Piezodorus guildinii ( Westwood) 429
The reasons for the permanent appearance of Piezodorus guildinii as a major pest of soybean north
and west of Florida in the United States are not clear. Published records fail to provide a picture of the
gradual movement of this insect across the southern states. However, by the early 2000s, it was being
reported as a soybean pest in several southern states where it had never been reported previously (Baur
et al. 2010).
Menezes (1981) found a single Piezodorus guildinii female near Quincy in northwestern Florida (“pan-
handle”) in 1977, and several more in 1978. By 1979, about 300 adults and nymphs were collected during
the season. Subsequently, specimens were collected in several southwestern Georgia counties adjoining
Florida with Menezes (1981) reporting that “This species is rapidly increasing in abundance” and warned
that it had almost completely displaced Nezara viridula in Brazil. McPherson et al. (1993) demonstrated
that P. guildinii was among four stink bug that composed 98% of recorded species from soybean during a
1987–1991 study in southeastern Georgia. However, a report of insect losses due to stink bugs in Georgia
soybean for 1996 mentioned N. viridula, Chinavia hilaris (as Acrosternum hilare), and Euschistus ser-
vus but not P. guildinii (Riley et al. 1997). A survey of stink bugs in soybean in southeastern Texas by
Drees and Rice (1990) during 1981–1983 did not yield P. guildinii, but a second survey by Vyavhare et
al. (2014) during 2011–2013 found that P. guildinii now composed 65% of the total population of major
species sampled. In 2007, in Mississippi, the reported stink bug complex included N. viridula, C. hilaris
(as A. hilare), E. servus, Thyanta spp., and P. guildinii as the major pests of soybean, infesting every acre
sampled and causing both yield and quality losses (Musser and Catchot 2008). In 2008, P. guildinii again
was listed among the same species that were the most economically important insects attacking soybean
in Mississippi and Tennessee (Musser et al. 2009).
Prior to 2000, Piezodorus guildinii had not been reported in Louisiana soybean, and specimens from
Louisiana were not present in the Louisiana State Arthropod Museum (Davis et al. 2011, Temple et al.
2013a). It initially was identified in southern Louisiana during 2000 by crop consultants and Louisiana
Cooperative Extension personnel (Baldwin 2004). Within two years, it exceeded the action threshold for
stink bugs (9 per 25 sweeps), requiring insecticide applications on much of the soybean crop in southern
Louisiana (Baldwin 2004). It quickly became the most devastating stink bug pest in Louisiana soybean
production (Temple et al. 2013a). The sudden appearance and subsequent expansion across the state of
Louisiana appears to be unique and is well documented, having been reported in all soybean producing
regions in Louisiana by 2006 (Davis et al. 2011, Temple et al. 2013a).
Subsequently, Piezodorus guildinii migrated north from Louisiana to Arkansas and Missouri (Temple
et al. 2013a). It was observed as a soybean pest in Arkansas for the first time in 2005, and breeding popu-
lations were seen in 2006 and 2007 (Smith et al. 2009). It was reported for the first time in Missouri in
2007 (Tindall and Fothergill 2011). By 2008, stink bugs had become the most economically important
pest group attacking soybeans across the southern states from South Carolina to Texas, with P. guildinii
the most important species (Musser et al. 2010).
8.4 Biology
8.4.1 Life History
Piezodorus guildinii has been a serious pest of soybean and leguminous pasture crops in South America
for many years and, thus, there have been several studies on its biology and ecology (see references in
Panizzi and Slansky 1985b, Panizzi et al. 2000b).
Most pentatomids, including Piezodorus guildinii, mate end-to-end (Figure 8.1D). Eggs of pentato-
mids usually are deposited in clusters (masses) composed of many rows (see Chapter 1). However,
eggs of P. guildinii typically are deposited in characteristic double rows (e.g., Fraga and Ochoa 1972,
Panizzi and Smith 1977, Grazia et al. 1980, Bundy and McPherson 2000, Galileo et al. 2007). Stink bugs
that deposit eggs in two rows usually prefer longitudinal substrates rather than leaf surfaces (Silva and
Panizzi 2008; Walker A. Jones and J. E. McPherson, personal observations). Panizzi and Smith (1977)
reported that 60% of 500 egg masses were deposited on soybean pods, and that the mean number of
eggs per mass was 15.1. Link et al. (1980) recorded that the number of eggs per mass for 542 masses