Predator-prey trophic relationships in response to organic management practices

Area of Science:

• Ecology
• Entomology
• Molecular Biology

Background:

• Predator-prey dynamics are crucial for community structure and are influenced by environmental conditions.
• Understanding trophic interactions is key to managing pest populations, especially in organic agriculture.
• The squash bug (Anasa tristis) is a significant pest of cucurbits in the United States, impacting organic production.

Purpose of the Study:

• To characterize the natural enemy community preying on the squash bug (Anasa tristis) using molecular gut-content analysis.
• To investigate the effects of organic management practices on trophic interactions and predator communities.
• To link molecular gut-content data with predator abundance and diversity metrics.

Main Methods:

• A molecular approach using primer pairs was employed to identify squash bug DNA in predator guts.
• Experimental open-field plots of butternut squash were subjected to different organic management treatments (including row covers).
• Predator gut contents were analyzed for squash bug DNA, and predator density and diversity were assessed throughout the growing season.

Main Results:

• Approximately 11% of the 640 tested predators had consumed squash bugs.
• Row-cover treatments significantly affected both squash bug and predator communities.
• Predation rates varied seasonally and differed among predator groups, including coccinellids, geocorids, nabids, and spiders.

Conclusions:

• Molecular gut-content analysis provides insights into the complex trophic interactions involving the squash bug.
• Organic management practices, such as row covers, can alter predator-prey relationships and influence biological control.
• This research highlights the importance of understanding specific predator-prey pathways for effective pest management in organic squash production.