The effects of nitrogen levels in sitka spruce needles on Elatobium abietinum (Walker) populations in North-Eastern Scotland

Oecologia ◽  
1974 ◽  
Vol 15 (4) ◽  
pp. 305-320 ◽  
Author(s):  
W. H. Parry
Keyword(s):  
Sitka Spruce ◽  
Nitrogen Levels ◽  
North Eastern ◽  
Elatobium Abietinum ◽  
Spruce Needles

scholarly journals Defoliation and dieback of Sitka spruce in Reykjavík, Iceland

2021 ◽  
Vol 34 ◽  
pp. 15-28
Author(s):  
Juliane Kuckuk ◽  
Sibren van Manen ◽  
Ólafur Eggertsson ◽  
Edda Sigurdís Oddsdóttir ◽  
Jan Esper
Keyword(s):  
Heavy Traffic ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Urban Trees ◽  
Tree Ring Data ◽  
Winter Temperatures ◽  
Elatobium Abietinum ◽  
One Year ◽  
Spruce Needles ◽  
Aphid Populations

The green spruce aphid Elatobium abietinum is an important defoliating pest of Sitka spruce (Picea sitchensis) in Iceland. A comparison of two urban Sitka stands in Reykjavík, from 2013-2017, reveals a distinct defoliation difference between trees located near a main road (94% defoliated) and several hundred meters away from heavy traffic (47%). Chemical analyses of the spruce needles demonstrate substantially higher nitrogen ratios in trees near traffic. Furthermore, the recently warming winter temperatures promoted larger overwintering aphid populations since 2003, as well as a shift of mass outbreaks from autumn to spring, accompanied by distinct growth suppressions one year after an aphid population spike in the post-2003 tree-ring data. The results of this study indicate that the mechanisms triggering Sitka spruce dieback in Reykjavík include a combination of increasing winter temperatures, more frequent and severe green spruce aphid outbreaks, as well as elevated N values in the needles of urban trees.

Observations on the flight periods of aphids in a Sitka spruce plantation in north-eastern Scotland

1973 ◽  
Vol 62 (3) ◽  
pp. 391-399 ◽  
Author(s):  
W. H. Parry
Keyword(s):  
Wind Speed ◽  
Sitka Spruce ◽  
Common Species ◽  
Flight Activity ◽  
Aphis Fabae ◽  
Aphid Population ◽  
Sticky Traps ◽  
Mild Winter ◽  
North Eastern ◽  
Elatobium Abietinum

Flight activity of aphids during 1969–71 in a Sitka spruce plantation in north-eastern Scotland was recorded by means of sticky traps. Two flight periods occurred, June–August and September–October. Fewer aphids were caught at 120 and 180 cm than at 60 cm above ground during June–August, while fewer were caught at 60 cm in September–October. After accounting for differences in wind speed at these heights, it was shown that aerial density was consistently higher at 60 cm. The first flight which comprised mostly Elatobium abietinum (Wlk.) was three weeks early in 1971; this was associated with the rapid increase in aphid population on spruce shoots, due to the preceding mild winter. Reinfestation by this species after spraying could follow under similar circumstances. Adelges laricis Vail. and A. viridis (Ratz.) sexuparae were caught in the first flight, and A. cooleyi (Gill.) gallicolae in the second; all galls on Sitka were by gallicolae of A. cooleyi. Aphis fabae Scop, was the most common species in the second flight.

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