430 Invasive Stink Bugs and Related Species (Pentatomoidea)
ranged between 4 and 39 and averaged 17.5; they also reported that oviposition mainly was on pods and,
additionally, that eggs were deposited over 30 cm above ground. Temple et al. (2016) reported that the
number of eggs per mass ranged from 2 to 55 and averaged 16.6. Fraga and Ochoa (1972) reported 13–17
eggs per mass.
Recently, oviposition has been studied in relationship to soybean maturity group (MG), plant structure,
and vertical distribution within the canopy (Temple et al. 2016). Plant structure by maturity group inter-
actions resulted in more egg masses deposited on leaves in MG IV (79.4%) and more on pods in MG V
(72.7%) (Temple et al. 2016). Only 29.9% of egg clusters in MG IV and 18.3% of egg clusters in MG V
were deposited in the upper 35 cm of the soybean canopy.
Eggs typically are barrel-shaped and black with a light band around the middle and have an overall
wooly or prickly appearance under low magnification (Figure 8.1A) (Bundy and McPherson 2000, Akin
et al. 2007, Silva and Panizzi 2008, La Porta et al. 2013). The eggs of certain other Piezodorus spp. are
similar (Hinton 1981, Candan 1998). As with most stink bug species, females of P. guildinii glue each
egg to the substrate and to adjacent eggs, probably using the last tarsomere of the hind leg to help position
each egg (Panizzi 2006). In Nezara viridula, the glue is produced by the follicular cells of the ovarioles,
and a component of this secretion acts as a host recognition kairomone for the egg parasitoid, Trissolcus
basalis (Wollaston) (Hymenoptera: Platygastridae) (Bin et al. 1993). T. basalis also has been reported as
a parasitoid of P. guildinii, and the relationship between the glue and the parasitoid probably is similar
in P. guildinii.
Panizzi and Smith (1977) were the first to detail the basic biological characters of Piezodorus guildinii
in Brazil. Under controlled laboratory conditions (24°C; 80% relative humidity), the minimum preovi-
position period was 22.6 days, with the total mean number of eggs deposited per female being 31.1 eggs
with a maximum of 114. The egg incubation period averaged 7.5 days, and the first instars clustered atop
the egg choria during the stadium (Figure 8.1A). The total nymphal stadia (hatching to adult) averaged
31.5 d ays.
Serra and La Porta (2001) studied development, longevity, and fecundity of the bugs when fed green
beans, Phaseolus vulgaris L. (Fabaceae), in the laboratory. Nymphal mortality was approximately 60%,
adult longevity ranged from 60 to 79 days, and the mean fecundity was 86.3 eggs per female.
Oliveira and Panizzi (2003) compared nymphal development and adult reproduction when the bugs
were provided different growth stages of soybean [see description of soybean development in Fehr et
al. (1971)]. Nymphs fed pods in the pod-filling stages (R5–R6) showed greater survivorship and shorter
developmental time compared to those fed pods in earlier (R3–R4) or later (R7–R8) stages. Similarly,
adults lived longer and had higher fecundity when fed soybean pods at R5–R6 compared to those fed
R3-R4 or R7-R8 soybean pods.
Though bacterial endosymbionts are known to impact stink bugs (both positively and negatively),
little information is available for symbionts of Piezodorus guildinii. Recent research indicates that
Enterobacter hormaechei may be the primary symbiont of P. guildinii (Husseneder et al. 2017).
Piezodorus guildinii is multivoltine. It has been reported to complete five generations per year (on
soybean and other crops) in Argentina (Fraga and Ochoa 1972, Panizzi and Slansky 1985b) and Brazil
(Panizzi 1997) and at least three generations per year in Louisiana (one to two on clover, two on soybean)
(Jeffrey A. Davis, unpublished data).
Abiotic factors can significantly affect the physiology and morphology of Piezodorus guildinii.
Temperature and day length affect the development rate, longevity, fecundity, and egg viability
(Zerbino et al. 2013). Generally, a long photophase with warmer temperatures positively increases
biological responses. Zerbino (2014), in a laboratory study, found that under a short photophase
and low temperature, P. guildinii adults accumulate lipid reserves, have undeveloped reproduc-
tive organs, are smaller in size, exhibit darker colored pronotal bands and connexiva, feed less
frequently, and enter reproductive diapause. Zerbino et al. (2013) found that, in Colonia, Uruguay,
P. guildinii did not reproduce unless soybean was available. Cividanes and Parra (1994) estimated
that the number of generations of P. guildinii in Brazil during the soybean season was higher than
that of Nezara viridula (i.e., 5.0 vs. 3.7 generations). Finally, Panizzi et al. (1980) and Costa and
Link (1982) found that nymphs and adults of P. guildinii, respectively, were more mobile than those
of N. viridula.