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Infestation

About: Infestation is a research topic. Over the lifetime, 8308 publications have been published within this topic receiving 82305 citations.


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Journal ArticleDOI
TL;DR: An acaricide application at a density treatment level of 50 mites/leaflet would provide effective T. urticae control on summer planted strawberries in southern California.
Abstract: Varying infestation levels of Tetranychus urticae Koch were created on strawberry plants by application of cyhexatin at density treatment levels of 0–5, 25, 50, 75, and 100 mites/leaflet, and subsequent yield responses were determined. Seasonal accumulations of 15597, 6261, and 6768 mite-days/leaflet in the untreated controls in 1976, 1977, and 1978, respectively, significantly reduced yield in comparison with cyhexatin treated plots. No yield differences occurred between plots treated at 25, 50, 75, and 100 mites/leaflet, although seasonal mite infestation levels ranged from 781 to 3631 mite-days/leaflet and from 1 to 4 cyhexatin applications were required. Four to 7 cyhexatin applications were necessary to maintain mite infestation below the 0–5 mites/leaflet level, and in 1977, these plots yielded significantly less than plots with higher mite treatment levels. Thus, an acaricide application at a density treatment level of 50 mites/leaflet would provide effective T. urticae control on summer planted strawberries in southern California. Predatory arthropods did not regulate mite populations in these studies. Seven predators were present with predominant species being the sixspotted thrips, Scolothrips sexmaculatus (Pergande), in 1976 and 1977 and a cecidomyiid, Arthrocnodax occidentalis Felt in 1978.

42 citations

Journal ArticleDOI
TL;DR: There is a pronounced seasonal fluctuation in populations of D. ovis, the heaviest infestation occurring in the period from June to September, withindividual sheep differ considerably in their susceptibility to artificial and to natural infestations.
Abstract: Experimental observations are recorded on the bionomics of Damalinia ovis on the sheep and in vitro. The optimal conditions for in-vitro rearing of D. ovis are 36.5°C. and 70-90 per cent, relative humidity when a mixture of skin scurf and baker's yeast is used as food. Under these conditions the life cycle closely approximates the estimated life cycle on the sheep. The incubation period is 9-10 days; the three nymphal instars are completed in 7, 5, and 9 days respectively; the preoviposition period is approximately 3 days, making a cycle of 34 days from egg to egg. The lice and their eggs are very susceptible to changes in temperature. The areas of heaviest infestation are along the mid-dorsal line and down the sides of the sheep. Individual sheep differ considerably in their susceptibility to artificial and to natural infestations. Sheep in poor condition tend to have the heaviest infestations, which are retained throughout the year. There is a pronounced seasonal fluctuation in populations of D. ovis, the heaviest infestation occurring in the period from June to September.

42 citations

Journal ArticleDOI
TL;DR: Plants under the stress of early-season infestation allocated more resources for leaf growth, but stem growth was severely retarded, and plants maintained aphid free after first-period infestation showed a 35% reduction in tuber dry weight at final harvest.
Abstract: The effects of Myzus persicae (Sulzer) infestations on potato foliage and tuber production were studied at 3 consecutive degree-day (DD) intervals (ca. 20 days each). Plants were harvested immediately after an infestation period, or after infestation they were maintained aphid free until the end of the experiment. The interval of aphid-free growth after infestation was used to determine whether the plant could resume normal growth and how infestation affected final yield. Infested plants exhibited the following reductions in dry weight: first period (DD = 519), no tubers for comparison; second period (DD = 745), 54% reduction; and third period (DD = 963), 17% reduction. Plants maintained aphid free after first-period infestation showed a 35% reduction in tuber dry weight at final harvest. Aphid feeding during any period decreased the moisture content of infested leaves. Plants under the stress of early-season infestation allocated more resources for leaf growth, but stem growth was severely retarded.

42 citations

Journal ArticleDOI
TL;DR: A comparative study has been made during 1928–1933 of the aphis infestation at successful seed potato producing centres, where there has been no increase in virus infection among the stocks, and also at unsuccessful centres,Where the increase inirus infection has been large and rapid.
Abstract: Summary. 1. A comparative study has been made during 1928–1933 of the aphis infestation at successful seed potato producing centres, where there has been no increase in virus infection among the stocks, and also at unsuccessful centres, where the increase in virus infection has been large and rapid. 2. The technique developed for this study—one which is applicable for an aphis survey of prospective seed potato producing areas—is given. Identification, in the field, of the different species of aphides infesting potato is desirable in such a survey, and descriptions, with photographs, are presented. 3. Ecological notes on the development of the aphis infestation show that M. persicae—the species that is generally responsible for the spread of virus diseases among potatoes—hibernates as apterae in considerable quantity on winter Brassicae, particularly savoys. These plants constitute the main source of alate spring migrants in most rural districts. The main migration of alatae takes place, normally, in early June, and, in North Wales, is largely from the east. Alatae are not common during July and August and do not increase until the late September migration from potatoes. 4. The index figure of infestation at centres in which there was a rapid increase in virus diseases among the potato stocks always exceeded 100 M. persicae per 100 leaves, and attained such numbers as 1000 individuals per 100 leaves. At centres where there has been no increase in virus infection, the index figure of infestation has not exceeded 20 M. persicae per 100 leaves. The period at which this index figure should be obtained is important, and, with certain exceptions, mid-July proved to be the most satisfactory. It is essential that the figure should be an index of the intensity of the initial infestation of alatae from outside Bources and their subsequent spread, and should not be simply an index of the rate of reproduction of aphides within the field.

41 citations

Journal ArticleDOI
TL;DR: This is the first study that demonstrates the effects of Africanization and ecological environment on V. destructor infestation rates in honey bee colonies in North America and there were no differences in bee population or capped brood between genotypes.
Abstract: Honey bee (Apis mellifera) colonies of African and European descent were compared for levels of Varroa destructor infestation in 3 different ecological regions in Mexico. The 300 colonies that were studied were located in subtropical, temperate sub-humid, and temperate dry climates. The morphotype and mitotype of adult bees as well as their rates of infestation by varroa mites were determined. Additionally, the number of combs with brood and covered with bees was recorded for each colony. The highest frequency of colonies that were classified as African-derived was found in the subtropical environment, whereas the lowest occurred in the temperate dry region. Overall, the colonies of African genotype had significantly lower mite infestation rates (3.5±0.34%) than the colonies of European genotype (4.7±0.49%) regardless of the region sampled. Significant effects of genotype and region on Varroa infestation rates were evident, and there were no differences in bee population or capped brood between genotypes. Mite infestation levels were significantly lower in the colonies of the temperate dry region than in the colonies of the other 2 regions. These results are discussed within the context of results from studies that were previously conducted in Brazil. This is the first study that demonstrates the effects of Africanization and ecological environment on V. destructor infestation rates in honey bee colonies in North America.

41 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
2023602
20221,428
2021276
2020344
2019294