Larvae of the aspen blotch miner, Phyllonorycter salicifoliella Chambers (Lepidoptera: Gracillariidae), feed within leaves of three host-tree species in north-central Minnesota, USA. Far more individuals occur on Populus tremuloides than on P. balsamifera or P. grandidentata. We tested whether this pattern of host use reflected variable performance among alternative hosts by examining survivorship, sources of mortality, pupal mass, feeding efficiency, and development time of miners on each tree species. We also determined foliar water, nitrogen, condensed tannin, and phenolic glycoside content of host trees to test if host-tree chemical attributes were responsible for differences in performance. There was no significant difference in egg-to-adult survival among miners on different hosts, although dominant sources of mortality did vary. Miners on P. grandidentata suffered less parasitism and more predation than those on the other hosts, even though most parasitoid species attacked miners on all hosts. The other performance parameters varied among host species, but not in a consistent pattern. Pupal mass was greatest on P. tremuloides and P. balsamifera, the hosts with comparatively high foliar nitrogen and low phenolic glycoside concentrations. However, feeding efficiency was greatest and development time shortest for miners on P. grandidentata. Thus, pupal mass was the only index of performance maximized on P. tremuloides, the most commonly used host. Infrequent occurrence of Phyllonorycter salicifoliella on P. grandidentata results in part from phenological differences between this and the other host species. Low oviposition rates on P. balsamifera are correlated with low abundance of this host at the study site and a phenolic glycoside profile different from that of the other host species.

Understanding how environmental drivers influence shark and ray spatial and temporal patterns can provide crucial knowledge for their evidence-based protection and long-term monitoring. However, information on which drivers of variation are most important for elasmobranch communities on soft sediments is limited. Using baited remote underwater stereo-video systems (stereo-BRUVs), we investigated how seasonal and environmental variables affected the elasmobranchs of the iSimangaliso Wetland Park marine protected area (MPA) in South Africa (SA). In total, 11 species were identified from 48 sites between 12 m and 33 m water depth in a sandy habitat. While species richness was similar across seasons, the total abundance of elasmobranchs recorded was higher in winter than summer. The species assemblage composition varied significantly between seasons, with the Human’s whaler shark Carcharhinus humani prevalent in summer and the Critically Endangered whitespotted wedgefish Rhynchobatus djiddensis more abundant during winter. Most species were sighted throughout the entire depth range, but rays were more common in shallower waters (< 25 m depth), while C. humani and R. djiddensis were more common in the deeper depth zone of this study. This research provides baseline information about this previously unexplored sandy habitat for elasmobranchs in a site of regional and global significance. Records of species of conservation concern in the sampling area highlight the importance of protecting sand environments within an MPA.