Preliminary observations on the biology and management of western corn rootworm (Diabrotica virgifera virgifera) in Italy

Preliminary data (obtained in the first research year, i.e. in 2004) on the biology of western corn rootworm (WCR; D. virgifera virgifera), evaluation of different trapping systems and agronomic management measures in Italy are reported. Larvae were found from the end of June until the end of July. The first specimens collected were 2nd and 3rd instar larvae, suggesting that egg hatch had begun in at least the first half of June. Pupae were present from the end of June onwards. Adults appeared at the end of June and continued to be found up to the beginning of October. According to mean captures, flight curves for both pheromone- and kairomone-baited traps showed 3 distinct peaks: at the beginning of July, at the beginning and end of August. Novapher traps (Dvv-n and Dvv-l) showed a similar trend to PAL traps, with less intense fluctuations. The same trend was shown by Novapher Dvv-l traps that were baited with a long-lasting pheromone, set at the beginning of the season and never changed. Csalomon YST traps demonstrated the same trend as PAL and PALs traps. Pherocon AM traps caught up to 20 times more adults than the Csalomon YST traps, exceeding the damage threshold; Csalomon YST catches were always below threshold levels. Crop rotation was confirmed as an efficient control practice for WCR because no adults were caught on the traps in the emerging cages. Some adults were collected in the summer maize, which might indicate that a few eggs can hatch very late in the season.