these two novel ideas to determine which of the approaches are more likely to be effective in the long run. The aspects covered will include the application, effectiveness, functionality, and problems with these approaches. The results could then be utilised by governments or organizations to select precise and effective methods in reducing the prevalence of dengue infections in their countries.
Impacts of Synthetic and Botanical Pesticides on Beneficial Insects  [PDF]
Baltazar Ndakidemi, Kelvin Mtei, Patrick A. Ndakidemi
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.76038
Abstract: Sustainable methods to control insect pests that affect crop yield have become a great challenge to mainly smallholder farmers. Beneficial insects in agricultural fields play an important role in natural pest control and pollination. The use of synthetic and botanical pesticides has detrimental effects to both natural enemies and pollinators in agricultural fields. The pesticides affect the survival of a range of life cycle stages, reductions in reproductive capacity, changes in the suitability of hosts for parasitising or predation, reduced emergence of parasitoids from sprayed host eggs and cause direct mortality. This has caused a serious menace to biological control agents and pollinators. When natural enemies are reduced, even more serious consequences may result for pest population dynamics which include the phenomena of resurgence and eruption of secondary pests. The decrease in pollinators reduces agricultural productivity. This review aims at exploring the side effects of synthetic and botanical pesticides on beneficial insects to give the basis for research on the negative impacts of synthetic and botanical pesticides on these insects. This information will assist in optimizing the use of pesticides in integrated pest management programmes by employing more sustainable and ecosystem benign practices such as the use of right dosage and selective pesticides in agricultural fields.
Biological Control of Erosion of Banana Drains in C?te D’ivoire  [PDF]
Kouadio Y. Prosper, Boraud N’Takpé Kama Maxime, Tiébré Marie-Solange, Djakalia Ouattara, Edouard Kouakou N’guessan
Agricultural Sciences (AS) , 2016, DOI: 10.4236/as.2016.77050
Abstract: The erosion of drains is a major limitation of the quality, the increasing of banana production and the environmental protection of industrial banana in Côte d'Ivoire. It leads inundations, death of banana trees and significant loss of production. Thence, the construction and the maintenance of drain costs too much and causes injure, snake bite, physical traumatisms, many diseases, … These events compromise the sustainable production of banana by reducing seriously worker’s the activities and finally increase the cost of production. The aim of the present work is to contribute to the sustainable development and human capacity building in the third world nations as far as banana production is concerned. The methods used so far to address this phenomenon proved inefficient. The technology innovation in this area has been to grow grass on the outer edges of the channels drained water. This resulted in a systematic reduction of erosion. Better still, it helped fertilize the soil, reduce the deportations of fertilizer and improve the quality of landscape of the plantations. Stenotaphrum secondatum is the best vegetable specie adapted to the biological control against water erosion of drains.
Biological Control of Insect Pests of Agricultural Crops through Habitat Management Was Discussed  [PDF]
M. S. Akter, S. S. Siddique, R. Momotaz, M. Arifunnahar, K. M. Alam, S. J. Mohiuddin
Journal of Agricultural Chemistry and Environment (JACEN) , 2019, DOI: 10.4236/jacen.2019.81001
Abstract: Biological control through habitat management leads to sustainable insect pest control. Different types of land composition such as multiple landscapes, patchiness of landscapes enhance the natural enemies which ultimately lead to control of insect pest. Plant characteristics such as flower shape, flower color and blooming period ensures excess food for natural enemies like nectar and pollen. Moreover, some agricultural practices such as tillage, crop rotation, and intercropping influence the natural enemies especially parasitoid and preda-tors. Consequently, they increase longevity and fecundity of parasitoid and predator that help to control insect pest. One of the most important recently used methods is push-pull which consists of semiochemicals called Herbi-vore-Induced Plant Volatiles (HIPVs). This compound has been used to pre-vent pest and attract natural enemies.
Record of two species of Orius Wolff (Hemiptera, Anthocoridae) in Brazil
Silveira, Luís Cláudio Paterno;Bueno, Vanda Helena Paes;Mendes, Simone Martins;
Revista Brasileira de Entomologia , 2003, DOI: 10.1590/S0085-56262003000200019
Abstract: the genus orius wolff, 1811 comprises predatory species, with approximately 70 known species. informations about the genus in brazil are scarce. therefore, the aim of this investigation was to identify orius species present in four localities in the southeastern brazil. samples were taken from several plants, and the material screened in laboratory. the genitalia of both sexes were studied and illustrated. two species were identified, orius insidiosus (say, 1832) and orius thyestes herring, 1966. o. insidiosus, the most common species, was collected in all of the localities sampled [lavras (mg), holambra, pindorama and campinas (sp)]. o. thyestes, registered for the first time in brazil, occurred only in lavras (mg) and pindorama (sp). some morphologic aspects of these two species are also presented.
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