Are sweep net sampling and pitfall trapping compatible with molecular analysis of predation?

Area of Science:

• Ecology
• Molecular Biology
• Entomology

Background:

• Accurate assessment of trophic linkages in food webs is crucial for ecological understanding.
• Molecular techniques like ELISA and PCR are vital for identifying predator-prey relationships.
• Potential errors in predator collection methods can lead to inaccurate feeding rate estimations.

Purpose of the Study:

• To evaluate if sweep-netting and hand collection methods introduce cross-contamination errors in molecular gut content analysis.
• To determine the suitability of pitfall traps with saline solution for collecting predators for ELISA analysis.
• To validate the reliability of ELISA for quantifying predator-prey interactions in an alfalfa agroecosystem.

Main Methods:

• Comparison of sweep-netting versus hand collection for predator (linyphiid spiders) and prey (Diptera) protein detection using ELISA.
• Assessment of ELISA's ability to detect prey proteins in predators collected via pitfall traps containing saline solution.
• Statistical analysis to compare positive reactivity rates between different collection methods.

Main Results:

• No significant difference in positive Diptera protein detection was found between sweep-net and hand-collected spiders.
• ELISA successfully detected prey proteins in predators from pitfall traps containing saline solution.
• The hypothesis that sweep-netting overestimates predation frequency due to contamination was rejected.

Conclusions:

• Sweep-netting and pitfall trapping into saline solution are suitable methods for predator collection in ELISA-based molecular gut content analysis.
• These validated methods provide reliable data for assessing predator-prey interactions.
• Caution is advised when applying these findings to PCR-based analyses or different ecological interactions, considering potential false-positive reactivity.