New aspects of the biology of the Melanesian rhinoceros beetle Scapanes australis (Col., Dynastidae) and evidence for field attraction to males

Scapanes australis is a major coconut pest, endemic in Papua New Guinea. Ea rly in the night, males placed singly into artificial galleries made in you ng coconut palms exhibited a sex-specific calling behaviour for 1 to 1.5 h. Coming to the gallery entrance, they raised the abdomen and the hind legs, the head lowered inside the gallery, and emitted a liquid secretion, rhyth mically smeared by crossing the legs. Females, which did not behave so, wer e very mobile. The adult flying period coincided with the male calling beha viour. In field assays with caged insects on coconut palms, attraction of b oth sexes to males was evidenced when they were calling. Males fought for g allery possession at a male arrival. No aggression but mating was observed with arriving females, which proved not to have developed oocytes. The stro ng male attraction was confirmed using automatic traps, baited with one liv e male in a sugarcane piece. Males were assumed to release an aggregation p heromone. Further studies are underway to identify the putative pheromone.