Plant preference during oviposition in the endangered dragonfly Lestes macrostigma (Odonata: Zygoptera) and consequences for its conservation

Abstract

Biotic and abiotic features impact the breeding success of animals and thereby induce selection pressures for habitat selection. Little is known about the plant selection by predatory insects which lay their eggs within plants. In previous work, we have highlighted that during oviposition males of Lestes macrostigma—an endangered dragonfly species—prefer to land on Bolboschoenus maritimus and dead shoots of Juncus maritimus but disfavour living shoots in that species, and that females seem to prefer dead material during substrate examination. In this study we assessed behavioural preference in females during substrate examination, substrates suitability for oviposition, the effort females had to make to lay their eggs and their resulting oviposition rate. We show L. macrostigma has a preference for B. maritimus and, albeit to a lesser extent, for dead substrates. No clear trend appeared regarding substrate suitability. Females had to make a greater effort to lay an egg within living shoots of J. maritimus. By contrast, this effort was less in B. maritimus and dead shoots of J. maritimus and the oviposition rates were higher for these two types of substrate. We hypothesize that these preferences are relevant in the selection of oviposition substrates which are more likely to be flooded earlier by rainfall, reducing risk of egg desiccation and increasing hatching success. With regard to conservation, B. maritimus and J. maritimus should be encouraged by wildlife managers especially in habitat restoration programs which aim to increase the number of suitable breeding sites for the species.