438 Invasive Stink Bugs and Related Species (Pentatomoidea)
In South America, the ground cloth or beat cloth method is the most popular method of sampling
stink bugs on soybean. Originally developed by Boyer and Dumas (1963), it was improved by Shepard
et al. (1974) and, later, by Drees and Rice (1985) who introduced the vertical beat sheet (VBS). Today,
use of the VBS is widespread in South America to sample stink bugs, including Piezodorus guildinii,
in soybean fields (see review by Corrêa-Ferreira 2012). In general, 10 randomly allocated samples are
taken per hectare to estimate the stink bug population; when populations reach two adults or late instar
nymphs per meter, control measures should be taken to avoid economic grain yield reduction. In the case
of soybean fields for seed production, one adult or late instar nymph per meter justifies control measures
(Panizzi et al. 2012).
8.7.2 Cultural Control
Producers can manipulate agronomic practices to avoid stink bug injury in soybean. By managing crop
maturity through planting of early maturing soybean varieties, producers can manipulate crop phenology
to have pod production and pod fill occurring when stink bugs are at their lowest numbers. Earlier in the
season, stink bugs are fewer in number and widely dispersed in the landscape. Conversely, during the
latter part of the production season, late-maturing soybeans concentrate stink bug populations as avail-
able host acreage diminishes. In the southern United States, soybean producers adopted an early soybean
production system, planting maturity group IV and V instead of VI and VII to allay late season drought
stress and stink bug pressure (Baur et al. 2000). This worked well until the arrival of Piezodorus guildinii.
Because P. guildinii reproduces primarily on legumes, earlier maturing soybeans concentrate populations
of this insect and, thus, insecticide applications for stink bugs have increased (Temple et al. 2013b).
Another cultural control tactic available to producers is trap crops. Trap crops concentrate stink bugs
in a confined area, reducing their movement and total acreage to be sprayed (Hokkanen 1991, Todd et al.
1994, Shelton and Badenes-Perez 2006). McPherson and Newsom (1984) confined 70 to 85% of the
Nezara viridula population to soybean trap crops using only 10% of the total acreage, thus reducing stink
bugs in the main crop to 0.1 per meter.
In South American soybean, the trap crop concept developed by Newsom and Herzog (1977) in the
United States for soybean pests was introduced and tested and results were positive for managing stink
bugs (Panizzi 1980). Although trap crops are effective, grower acceptance is low because trap crops usu-
ally are insect species-specific, often are planted at times different from those of the main crop, and are
not harvestable (Shelton and Badenes-Perez 2006).
A final cultural tactic combines the understanding of stink bug movement and the use of insecticides.
Field colonization behavior of many stink bugs is known to be aggregated (e.g., Todd and Herzog 1980,
Venugopal et al. 2014). Therefore, site-specific targeting of insecticide applications is possible, particu-
larly for aggregations of stink bugs within field margins. This could reduce pesticide applications, saving
growers money while conserving natural enemies. Davis et al. (2011) conducted small plot (0.5 acre) field
experiments to test this hypothesis. Treatments included plots that never were sprayed, plots that had the
entire area treated (100% of acreage treated), and plots that had only the four rows on either side treated
(25% of acreage treated). Three insecticide applications occurred from R5 (pod filling) to R7 (mature
pods). Perimeter insecticide applications reduced Piezodorus guildinii plot colonization by two weeks
compared to the untreated plots. Treating only the perimeter also kept P. guildinii below the action
threshold (16 stink bugs per 100 sweeps) (Davis et al. 2011).
8.7.3 Biological Control
Egg parasitoids are important biological control agents that cause natural mortality of stink bug eggs
in soybean (Yeargan 1979, Orr et al. 1986, Koppel et al. 2009). Most egg parasitoids of stink bugs
belong to the genera Trissolcus and Telenomus (Hymenoptera: Platygastridae) (Johnson 1984). In Brazil,
Telenomus podisi Ashmead (previously reported as T. mormideae Costa Lima) parasitized 27% of
Piezodorus guildinii egg masses (Panizzi and Smith 1976b); more recently, over 50% of P. guildinii
and Nezara viridula egg masses were parasitized by T. podisi (Corrêa-Ferreira and Moscardi 1994).
In Uruguay, Castiglioni et al. (2010) found the following species of egg parasitoids of P. guildinii on