CARBOHYDRATE BAIT PREFERENCES OF WASPS (VESPULA-VULGARIS AND VESPULA-GERMANICA) (HYMENOPTERA, VESPIDAE) IN NEW-ZEALAND

Carbohydrates an both a source of food and a potential bait for contro l of common and German wasps. Carbohydrate preferences of wasps were d etermined in a series of paired trials by counting the number of wasps caught in traps baited with carbohydrate-based baits versus a standar d protein-based bait. Factors influencing wasp attraction to carbohydr ate-based baits included bait type, season, weather, and location. A 3 0% sucrose solution was more attractive than honey,jams, gels, or dry (solid) sugars. The sucrose solution was more attractive in spring and autumn than in summer, probably because rainfall washed away natural carbohydrate supplies. There was a significant relationship between ra infall in the previous week and the proportion of wasps caught in trap s baited with sucrose solution versus sardine cat-food. A higher propo rtion of German wasps than common wasps was caught in sucrose-baited t raps. This may have been related to seasonal differences in abundance and/or behavioural differences between the two species. In some locati ons, more wasps were caught in traps baited with sucrose solution than in those baited with sardine cat-food. The proportion of wasps caught in sucrose-baited traps was higher in locations without beech scale h oneydew than with beech scale honeydew. Proportionally more non-target species (mainly honey bees) and fewer wasps were caught in traps bait ed with sucrose solution than in those baited with sardine cat-food. A ll five bee repellents tested also repelled wasps. These results indic ate the importance of determining the bait preferences of wasps (carbo hydrate or protein) and the presence of non-target species before atte mpting a poison-baiting operation. They also emphasise the need for a wasp-specific carbohydrate-based bait.