Know your foe: synanthropic spiders are deterred by semiochemicals of European fire ants

Abstract

Many ants prey on spiders, suggesting that web-building spiders may avoid micro-locations near ant colonies or frequented by foraging ants. Here we tested the hypothesis that ant-derived semiochemicals deter synanthropic spiders. To generate stimuli, we exposed filter paper for 12 h to workers of European fire ants, Myrmica rubra, black garden ants, Lasius niger, or western carpenter ants, Camponotus modoc , and then offered select urban spiders in three-chamber olfactometer bioassays a choice between ant-exposed filter paper and unexposed control filter paper. Semiochemical deposits of M. rubra , but not of L. niger or C. modoc , had a significant deterrent effect on subadults of the false black widow, Steatoda grossa, the black widow, Latrodectus hesperus , and the hobo spider, Eratigena agrestis, as well as a moderate (but statistically not significant) deterrent effect on the cross spider, Araneus diadematus . The deterrent effect caused by semiochemical deposits of M. rubra may be attributable to the aggressive nature and efficient foraging of M. rubra in its invaded North American range, exerting selection pressure on community members to recognize M. rubra semiochemicals and to avoid micro-locations occupied by M. rubra .

All sugars ain't sweet: selection of particular mono-, di- and trisaccharides by western carpenter ants and European fire ants

“…As worker ants of M. rubra are significantly smaller and 12 times lighter than those of Ca. modoc [ 64 ], and accordingly consume less sugar solution per unit time, we extended the total bioassay time from 165 min (as in bioassays with Ca. modoc ) to 360 min.…”

Host Plant Specificity in Web-Building Spiders

“…We refer readers to the recent excellent review by Fischer [ 19 ] on chemical communication in spiders focusing on a methodological overview on how to study their pheromones. Spiders can also detect predators such as ants through semiochemicals [ 125 ], and they are sensitive to the chemical cues of potential predators [ 126 , 127 ]. The wolf spider Pardos milvina , for example, alters where it forages when it chemically detects one of its predators, the larger wolf spider Trigrosa helluo [ 126 ].…”

Blacklegged ticks, Ixodes scapularis , reduce predation risk by eavesdropping on communication signals of Formica oreas thatching ants

“…Ants use a plethora of chemical communication signals to coordinate group tasks such as nest defence, brood care and foraging behaviour [17]. Potential prey of ants, including spiders, bees and fruit flies, eavesdrop on these ant communication signals, and avoid areas where they have been deposited [18][19][20][21][22]. Whether ticks avoid ant semiochemicals has not yet, to our knowledge, been investigated.…”