Plant nitrogen, insect population

The extent and severity of the damage attributable to acid depositions are difficult to estimate, since impacts vary according to soil type, plant species, atmospheric conditions, insect populations, and other factors that are not well understood. Nitrates in precipitation may actually increase forest growth in areas with nitrogen-deficient soils. 

Sequestration of plant natural products by herbivorous insects is widespread. This is not surprising, since most insects are herbivorous and it is estimated that there are between two and six million species. While these sequestrators obviously exploit their alkaloid-rich host plants, such specialists represent a very minor component of the total herbivorous population. In essence, these nitrogenous compounds are highly effective deterrents for most of the herbivorous species with which they share their world. On the other hand, a brief discussion of some of the alkaloids and their specialist herbivores illustrates the versatiliity of these insects as exploiters of toxic compounds This alkaloidal treatment has been derived from the tables of Brown and Trigo10 and emphasizes... 

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