Megacopta cribraria ( F.) 317
Despite a few reports of feeding on all plant structures in soybeans by Megacopta cribraria, feeding
injury has been confined primarily to stems and petioles in the United States (Figure 5.1H) with no
reports of feeding on pods. Because this bug is a stem feeder and likely a phloem feeder, yield losses in
soybeans undoubtedly are due to indirect injury to the plant, probably resulting in reduced capacity to
produce and transport photosynthate throughout the plant.
Although Megacopta cribraria has been reported from numerous plant species, many of these likely
are incidental occurrences (Eger et al. 2010, Gardner et al. 2013a); however, data are limited relative to
pest status across hosts (see Section 5.4.2, Host Plants, for further discussion). Being a host on which
these bugs can develop may be a requirement for crops to suffer economic loss because field observa-
tions seem to indicate that the presence of large numbers of immatures often is associated with eco-
nomic losses. In no-choice studies (Blount et al 2015; Medal et al. 2013b, 2016a; and Golec et al. 2015)
black-eyed pea, lima bean, mung bean, pigeon pea, pinto bean and soybean, were reported as devel-
opmental hosts. Soybean and pigeon pea were the best developmental hosts, whereas only a few indi-
viduals of M. cribraria developed to adulthood on most of these plants. Sporadic occurrence of adult
M. cribraria on cotton and other crops has been noted. Survival to adulthood on cotton was reported by
Srinivasaperumal et al. (1992); however, in these no-choice assays, M. cribraria had reduced fecundity
and size and took longer to develop than on a legume host. Occasionally, adults may be observed in
cotton during periods of adult movement; however, reproducing populations have not been observed on
cotton in Georgia or South Carolina, and this bug is not considered an economic pest of cotton.
5.6.2.2 Scouting and Control on Crops
Scouting and management programs for Megacopta cribraria are best understood in soybeans, but sam-
pling techniques likely would be similar across other crop hosts. These bugs infest soybean during
vegetative and/or reproductive stages (Del Pozo-Valdivia and Reisig 2013), feed on plant sap primarily
from stems and petioles, and tend to congregate at nodes (Tayutivutikul and Yano 1990, Thippeswamy
and Rajagopal 2005a, Suiter et al. 2010). The species appears to be bivoltine in soybeans in the United
States (Greene et al. 2012, Zhang et al. 2012, Gardner et al. 2013a). Seiter et al. (2013c) reported that
adults and nymphs of M. cribraria exhibit a generally aggregated spatial distribution and often are more
numerous on field edges. A potential management tactic that could exploit this colonization behavior
would be an in-field border application of insecticide to mitigate populations that develop around field
perimeters initially. This could be a cost-saving approach to controlling these bugs, at least for the initial
spray application, and the effectiveness of border sprays is being researched.
Stubbins et al. (2014) found that sweep nets and drop cloths are effective methods to estimate num-
bers of these bugs in soybeans. They reported that at all adult and nymph densities, fewer sweep-net
samples were required for population estimations compared with the number of beat-cloth samples,
but the beat-cloth method was more cost reliable than the sweep-net method at all but very low densi-
ties. Stubbins et al. (2016) compared cross-vane traps (Horn and Hanula 2011) with sweep net sam-
pling in soybean fields. Cross-vane traps detected adults before they were found in sweep net samples,
and there was a strong positive association between trap and sweep net samples at different distances
from the field borders. Greene et al. (2012) noted that visual observation of the bugs on main stems
and petioles in soybeans also appears to be an important means of assessing developing populations.
Control of Megacopta cribraria with insecticides in soybeans is not difficult, as the species appears to
be susceptible to a variety of insecticides (Wu et al. 1992, Li et al. 2001, Zhang and Yu 2005, Brown
et al. 2015, Seiter et al. 2015b, Del Pozo-Valdivia et al. 2017) although commercial seed treated with
insecticides did not offer protection from this pest (All et al. 2016). Even sublethal and low lethal
doses of bifenthrin, imidicloprid, and acephate resulted in increased nymphal development time and
decreased adult emergence Miao et al. 2016). Many of the insecticides currently labeled and recom-
mended for use on other insect pests of soybeans (e.g., stink bugs), primarily the pyrethroids, are
effective in controlling these bugs. However, these broad-spectrum insecticides can disrupt natural
controls and increase the risk of outbreaks of other pests that are not susceptible to pyrethroids, such
as soybean looper, Chrysodeixis includens (Walker) (Noctuidae), so scouting information throughout
the growing season is vital.