624 Invasive Stink Bugs and Related Species (Pentatomoidea)
pentatomids, coreids, and mirids in the orchards may be to provide germination sites for existing spores
by causing fluids to ooze from feeding punctures (Daane et al. 2005). Stink bug monitoring and control
is only one part of a management plan that includes pruning, fungicide sprays, and modification of irriga-
tion methods (Holtz 2002).
- 5.6 Rice
Pecky rice is a general term for rice of inferior quality with imperfections; the kernel is discolored and
often breaks during milling. The condition is associated with stink bug feeding and is thought to result
also from fungi introduced via feeding because two distinctly different types of spots are produced,
a round chalky lesion and a darker discoloration. A detailed discussion of the relationship between
Oebalus pugnax pugnax (F.), fungal infections, and pecky rice is given by McPherson and McPherson
(2000), and therefore only selected papers will be summarized here.
Gelling saliva is produced by pentatomids as the stylets contact and penetrate plant tissue, forming a
surface flange and a sheath lining the path of the stylets. Superficial salivary sheaths of Oebalus pug-
nax harbor fungi on their interior and exterior walls. Hull penetration (indicated by an internal sheath)
results in the presence of fungi in and around puncture wounds to the kernel and underneath the hull.
As stylets are removed, sheath material usually seals the flange; however, scanning electron microscopy
showed some sheaths on the rice hull remained open, which may provide an additional infection route.
The authors concluded that fungi may enter the kernel either via the stylets during the feeding process or
through an open puncture after feeding (Hollay et al. 1987).
Five different fungi, isolated from damaged rice, caused peck symptoms when inoculated with a wire
into the endosperm of rice kernels at the soft dough stage; the wire was intended to mimic stylet penetra-
tion. Inoculation attempts without the wire were unsuccessful (Lee et al. 1993). Two fungi that caused
discoloration in inoculation trials also were cultured from excised stylets of O. pugnax: Alternaria alter-
nata (Fr.) Keissler and Curvularia lunata (Wakker) Boedijn. Based on these studies and additional field
experiments, these authors concluded that the discolored spots characteristic of pecky rice are caused by
fungi introduced as O. pugnax feeds, but that the relationship between the bug and the fungi is a loose
one (Lee et al. 1993).
13.5.7 Other Crops
Eremothecium coryli infests fruits representing at least 16 genera (Ashby and Nowell 1926); in all cases
when the vector has been sought, it has been a heteropteran. In addition to the crops already discussed
above, serious outbreaks of this pathogen have been reported in tomato and in citrus. Fruit rot of tomato
in California in 1998 led to extensive losses where portions of fields were completely abandoned due
to deterioration of ripe fruit at harvest time. The presence of Euschistus conspersus Uhler in the fields
prompted inoculation experiments simulating bug probing. Lesions appeared only if E. coryli inoculum
was injected to a depth of 4 mm; an ascospore suspension placed on the surface of the fruit failed to cause
infection (Miyao et al. 2000).
In Cuba, Eremothecium coryli infests tomato fruit but also produces round yellow spots on the surface
of green oranges, often causing fruit drop and rendering the oranges unmarketable (Grillo and Alvarez
1983). In the center of each yellow lesion, a salivary sheath was evident with stylets penetrating to
the juice vesicles. The coreid Leptoglossus gonagra (F.) was responsible for most damage, but Nezara
viridula also was present in orange groves. Fruits exposed in the laboratory to insects of both species
(field-collected from citrus and cucurbit weeds) developed the typical yellow lesions, with ascospores
and vegetative cells of E. coryli present in the vesicles. Vegetative cells also were found in the hindgut
of both L. gonagra and N. viridula. Heads of L. gonagra were dissected and subjected to histological
examination, but no E. coryli were observed in any form, possibly due to the small sample size. The bugs
likely transfer the yeast in the field from their cucurbit hosts (e.g., Momordica charantia L.) to citrus
(Grillo and Alvarez 1983). Two other pentatomid species are reported by Frazer (1944) to transmit stig-
matomycosis of citrus: Rhynchocoris poseidon Kirkaldy (as Rhynchocoris serratus Don.) and Cappaea
taprobanensis (Dallas). In Australia, the disease is known as dry rot, and may be associated with the