Print PageThe larvae of many Lepidoptera are oligophagous or polyphagous, utilizing multiple host plants as food sources. Variation in larval host plant diet can occur spatially (across the larval species range) and/or temporally (at different stages of larval growth). We are interested in the impact of host plant diet on larval fitness for the polyphagous larvae of the Geometrid moth Epimecis hortaria. These larvae are found on a number of host plants, including Liriodendron tulipifera, Asimina triloba, Sassafras albidum, and Lindera benzoin. We collected larvae of E. hortaria at Alapocas Run State Park in DE from the common understory shrub L. benzoin, and the common small tree A. triloba. Offspring of wild-caught larvae were raised from eggs in the laboratory and fed a single host plant diet (L. tulipifera, A. triloba, S. albidum or L. benzoin) until pupation. Larval weights were recorded every 2 to 3 days until pupation. Initial pupal weight, emerging moth weight and moth sex were also recorded.
Results/Conclusions
Larvae raised on A. triloba grew more slowly than larvae raised on S. albidum or L. benzoin and took significantly longer to pupate (P<0.001). This resulted in higher maximum larval weights for larvae fed A. triloba than for larvae fed S. albidum (P=0.019). However, weight loss during pupation was dramatically greater in larvae raised on A. triloba (P<0.001), transforming the larvae with the highest larval weights into the pupae with the lowest pupal weights (P=0.019). Pupal weights were positively correlated with moth weights at emergence (P<0.001), suggesting an effect of host plant on adult moth fitness. In ongoing studies, larvae reared on individual host plant diets are subjected to food choice assays of alternative host plants.
