Influence of honey bee (Apis mellifera) on kiwifruit pollination and fruit quality under Australian conditions

The influence of honey bee (Apis mellifera L.) pollination of kiwifruit (Actinidia deliciosa (A.Chev.) C.F. Liang et A.R. Ferguson) under different pollination regimes (viz. honey bee supplementation, honey bee saturation in a cage with a single male cultivar, and honey bee exclusion) was investigated under Australian conditions during 1993/94 and 1995/96 seasons. Vines that had no access to honey bees had significantly (P less than or equal to0.01) lower fruit set (24%) compared to honey bee supplementation (91%) and bee saturation (89%). The mean yield (kg/vine) and the mean number of fruit/vine in bee-supplemented and bee-saturated treatments did not differ significantly, although vines that were excluded from honey bees produced significantly (P less than or equal to0.01) lower yields. However, individual fruit weight in the bee-saturated treatments was affected. There were significantly more small fruit in bee-saturated vines than in vines that were supplementary pollinated by honey bees. Bee activity as assessed by the number of bee visits on flowers (bees/vine per min) was significantly higher on male vines than female vines during the first 2 weeks of the flowering period. Honey bees were the main contributor to pollination and fruit set, although low numbers of other potential insect pollinators such as ladybird beetles and hover flies were also observed. The mean seed numbers in comparable fruit from higher weight groupings (i.e., 70-89, 90-109, and greater than or equal to 110 g) in bee-supplemented and bee-saturated vines did not differ significantly, suggesting adequate pollination and fertilisation of ovules in these two treatments. Vines that were caged with a single male cultivar produced fruit with significantly higher (P less than or equal to0.01) total soluble solids concentration than did those that were honey bee supplemented. Possible reasons for the reduced mean fruit weight under honey bee saturation are discussed.