Octopamine and serotonin have opposite effects on antipredator behavior in the orb-weaving spider, Larinioides cornutus

Abstract

In this study, we experimentally elevated levels of octopamine and serotonin in an orb-weaving spider, and observed the effects on the antipredator behavior thanatosis (death feigning), activity level, and running speed. We found that octopamine significantly shortened the duration of thanatosis, and its effect wore off over 24 h. We also found that serotonin significantly lengthened thanatosis, but in this case, the effect persisted for over 24 h. Neither octopamine nor serotonin affected the general activity or running speed of the spiders. To our knowledge, this is the first study to directly explore the role of biogenic amines on a specific antipredator behavior in spiders. Given that spiders must be both aggressive toward prey, yet wary of predators, we believe that this system will be an outstanding model to explore connections between behavioral ecology and neurochemistry.

Octopamine levels relate to male mating tactic expression in the wolf spider Rabidosa punctulata

“…In burying beetles, the octopaminergic system is associated with resource defense, alternative mating tactics, social tolerance and indirect parental care (Cunningham et al, 2014). In spiders, most studies have thus far examined its proximate role in mechanoreception (Torkkeli & Panek, 2002;Torkkeli et al, 2011;Widmer et al, 2005), but a few have examined its role in behavioral variation as well (Jones et al, 2011;Punzo & Punzo, 2001). Our results on alternative mating tactics and OA levels in spiders add to the growing evidence accumulating across diverse arthropod taxa suggesting a fundamental role of neurohormonal regulation in behavioral flexibility.…”

“…An activation of the octopaminergic system could enhance performance, as locally increased levels of OA have been found to increase the amplitude of skeletal muscle contraction in tarantulas (Grega,1978) and enhance mechanosensory sensitivity (Torkkeli, Panek, & Meisner, 2011;Widmer, Hoger, Meisner, French, & Torkkeli, 2005). OA levels have also been found to influence behaviors involved in interspecific interactions, as increased levels of OA shorten the duration of death feigning, an antipredator behavior in the orb-weaving spider Larinoides cornutus (Jones et al, 2011). Interestingly, the occurrence and frequency of this death-feigning behavior has been identified as a part of a larger behavioral syndrome related to aggression (Pruitt et al, 2010;Pruitt, Riechert, & Jones, 2008).…”

The behavioural effects of predator-induced stress responses in the cricket (Gryllus texensis): the upside of the stress response

“…2). Similarly, raising octopamine levels decreased the use of immobility as an anti-predator behaviour in both an orb-weaving spider (Jones et al, 2011) and the beetle T. castaneum (Nishi et al, 2010). These results suggest that octopamine may be involved in altering the threshold for different defensive behaviours in many arthropods.…”

“…However, the lack of effect of octopamine on locomotion seems puzzling, given its postulated role in mediating general arousal (Roeder, 1999). Nevertheless, octopamine also had no affect on general locomotion in the orb-weaving spider (Jones et al, 2011). We hypothesize that one of the effects of elevated octopamine is that it shifts anti-predator behaviour towards defensive behaviours used for more serious threats.…”

“…Elevated levels of octopamine produce a number of physiological changes that enhance physical performance, similar to the effects of vertebrate stress hormones (Roeder, 1999;Roeder, 2005). Octopamine modulates anti-predator behaviour in beetles (Tribolium castaneum) (Nishi et al, 2010) and an orb-weaving spider (Jones et al, 2011). The behavioural effects of predator-induced stress can also be monitored in insects.…”