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35000 j
30000
25000 b b
<
w 20000
IZ: <
b
m 15000 b
O.
10000
b
m Preferred 1
a IW Control A
r'l Preferred 2
a a a b
5000 c a
0 . . .
1 2 3 4 5 6 7 8
PEAK NUMBER
Figure 4.--Comparative mean areas of the indicated peaks in the HPLC analysis of the nonhydrolyzed fraction of ethyl
acetate extractables from ash foliage. Data are for preferred 1 (elicited with 25 IU / ml), preferred 2 (elicited with 50
IU / ml and control A (elicited only with solvent) foliage. Leaves were removed from these trees at 16 days after
elicitation. Peak areas not followed by the same letter are significantly different at p < 0.05.
DISCUSSION
Antioxidant Altered Foliar Antixenosis
The findings support the interpretationthat preference / non-preference decisions by M. disstria larvae regarding __
tocopherol-elicited versus solvent (control)-elicited green ash foliage are probably attributable to quantitative changes in
several compounds, not just in one chemical. Elicitation by _-tocopherol alters the quantitative contributions of at least
several chemicals in the mixture of secondary metabolites. The effects are very dynamic, e.g., changing from increased to
decreased antixenosis between 8 and 16 days after elicitation with 25 IU / ml. These findings seem compatible with the
knowledge that survivor plants systematically switch their major allocation of nutrient and energy resources between primary
growth and secondary growth-differentiation including defensive chemistry. Such dynamic switching seems reasonable
because survivor plants must grow, but they must also defend themselves from potentially lethal environmental stresses,
50
b
i