The ladybird beetle, Cheilomenes sexmaculata (Fabricius), has been extending its distribution in and around urban areas at higher latitudes in Japan over the past 100 years. Between 2003 and 2011, we investigated the seasonal occurrence, aphid prey and population dynamics of this species in an urban park in Osaka City, central Japan. We found that C. sexmaculata completes three generations a year in Osaka. Overwintered adults emerge in March or April and produce two (or rarely one) generations by summer. Second-generation adults aestivate and subsequently produce another generation in autumn. This species feeds on five species of aphids that infest planted shrubs and alien weeds throughout the vegetative season. We analyzed the association between accumulated temperature and when overwintered adults first emerged. In addition, we determined the association between their time of emergence, peak abundance and last occurrence, and meteorological conditions. There was no association between the sum of effective temperatures and termination of adult overwintering. There was, however, an association between first occurrence and peak abundance, and climatic conditions, such as warm temperatures or low humidity. This species maintained a stable population in an urban park by becoming quiescent when climatic conditions were unfavourable or prey was scarce. We discussed these findings in relation to urban environmental factors, such as climate, food conditions and vegetation., Yasuko Kawakami, Kazuo Yamazaki, Kazunori Ohashi., and Obsahuje bibliografii
Many insects masquerade as parts of plants, such as bark or leaves, or mimic poisonous organisms in order to defend themselves against predators. However, recent studies indicate that plants may mimic insects and other arthropods to deter herbivores. Here, I report visually similar white structures of plants and arthropods in Japan and suggest they are part of a mimicry complex. Young shoots covered with white trichomes or waxy substances may mimic wax-producing insects, such as woolly aphids, coccids and caterpillars, potentially resulting in reduced herbivory. Since wax-producing insects would reduce plant quality and quantity, be distasteful and attract natural enemies, herbivorous insects and mammals may avoid such white shoots. Furthermore, fungus-infected insects, gregarious braconid cocoons, spider egg sacs and froth made by froghopper nymphs or blasticotomid sawfly larvae are also conspicuously white and impose risks for herbivorous insects. Thus, these white structures may be mimicry models for white shoots and are likely to be part of a defensive mimicry complex. Although this study focuses on defence against herbivores, there are simultaneous physiological roles for white colouration that will not be discussed in depth here., Kazuo Yamazaki., and Obsahuje bibliografii