Water Deficit Stress - Host Plant Nutrient Accumulations and Associations with Phytophagous Arthropods - Abiotic Stress: Plant Responses and Applications in Agriculture - page 395

ate stress accumulate sugars (Hemaprabha et al., 2004), and Mexican rice borer preference
among species of host plants (Showler et al., 2011) has been associated with concentrations of
fructose (Showler, unpublished data). Differences in oviposition preference were not ob‐
served on excised dry leaf tissue regardless of whether the sugarcane plant from which it origi‐
nated was water deficit stressed or well watered; hence, the expression of sugarcane
vulnerability or resistance appears to require the pest's ability to detect nutrients in living leaf
tissue (Showler & Castro, 2010b). Although a sugarcane cultivar with some degree of resist‐
ance to the Mexican rice borer was still better protected than a susceptible variety under
drought conditions, water deficit increased injury to the crop by ≈2.5-fold in each (Reay-Jones
et al., 2005). Reay-Jones et al. (2003) also reported that high soil salinity, a stress factor that also
heightens free amino acid accumulations in plants (Labanauskas et al., 1981; Cusido et al.,
1987), increases Mexican rice borer infestations in sugarcane. Further, relatively high concen‐
trations of organic matter incorporated into soil of the Lower Rio Grande Valley (and conven‐
tionally fertilized with nitrogen) resulted in 18% more stalk production per sugarcane stool but
this effect was offset by substantial increases in Mexican rice borer infestation, causing stalk
weight, length, and percentage brix reductions relative to sugarcane fertilized with conven‐
tional nitrogen fertilizer or chicken litter (Showler, unpublished data). The composted soil was
associated with greater accumulations of free amino acids and fructose (Showler, unpublished
data). These associations reveal that the pest is not responding simply to water deficit, but in‐
stead to nutritional enhancement of the plant whether moderated by stress or by other factors.
a One-way ANOVA, randomized complete block design, df = 3,15.
b W, well watered; D, drought stressed.
Table 1. Mean (± SE) water potential (bar), and numbers of dry leaves, Mexican rice borer egg clusters, total eggs,
entry holes, and exit holes per stalk of two sugarcane varieties maintained under well watered or drought stressed
greenhouse conditions (Showler & Castro, 2010a)