Water Deficit Stress - Host Plant Nutrient Accumulations and Associations with Phytophagous Arthropods - Abiotic Stress: Plant Responses and Applications in Agriculture - page 394

toids (Hummel et al., 2008). Pupation occurs within the stalk after mature larvae make emer‐
gence holes protected with a thin window of outer plant tissue (Hummel et al., 2008). In the
Lower Rio Grande Valley, a life cycle takes 30-45 days, and there are 4-6 overlapping genera‐
tions per year (Johnson, 1985; Legaspi et al., 1997). Tunneling damage and the insect's preva‐
lence has made it the key sugarcane pest of south Texas, displacing the sugarcane borer,
Diatraea saccharalis (F.) (Van Leerdam et al., 1984; Legaspi et al., 1997).
Figure 2. Mean (± SE) numbers of Mexican rice borer larval entry holes per sugarcane stalk; ANOVA, Tukeys HSD ( P <
0.05), n = 7 replicates per assay (Showler & Castro, 2010b).
Approximately 20% of sugarcane internodes are injured by Mexican rice borers in south
Texas, and larval entry holes also provide portals for red rot, resulting in additional loss of
sugar (Van Zwaluwenberg, 1926; Osborn & Phillips, 1946; Johnson, 1985). On some varieties
of sugarcane, up to 50% bored internodes have been reported (Johnson, 1981); Mexican rice
borer injury results in losses of US$575 per hectare of sugarcane (Meagher et al., 1994) and
US$10-20 million annually (Legaspi et al., 1997, 1999). Projected economic consequences of
Mexican rice borer infestation of Louisiana includes US$220 million in sugarcane and US$45
million in rice (Reay-Jones et al., 2008). In corn, stalk boring and secondary infection by stalk
rot pathogens can cause shattering, lodging, and complete collapse of stalks (Showler et al.,
2011) such that by season's end >50% of stalks of susceptible varieties are destroyed (Show‐
ler, unpublished data).
A connection between irrigation practices and severity of Mexican rice borer infestation was
first suggested by Meagher et al. (1993), and later studies indicated that drought stressed sug‐
arcane is preferred for oviposition because there is more dry leaf tissue and the nutritional val‐
ue, at least in terms of a number of important free amino acids, is enhanced (Tables 1 & 2)
(Muquing & Ru-Kai, 1998; Reay-Jones et al., 2005, 2007; Showler & Castro, 2010a). Although se‐
vere water deficit stress of sugarcane reduces sugar production, some cultivars under moder‐