A review of New Zealand's deliberately introduced bee fauna: current status and potential impacts

Eight bee species have been deliberately released into New Zealand since the 1830's. The honey bee (Apis mellifera L.) was introduced primarily for honey production but has become the most important insect pollinator of seed, vegetable, fruit crops and pastures. The remaining species (Bombus terrestris (L.), B. hortorum (L.), B. ruderatus (F.), B. subterraneus (L.), Megachile rotundata (F.), Nomia melanderi (Cockerell), Osmia coerulescens (L.) were introduced to pollinate either red clover (Trifolium pratense) or lucerne (Medicago sativa). The honey bee has almost exclusively been relied upon for crop pollination although species of Bombus and M. rotundata are occasionally used commercially. The spread throughout New Zealand of the varroa mite (Varroa destructor Anderson & Trueman), a parasite that exclusively kills honey bees, has increased the cost of managing honey bee hives. The use of alternative bee species for crop pollination may reduce the potential impact of factors infl uencing the availability and cost of honey bee pollination services. However, consideration must be given to the potential impact that expanding populations of introduced bees could have on native and exotic fl ora and fauna. This review examines the current and potential use of the eight deliberately introduced bee species in New Zealand, their distribution, and potential impact on New Zealand's biota.