Characterizing Soybean Host Plant Resistance to Kudzu Bug

Soybeans are constantly under attack from a barrage of insect pests that reduce seed quality and yield.  The kudzu bug (Megacopta cribraria var. punctatissima) is the most recent introduced insect pest of soybean in the U.S.  First identified near Atlanta, GA in 2009, the insect has since spread, and is currently found as far west as the Mississippi Delta and north into Maryland.  Average yield loss in soybean due to this pest is 20%, with a maximum reported loss of 60%.  Host plant resistance successfully controls other well-studied insect pests of soybean, and is an effective method for reducing pesticide use, benefiting both the farmer and the environment.  One previously described QTL for leaf-chewing insects, known as QTL-H, reduces kudzu bug infestation level by half compared to the susceptible check.  QTL-H maps within a 5.2 megabase pericentromeric region on chromosome 12, where gene density and recombination are low.  Therefore the use of a recombinant mapping population is not feasible.  As an alternative, genotype by sequencing is being used to identify polymorphisms between resistant (PI229358) and susceptible lines.  This will narrow down the list of candidate genes by allowing future work to focus on genes with polymporphisms unique to resistant lines.  In addition, 30 plant introductions known to be resistant to other piercing-sucking insects were screened for kudzu bug resistance.  Six of these lines were identified as resistant and may represent additional sources of resistance for developing soybean cultivars resistant to kudzu bug.