Original Article

Population Ecology

, Volume 52, Issue 2, pp 317-327

Interannual dynamics of aerial and arboreal green spruce aphid populations

  • Keith Richard DayAffiliated withSchool of Environmental Sciences, University of Ulster Email author 
  • , Matthew P. AyresAffiliated withDepartment of Biological Sciences, Dartmouth College
  • , Richard HarringtonAffiliated withRothamsted Research, Harpenden
  • , Neil A. C. KiddAffiliated withSchool of Biosciences, Cardiff University

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Abstract

Partial defoliation of spruce by the green spruce aphid Elatobium abietinum (Walker) is a recurrent event in European and, increasingly, North American forests. The patterns of insect abundance on trees have never been satisfactorily described by a numerical model despite considerable knowledge of endogenous and exogenous factors in the population dynamics of the species. Long-term field population estimates of the aphid on foliage provided the opportunity to evaluate such a model. Unlike comparable models for tree-dwelling aphids, this was also applicable to almost completely independent aphid field data derived from the Rothamsted Insect Survey’s nationwide network of suction traps. Although based on relatively few parameters, the model was robust in its predictions of alate aphids geographically remote from the forest in which the original population was estimated. The population maximum, which causes the greatest forest damage, is reached in early summer and can be predicted from knowledge of winter temperature (chill bouts), spring temperature (thermal sum), and interannual negative feedback (density dependence). The model provides confirmation that alate populations of spruce aphids, upon which a number of other extensive studies have been based, are ultimately influenced by similar endogenous and climatic factors and that they are a reasonable proxy for aphids on trees.

Keywords

Climate Defoliator Elatobium abietinum Picea sitchensis Population time series