| dc.description.abstract | A suite of plants from the maize genus Zea L. (Poaceae) and the specialist
herbivore Dalbulus maidis (DeLong and Wolcott, 1923) (Hemiptera: Cicadellidae) were
used to test the hypotheses that anti-herbivore defenses are affected by plant life-history
evolution and human intervention through domestication and breeding for high yield.
The suite of plants included a commercial hybrid maize (Zea mays ssp. mays L.), a
landrace maize, two populations of annual Balsas teosinte (Z. mays ssp. parviglumis Iltis
& Doebley), and perennial teosinte (Z. diploperennis Iltis, Doebley & Guzman). Leaf
toughness and pubescence, oviposition preference, and feeding and oviposition
acceptance parameters were compared among the suite of host plants looking for effects
of transitions in life history (perennial to annual teosinte), domestication (annual teosinte
to landrace maize), and breeding (landrace maize to hybrid maize) on defenses against
D. maidis. Observations on leaf toughness suggested that the life history and
domestication transitions weakened the plant’s resistance to penetration by the
herbivore’s mouthparts and ovipositor, as expected, while observations on pubescence
suggested that the breeding transition led to stronger defense in hybrid maize compared
to landrace maize, contrary to expectation. Observations on oviposition preference of D.
maidis coincided with the expectations that life history and domestication transitions
would lead to preference for Balsas teosinte over perennial teosinte, and of landrace
maize over Balsas teosinte. A negative correlation suggested that oviposition preference
is significantly influenced by leaf toughness. Observations on host plant feeding and
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oviposition acceptance under no-choice conditions suggested that D. maidis equally
accepts all host plants considered in this study, thus these observations did not support
the hypotheses associated with the life history, domestication, and breeding transitions
evident in the herbivore’s host genus. Overall, the results of this study suggested that
plant defenses against specialist herbivores are variably affected by plant life history
evolution, domestication, and breeding. Additionally, the study’s results suggested that
chemical defenses may play a role in Zea antiherbivore defense because the two physical
defenses that were evaluated (i.e. leaf toughness and pubescence) only partially
explained host preference of D. maidis | en |
