Effects of diet mixing on the survival and performance of the brachypterous grasshopper <scp><i>Podisma sapporensis</i></scp> (Orthoptera: Acrididae) nymphs and adults

Abstract This study examined the effects of diet mixing during the nymphal stage on the performance of the brachypterous grasshopper Podisma sapporensis during both the nymphal and adult stages. This species mainly feed on the leaves of Japanese butterbur, Petasites japonicus var. giganteus (Pjg), and also feed on the leaves of giant knotweed, Reynoutria sachalinensis (Rs), wormwood leaves, Artemisia montana , and angular Solomon's seal, Polygonatum odoratum var. maximowiczii . We investigated whether diet mixing with Pjg during the nymphal stage enhances the survival or fecundity of this grasshopper. It was revealed that feeding nutritionally inferior Rs to nymphs extended the adult lifespan. The reproductive speed per lifespan was reduced in females fed the mixed diet, as there was no significant difference in the number of eggs laid per lifespan regardless of the Rs ingested. These results indicate that diet mixing, or the additional Rs intake, had an opposite effect on the life history in the form of higher nymphal mortality and longer adult lifespan of P. sapporensis , altering the reproduction schedule.