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Mortality dynamics and population regulation in Bemisia tabaci

Mortality dynamics and population regulation in Bemisia tabaci,Steven E. Naranjo,Peter C. Ellsworth

Mortality dynamics and population regulation in Bemisia tabaci   (Citations: 29)
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Natural mortality is an important determinant of the population dynamics of a species, and an understanding of mortality forces should aid in the development of better management strategies for insect pests. An in situ, observational method was used to construct cohort-based life tables for Bemisia tabaci (Gennadius) Biotype B (Homoptera: Aleyrodidae) over 14 generations on cotton in central Arizona, USA, from 1997 to 1999. In descending order, median marginal rates of mortality were highest for predation, dislodgment, unknown causes, egg inviability, and parasitism. The highest mortality occurred during the 4th nymphal stadium, and the median rate of immature survival over 14 genera- tions was 6.6%. Predation during the 4th nymphal stadium was the primary key factor. Irreplaceable mortality was highest for predation and dislodgment, with the absence of these mortality factors leading to the greatest increases in estimated net reproduction. There was little evidence of direct or delayed density-dependence for any mortality factor. Wind, rainfall, and predator densities were associated with dislodgment, and rates of predation were related to densities of Geocoris spp., Orius tristicolor (White), Chrysoperla carnea s.l. Stephens, and Lygus hesperus Knight. Simulations suggest that immigration and emigration play important roles in site-specific dynamics by explaining departures from observed population trajectories based solely on endogenous reproduction and mortality. By a direct measurement of these mortality factors and indirect evidence of adult movement, we con- clude that efficient pest management may be best accomplished by fostering greater mortality during the 4th stadium, largely through a conservation of predators and by managing immigrating adult populations at their sources.
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    • ...2001), and some evidence suggests generalist predators and aphelinid parasitoids act as key factors in the population dynamics of this pest in several crops in the absence of insecticides (Naranjo and Ellsworth 2005; Asiimwe et al...

    S. A. Hoseiniet al. Impacts of two conventional insecticides on different stages of Encars...

    • ...2001), and some evidence suggests generalist predators and aphelinid parasitoids act as key factors in the population dynamics of this pest in several crops in the absence of insecticides (Naranjo and Ellsworth 2005; Asiimwe et al...

    S. A. Hoseiniet al. Impacts of two conventional insecticides on different stages of Encars...

    • ...Many studies have focused on the biology of this species in different crops and on the analysis of life tables to investigate different parameters of the population or the key factors that regulate its population (Von Arx et al. 1983; Horowitz et al. 1984; Baumgartner et al. 1986; Baumgartner and Yano 1990; Naranjo and Ellsworth 2005; Asiimwe et al. 2007)...
    • ...The egg and N1 and N4 instar stages had the greatest effect on the B. tabaci population in the life table analysis in different locations and crops (Horowitz et al. 1984; Naranjo and Ellsworth 2005; Asiimwe et al. 2007)...
    • ...Predation (Naranjo and Ellsworth 2005) and parasitisation (Asiimwe et al. 2007) were the principal factors responsible for decreasing populations, affecting mainly the N4 instar, and dislodgement was second in most of the previous studies...

    J. E. González-Zamoraet al. Model selection and averaging in the estimation of population paramete...

    • ...This observation is also supported by two recent studies onBemisiatabaci (Gennadius) in Arizona and Uganda, which reported that the largest irreplaceable mortalities were from predators and parasitism, respectively (Naranjo and Ellsworth 2005, Asiimwe et al. 2007)...

    Robert K. D. Petersonet al. Mortality Risk in Insects

    • ...(van den Bosch and Hagen 1966, Sterling et al. 1989, Naranjo and Ellsworth 2005)...
    • ...In Arizona, predators are a major source of whiteßy mortality (Naranjo and Ellsworth 2005), and a variety of species, including Geocoris spp., Orius tristicolor (White), and adults of Drapetis, a small predatory ßy, commonly feed on whiteßies in cotton (Naranjo and Hagler 1998, Hagler and Naranjo 2005)...

    Allen E. Knutsonet al. Evaluation of Sampling Methods and Development of Sample Plans for Est...

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