Population fluctuation in phytophagous insects

We examined how community interactions affect year-to-year population variability in three groups of phytophagous insects: British aphids and moths, and Canadian moths. We first examined how the number of host plant species on which a given phytophagous insect species feeds affects its population variability. Specialist insect species showed a weak tendency to be more variable than generalist species. We then examined how the number of species of parasitoids from which a given phytophagous insects species suffers affects its population variability. Species that are host to few parasitoid species showed a weak tendency to be more variable than species with many parsitoid species. These relationships also depend on other aspects of the life histories of the phytophagous insect species.