Cushion plants as microclimatic shelters for two ladybird beetles species in alpine zone of central Chile

Abstract

High mountain environments are highly stressful for insect survival. It has been suggested that small microtopographic variations generating less stressful microclimatic conditions than the surrounding environment would provide more suitable sites for insect development. Cushion plants represent one of the life forms best adapted to the extreme alpine habitats. Cushion plants can modify microclimatic conditions within and under their canopy, generating less severe microsites than the surrounding environment. In this study, we characterized the microclimatic modifications made by the cushion plants Azorella monantha and Laretia acaulis and examine their role as microcliniatic shelters for two species of high Andean coleopterans (Coccinelidae): Eriopis connexa and Hippodamia variegata at 3200 in a.s.l. in the Andes of central Chile. Results showed that the cushion species create microhabitats with higher availability of water and less oscillating temperatures. However, the intensity of modifications was higher in A. monantha compared to L. acaulis. The abundance of the two ladybird beetle species was higher within cushions than outside, although E. connexa showed higher abundances compared to H. variegata. However, a habitat selection experiment in a greenhouse showed that under milder temperature conditions ladybird beetles species do not prefer cushions. This suggests that in the harsh alpine climate, cushion plants may act as microclimatic shelters since they reduce stressful environmental conditions, allowing greater abundances of coleopterans than in the surrounding environment.