Why is ecology important to agriculture? Ask the Plataspids.

posted in: Science | 4

Before moving to the southern US, I lived in Iowa. If there’s one thing Iowa’s known for, it’s known for our row crops. Everywhere in the summer is green and pretty and filled with all sorts of farmland and not much visible biodiversity outside of that.

If you live in certain areas of the south, it’s really actually very similar. There are lots of rowcrops… peanuts and soybeans instead of corn and soybeans but still a similar concept. Lots of crops. Everything’s green and pretty without a whole lot of biodiversity. There’s one other major difference, though…lots of areas look like this:

Image courtesy of Wikipedia Commons

The green curtain draped over everything? Kudzu.

Kudzu was a vine originally planted to control erosion which grew out of control. It grows quickly, is hard to kill and covers everything with a green blanket and crowds everything out by keeping sunlight from reaching the plants. The trees under that green carpet are all dead.

So… how can things get worse?

Simple, really… just introduce something which lives on kudzu.

In 2009, a graduate student at the University of Georgia’s department of entomology found a very odd insect which resembled a beetle, but wasn’t. It had sucking mouthparts and a bunch of other features which landed it in a group of insects called the Heteroptera. The problem is that the insect wasn’t able to be identified with any of the keys available for the US. It was a new family which hadn’t been recorded in the New World before. The insect was eventually identified by another group of researchers as belonging to the family Plataspidae, and the species found was Megacopta cribraria, which lives on Kudzu but also on beans.

Megacopta species are known pests of various beans, including soybeans. From a recent review of Megacopta biology:

A number of authors report that Megacopta spp. are pests of soybeans. Soybean yield loss ranged from 1-50% depending on density of the bugs. The reported pest status ranges from minor to severe. As an introduced species, this bug appears to have potential to be a pest of legume crops in the United States.

They also invade houses during the fall while looking for a place to overwinter and can be smelled from some distance away, so they’re an urban pest as well.

The pest status of this species isn’t really certain; experimental crops infested with the species showed no apparent damage, I can’t find any information about thresholds for this species in particular and a lot of the information out there seems to be for the genus level and not this particular species so I can’t tell how well it’s been studied in it’s native range. There just simply isn’t enough information at this time to say if it’ll be apocalyptic, a flash-in-the-pan concern or something in between which is dependent on region, weather and/or biotype.

However, it’s considered a pest species in most of it’s range and this still presents a serious potential problem for soybean growers in the south because we now have a species that quickly reproduces, can grow to huge populations and which has a refuge which quite literally covers the entire south.

ResearchBlogging.orgD. R. Suiter,1 J. E. Eger, Jr.,2 W. A. Gardner, R. C. Kemerait,3 J. N. All,4 P. M. Roberts,5 J. K. Greene,6 L. M. Ames,, & G. D. Buntin, T. M. Jenkins, and G. K. Douce5 (2010). Discovery and Distribution of Megacopta cribraria (Hemiptera: Heteroptera: Plataspidae) in Northeast Georgia Journal of Integrated Pest Management

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Joe Ballenger is an entomologist who works in the biotech industry as a contractor. In his spare time, he helps answer questions about bugs at Ask an Entomologist. https://askentomologists.wordpress.com/