Winning Fights Induces Hyperaggression via the Action of the Biogenic Amine Octopamine in Crickets

Winning an agonistic interaction against a conspecific is known to heighten aggressiveness, but the underlying events and mechanism are poorly understood. We quantified the effect of experiencing successive wins on aggression in adult male crickets (Gryllus bimaculatus) by staging knockout tournaments and investigated its dependence on biogenic amines by treatment with amine receptor antagonists. For an inter-fight interval of 5 min, fights between winners escalated to higher levels of aggression and lasted significantly longer than the preceding round. This winner effect is transient, and no longer evident for an inter-fight interval of 20 min, indicating that it does not result from selecting individuals that were hyper-aggressive from the outset. A winner effect was also evident in crickets that experienced wins without physical exertion, or that engaged in fights that were interrupted before a win was experienced. Finally, the winner effect was abolished by prior treatment with epinastine, a highly selective octopamine receptor blocker, but not by propranolol, a ß-adrenergic receptor antagonist, nor by yohimbine, an insect tyramine receptor blocker nor by fluphenazine an insect dopamine-receptor blocker. Taken together our study in the cricket indicates that the physical exertion of fighting, together with some rewarding aspect of the actual winning experience, leads to a transient increase in aggressive motivation via activation of the octopaminergic system, the invertebrate equivalent to the adrenergic system of vertebrates

Trade-off in ecosystem services of the Somerset Levels and Moors wetlands

It is widely recognised that healthy ecosystems can provide considerable benefits to people, including food, timber, freshwater, protection from floods and much of what we call quality of life. A global review of these ecosystem services carried out as part of the Millennium Ecosystem Assessment (MA) provided a framework for national and local studies. Using the MA approach, this paper reviews the ecosystem services provided by the Somerset Levels and Moors wetland system in south-west England. This wetland provides a series of important services that are beneficial locally, regional and globally, including grazing for cattle, potential carbon sequestration, flood water storage, recreation and archaeology. Some services are synergistic and reinforcing; for example, maintaining wet conditions supports wetland bird life that maintains biological diversity, attracts tourists, protects archaeological artefacts and reduces CO2 emissions. Other services are potentially conflicting, for example raising water levels may reduce potential flood water storage and increase methane emissions. Comparison of the services of the wetland with those of drier habitats reveals for example that carbon sequestration, bird habitat provision and hay production is greater in wetlands, whilst grazing quality and plant diversity may be reduced and distributions of disease vectors may be altered by wetland restoration through raising water levels. Management decisions affecting wetlands may necessitate a trade-off of ecosystem services