TOLERANCE TO HERBIVORY BY A STEMBORING CATERPILLAR IN ARCHITECTURALLYDISTINCT MAIZES AND WILD RELATIVES

In a screenhouse experiment in southwest Mexico, we infested two maize cultivars, a land-race and a modern high-yielding variety, and two wi ld teosintes, Zea diploperennis and Zea mays parviglumis, with newly h atched larvae of the stemborer, Diatraea grandiosella. While subsequen t damage levels, when corrected for differences in plant size, were hi ghest in the wild perennial, Zea diploperennis, this taxon showed the lowest absolute and proportional reductions in growth and reproduction , i.e., it was most tolerant to the damage. Higher growth rates were n ot associated with tolerance. Rather, a greater number of tillers and leaves in the wild taxa allowed for compartmentalization of damage and greater developmental plasticity. These results, when combined with p revious findings on effective defense patterns, indicate that toleranc e in maizes and wild relatives may be positively associated with defen se against stemboring by the same insect. Because the probable mechani sms for defense (tissue fiber) and tolerance (plant architecture) are unrelated, a positive association is contrary to the predictions of so me optimal defense theories, which posit a negative relationship betwe en tolerance and defense.