Potential Costs of Selecting Good Sites For Offspring: Increased Risk of Drowning And Negative Effects on Egg Production

Many studies have shown the benefits of selecting suitable sites for offspring survival and growth. However, costs of selecting suitable sites have been little covered. If the female's costs associated with selecting suitable sites exceed the benefit from improvement of offspring performance, selecting such sites can have a negative effect on the ongoing reproductive success for ovipositing females. We investigate the potential costs of selecting suitable sites in the water strider Aquarius paludum insularis. Where there exists a risk of egg parasitism, the female A. paludum will submerge and select a deep site, more suitable for offspring survival, for oviposition. By forcing A. paludum underwater once a day for 10 d, we investigated the potential costs associated with oviposition at deep sites, firstly relating to the performance of submergence (latency to asphyxiation or proportion of buoyancy loss) and, secondly, in the number of eggs laid. Buoyancy became weaker and the latency to asphyxiation became shorter with the number of submergences. The number of eggs laid in the period of forced submergence was smaller than both before and after the period. Selecting deep sites can therefore increase the mortality risk of ovipositing females and also decrease the number of eggs laid in their lives. Selecting suitable sites in all the oviposition bouts can decrease ovipositing females' reproductive success. Costs, not only benefits, should be taken into consideration for understanding oviposition site selection during the lifespan of an ovipositing female.