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Abstract: Among characteristics that are thought to determine the success of invasive species, life‐history traits feature prominently. However, in most cases, these have been determined under laboratory conditions. Here, we use a field set‐up to determine immature development time and survival of invasive Harmonia axyridis (Pallas) and native Adalia bipunctata L. (both Coleoptera: Coccinellidae). On caged Tilia × europaea L. cv. Pallida trees (Malvaceae) with ample amounts of aphid food, we introduced freshly hatched larvae of a single or of both ladybird species and followed their development until emergence of adults. Under the condition of ample prey availability, both ladybird species apparently hardly interacted and intraguild predation did not cause significant mortality. Development time of both species is in line with data from laboratory tests under controlled conditions. Immature survival can reach high levels, but is considerably higher for H. axyridis (44–100%) than for A. bipunctata (11–77%), resulting in faster increase of H. axyridis populations, which is one of the factors that may explain its invasion success. [ABSTRACT FROM AUTHOR]

The Asian ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is regarded as an invasive species in many parts of the world. In a previous study we hypothesised that H. axyridis enters diapause at the end of October and then shifts to a quiescent state in December in northwestern Europe. In the present study we test this idea of a short, early period of diapause by sampling beetles from their hibernation sites immediately after their migratory flights in October, subsequently keeping them in outdoor cages, and then, after certain time-intervals, measuring the pre-oviposition time under optimal egg-laying laboratory conditions at 25°C. We did this at both short (12L) and long (16L) photoperiods, since a photoperiodic response is an indicator of true diapause, rather than quiescence. A significant, albeit small, difference in pre-oviposition period between the two photoperiods, which disappears in December, corroborates our earlier hypothesis that the ladybirds are in a state of diapause until mid-December. Compared with that of native ladybirds the diapause of H. axyridis generally is relatively short and weak; moreover, it appears to have become shorter over the last decade. This flexibility in diapausing behaviour may be an important factor that contributes to the invasive success of H. axyridis. [ABSTRACT FROM AUTHOR]

Studies the differences in thermal balance, body temperature and activity between melanic and non-melanic two-spot ladybird beetles, Adalia bipunctata under controlled conditions. Higher body temperature and walking speed for melanic beetles under most conditions; Effect of ambient temperature and radiation intensity to walking speed.

Studies the genetics and cost of chemical defense of the two-spot ladybird or Adalia bipunctata insect. Genetic trade-off between the insect's defense and fitness characters; Evidence of sex-dependent gene expression.

Abstract: Since the establishment of Harmonia axyridis in Europe, populations of native ladybirds have decreased. Overwintering survival is one of the aspects of the biology of H. axyridis that may contribute to its firm establishment in and invasion of a new area. In this study winter survival of five wild H. axyridis populations was assessed under natural and semi-natural conditions, with a focus on the potential influence of location and orientation on winter survival. Overwintering survival of H. axyridis in the Netherlands is high: 70.8–88.2%. When overwintering at one central site, populations sampled at five locations showed statistically significant different mortality rates. Furthermore, winter survival of H. axyridis at the sample sites was higher when beetles were hibernating at the southwestern sides of buildings, where most aggregations of ladybirds were found. Survival was higher at sheltered sites compared to exposed sites. Harmonia axyridis has a comparable or higher overwintering survival than most common native ladybird species. A high overwintering survival results in a large post-hibernation population in spring, leading to a rapid population build-up. Thus, the high winter survival probably contributes to the success of the exotic H. axyridis. [Copyright &y& Elsevier]