300 Invasive Stink Bugs and Related Species (Pentatomoidea)
Shi et al. (2014) studied development at different temperatures and found that eggs developed in
3.8–18.0 days at temperatures of 33–17°C.
There are five nymphal instars, which have been described or illustrated by Kershaw (1910), Moizuddin
and Ahmad (1979), Zhang et al. (2012), and Leslie et al. (2014). Nymphs tend to be yellow-brown, or
greenish-yellow to olive-brown, somewhat flattened, and covered in long setae (Figure 5.1C-D). Most
native pentatomoid nymphs are relatively free of setae or have a few short setae. At different tempera-
tures, Shi et al. (2014) found that nymphal development required 34–97 days, numbers that are close to
the 32–48 days reported by Thippeswamy and Rajagopal (2005a,b). Ahmad and Moizuddin (1977) pro-
vided the following stadia for the first to fifth (1–5) instars: 1, 7.3 days; 2, 7 days; 3, 7 days; 4, 6.4 days;
and 5, 8.3 days for males and 10 days for females. Ramakrishna Aiyar (1913) reported similar times of
6, 6, 9, 9, and 10 days, respectively, for instars 1-5. Tayutivutikul and Yano (1990) determined the devel-
opmental threshold for eggs and nymphs of males and females to be 14.9, 9.6, and 9.5°C, respectively,
with a thermal constant of 1190–1299 degree-days for males and females. A similar study by Shi et al.
(2014) found that the developmental threshold was 14.25°C with a thermal constant of 850 degree-days.
Megacopta cribraria overwinters as an adult under stones and grasses or in crevices in its natural habi-
tat (Ren 1984). Lahiri et al. (2015) evaluated overwintering sites in woodlands adjacent to soybean fields
in South Carolina, United States. They found the bugs preferred leaf litter over crevices in tree bark, and
leaf litter at the base of the south-facing side of trees over leaf litter at the base of the north-facing side of
trees or between trees. Movement away from feeding sites to overwintering sites resulted in the tendency
for this pest to invade homes in the fall. Golec and Hu (2015) found that about 15% of overwintering
females mated prior to overwintering, and these females were able to store live sperm throughout the
winter. They also saw a decrease in the ratio of males to females as the winter progressed, suggesting that
females are better able to survive cold temperatures than males. The fact that overwintering females may
not be dependent on finding mates for reproduction when leaving overwintering sites may explain how a
single female was able to establish an invasive population in the southeastern United States (see Section
5.5, Population Genetics, for further discussion).
5.4.2 Host Plants
Megacopta cribraria has been associated with a large number of plant species in its native and intro-
duced ranges (Table 5.1). This is an active and mobile bug that migrates away from its host in prepara-
tion for overwintering in the fall and migrates out of overwintering sites in the spring. Therefore, it is
not surprising that it has been observed on a number of different plants. It is considered to be primarily
a legume feeder with kudzu being the preferred or natural host plant. It has been reported as a pest of
several species of legumes (Fabaceae) but primarily soybean in Asia and lablab bean in China, India, and
Pakistan. Eger et al. (2010) suggested that reports from plants other than legumes may be simply inciden-
tal sightings. However, Srinivasaperumal et al. (1992) reported that M. cribraria was able to complete
development on firecracker plant, Crossandra infundibuliformis (L.) Nees (Acanthaceae) and cotton,
Gossypium hirsutum L. (Malvaceae), but development was delayed and adult weight and fecundity were
lower than for bugs reared on agathi, Sesbania grandiflora (L.) Pers. (Fabaceae). This is the only report
of rearing this bug on plants other than legumes. Because the interaction with endosymbionts may affect
host specificity of this bug (see Section 5.4.4, Endosymbionts, for further discussion), host range may
differ for different populations. Yamazake and Sugiura (2005) reported M. cribraria feeding on a gall
formed by an aphid, Schlectendalia chinensis Bell (Aphididae), rather than feeding directly on the plant,
Chinese sumac (Rhus chinensis Miller) (Anacardiaceae).
In the southeastern United States, Zhang et al. (2012) studied the development of Megacopta cribraria
on twelve potential legume host plants including lablab bean. Eggs were laid on many of these plants,
but survival from egg to adult was observed only on kudzu and soybean. The lack of survival on lablab
bean is interesting in that a number of studies in Pakistan and India report rearing this bug on the
same host plant (Ahmad and Moizuddin 1977; Thippeswamy and Rajagopal 2005a,b). Medal et al.
(2013b) conducted a similar study with 11 legumes and orange [Citrus sinensis (L.) Osbeck] (Rutaceae).
M. cribraria completed development on kudzu, soybean, pigeon pea [Cajanus cajan (L.) Millsp.], black-
eyed pea [Vigna unguiculata (L.) as Vigna sinensis (L.)], lima bean (Phaseolus lunatus L.), and pinto