Lima beans with improved lygus bug tolerance

limaResearch adviser: Paul Gepts
Team Leader: Kimberly Gibson –

The goal of this project is to develop improved cultivars of Lima bean with lygus tolerance.

Lima beans are an important food legume and a great rotation crop. Dry lima beans are typically row cropped, planted in early May and harvested in September, by windrowing then threshing. They come in a wide variety of shapes, colors, and sizes but the main market classes are white large and baby seeded types. Both the bush and vine type produce a tremendous amount of biomass. The main production constraint for Lima bean in the western US is the insect pest, Lygus hesperus, which causes significant reduction in both yield and grain quality by feeding on the flowers and developing pods.

In 2012 a Ph.D. student in the Gepts lab crossed a baby seeded vine type with some tolerance to lygus with a large seeded bush type. The progeny were then inbred for multiple generations and field tested for lygus resistance at UC Davis during the 2014 and 2015 growing season. Two of the 250 varieties tested from this cross are potentially more lygus resistant than the original parent with good seed quality. These varieties will be ready for preliminary farm trials in 2016. Both are baby seeded vine types.

In addition to moving forward with testing these two baby seeded viney lines we are also crossing resistant varieties to larger seeded and bush types in hopes of obtaining lygus tolerant lines for baby and large seeded bush and vine types to meet the management and marketing goals of growers.

Our group has also initiated crosses with colorful patterned Lima beans which may be of interest to niche markets.

This project will give students experience in managing field trials at the UCD student farm and in collaboration with organic growers, performing crosses and generation advances in greenhouses and fields and experience with in field selections