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Oviposition preference and larval performance of the western spruce budworm (Lepidoptera: Tortricidae)
- Leyva, K.J., Clancy, K.M., Price, P.W.
- Environmental entomology 2000 v.29 no.2 pp. 281-289
- Choristoneura occidentalis, oviposition, fecundity, ova, viability, larvae, host plants, Pseudotsuga menziesii, Abies concolor, Picea engelmannii, conifer needles, tree age, vigor, Arizona
- Many preference and performance studies have been done on latent species of insect herbivores, but few studies have examined whether eruptive species exhibit preferences for oviposition sites that affect larval survival. We used choice experiments to test whether female moths of an eruptive species (the western spruce budworm, Choristoneura occidentalis Freeman) exhibited oviposition preferences for needle age class, for age of host trees, and for host vigor among individuals of one species, Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco. We also evaluated oviposition preferences among three common host species (Douglas-fir, white fir, Abies concolor Lindl., and Engelmann spruce, Picea engelmannii Parry). Females laid more egg masses on older branches (45-60 yr old) than on younger branches (10-15 yr old) of Douglas-fir trees. Also, proportionately more eggs were laid on branches from white fir than on branches from Douglas-fir or Engelmann spruce. There were no differences in the distribution of egg masses when females were offered a choice between 1- and 4-yr-old Douglas-fir needles or between long and short shoots of Douglas-fir. These general patterns were obtained across two generations. However, there were no differences in viability of the F1 or F2 egg masses or weights of F1 female pupae (i.e., fecundity) among treatments for any experiment. Consequently, although female moths of this eruptive species appeared to use foliar cues to determine oviposition sites, we could not link these preferences to any effects on offspring performance because performance did not vary. This contrasts with the tight linkages between preference and performance documented for many latent species.