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Laboratory Rearing Experiment
P,esults from the laboratory rearing experiment indicated that the various feeding scenarios tested in this study
significantly affected female spruce budwonn growth (Fig. 8) and development (Fig. 9) (Wilk's lambda F[49,15] = 4.7, p =
().(}012).
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Figure 8.---Female spruce budworm weight per instar according to various feeding scenarios using flesh food from flowering
(F) and from nonflowering (NF) balsam fir trees. Two trees served as food sources for two groups of 25 individually
reared larvae per feeding scenario (T = 12°C, RH = 65%, 18L:6D, + larvae fed on current-year foliage from the given
crown section, - larvae fed on current-year foliage prior to reaching sixth instar and l-year old foliage thereafter, *
larvae fed on current-year foliage from the midcrown prior to reaching sixth instar and current-year foliage from the
lower"crown section thereafter). For a given instar, means followed by the same letter are not significantly different
(p < 0.05).
Insects fed on pollen during their early stages of development were smaller when they reached their sixth instar than
those that did not have access to staminate flowers (Fig. 8). However, they had similar pupal weight as those that did not eat
pollen but had access to current-year foliage during their whole development. The presence of pollen in the insect diet
caused a significant 5 d reduction in development time prior to reaching sixth instar, and a significant 3 d reduction during
pupal stage (Fig. 9). Although backfeeding during the insect sixth instar did not significantly affect development time, it
reduced the pupal weight of larvae fed on food from flowering and nonflowering trees by 32% and 28% respectively (Fig. 8).
On the other hand, dispersal from the midcrown to the lower crown section, when larvae reached sixth instar, did not significandy
affect pupal weight. However, this feeding scenario resulted in a 6 d increase in the development time from sixth
instar to moth emergence (Fig. 9).
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