Stable fly, Stomoxys calcitrans, mouthpart removal influences stress and anticipatory responses in mice

Abstract

Biting fly attack induces a variety of stress and anxiety related changes in the physiology and behaviour of the target animals. Significant reductions in pain, or more appropriately, nociceptive sensitivity (latency of a foot-lifting response to an aversive thermal stimulus), are evident in laboratory mice after a 1 h exposure to stable flies, Stomoxys calcitrans. The role of the various components of biting fly attack in the development of this stress-induced reduction in pain sensitivity (analgesia) is, however, unclear. This study demonstrates that fly-naive mice do not exhibit a stress-induced analgesia when exposed to stable flies whose biting mouthparts have been removed. In contrast, mice that have been previously exposed to intact stable flies exhibit significant analgesia when exposed to flies that are incapable of biting. However, the level of analgesia induced is lower than that elicited by exposure to intact stable flies. Exposure to nonbiting house flies, Musca domestica, has no effect on nociceptive sensitivity. It appears that the actual bite of the stable fly is necessary for the induction of analgesia and probably other stress and anxiety associated responses in fly naive mice. However, mice rapidly learn to recognize biting flies and exhibit significant, possibly anticipatory analgesic responses to the mere presence of biting flies.

Learning from others to cope with biting flies: Social learning of fear-induced conditioned analgesia and active avoidance.

“…Demonstrators that were exposed to biting flies on both the acquisition and test day displayed equivalent, significant increases in response latency on both days, F (1, 9) > 235.08, p s < .0001, indicative of the induction of analgesia (Figure 2A). This confirms and extends prior findings that a 30-min exposure to biting flies induces opioid-mediated analgesia in laboratory and deer mice (Colwell & Kavaliers, 1990, 1992; Colwell, Kavaliers, & Lysyk, 1997; Kavaliers et al, 1998, 1999). Fly-naive mice that were exposed to either house flies or stable flies from which the biting parts were removed failed to show any analgesic responses (Colwell et al, 1997; Kavaliers et al, 1999).…”

“…This confirms and extends prior findings that a 30-min exposure to biting flies induces opioid-mediated analgesia in laboratory and deer mice (Colwell & Kavaliers, 1990, 1992; Colwell, Kavaliers, & Lysyk, 1997; Kavaliers et al, 1998, 1999). Fly-naive mice that were exposed to either house flies or stable flies from which the biting parts were removed failed to show any analgesic responses (Colwell et al, 1997; Kavaliers et al, 1999).…”

“…The present results from the fly-attacked demonstrators confirm and extend prior findings that exposure of rodents to biting and blood-feeding insects induces analgesia and elicits other fearrelated behaviors such as self-burying (Colwell et al, 1997;Colwell & Kavaliers, 1990;Edman et al, 1974;Kavaliers et al, 1999). The results from the observer mice are consistent with the findings that exposure to the cues of a stressed individual induces analgesia in a conspecific (e.g., Colwell & Kavaliers, 1990;Fanselow, 1985;Mackay-Sim & Laing, 1980;Zalaquett & Thiessen, 1991).…”

“…In addition, the level of analgesia at 15 min after exposure on the acquisition day was significantly higher than that recorded on Test Days 1 and 2, F(l, 9) > 31.63, ps < .0001, with no significant differences between Days 1 and 2, F(l, 9) = 0.05, ns. A similar time course of response was seen both following direct exposure to intact flies (Colwell et al, 1997;Kavaliers et al, 1998) and in the individually acquired conditioned analgesia (Kavaliers et al, 1999).…”

“…The results of Experiment 1A showed that conditioned analgesia and self-burying to avoid biting flies can be socially acquired by male mice. Results of prior studies showed that individually acquired conditioned analgesia persisted for at least 2 days with maximum analgesia at 0-15 min postexposure, declining to basal levels 30-60 min postexposure (Colwell et al, 1997;. In this experiment we were concerned with and examined the temporal properties of the socially acquired conditioned analgesia.…”