Plants Attracting Killers: Using Resistance Traits that Attract Insect Predators to Suppress Sorghum Aphids

View the project report

Commodities

• Agronomic: sorghum

Practices

• Crop Production: varieties and cultivars
• Pest Management: integrated pest management

Resistant sorghum varieties and resident natural enemies play a crucial role in suppressing the sorghum aphid (Melanaphis sorghi) and enhancing profitability and sustainability of sorghum growing operations. This economically relevant pest has invaded over 90% of sorghum-growing states and caused millions of dollars of damage. To continue to develop and deploy resistant varieties, it is critical to understand which resistance traits can effectively control pests. Plant volatiles, or chemical compounds that assist natural enemies in locating their prey, are plant traits that have yet to be incorporated into resistant varieties. Our previous work has identified one variety that both decreases aphid reproduction (antibiosis) and produces plant volatiles to attract natural enemies. Our preliminary field experiments have shown that this dually resistant variety not only maintains lower aphid abundances, but also attracts significantly more natural enemies compared to varieties without this trait. The main objectives of the project are: 1) screen a broad range of sorghum varieties for both antibiotic and volatile traits and 2) assess if varieties with enhanced resistance will also have enhanced yield and suppress aphids across multiple growing regions. We will test both experimental and commercially available hybrids. This will allow us to identify genetic sources of different resistance traits for future crop breeding and inform growers on which varieties best suppress pests for their growing region. Using dually resistant varieties will allow growers to control aphids using both host plant resistance and biological control, thereby decreasing the need for insecticide applications, increasing yield, and increasing profitability.

Objective 1: Screen 10 varieties of sorghum for antibiotic and volatile resistance traits. We predict that sorghum varieties will vastly differ in their propensity to decrease aphid population growth and attract natural enemies.

Objective 2: Measure the effectiveness of 5 dually resistant sorghum varieties at suppressing aphids and producing high yields in several growing regions of Texas. We predict that varieties with both antibiotic and volatile traits will better protect sorghum from sorghum aphid than varieties with only antibiotic traits. Dually resistant varieties will keep aphid populations from growing and kill remaining aphids via attraction of natural enemies such as insect parasitoids and predators. In addition, we predict that dually resistant varieties will protect sorghum in different growing regions, making it effective for a broad range of growers. We also predict that dually resistant varieties will have enhanced yield, owing to their genetic background and enhanced resistance to aphid damage.