The chemical ecology of the Pacific beetle cockroach, Diploptera punctata

The cockroach, Diploptera punctata, has a wide geographic distribution throughout much of Asia and Hawaii, and as is one of the few vivaparous insect species know, it has been extensively studied by to gain insight into the underlying physiology of this unusual form of reproduction. However, there is not a great deal known about the mating behaviour of this species. We will present results, using populations from Hawaii and Thailand, showing that (i) there is very little interbreeding between the two populations, (ii) short distance pheromones are involved in mating, (iii) there are marked intersexual and inter-race differences in the cuticular profiles (iv) cuticular profiles change with age, and that in a Y tube olfactometer males respond preferentially to 5-day-old virgins over air but do not discriminate between air and newly - emerged virgins. The last observation was interesting, given that in the literature it has been reported that ma ting occurs just after the female has moulted, before her cuticle has even hardened. Furthermore, while newly - mated females show no overt courtship behaviour, older individuals do, including strong rejection behaviours when courted. We postulated that the idea that females normally mate immediately after emergence is an artefact of the rather simple cages used in laboratory rearings. We found that mating success declined as the complexity of the environment was increased, suggesting that in nature a female may hide during moulting and only mate once her cuticle has hardened