Spiders Reduce Herbivory: Nonlethal Effects of Spiders on the Consumption of Soybean Leaves by Beetle Pests

To explore the relationship between spiders and insects in agroecosytems, we ran two laboratory experiments to determine if pest insects reduced their foraging activity in the presence of spiders or cues left by spiders. First, we quantified the damage to soybean leaves [Glycine max L. (Merrill); Fabaceae] caused by Japanese beetles [Coleoptera; Scarabeidae; Popilliae japonica (Newman)] and Mexican bean beetles [Coleoptera; Coccinellidae; Epilachna varivestis (Mulsant)] in the presence of either the tangle weaver, Achaearanea tepidariorum (C.L. Koch) (Araneae; Theridiidae), or the orb weaver, Arigope trifasciata (Forskal) (Araneae; Araneidae). Although most beetles survived, they consumed less of the soybean leaf than the beetles in control containers with no spiders. In a second experiment, we attempted to determine if Japanese beetles responded to the cues (e.g., silk draglines and feces) left by three species of wolf spider [Araneae; Lycosidae: Pardosa milvina Hentz, Rabidosa rabida Walckenaer...