320 Invasive Stink Bugs and Related Species (Pentatomoidea)
to Ensure Freedom from Megacopta cribraria. The protocol outlined steps for inspecting for and elimi-
nating bugs from the packing and loading areas and from the shipping containers prior to loading and
standard certification by an inspector. The protocol was implemented by United States cotton product
exporters and shippers in 2012 (National Cotton Council of America 2012).
University of Georgia scientists also assisted with various aspects of risk assessment for the import
partners. Choice, no-choice, and field preference testing demonstrated that Megacopta cribraria did not
establish successfully or develop on several varieties of pinto beans and winter pea (Pisum sativum L .)
(Fabaceae) supplied by Guatemalan and Honduran sources (Blount et al. 2015). They concluded that
if M. cribraria were accidentally introduced into Central America, it would not become a serious pest
of pinto bean and winter pea grown in that region. Furthermore, they suggested that tropical kudzu
[Pueraria phaseoloides (Roxburgh) Bentham], which is grown as a cover crop for nitrogen fixation in
orchards in that region, is not a suitable host for M. cribraria. Nymphs developed to late second instar on
that kudzu host, but survival rapidly decreased thereafter.
As a further risk assessment, lower lethal temperatures were established for Megacopta cribraria
adults using a programmable water bath. No adults survived at -18 °C, the temperature at which frozen
products are shipped, and there appeared to be no supercooling point in adult bugs (Wayne A. Gardner,
unpublished data). Thus, there should be no concerns of adult M. cribraria surviving in shipments of
frozen food products to import nations.
5.7 Why Has Megacopta cribraria Been so Successful?
The location of the introduction of this species was quite fortuitous as its preferred host, kudzu, is abun-
dant in north Georgia. Zhu et al. (2012) used environmental parameters from the native range of the bug
and determined that the southeastern United States is an area that is highly suitable for invasion by this
bug. In addition to kudzu, soybeans commonly are grown in Georgia and South Carolina in areas not too
far from the initial infestation. The ability of females to store sperm over the winter (Golec and Hu 2015)
and the tendency of overwintering bugs to seek shelter may have enabled a single female to find its way
to Georgia and start this infestation. The bug is a strong flier and has been found as high as 32 stories
above ground level (Gardner et al. 2013a), enabling it to take advantage of weather patterns that may
have pushed the population north and east of the originally infested area. Because kudzu, a reproductive
host plant, is an invasive weed occurring in much of the area where Megacopta cribraria has spread, the
bug has a source of food that is abundant and readily available. Shelter-seeking behavior also may have
allowed this bug to spread more rapidly because its attraction to light colors (Horn and Hanula 2011)
probably has resulted in its hitchhiking to new locations in vehicles. Indeed, the first findings of the bug
in new locations tended to be along interstate highways or major roadways.
Because Megacopta cribraria belongs to a family, Plataspidae, that previously had not been found
in its invasive range, the ability of native natural enemies to adapt to this species may be less than that
for members of families that naturally occur in the New World (Strauss et al. 2006). The specificity of
Paratelenomus saccharalis for plataspids suggests that these bugs are different enough to avoid most of
the native parasitoids. The rapid increase in numbers of these bugs certainly suggests that there are few
native natural enemies providing control of this species in its invasive range. Ruberson et al. (2013) noted
that few natural enemies were found in their surveys in Georgia.
5.8 What Does the Future Hold?
Zhu et al. (2012) used niche models to predict areas suitable for colonization by Megacopta cribraria. Much
of the eastern United States appears to be suitable with the southeastern United States being the most suit-
able for development. Other areas where invasion potential for this bug is high include southeastern South
America, southwestern Europe, southern Africa, and eastern coastal Australia. The Pacific Northwest in
the United States, where kudzu has established, shows moderate potential for invasion and establishment.
Kudzu is found in much of the area in the United States where the model predicts moderate to high invasion