Larvae of the ladybird Harmonia axyridis are reported to suffer high mortality when they are fed with the aphid Aulacorthum magnoliae associated with the elder Sambucus sieboldiana. In the present study we first examined whether aphid toxicity to H. axyridis was altered when the aphids were reared on different host plants, and second whether some ladybird families could adapt specially to the toxic aphids. Ladybird larvae from each egg batch were divided into two groups; one group was fed with A. magnoliae reared on potato, and the other group was fed with A. magnoliae reared on elder. The ladybird larvae fed with elder aphids suffered significantly higher mortality and grew more slowly than did larvae fed with potato aphids. This result indicates that A. magnoliae aphids absorbed toxic substances or their precursors from S. sieboldiana. We suggest that host association of A. magnoliae with the primary host plant S. sieboldiana has been maintained because of the advantage of deterring predation. Significant and positive correlation was detected across H. axyridis sib families between the mean weight of larvae fed with elder aphids and the mean weight of larvae fed with potato aphids. The hypothesis that some ladybird families adapt specially to the toxic aphids was not supported. However, the available evidence showed that a large amount of genetic variance in performance is maintained in a wild population of the ladybird H. axyridis.

Novel thin film fuel cell based on the 100 nm-thick electrolyte of amorphous ZrP 2.6 O x , working at 400 C, was demonstrated. The hydrogen permeable membrane fuel cell (HMFC) using a Pd foil as a nonporous solid anode was fabricated. Ni interlayer of several hundreds nm thickness was introduced between the Pd anode and the ZrP 2.6 O x electrolyte in order to suppress the deterioration of the electrolyte nanofilm by the deformation of the Pd anode during hydrogen absorption. In the ZrP 2.6 O x electrolyte the transport number of proton was unity at 400 C as determined by an EMF measurement. The modification of the Ni anode surface by an ultrathin Pt or Pd layer effectively decreased the anode/electrolyte interfacial polarization. Consequently, the HMFC revealed the OCV of 1.0 V and the maximum power density of 1.8 mW cm À2 at 400 C.