Trophically-acquired Herbicide Exposure of Wolf Spiders Can Cause Weight Loss but No Change in Prey Capture Efficiency

Grace Chamberlain and Dr. Matthew Persons, Department of Biology- Ecology Program, Susquehanna University, 514 University Ave, Selinsgrove, PA 17870

Herbicide use in commercial agriculture has increased in both diversity and quantity over the last fifty years, yet herbicide impact is poorly understood for non-target beneficial species such as spiders. Spiders may be exposed to herbicides through direct spraying, contact with treated soil and plants or trophically through consumption of herbicide-sprayed prey. The wolf spider Pardosa milvina is a common vagile ground species found in agricultural systems in the Eastern United States. We measured the lethal and sublethal feeding effects of offering herbicide-contaminated prey to spiders. Using a 5x2 experimental design, we exposed first-instar cricket nymphs (Gryllodes sigillatus) to one of four different herbicides (atrazine, s-metolachlor, dicamba, or 2,4-D) or a distilled water control. Spiders were presented either freshly sprayed crickets or crickets coated with dried herbicide residue. Spider response to prey was measured during a 20-minute feeding trial. During each trial, spider lunge latency and capture were recorded as well as prey rejection. Spiders were fed a diet of one of the ten cricket herbicide treatments (n=30, N=300) for a six-week period. Spider feeding behavior  and weight change were measured weekly while spider mortality was checked daily. Herbicide-sprayed crickets did not significantly increase spider mortality or reduce prey capture latency across treatments compared to the water control but we did find significant differences in prey lunge latency and large differences in weight change over time. Spider lunge latency was significantly slower for 2,4-D and dicamba initially but this difference diminished over subsequent weeks. Only spiders in the control and dicamba treatments gained weight over time while s-metolachlor, atrazine, and 2-4,D resulted in weight loss for spiders despite spiders feeding on prey. Prey contaminated with these herbicide or herbicide residues have significant sublethal effects on these beneficial agricultural predators.

Additional Abstract Information

Presenter: Grace Chamberlain

Institution: Susquehanna University

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4099