Specificity of communication channels in four limacodid moths: Darna bradleyi, Darna trima, Setothosea asigna, and Setora nitens (Lepidoptera : Limacodidae)

Darna bradleyi Holloway, D. trima Moore, Setothosea asigna van Eecke and Se tora nitens Walker are sympatric and coseasonal limacodid moths in plantati ons of oil palm, Elaeis guineensis Jacq. (Arecales: Palmae), in Borneo, sou theast Asia. We tested the hypothesis that these four species maintain repr oductive isolation through specificity in diel periods of communication, mi crolocation for communication and/or communication signal (pheromone). Stud ying diel periodicity of calling behavior by female moths and response by m ale moths to traps baited with virgin females or synthetic pheromone, we de termined that sexual communication of D. bradleyi and D. trima took place f rom similar to 17:30 to 18:45 hr and that of S. asigna and S. nitens from s imilar to 18:45 to 20:00 hr and from similar to 18:30 to 19.30 hr, respecti vely. Over 80% of male S, asigna and S. nitens were captured in pheromone-b aited traps suspended >5 m high, whereas male D. bradleyi and D. trima were captured mostly in traps < 5 m high. Synthetic pheromone baits attracted m ale moths in a species-specific manner. Moreover, baits containing both S. asigna and S. nitens pheromones failed to attract any male moths, indicatin g that female S. asigna and S. nitens, with overlapping communication perio ds, use bifunctional pheromone components that attract conspecific males wh ile repelling heterospecifics. Similarly, addition of D. bradleyi pheromone to S. asigna or S. rnitens pheromone reduced attraction of male S. asigna and S. nitens. The failure of D. bradleyi and D. trima, which overlap in ti me and microlocation for communication, to evolve bifunctional pheromones m ay be attributed to the recent occurrence of sympatry between D. bradleyi a nd D. trima in Borneo, apparently too recent for bifunctional pheromones to have evolved. We conclude that D, br bradleyi, D. trima, S. asigna and S. nitens utilize any or all of diel periodicity, intra and interspecific effe cts of communication signal and/or microlocation for signaling, allowing th ese limacodids to co-inhabit the same habitat and remain reproductively iso lated.