Water Deficit Stress - Host Plant Nutrient Accumulations and Associations with Phytophagous Arthropods - Abiotic Stress: Plant Responses and Applications in Agriculture - page 393

2008 it moved into Louisiana (Hummel et al., 2008, 2010). Because the Mexican rice borer
was recently determined to prefer corn over other crop plants (Showler et al., 2011), its as‐
sumed range might be considerably underestimated (Showler & Reagan, 2012).
Eggs are mostly deposited in clusters within folds of dry sugarcane leaves, although eggs
are also laid in folded green living tissue if available (Showler & Castro, 2010b). Van Leer‐
dam et al. (1986) found 96% of the pest's eggs on the basal 80 cm of sugarcane plants where
most dry leaf tissue is located. The Mexican rice borer is not so much stress-oriented as it is
nutritionally-oriented in that it prefers to lay eggs on dry foliage of plants stressed by limit‐
ed water and of plants growing in enriched soil (Showler & Castro, 2010a; Showler & Rea‐
gan, 2012). Water deficit stress in sugarcane plants, however, unlike over-fertilized plants,
offers increased quantities of dry, folded leaf tissue per plant, contributing to the crop's vul‐
nerability (Reay-Jones et al., 2005; Showler & Castro, 2010b). In a greenhouse no-choice cage
experiment using sugarcane plants from which all dry leaf tissue was excised and removed
from the cages, or placed at the bottom of the cages like a mulch, and intact (dry leaf tissue
remained on the plants) sugarcane plants (controls), numbers of eggs and the degree of larv‐
al infestation was distinctly greater on the controls (Figs. 1 & 2; Showler & Castro, 2010b).
Figure 1. Mean (± SE) numbers of Mexican rice borer eggs on green and dry leaf tissue per sugarcane plant; ANOVA,
Tukeys HSD ( P < 0.05), n = 7 replicates per assay (Showler & Castro, 2010b).
Early instars feed on living leaf tissue, under fresh leaf sheaths, and some tunnel into the leaf
midrib; later instars bore into the main stalk (Wilson, 2011). Injury from stalk tunneling results
in deadheart, decreased sugar production, and stunting or lodging of stalks sometimes so se‐
vere that harvest becomes unfeasible (Johnson, 1985; Legaspi et al., 1997; Hummel et al., 2008).
Tunnels within host plant stalks are packed with frass, blocking entry of predators and parasi‐