INCREASED DOPAMINE LEVELS DO NOT INFLUENCE AGGRESSIVE BEHAVIOR IN BLACK WIDOW SPIDERS (LATRODECTUS HESPERUS)

Abstract

Discovering the driving forces of individual personality differences in animals is an emerging goal of animal behavior research. Biogenic amines have been known to mediate various aspects of behavior, including aggression, which is one of the most commonly varying individual personality differences among animals. In addition to aggression, a large number of other behaviors across a wide variety of species are influenced by biogenic amines. Arthropods specifically provide an ideal system to manipulate biogenic amines and observe behavioral changes. In this study, we used Latrodectus hesperus, the western black widow spider, as our model organism because of their consistent individual behavioral differences, which appear to relate to differing individual life history strategies. For example, higher aggression, as measured by attacks on simulated prey items, relates to higher rates of egg laying in “fast life history strategy” individuals. Here, Iinvestigated the role that dopamine (DA) has on the individual’s aggressive behavior, measured by the number of times they attack a potential prey in their web. I injected spiders with the neurotransmitter, which is a precise way to manipulate the biogenic amine concentration and observed the changes in behavior that may follow. I looked for whether there was a significant difference between aggressiveness of biogenic amine-injected individuals, individuals injected with a saline solution, and non-injected individuals. We discovered that the injection of dopamine had no effect on black widow aggression. These results indicate that biogenic amines may not play as big a role in individual personality differences as previously thought, and that aggressive behavior is influenced by other factors, such as genetics, metabolic rates, environment, or some other traits.