Page 13 - Volume 2,Issue 2, July 2009

Hellenic Plant Protection Journal

2:

57-66, 2009

Effectiveness of

Apis mellifera

and

Bombus impatiens

as

dispersers of the Rootshield® biofungicide (

Trichoderma

harzianum

, strain T-22) in a strawberry crop

S. Albano

1

, M. Chagnon

2,3

, D. de Oliveira

2

, E. Houle

3

, P.O. Thibodeau

†

and A. Mexia

4

Summary

Two experiments were performed in Québec (Canada), in the field and in a greenhouse,

to assess the effectiveness of

Apis mellifera

L. and

Bombus impatiens

Cresson

(Hymenoptera: Apidae) in

transmitting

Trichoderma harzianum

Rifai, strain T-22, to strawberry flowers from hives-mounted dis-

pensers containing the biofungicide Rootshield®. The number of Colony Forming Units (CFU) of

T. har-

zianum

was determined: (i) on bees exiting from hives-mounted dispensers containing the biofungi-

cide; (ii) on foragers visiting the strawberry flowers; (iii) on open flowers exposed to pollinator visits;

(iv) on flowers that had only one visit, and (v) on flowers without visits. The results showed that both

honey bees and bumble bees have the potential to get dusted with

T. harzianum

from the Houle-dis-

pensers and disperse the biofungicide to the flowers. The assay with bumble bees allowed to obtain

positive correlations between the CFU per bumble bee and the CFU per flower and also, between the

length of visit and the CFU per flower. The density of inoculum that was deposited after one single vis-

it of honey bee or bumble bee was also determined. Advantages and limitations of the used hive-dis-

pensers were identified for future improvements.

Additional keywords

: bumble bees, disseminators, honey bees, inoculum dispenser

Introduction

The use of pollinator insects to disperse bi-

ological control agents is a relatively recent

technique, which has been tested in sever-

al scientific works since 1990. The technique

has already been tested for the control of

several pests affecting diverse agricultur-

al crops (2, 7, 11, 14, 16, 23, 30, 31). The pol-

linators mainly used were honey bees and

bumble bees as they have hives easier to

manipulate although, more recently, these

types of studies have been using other spe-

cies such as

Osmia cornuta

Latreille (Hy-

menoptera: Megachilidae)

(22). This new

technique makes pollinators useful by two

means which influence productivity of

crops: pollination and crop protection. This

method can be a practical option for grow-

ers working under integrated and biological

pest management requirements (20).

Historically, however, this biocontrol

method has mostly been used to fight grey

mould (

Botrytis cinerea

Persoon: Fries), which

is the main fungal pathogen affecting ber-

ry fruit crops like strawberry (17, 18, 19, 25,

27, 29).

Since in this pathosystem the flow-

er serves as an infection site (6), the

disper-

sal of a control agent directly to the flowers

against this pathogen thus explains the suc-

cess of this technique on this crop. Further-

more, the use of bee colonies to assure a bet-

ter pollination of strawberry is a common

practice among farmers since several stud-

1

INRB – Instituto Nacional dos Recursos Biológicos (L.-

INIA). Unidade de Protecção das Plantas. Quinta do

Marquês, Nova Oeiras, 2784-505 Oeiras, Portugal.

2

UQAM - Université du Québec à Montréal Départe-

ment des sciences biologiques, C.P. 8888, Succ. Cen-

tre-ville, Montréal (Québec), Canada, H3C 3P8.

3

CRSAD - Centre de Recherche en Sciences Animale de

Deschambault, 120A Chemin du Roi Deschambault,

(Québec), Canada, G0A 1S0.

†

IRDA - Institut de Recherche et de Développement en

Agroenvironnement, Complexe Scientifique, 2700,

rue Einstein, Québec, Canada, G1P 3W8.

4

ISA - Instituto Superior de Agronomia, Secção de Pro-

tecção Integrada (SAPI)/ Departamento de Protecção

das Plantas e de Fitoecologia (DPPF), 1349-017 Tapa-

da da Ajuda, Lisboa, Portugal.

Corresponding author:

silviamalbano@yahoo.com