Interactions between size-dependent predation by wolf spiders (Schizocosa spp.) and food quality to the grasshopper Ageneotettix deorum (Scudder) were investigated. Nymphs are susceptible to wolf spider predation with decreasing impact as the age and grow; adults are not attacked by wolf spiders at this site. Predation risk from spider predation had great impact on grasshopper foraging rates, which slowed growth and developmental rates, and decreased survival. Increased food quality shows the opposite effect on performance attributes. Similar effects on grasshopper behavior and performance were observed when spiders were fully armed and capable of feeding or when chelicerae were blocked with small amounts of beeswax. Lifetime egg production in A. deorum was also reduced in response to prior experience with spiders, resulting from later age of first reproduction. However, high quality food compensates for negative effects of wolf spider predation such that no differences in grasshopper performance responses are seen for S+/F+ vs. S-/F- combinations.
Species 1: Orthoptera Acrididae Ageneotettix deorum
Species 2: Araneae Lycosidae Schizocosa (wolf spider)
Keywords: food quality, spider predation
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