The impact of common and German wasps (Hymenoptera: Vespidae) on the New Zealand beekeeping industry

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Abstract
We compared the proportion of common wasps (Vespula vulgaris) in samples sent to us by members of the public with the proportion in samples sent by beekeepers from their apiaries. Common wasps robbed beehives less frequently than German wasps (V. germanica) relative to their population levels in the environment. A questionnaire was sent to 600 beekeepers throughout New Zealand asking for information on the impact of wasps on their operations in the 1985/86 and 1986/87 seasons. The majority (83.8%) of the 278 respondents considered wasps to be a nuisance. Beekeepers found more wasps nests in areas with (referred to as “vulgaris” areas) than without the common wasp (“non-vulgaris” areas), even though they spent no more time in wasp control. Similar numbers of overwintering nests were found in vulgaris and nonvulgaris zones. Overwintering nests were more common, and wasps caused more problems during spring buildup in the North Island than the South Island. Wasps totally destroyed or seriously affected 8.13% of hives in 1985/86 and 9.35% in 1986/87. South Island beekeepers in honeydew beech forests where common wasps were present faced greater hive damage levels than beekeepers elsewhere in the country. However, the increase in damage between the two seasons was much lower than the increase in the wasp population over the same time. Further, the number of hives totally destroyed by wasps in the common wasp infested regions of the South Island changed little between seasons. The increased damage levels resulted mostly from an increase in seriously affected hives. It is concluded that high wasp abundance was probably the reason for the high hive damage levels in the honeydew forests in 1986/87. This was offset by the low rate of robbing and lack of overwintering nests of the common wasp, which poses less of a threat than the German wasp to the New Zealand beekeeping industry.