Impact of Chemical Insecticide Application on Beneficial Insects in Maize.

The European corn borer (ECB) (Ostrinia nubilalis Hübner) and to a lesser extent the western corn rootworm (Diabrotica virgifera virgifera LeConte) are a threat to maize in the Po Valley (Northern Italy), and their control can require insecticide applications. The results of a study to evaluate the effects of insecticide sprays on the beneficial insect Trichogramma brassicae (Hymenoptera: Trichogrammatidae) and aphid predators are reported. A three-year research project was carried out in two Study Areas, in Lombardy. In area 1, crop rotation was a common practice, while in area 2 repeated maize crop was practiced. The natural trend of ECB egg masses attacked by T. brassicae was affected and parasitism rates were reduced as a result of insecticide exposure (chlorpyriphos methyl, cypermethrin, alphacypermethrine). Repeated maize crop and insecticides spraying increased the abundance of the aphid population and negatively affected the aphid predator community, which mainly included ladybirds, hoverflies, true bugs and lacewings. The predator community was dominated by hoverflies in sprayed fields managed according to repeated maize crop protocols, whereas ladybirds and Orius spp. dominated in maize fields managed according to crop rotation protocols. Crop rotation protocols help to prevent ECB outbreaks; when the risk of exceeding the economic threshold limit is high, and this may be the case when maize is cultivated for seeds or for horticultural crops such as sweet corn, inundative release of T. brassicae and/or microbial control (i.e., use of Bacillus thuringiensis preparations) can integrate natural biocontrol, and provide a valuable alternative to chemical insecticides.

Landfill restoration and biodiversity: a case of study in Northern Italy.

Landfilling is a worldwide common waste treatment method. Final recovery usually consists of capping the area with top soil on which vegetation can grow. Depending on the suitability of the recovery pattern, landfill sites can work as potential reserve of semi-natural habitats. A recovery pattern applied to land reclamation of two hazardous waste landfills sited in Northern Italy (Po floodplain) was studied to assess the results in terms of biodiversity. These landfills lie within a landscape dominated by intensive agriculture. After final sealing, both landfills were covered by soil on which a meadow was sown and a hedgerow was planted around the borders. One of the compared areas was not provided with a pond and the hedgerow was incomplete. Butterflies and birds were used as indicators, and their seasonal abundance was related to habitat structure and ecological factors. Meadows grown on both areas supported a rich butterfly population (30 species), including some species that are by now uncommon in the Po floodplain. In both areas butterfly abundance was affected by summer drought. The birds' community included 57 species; 16 Species of European Conservation Concern (SPECs) were observed. Each bird community was different in the compared study areas because of their different size and habitat structure. For example, landfill A, provided with a pond and a more complex structure of the hedgerow, supported a richer birds community (52 species versus 39). Both restored landfills worked well as a stepping stone for migratory birds, but they were a reproductive habitat of poor quality.

Spread and habitat selection of Chrysomya albiceps (Wiedemann) (Diptera Calliphoridae) in Northern Italy: forensic implications.

Habitat selection exploited by Chrysomya albiceps during its initial spread in Northern Italy was analyzed in relation to landscape structure. The results of two short studies and a case report are here discussed. C. albiceps was not found on experimental pig carcasses in the urban area of Pavia. It was missing in the woody mountains surrounding Lecco, but it was found in the same area, at a lower altitude, within the typical "urban sprawl" landscape. It was then recorded in a natural reserve, among a rich carrion-fly population. Indications coming from habitat selection suggest that C. albiceps has not yet saturated its potential ecological niche in newly colonized areas of Northern Italy. Factors like temperature, altitude, and interspecific competition can act as limiting factors, affecting habitat selection and distribution in newly colonized areas; the influence of those factors has to be taken into account for forensic purposes.