BETWEEN AND WITHIN FIELD VARIABILITY OF NEW ZEALAND INDIGENOUS FLOWER VISITORS TO ONIONS

In New Zealand, few studies have documented the occurrence of indigenous fl ower visitors within crops. A fi ve-year survey is examining the distribution, diversity and abundance of fl ower visitors in onion (Allium cepa)fi elds located throughout New Zealand. Day-time observations from the fi rst year of the survey recorded nine arthropod orders visiting onion fl owers in the South Island, with Diptera (fl ies) and Hymenoptera being the most abundant. Over six fi elds the proportion of bees that were indigenous species (Apoidea) ranged from <1% to 63.6%. Common bee genera and fl y families varied considerably in their presence and abundance, even over 17 km. Moreover, counts of Lasioglossum spp. at fi ve points within one fi eld ranged from 0 to 576, demonstrating that the distribution of some fl ower visitors can be highly variable. Understanding crop fl ower visitors may help develop systems to reduce transgene fl ow should genetically modifi ed crops be commercially produced in New Zealand.