The Pheromone of the Cave Cricket,Hadenoecus cumberlandicus, Causes Cricket Aggregation but Does Not Attract the Co-Distributed Predatory Spider,Meta ovalis

Abstract

Food input by the cave cricket, Hadenoecus cumberlandicus Hubble & Norton (Orthoptera: Rhaphidophoridae), is vital to the cave community, making this cricket a true keystone species. Bioassays conducted on cave walls and in the laboratory show that clustering in H. cumberlandicus is guided by a pheromone, presumably excreta. This aggregation pheromone was demonstrated by using filter paper discs that had previous adult H. cumberlandicus exposure, resulting in > 70% response by either nymphs or adults, prompting attraction (thus, active component is a volatile), followed by reduced mobility (arrestment) on treated surfaces. Adults were similarly responsive to pheromone from nymphs, agreeing with mixed stage composition of clusters in the cave. Effects of [0.001M – 0.1M] uric acid (insect excreta's principle component) on H. cumberlandicus behavior were inconsistent. This pheromone is not a host cue (kairomone) and is not used as a repellent (allomone) as noted through lack of responses to natural H. cumberlandicus pheromone and uric acid concentrations by a co-occurring predatory cave orb weaver spider, Meta ovalis Gertsch (Araneae: Tetragnathidae). This pheromone is not serving as a sex pheromone because nymphs were affected by it and because this population of H. cumberlandicus is parthenogenic. The conclusion of this study is that the biological value of the aggregation pheromone is to concentrate H. cumberlandicus in sheltered sites in the cave conducive for minimizing water stress. Rather than signaling H. cumberlandicus presence and quality, the reduced mobility expressed as a result of contacting this pheromone conceivably may act as a defense tactic (antipredator behavior) against M. ovalis, which shares this favored habitat site.

Reproductive biology of Hawaiian lava crickets

“…Lava crickets of both sexes have extremely elongated antennae, reflecting their reliance on mechanosensory and chemosensory cues to navigate their environment (personal observation, all authors). Other wingless cave cricket species of both sexes use excreta-based cues for aggregation ( Yoder et al, 2010 ), as do other common cricket species ( McFarlane et al, 1983 ; Nagel and Cade, 1983 ). Lava cricket mating may parallel that of the wingless Cook Strait giant weta, wherein males compete in scrambles for mates ( Kelly and Gwynne, 2022 ; Kelly and Gwynne, 2023 ), and further work could explore this possibility.…”

Population structure and habitat preference of cave crickets (<i>Rhaphidophora</i> sp. (Orthoptera: Rhaphidophoridae)) in Sanghyang Kenit cave, Citatah karst area, West Java

“…Besides, their eggs are also consumed by smaller-sized arthropod groups like carabid beetles (Lavoie et al 2007;Culver & Pipan 2009). Thus, cave crickets are often considered as keystone species in many cave ecosystems (Yoder et al 2010;Epps et al 2014).…”