Effects of industrial air pollution on pine insects : Air Pollution and Forest Decline. 14th International Meeting for Specialists in Air Pollution Effects on Forest Ecosystems

1989

S. 303-308

7 Abb., 47 Lit. Ang., En, Zfsg. En

Unselbständiges Werk

200034693

The influence of atmospheric pollution on scots pine (Pinus sylvestris) herbivores consisting of 9 sample plots located at log distances from a distinctive pollution source (SO2, heavy metals, dust) in SW Finland. Several insects, including aphids, pine bark bugs, diprionids and tortricid moths, showed a peak in numbers in the moderately polluted pine stands, whereas herbiores excluding aphids were scarce in the immediate vicinity. Eight defoliator species (Lepidoptera: Panolis flammea, Bupalus piniarius; Hymenoptera: Neodiprion sertifer, Diprion pini, Gilpinia socia, G. virens, G. frutetorum, Microdiprion pallipes) were reared in the laboratory on needles collected rom the sample plots. The elemental composition of the needles (P, K, Mg, Mn; Fe, Al, Cu, Zn, Na, Ca, C, H, N, ash weight, dry weight) was determined. The size of the pupea/cocoons was found to be dependent on the distance from the industrial plants, the smallest pupea/cocoons being those obtained in the field. Regression models suggest that the size differences were largely attributable to the heavy metal concentrations. The N. serfifer females reared on unpolluted needles produced an average of 79 eggs, while those reared on heavily polluted needles 69 eggs. However, egg viability analyses showed that the difference in fecundity was later evened out during embryonal development. The developmental time of P. pini fed on polluted needles was longer. The high pest densities in moderately polluted stands could be due either to decreased parasitoid pressure or to decreased resistance of pine-favouring defoliators.