Ecology of the New Zealand Glowworm,Arachnocampa luminosa(Diptera: Keroplatidae), in the Glowworm Cave, Waitomo

Abstract

The temperature and relative humidity inside the Glowworm Cave are spatially and temporally variable to a degree atypical of other caves in temperate latitudes. Comparison between the climatic data for 1977-80 and for 1955 shows that the climate of the cave was much more stable in 1955 than it is at present. This paper suggests that the increase in climatic variability is closely related to the fact that since 1975, when the Upper Entrance was unblocked, the cave has behaved as a wind tunnel: the difference in density between the atmosphere inside and outside the cave allows the outside air to flow freely through the interior between the Upper and Lower Entrances.Climatic fluctuations are considered to be the main factor responsible for the decline in the total population of Arachnacampa tuminasa (Skuse) observed between 1975 and 1980. Climatic changes may also explain why the numbers and diversity of other cave fauna are low.A. tuminasa has five larval instars. Larval development is homodynamic; the mqjority of the population follows a distinct annual cycle, in which most larvae hatch in spring. The distribution of glowworm larvae in the cave is largely determined by food supply and climatic conditions. The main source of food is the insects that emerge from the Waitomo Stream as it flows through the cave lakes. The main causes of mortality of glowworm larvae are cannibalism, an entomogenous fungus, cave opiliones, desiccation and flooding.

Glowworms: a review of Arachnocampa spp. and kin

“…From the jungles of Honduras and Costa Rica the non-luminescent keroplatinid Orfelia aeropiscator has been described from the underside of large leaves (20). Reports of a similar nature also come from Guatemala (21) and Mexico [personal communication, P. Mothes, cited in (12)]. The Columbian Andes (22) are inhabited by some species of carnivorous fungus gnat, Other cave-dwelling keroplatids that trap prey, but with the help of more or less horizontal web-sheets rather than with vertical sticky threads, are the nonluminescent species Macrocera fasciata from European caves (26)(27)(28) and M. nobilis (29).…”

“…literature review by Pugsley (12)] and A. richardsae, A. flava and A. tasmaniensis of Figure 1. Photograph from the cover of (10), showing larval Arachnocampa luminosa in its slime nest and vertical fishing lines with tiny droplets of sticky mucus.…”

“…(12), on the taxonomic history of Arachnocampa and related genera]. Osten-Sacken (35) recognized that the glowworm was actually the larva of a mycetophilid and Skuse (36) in his original description used the name Bolitophila luminosa, Sect.…”

Cave fauna monitoring and management at Ida Bay, Tasmania

“…The only other known place in the world where similar displays occur is at Waitomo Cave in New Zealand. Waitomo Cave glowworms were first monitored in 1975 following a serious decline in their numbers caused by modification to the cave climate and catchment disturbance affecting the cave stream and food supply (Wiiliams, 1975;Pugsley, 1984). However, the New Zealand and Tasmanian experience clearly show that glowworm colonies can successfully survive in public show caves subject to very high levels of human visitation, providing that the cave climate conditions and food supply are maintained.…”

Slaves of the environment: the movement of herbivorous insects in relation to their ecology and genotype

“…Alternatively, they obtain all their resources within a limited area, e.g. the larvae of the cave-dwelling glow-worm £y, Arachnocampa luminosa, which catch their prey as it £ies by using illuminated sticky lures (Pugsley 1983). Most other adult insects, including the adult glow-worm £y, have to undergo spatial displacements either to obtain resources and/or exchange genes.…”