酸性降下物が森林の生物群集の相互作用に与える影響 : 3.大気汚染が森林の植食性昆虫の個体群動態に与える影響

抄録

A number of studies have found evidence to suggest that an increase in the level of air pollution, including acidic precipitation, could be related closely to changes in the patterns of insect attack on forest trees. The present article reviews current knowledge on the effects of airpolluted environments on phytophagous insect populations and the underlying mechanisms involved. Many field observations carried out along pollution gradients have found a general trend for increases in the density of phytophagous insects, particularly sap-feeders such as aphids, in zones with high and / or intermediate levels of pollution, although the response differs among insect species. Experimental studies have revealed that increased growth and reproduction in phytophagous populations on plants prefumigated with gaseous pollutants such as SO₂,O₃ and oxides of nitrogen, are probably attributable to changes in the nutritional value and the level of secondary metabolites as allochemicals in the plants. Most of the results of recent studies using either approach have strongly suggested that air pollution has a dual effect of increasing the palatability of the plants to insects and reducing parasitism and predation, which may partly account for the causal mechanisms of outbreaks of phytophagous insects in forests.