Invasive Stink Bugs and Related Species (Pentatomoidea)

628 Invasive Stink Bugs and Related Species (Pentatomoidea)

The potential for biological control by a wheel bug, Arilus sp., was investigated in Brazil; 32 of 50 field-
collected specimens were found to harbor the Phytomonas in their digestive tracts, strongly suggesting
predation on L. lobuliger, the local vector species (Meneguetti and Trevisan 2010).
Ecological observations of several Lincus spp. inhabiting native palms in the genus Astrocaryum in
Peru (Couturier and Kahn 1989, 1992; Llosa et al. 1990) have added to our knowledge of the group.
These bugs reside within the green leaf sheaths on the back of the petiole, hiding between the spines and
the leaf sheath fibers, or they hide under litter. Of the three species observed on these native palms in
Peru (i.e., L. malevolus Rolston, L. hebes Rolston, and L. spurcus), only L. spurcus has been reported
from oil palm (Elaeis guineensis) plantations.
Lincus spp. are strictly Neoptropical, and these trypanosome diseases are not known to occur among
African oil palms in their native habitat. However, with worldwide movement of plants, the possibility
always exists for inadvertent colonization, and the effect of such invasive introductions outside of the
Neotropics could be disastrous.

13.7 Epidemiology of Pentatomid-Borne Pathogens

As mentioned in Section 13.1, transmission modes largely define the epidemiology of plant pathogens.
Madden et al. (2000) hypothesized that the rate of spread of a given vector-borne pathogen would be most sen-
sitive to different epidemiological parameters depending on the pathogen’s mode of transmission (see Section
13.1.1). They developed a series of compartmental epidemic models to explore the parameters to which each
transmission mode would be most sensitive: rates of spread for non-persistently transmitted pathogens were
most sensitive to vector movement rates, whereas persistently transmitted pathogens were most sensitive to
vector longevity, acquisition rate, and inoculation rate. Semi-persistent pathogens were an intermediate case.
Little work has been done on the epidemiology of pentatomid-borne pathogens. Sgrillo et al. (2005)
developed an epidemic model of the spread of Phytomonas staheli by Lincus lobuliger and showed that
the spread of P. staheli was most sensitive to movement rates of the vectors. Given the paucity of epide-
miological work, we developed two epidemic models specific to pentatomid-borne pathogens to explore
the factors most important for pathogen spread. Plant pathogens can have either symbiotic or facultative
relationships with pentatomid vectors. Symbiotic pathogens colonize the bodies of their pentatomid vec-
tors, whereas facultative pathogens use feeding holes made by pentatomids as entry points into the tissues
of their host plants. We developed separate models for the epidemiology of these two pathogen groups.

13.7.1 Symbiotic Pathogens

Pentatomid-borne pathogens occupy nearly all transmission modes—from non-persistent to persistent.
As such, our model focuses on epidemiological factors that vary among these forms of transmission.
Following Brauer et al. (2008), model 13.1 includes two host compartments and two vector compartments:

dS

dt

SV

N

aI

dI

dt

SV

N

aI

dU

dt

b

KU

K

u UV

=− +

=−

=

 −





 +−

β

β

μ

αα

α

μ

UI

N

dU

dV

dt

b

KV

K

V

UI

N

VdV

u

vv

−

=

 −







+−−

(13.1)

The variables S, I, U, and V relate to susceptible hosts, infected hosts, non-infectious vectors, and infectious
vectors, respectively. As this model consists of a system of differential equations, the values of these variables