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RESULTS
Field Rearing Experiment
The production of staminate flox_ers significantly affected spruce budworm larval biology (9: Wilk's lambda F[2,171
= 18.3, p = 0.0(_1, if: Wilk's lambda F[2,171 = 13. l, p = 0.0004) (Fig. 1, 2). Larval biolog 5 also significantly xaried
according to crown sections (9: Wilk's lambda F[2,17] = 458.6, p = 0.0001 ; Of: Wilk's lambda F:[2,171= 331.8, p = 0.0001).
However, the interaction between flo_vering class and crown section was significant (9: Wilk's lambda F[2,17] = 329.3, p =
0.0(X)I o": Wilk's lambda F[2,17] = 549.9, p = 0.0001). This significant interaction results from the fact that floxvering
affected budworm biology only in the midcrown of flowering trees where staminate flowers were available for consumption
(Figs. 1, 2).
F F NF NF
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E loo ab
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Figure 1.--Pupal weight of male and female spruce budworm reared in the midcrown and the lower sections (*) of flowering
(F) and nonflowering (NF) balsam fir trees. Staminate flowers were present only in the midcrown of flowering trees
(n = 10 trees). For a given sex, means followed by the same letter are not significantly different (p < 0.05).
Both male and female budworms that had access to staminate flowers in the midcrown of flowering trees exhibited 5
d shorter development time (9: F[1,18] = 32.7, p = 0.0001; _: F[1,18] = 27. l, p = 0.0001) and 9_'_(9) to 15% (o_) reduced
pupal weight (9: F[1,18] = 12.3, p = 0.0026; if: F[1,1811= 4.9, p = 0.0397) compared to those located where staminate
flowers were not available for consumption. However, no significant impact of flowering on budworm survival was detected
(Chi-square = 75, df = 69, p = 0.28, n = 40) (Fig. 3).
Insects reared on flowering branches had lower fecundity (F[ 1,18] = 10.8, p = 0.0041) than those reared on nonflowering
branches (Fig. 4), but they produced individual eggs of similar weight (F[1,8] = 1.8, p = 0.21) (Fig. 5). At the end of
the 29 week long diapause period, no significant difference was detected in terms of survival of the progeny maintained at
2°C during their diapausing stage (Chi-square = 132, df = 129, p = 0.41, n = 46) (Fig. 6).
Flowering branches produced significantly less current-year R_liagethan nonflowering branches (F[1,181 = 4.4, p =
0.04) (Fig. 7). Although the insects reared on flowering branches removed approximately the same amount of current-year
foliage as those reared on nonflowering branches (F[1,1811= 1.95, p = 0.18), they back-fed on 1-year old foliage, while the
others did not (F[l, 18] = 23, p = 0.0(Y01) (Fig. 7). This indicates a possible reduction in the nutritive quality of the currentfoliage
produced by flowering branches.
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