Emergence rates of stink bugs and parasitoids under four heat wave conditions

Heat waves are becoming more frequent with climate change and their impact on lower and higher trophic levels can differ. Higher trophic levels, such as predators and parasitoids, are predicted to be more strongly affected by heat waves than herbivores because they may have smaller thermal windows and because of altered ecological interactions with lower trophic levels. We tested the effects of heat waves of varying intensity (36-42˚C), imposed for four hours during five consecutive days on the egg stage of an invasive herbivore, the brown marmorated stink bug (Halyomorpha halys) and on various developmental stages of its parasitoid, Trissolcus japonicus. Halyomorpha halys eggs had lower hatching success and fewer nymphs emerging with increasing intensity of heat stress, while exposure during the egg and larval stages of T. japonicus did not decrease adult emergence rates. Heat waves increased development time of parasitoids and decreased adult emergence when pupal stages were exposed. ...