Reproductive biology of Hawaiian lava crickets

Insects have spread across diverse ecological niches, including extreme environments requiring specialized traits for survival. However, little is understood about the reproductive traits required to facilitate persistence in such environments. Here, we report on the reproductive biology of two species of endemic Hawaiian lava crickets (Caconemobius fori and Caconemobius anahulu) that inhabit barren lava flows on the Big Island. We examine traits that reflect investment into reproduction for both male and female lava crickets and compare them to the non-extremophile Allard’s ground cricket (Allonemobius allardi) in the same sub-family. Lava cricket females possessed fewer, but much larger eggs than ground crickets, while males do not provide the costly nuptial gifts that are characteristic of the Nemobiinae subfamily. Lava crickets also have longer ovipositors relative to their body length than related Caconemobius species that occupy cave habitats on the Hawaiian islands. The differences in reproduction we report reveal how these little-known cricket species can increase the survival of their offspring in the resource-deprived conditions of their hot, dry environments.