I smell a wolf spider burrow! Evidence for an airborne kairomone among lycosids: a field test Hogna helluo, Pardosa milvina, and Trochosa ruricola are three syntopic species of wolf spider common to agricultural fields in the Eastern United States. The larger species, Hogna helluo, is a common predator of the two smaller species. Hogna is nocturnally active but frequently resides within soil fissures during the day and may attack Pardosa (diurnal) or Trochosa (nocturnal) that enter or walk near these fissures. The ability to detect chemical cues associated with these predators (enemy-avoidance kairomones) may allow Trochosa and Pardosa to avoid Hogna-containing fissures from some distance. We tested for the presence of a kairomone on avoidance behavior among Pardosa and Trochosa under field conditions. To simulate soil fissures, we tested the ability of Pardosa and Trochosa to detect and avoid pitfall traps baited with one of the following (N = 20 traps/treatment) 1) adult male Hogna, 2) adult female Hogna, 3) a house cricket (Acheta domesticus), or 4) nothing (an empty trap) using only olfactory information. Pardosa milvina showed a significant avoidance of pitfall traps baited with Hogna while Trochosa showed no significant avoidance of Hogna-baited traps. To our knowledge, this study demonstrates the first field evidence of an airborne enemy-avoidance kairomone mediating spider behavior.
