Page 15 - Volume 2,Issue 2, July 2009

© Benaki Phytopathological Institute
Honey bees and bumble bees as dispersers of a biofungicide 59
dependent from each other. The fungicide
container (drawer) can be removed and re-
placed in order to be emptied and cleaned
without effort.
A small dispenser that is adjustable to
commercial bumble bee hives was also de-
veloped by Emile Houle, based on work
by Kovach et al. (17). Following preliminary
tests, it was also modified in order to allow
bees to exit and enter the hive by separate
paths (Figure 2) therefore avoiding fungi-
cide to be carried inside the hive. Addition-
al procedures were later carried out in or-
der to assure a better adaptation of bumble
bees to the dispensers: (i) the area surround-
ing the entrance holes were coloured in yel-
low (A’) (Figure 2) in order to help the insects
to detect and remember their location, and
(ii) the dipensers were installed on the very
first day the hives were open. Koppert hives,
used in our experiments, have an one-way
door for entries (A) and a two-way door for
entries and exits (B) (Figure 2). Following the
application of the above mentioned proce-
dures, bumble bees were observed always
entering door A’ and exiting door B’ (Figure
2).
2. Experimental procedure
The assays for both honey bees and
bumble bees took place in Québec, Can-
ada, during June and July 2005. The hon-
ey bee assay was done at Île d’Orléans, and
at the Saint-Lambert Experimental Station
(IRDA). Four honey bee [Apis mellifera L. (Hy-
menoptera: Apidae)] hives with 20 frames
each were placed at about 50 meters from
the 1 ha experimental strawberry [Fragar-
ia × ananassa Duch. (Rosaceae)] fields with
the cultivar Seascape. The beehives at the
Saint-Lambert Experimental Station were
used only for the capture of honey bees ex-
iting from hives-mounted dispensers con-
taining T. harzianum. The bumble bee as-
say took place in July 2005 in a greenhouse
(80 m2) at the IRDA (Institut de Recherche et
Développement en Agroenvironnement), in
which a Koppert commercial hive for bum-
ble bees [ Bombus impatiens Cresson (Hy-
menoptera: Apidae)] was installed. The cul-
tivar used was also Seascape.
The methodological approaches were
similar for both the field and greenhouse
activities as well as for the laboratory pro-
cedures. In order to allow a better adapta-
tion of the bees, empty dispensers were fas-
tened to the hives a few days before the
experiments begun.
2.1. Fieldwork
All the dispensers used in the experi-
ments were filled on a daily basis with the
biocontrol agent T. harzianum, strain T-22
(commercial label: Rootshield®, BioWorks,
Inc). Every morning, when the weather con-
ditions were favourable for bee activity,
the dispensers in the honey bee and bum-
ble bee hives were filled with 6g and 2g of
the biofungicide, respectively. The biofun-
Figure 2. Houle-dispenser adapted to com-
mercial hives for bumble bees. A - colony box
entrance, B - colony box entrance/exit, A’- dis-
penser entrance, B’- dispenser exit.
Figure. 1. Houle-dispenser adapted to hives
for honey bees [drawing by Jocelyn Boulianne
in Chagnon et al. (10)].