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Infestation Patterns (infestation + pattern)
Selected AbstractsWithin-plant distribution and infestation pattern of the B- and Q-biotypes of the whitefly, Bemisia tabaci, on tomato and pepperENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2-3 2002M. Muñiz First page of article [source] Space allocation in Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger) (Col., Buprestidae) in the attack of Greek fir [Abies cephalonica Loud. var. graeca (Fraas) Liu]: a pattern to process approachJOURNAL OF APPLIED ENTOMOLOGY, Issue 1 2004P. V. Petrakis Abstract: The phloeo-cambiophagous buprestid Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger.) is not a primary factor of fir decline problem although the beetle substantially contributes to Greek fir Abies cephalonica Loud. var. graeca (Fraas) Liu mortality. By using mapping depiction of the exit holes of the insect on a set of fir trees located on a line transect in a randomized point-centred quarter scheme and employing pattern analysis techniques we were able to reveal various scales of the infestation pattern. Four scales were recognized, two of them corresponding to the pattern of microsite selection on the bark of a fir tree. While the dispersed exit holes exhibited a statistically significant random dispersion on the bark, within each aggregation the pattern was uniform. The area of compartments created by Dirichlet partition approximated very well the sizes of the actual larval galleries. The Dirichlet tessellation of the bark space and the analysis of the parameter of the resulting partitions showed the predominance of the hexagonal conformation of the larval spaces when space was limited. When some exit holes were positioned close together it was found that they were directed away from each other so the resulting galleries were well separated. Several hypotheses are presented as to the mechanisms underpinning the observed patterns. The allocation of space is in accordance with the widely accepted ,central place theory' of W. Christaller, a general theory of pattern generated in the geographical dispersion of human settlements. The revealed pattern was also in accordance with the predictions of the theory of ,central place foraging' of R. H. MacArthur and the theory of ,resource concentration hypothesis' of R. Root. [source] A comparison of infestation patterns by Ixodes ticks in urban and rural populations of the Common Blackbird Turdus merulaIBIS, Issue 4 2002Arnaud Gregoire Although spatial variation in the patterns of parasite infestations among host populations may have important ecological and epidemiological consequences, the causes underlying such variation are poorly known. In the context of a long-term study on the population biology of Common Blackbirds Turdus merula, we examined the prevalence and intensity of infestation by Ixodes ticks between birds living in rural vs. urban habitats. The overall prevalence of tick infestations was significantly higher in the rural habitat where 74% of individuals (n = 130) were infested. This result contrasted markedly with the situation in the urban habitat where less than 2% of individuals (n = 360) carried ticks. There was no significant effect of the sex of the host on the intensity or prevalence of tick infestations. There was a significant effect of the age of the host on tick infestations essentially due to the absence of ticks on nestlings. Possible mechanisms responsible for the differences between habitats could include differences in tick survival and/or host resistance towards ticks. Previous studies have shown higher population densities and suggested longer survival for Blackbirds in urban than in rural habitats. Given that ixodid ticks are known to transmit pathogens like Borrelia spp. to wild birds, and that Blackbirds can act as reservoirs for these pathogens, the infection patterns observed in our study area provide a suitable situation to study the interrelations between ticks, Blackbirds and pathogens. [source] Tick prevalence and species diversity on Aldabran giant tortoises (Dipsochelys dussumieri) in relation to host range and host size in a restored ecosystem, KenyaAFRICAN JOURNAL OF ECOLOGY, Issue 3 2006Sharon Okanga Abstract Tick species density and diversity on Aldabran tortoises was investigated in relation to the habitat range and size of each tortoise. Identification of tick infestation patterns forms an important aspect of effective tick control. Ten Aldabran tortoises were de-ticked and monitored over the course of 2 months. Tick species found were Amblyomma sparsum, Amblyomma nuttalli, Amblyomma hebraeum and Boophilus decoloratus, with the most prevalent species found being A. sparsum. Tick loads varied considerably from 20 to 214 ticks per tortoise, with most ticks collected from the head/neck region. Tortoises ranging outside Haller Park had higher tick loads (70,214) compared with tortoises ranging within Haller Park (20,99). Tick load was not correlated with tortoise size. Results indicate that tick loads are related to the habitat range of the tortoises and may indirectly also be related to food preference and host food availability. Implications of the findings and appropriate tick control measures are discussed. Résumé On a étudié la densité et la diversité des espèces de tiques sur les tortues d'Aldabra, en relation avec la répartition et la taille de l'habitat de chaque tortue. L'identification des schémas d'infestation par les tiques est un aspect important du contrôle efficace des tiques. On a enlevé toutes les tiques de dix tortues d'Aldabra et on les a surveillées pendant deux mois. Les espèces trouvées étaient Amblyomma sparsum, Amblyomma nuttalli, Amblyomma hebraeum et Boophilus decoloratus, l'espèce prévalente étant A. sparsum. Le nombre de tiques variait considérablement, allant de 20 à 214 par tortue, le plus grand nombre étant récolté dans la région de la tête et du cou. Les tortues vivant en dehors du Haller Park étaient plus infestées par les tiques (70,214) que celles de l'intérieur du parc (20,99). L'infestation par les tiques n'était pas lièe à la taille des tortues. Les résultats montrent que les infestations sont liées à l'habitat des tortues et qu'elles peuvent être indirectement liées à leurs préférences alimentaires et à la disponibilité de la nourriture pour leurs hôtes. On discute des implications de ces découvertes et de mesures appropriées pour le contrôle des tiques. [source] Changes in epidemiological patterns of sea lice infestation on farmed Atlantic salmon, Salmo salar L., in Scotland between 1996 and 2006JOURNAL OF FISH DISEASES, Issue 4 2008F Lees Abstract Analyses of a unique database containing sea lice records over an 11 year period provide evidence of changing infestation patterns in Scotland. The data, collected from more than 50 commercial Atlantic salmon farms, indicate that both species of sea lice commonly found in Scotland, Lepeophtheirus salmonis and Caligus elongatus, have declined on farms over the past decade. Reductions for both species have been particularly marked since 2001 when more effective veterinary medicines became available. Treatment data were also available in the database and these show a growing trend towards the use of the in-feed medication emamectin benzoate (Slice®), particularly in the first year of the salmon production cycle. However, this trend towards single product use has not been sustained in 2006, the latest year for which data are available. There is some evidence of region to region variation within Scotland with the Western Isles experiencing higher levels of infestation. However, compared to the levels observed between 1996 and 2000, all regions have benefited from reduced lice infestation, with the overall pattern showing a particular reduction in the second and third quarters of the second year of production. [source] Does the mode of transmission between hosts affect the host choice strategies of parasites?OIKOS, Issue 2 2009Implications from a field study on bat fly, wing mite infestation of Bechstein's bats In a two-year field study, we analyzed the distribution of two hematophagous ectoparasites, the bat fly Basilia nana and the wing mite Spinturnix bechsteini, within and among 14 female colonies and among 26 solitary male Bechstein's bats Myotis bechsteinii. Our goal was to investigate whether differences in the transmission mode of the parasites, which result from differences in their life cycle, affect their distribution between host colonies and among host individuals within colonies. Bat flies deposit puparia in bat roosts, allowing for the transmission of hatched flies via successively shared roosts, independent of body contact between hosts or of hosts occupying a roost at the same time. In contrast, wing mites stay on the bat's body and are transmitted exclusively by contact of bats that roost together. As expected in cases of higher inter-colony transmissibility, bat flies were more prevalent among the demographically isolated Bechstein's bat colonies and among solitary male bats, as compared to wing mites. Moreover, the prevalence and density of wing mites, but not of bat flies, was positively correlated with colony size, as expected in cases of low inter-colony transmissibility. Within colonies, bat flies showed higher abundance on host individuals in good body condition, which are likely to have high nutritional status and strong immunity. Wing mites showed higher abundance on hosts in medium body condition and on reproductive females and juveniles, which are likely to have relatively weak immunity. We suggest that the observed infestation patterns within host colonies reflect different host choice strategies of bat flies and wing mites, which may result from differences in their inter-colony transmissibility. Our data also indicate that infestation with wing mites, but not with bat flies, might be a cost of sociality in Bechstein's bats. [source] Host infestation patterns of the massive liana Hydrangea serratifolia (Hydrangeaceae) in a Chilean temperate rainforestAUSTRAL ECOLOGY, Issue 7 2009MYLTHON JIMÉNEZ-CASTILLO Abstract As competition from lianas reduces fitness of host trees, lianas could influence community composition and structure if potential host species differ in susceptibility to infestation. We quantified infestation frequencies of Chilean temperate rainforest tree species by the massive liana Hydrangea serratifolia (H. et A.) F. Phil (Hydrangeaceae), which climbs using adhesive adventitious roots, and examined relationships with host light requirements and stem diameter. We recorded presence or absence of H. serratifolia in a random sample of 515 trees ,10 cm diameter. Fifty-four per cent of trees were infested by at least one individual of H. serratifolia. Although there was significant interspecific variation in infestation frequency, this variation was not systematically related to light requirements of host tree species. Probability of infestation increased with diameter for most host tree species, and old trees were found to be infested by a wide range of liana size classes, including some stems <2 cm diameter. This evidence supports the proposal that lianas which attach by adhesive roots can colonize host stems of any size. [source] | ||||||||||||||||||||||