PRIMARY RESEARCH PAPER Oviposition plant choice maximizes offspring fitness in an aquatic predatory insect Philippe Lambret . Imogen Rutter . Patrick Grillas . Robby Stoks Received: 23 March 2018 / Revised: 14 May 2018 / Accepted: 20 May 2018 Ó Springer International Publishing AG, part of Springer Nature 2018 Abstract Evidence for the adaptive value of ovipo- sition site selection in terms of increased offspring fitness is rare in predatory insects. We tested this in the damselfly Lestes macrostigma that prefers the plant Bolboschoenus maritimus. We carried out two exper- iments with shoots containing eggs: we flooded (1) some shoots of the same type (i.e. combination of species and desiccation state) at different dates and (2) different shoot types at the same date. Earlier flooding increased hatching success. Because B. maritimus grows in deeper parts of temporary ponds, it is flooded before other plants after the drought season, suggest- ing that adult oviposition site selection is driven by lower egg desiccation risk. Independently of flooding date, hatching success was higher and larvae hatched earlier when eggs were laid in B. maritimus. Faster embryonic development enhances chances to com- plete larval development before pond desiccation and reduces costs associated with time stress. Offspring higher fitness was more constant between shoots of B. maritimus compared to the other types of shoot, suggesting that laying eggs in one shoot of this plant leads offspring to high fitness more surely. Our results indicate that adults choose oviposition plants maxi- mizing offspring fitness (higher hatching success and faster embryonic development). Keywords Conservation Á Endophytic egg-laying Á Habitat selection Á Lestes macrostigma Á Odonata Á Temporary pond Introduction In organisms using an opportunistic reproductive strategy (r-selection), such as insects that lay large egg clutches, oviposition site selection is key to increase offspring survival, and therefore can be regarded as a form of parental care (Janz, 2002; but see Garcı ´a-Robledo & Horvitz, 2012). Indeed, ovipo- sition site characteristics such as abiotic conditions, vegetation abundance or structure and the presence of natural enemies can have dramatic impact on egg and larval survival in various insect orders (e.g. Rausher, 1979; Sweeney & Quiring, 1998; Pasquier-Barre et al., 2001; Hirayama & Kasuya, 2009; Knorp & Dorn, 2016). Therefore, adult selection of oviposition sites is of paramount importance for population dynamics. Oviposition site selection in relation to plant features Handling editor: Dani Boix P. Lambret (&) Á I. Rutter Á P. Grillas Tour du Valat, Research Institute for the Conservation of Mediterranean Wetlands, Le Sambuc, 13200 Arles, France e-mail: lambret@tourduvalat.org P. Lambret Á R. Stoks Laboratory of Aquatic Ecology, Evolution and Conservation, Deberiotstraat 32, 3000 Louvain, Belgium 123 Hydrobiologia https://doi.org/10.1007/s10750-018-3663-3