Effect of a Nitric Oxide Synthase Inhibitor on Fighting Behavior of Male Crickets Velarifictorus aspersus (Orthoptera: Gryllidae) under Different Resource Conditions

Abstract The availability of resources can have important effects on the fighting behaviors of insects, but the physiological mechanism that might underlie the effect of resources is unclear. Nitric oxide (NO) is a gaseous neurotransmitter that is capable of directly diffusing into cells and acting as a messenger. Several studies have reported that NO may be involved in modulating the fighting behavior of insects. In the present study, we investigated the effect of different resources on the fighting behavior of Velarifictorus aspersus Walker male crickets (Orthoptera: Gryllidae), and tested whether this effect is regulated by NO. We found that when a burrow or female was available, the fighting level and fighting duration were significantly greater in males compared with those when no resources were available, thereby suggesting that the presence of a valuable resource motivated male crickets to fight more aggressively. In a novel environment, treatment with an NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) significantly increased the fighting level and fighting duration in male crickets, and males treated with L-NAME won more fights against males treated with water. However, when a burrow or female was available, treatment with L-NAME did not affect the fighting level and fighting duration in males, and males treated with L-NAME lost more fights against males treated with water. These results suggest that NO may have different effects on modulating the fighting behavior of male V. aspersus crickets under different resource conditions.