Jt. Cronin et al., Temporal variation in herbivore host-plant preference and performance: constraints on host-plant adaptation, OIKOS, 93(2), 2001, pp. 312-320
Temporal variation in the acceptability or suitability of plant genotypes t
o an herbivore has seldom been considered as a possible constraint limiting
the adaptation of herbivores to particular plant genotypes, or the occurre
nce of a positive correlation between host-plant preference and offspring p
erformance. In this study, we used data spanning 12 yr from the same 20 clo
nes of goldenrod (Solidago altissima) to examine the temporal variation in
oviposition preference and offspring performance of a stem-galling fly, Eur
osta solidaginis. We found that the stem galler's preference for, or perfor
mance on, the different clones was uncorrelated between years of this study
. Furthermore, we found that the relative rankings of clones changed by an
average of 31% between successive years. We suggest that these consistently
high year-to-year fluctuations in preference and performance by E. solidag
inis are likely due to environmental factors (e.g., water and nutrient leve
ls, or abundance of interspecific herbivores) that fluctuate over time and
are known to differentially affect the acceptability and suitability of clo
nes to herbivores; i.e., genotype x environment interactions. These results
are significant because temporal fluctuations in host-plant preference and
performance are likely to favor a more generalized diet by herbivorous ins
ects.