Understanding the role of unmanaged arthropod flower visitors as crop pollinators is critical if robust and reliable long‐term alternatives are to be found for honey bee pollination. However, data on pollinator assemblages can be scant. Field observation of crop flower visitors is a common data collection technique but it can be inadequate for species identification and is labour‐intensive if used across many sites. Trapping may reduce this problem, but trap performance and sampling consistency over long distances (sites separated by >100 km) are rarely examined. Window traps were designed to collect flower‐visiting arthropods from peak‐flowering onion (Allium cepa) and pak choi (Brassica rapa var. chinensis) fields across several regions throughout New Zealand. Trap efficacy was evaluated by comparing trapped samples with observations of flower visiting arthropods during the same trapping period, from dawn (6:00 to 7:00 hours) through to dusk (20:00–21:00 hours) at the same locations. Similar types of larger arthropods (length ≥3 mm) were observed and trapped within both crops, with the hymenopteran genera Apidae, Colletidae and Halictidae and the dipteran families Syrphidae, Calliphoridae, Anthomyiidae, Stratiomyidae, Sarcophagidae, Bibionidae, Tachinidae and Muscidae the most commonly recorded. The total counts of these taxa across fields were strongly correlated between the two methods; however, the ratio of trapped to observed individuals could vary greatly between taxa. Trapping allowed more arthropods to be identified to the species level and also helped record more small arthropods (body length <3 mm) when compared with observation. Window traps can be effective for assessing the relative diversity of flower visitor assemblages and the abundance of specific taxa in specific cropping systems at the regional scale, but variation in trap efficiency between arthropod taxa must be assessed for a true measure of assemblage composition.

In the 3 years 1971-73, of 340 field nest boxes and hives of several different designs, 84 (24.7%) were occupied by all 4 introduced bumble bee species in New Zealand. Fieldcollected and induced nests were generally similar in bee productivity. Reproductive nests of Bombus hortorllln and B. terrestris produced from 2 to 5 times as many individuals as did nests of the same 2 species in Europe. The increase is attributable to the bumble bees freedom in New Zealand from all but 3 of their enemies present in Europe, the lack of endemic New Zealand enemies, and the r':lative freedom from competition for food by other bee species. Some nests of these 2 species were founded throughout most of the year. Nests of B. ruderatus and B. subterraneus were similar in production of total individuals to nests of the same 2 species in Europe: nests were founded only in spring and summer, and competition for food from the other 2 species may have limited nest size. Only 32 (38.1 %) of the induced nests produced new queens. Nest mortality was greatest when the foundress queens disappeared or died in the nest (52.4%). In the 3 seasons, the number of new queens produced by reproductive nests was 12.4 times greater than the number of queens (tOO) involved in founding all 84 nests. New queens that return to maternal nests may investigate replicas of the maternal nests when nest site searching. The tendency of some new queens to return to the vicinity of the maternal nests the following season, and the increased numbers of foundress queens present in subsequent years because of the presence of hives, may lead to increasingly high acceptance rates from season to season. The designed hives were adequate for all phases of nest development, but future hives should allow for better drainage and should be constructed of more durable materials. Prospects for increasing populations of bumble bees in New Zealand by use of simply constructed field-placed hives appear to be excellent. 733

The literature on the biology of Sphecophaga vesparum (Curtis) is reviewed. New data are added and the life cycle is outlined. Winged adults emerge from yellow, overwintering cocoons from one to four springs/summers after the season in which the cocoons were formed, and may live for up to 3 weeks. The species is at least facultatively deuterotokous, but mating can occur. Within wasp nests, winged and brachypterous females prefer to oviposit into cells within which host pupation has most recently occurred. The species is ectoparasitic on wasp iinmatures within capped cells. Both female morphs lay three kinds of eggs: those that give rise to white cocoons and then brachypterous females within 13 days, those that give rise to weak, yellow cocoons that produce winged females and possibly males within 15 days, and those that give rise to resistant, yellow, overwintering cocoons. Many generations may originate from one invasive winged female in one year.The species is very well adapted to take maximum advantage of its host's life cycle. Productivity of individual females, whether fertilisation occurs, and the mode of entry of winged females into wasp nests, have yet to be determined.

No abstract

No abstract

Abstract1 Eighty four‐unit domiciles for introduced bumble bees (Bombus spp.) were placed in 16 field margins at Lincoln, New Zealand in the 1995–96 southern summer. Fifty‐five were placed in the margins of intensively managed fields, with the remaining 25 being in less disturbed habitats, which had more spring/summer floral resources.2 The number of nests founded over the four‐year study period increased from one to 27. Bombus hortorum was a much more frequent colonist than was B. terrestris, with B. ruderatus colonizing only in the fourth year.3 In the ‘intensive’ sites, mean four‐year occupancy was only 2%, whereas in the less disturbed sites it was 13%.4 There was a positive association between bumble bee occupancy of the domicile compartments in the previous year and occupancy in the current year. No association was found between previous occupancy by mice and subsequent occupancy by bumble bees.5 The potential for adding Bombus nest sites to agricultural land to enhance local populations, and, potentially, pollination of seed crops, is discussed. Adding domiciles in intensively managed landscapes may not be very effective unless spring floral resources are enhanced as well.

No abstract

After occurring sporadically in New