Food stress and predator-induced stress shape developmental performance ina damselfly

I studied effects of stress factors like food shortage, non-lethal predator presence and autotomy on survival and larval performance (growth rate, dev elopment rate and developmental stability) of larvae of the damselfly Leste s sponsa. In a laboratory experiment, larvae were raised during their last two instars at two food levels thigh or low) crossed with two levels of aut otomy (caudal lamellae present or absent). These treatments were nested wit hin three levels of predation risk (Aeshna cyanea absent, Chironomus-fed ca ged Aeshna or Lestes-fed caged Aeshna). The diet of the predator had no eff ects. The low food level and the presence of Aeshna independently increased mortality rates of L. sponsa larvae. The low food level, presence of a cag ed Aeshna and autotomy all independently reduced growth rate (mass and body size at day 40) and wing size at emergence, and the first two stress facto rs also reduced development rate. Regardless of predator presence and autot omy, all damselfly larvae consumed the food available. This indicated that the predator-induced stress effects were not due to reduced food uptake, bu t probably reflected lowered assimilation efficiency and/or a higher metabo lic rate. Besides a low food level, the presence of caged Aeshna predator l arvae and autotomy also increased hind wing asymmetry. This result demonstr ated that predator-induced stress may reduce developmental stability in the grey.