Laboratory studies on Harmonia axyridis (Pallas) in Italy and the UK

The exotic coccinellid Harmonia axyridis (Pallas), active predator of aphids and other pest-insects, has long been used as a biological control agent and introduced in many countries. In recent decades this species has aroused worries concerning its high capacity of dispersal and acclimatization, as well as possible negative effects on native species. A first part of this study, performed at DipSA (University of Bologna, Italy), was related to the effects of high temperature on the fitness of the coccinellid. A second part, performed at CERC (Harper Adams University, England), was aimed at analyzing the susceptibility to treatments with an insecticide comparing H. axyridis with a native coccinellid species. The test carried out in Italy showed that, in general, the fitness of H. axyridis was negatively affected by the exposure at high temperature (30°C). In particular, the reproductive parameters of adults have shown remarkable effects. The mean duration of the oviposition period was shorter at 30°C; the adults laid less eggs from which a smaller number of 1st instar larvae was obtained. The test carried out in England has shown that H. axyridis was less susceptible than the native coccinellid species, after one week of staying on the treated plants.