Identifying the Roles of Predatory Natural Enemies in Pecan Systems: Molecular-based framework for sustainable pest management

View the project final report

Commodities

• Nuts: pecans

Practices

• Pest Management: biological control, integrated pest management, prevention

Pecan trees are indigenous to North America and are largely grown in the southern United States, particularly in the state of Georgia, one of the country’s top producers. Pecan orchards are often attacked by arthropod pests and sap-sucking aphids are among the group that concerns growers due to their potential to impair tree productivity. Aphid management practices in pecan orchards are currently reliant on the use of synthetic insecticides, which are known to negatively impact the environment, non-target organisms (e.g., natural enemies and pollinators) as well as humans. Hence, the development of alternative and more sustainable aphid management in pecan systems should not be left aside. Improving biological control using predatory natural enemies is a plausible option because pecan orchards are known to harbor diverse predators of aphids (e.g. ladybeetles, lacewings, syrphid flies, and minute pirate bugs); however, the specific roles these biocontrol agents play in pecan fields has received relatively little attention. To advance the augmentative and/or conservational biological control programs, it is crucial to understand the trophic interactions among these common natural enemies. Thus, our objectives are to 1) examine the positive services (i.e. predation) and disservices (i.e. intraguild predation) of predatory arthropods in pecan systems, and 2) determine if services depend on different locations within pecan trees (i.e. in the upper and lower canopies) and vary during the season (early and late season) through molecular gut content analysis. This study will contribute to a strong ecological basis for advancing sustainable pest management in southern US pecan orchards.

Our main goal with this project is to understand the specific roles that predatory natural enemies play within the southern US pecan agroecosystems and contribute to a strong ecological basis for advancing sustainable management through:

1. Identifying the community of pecan-resident predators that contribute to the biological control of each aphid species (e. black pecan aphids, yellow pecan aphids, and blackmargined aphids).

2. Identifying potential intraguild predation events among predators of aphids.

3. Understanding how tree strata (upper versus lower canopy) or seasonal differences (early versus late season) play a role in the interactions among predators and with their prey.

Additionally, we will use the information acquired in 1, 2, and 3 to pursue our fourth goal with this project, which is:

4. To produce a visual, durable, extension field guide to natural enemies and their role as biocontrol agents of pecan aphids for Georgia pecan growers.