Numerous studies deal with insect attachment onto surfaces with different roughness; however, little is known about insect attachment onto surfaces that have different chemistry. In the present study, we describe the attachment structures of the water-lily leaf beetle Galerucella nymphaeae and test the hypothesis that the larval and adult stages generate the strongest attachment on surfaces with contact angles that are similar to those of leaves of their host plants. The larvae bear a smooth attachment system with arolium-like structures at their legs and a pygopodium at the abdomen tip. Adults have pointed setae on the ventral side of the two proximal tarsomeres and densely arranged spatula-shaped ones on their third tarsomere. In a centrifugal force tester, larvae and adults attained the highest friction forces and safety factors on surfaces with a water contact angle of 83 deg compared to those of 6, 26 and 109 deg. This comes close to the contact angle of their host plant Nuphar lutea (86 deg). The similarity in larval and adult performances might be a result of the similar chemical composition of their attachment fluid. We compare our findings with previous studies on the forces that insects generate on surfaces with different surface energies.

The concept of energy serves biologists as a powerful analytical model to describe phenomena that occurs in the natural world. Due to the concept's relevance, educational standards of different countries identify energy as a core idea for the teaching and learning of biology and other science subjects. However, previous research on students' energy understanding has mostly focused on physics contexts. This cross-sectional study extends insight to the field by providing a systematic analysis of students' (N = 30, grades 5, 7, 9, 11) conceptions about energy in biological contexts. In order to connect the findings to previous research, the study analyses conceptions about four energy aspects that are regarded as central for understanding the concept in different disciplinary contexts, i.e. (1) energy forms/sources, (2) transfer/ transformation, (3) degradation/dissipation and (4) energy conservation. The findings identify substantial changes in students' conceptions about energy between the different grade levels, but also highlight conceptions that students consistently employed across age groups. The results are discussed in the light of previous research on students' progressing energy understanding and the connection of their energy understanding across different disciplinary contexts. Lastly, the article provides implications for the further development of energy teaching in biological contexts.