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Q&A ViewAttendees 8

Plant-Insect Ecosystems

Student Competition 10-Minute Paper

Grad P-IE: IPM - Field Crops 3

Direct and indirect plant defenses: Synergistic defense against sugarcane aphids in sorghum?

Monday, November 1, 2021
11:06 AM – 11:18 AM MT
Location: Colorado Convention Center, Four Seasons Ballroom 1
In-Person Student Competition
The sorghum aphid (Melanaphis sorghi) is an emerging pest that can cause substantial yield loss and a reduction in grain quality in sorghum. Coupling host-plant resistance and biological control has the potential to reduce insecticide use and cost of aphid suppression. Direct defenses (e.g., plant traits that directly affect pest behavior or physiology) and indirect defenses (e.g., herbivore-induced volatile compounds (HIPVs) that attract natural enemies) could be negatively correlated, positively correlated, or not correlated. We tested the hypothesis that direct and indirect defenses are positively correlated or independent of one another by quantifying defenses in 6 varieties of sorghum. We collected HIPVs from sorghum, studied natural enemy attraction to aphid-infested plants in an olfactometer, and measured aphid population growth. We found that direct and indirect defenses are independent of one another. For example, ATx3409/RTx436 produced high levels of volatiles (i.e., high indirect defenses) and had low aphid population growth (i.e., high direct defenses). This work indicates that indirect defenses should be incorporated into sugarcane aphid IPM programs to increase the effectiveness of crop resistance and pest management.