FIGURE 4.3 Numbers of eggs produced and hatched from first generation collembola (Folsomia candida) when fed upon a variety of arbuscular mycorrhizal fungi. Source: Data from Klironomos et al. (1999).

As we have seen, mycorrhizae are capable of altering the chemistry of their host plants, particularly in terms of their nutrient content. The selection of plant parts as food for invertebrates is often dependent upon the chemistry of the plant; it is possible that there could be an influence of the mycorrhizal colonization of plant roots and the palatability of above-ground plant parts to grazing herbivores. Goverde et al. (2000) attempted to test this idea using larvae of the common blue butterfly, Polyommatus icarus, that were fed with sprigs of Lotus corniculatus (Fabaceae) plants that had been inoculated with one of two different arbuscular mycorrhizal species, with a mixture of these mycorrhizae, or with uninoculated plants. Survival of third instar larvae fed with plants colonized by both mycorrhizae was 3.8 times higher than with a single mycorrhizal

species and 1.6 times greater than that of larvae fed with nonmycorrhizal plants. Larvae fed with mycorrhizal plants had double the weight of those feeding on nonmycorrhizal plants after 11 days (Table 4.10). These differences are attributable to the improved chemistry of mycorrhizal plants that had three times higher leaf P concentration and a higher C/N ratio than the nonmycorrhizal plants.