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Population responses of a conifer-dwelling aphid to seasonal changes in its host

Day, KR, Armour, H and Docherty, M (2004) Population responses of a conifer-dwelling aphid to seasonal changes in its host. ECOLOGICAL ENTOMOLOGY, 29 (5). pp. 555-565. [Journal article]

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1. Current evidence suggests that seasonal changes in spruce needle sap nutrients have a decisive influence on green spruce aphid (Elatobium abietinum) population density, but the mechanisms of population change, the roles of development rate, fertility and mortality, and the existence of density-dependent processes, are not clearly understood. 2. Experimental studies of aphid populations were conducted in controlled environments to estimate seasonal patterns in aphid mean relative growth rate, prenatal development, fertility, and mortality. Studies were also made of the effect of aphid crowding on vital rates. 3. Independent of the degree of aphid crowding, seasonal changes in the amino acid concentration of needle sap were tracked by aphid growth rate, fertility (and adult size), but not by rates of aphid mortality. The most pronounced change in vital rates, and the one most likely to drive seasonal population change, was in fertility. Prenatal development time actually became shorter in periods when nutrients were scarce, but the resulting adult aphids were smaller and less fertile than during periods of improved nutrition. 4. Density dependence of vital rates was only observed during mid-summer when nutrients were least available. Mortality, growth rate, and prenatal development were the most strongly density-dependent processes. In contrast, there was no evidence that fertility rates were likely to respond to crowding. 5. There were no important differences between populations reared on small, potted spruce trees and those on plantation trees aged 25 years. This gives confidence that demographic data from a variety of field and laboratory sources could be used to compile data appropriate for population models.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Geography and Environmental Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
ID Code:2330
Deposited By: Professor Keith Day
Deposited On:13 Jan 2010 13:59
Last Modified:05 Oct 2017 09:54

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