pdf, 57.71Mb - Entomological Society of Canada

90 R. J. McClanahan
Releases and Recoveries
Table 15
Evaluation of Control Attempts
The use of E. fonnosa for whitefly control is so extensive that it is difficult to estimate
the numbers released (Table 15). In the early 19705 production and distribution were
handled by the Harrow Research Station. Parasitized whiteflies on tobacco leaves were
packaged in lots estimated to contain 2, 5, or 10 thousand.
A number of small businesses have been involved in E. fonnosa production and sales.
Greenhouse Bio-Controls (1972-77) mainly supplied hobby greenhouse owners, with
most sales to points in the United States. In 1973 and 1974 Greenhouse Bio-Controls
supplied some of the needs of the Ontario Greenhouse Vegetable Producers' Marketing
Board (OGVPMB) members, with 650000 and 947 000 parasitoids sold to the Board and
distributed by them. This accounts for the increased Canadian distribution from this
source in those years. In 1974-75, OGVPMB contracted E. formosa production to a
grower, but that was not as successful as a subsequent arrangement whereby they
provided partial salary for a technician supervised by Ontario Ministry of Agriculture
and Food, with the rearing done in an isolated greenhouse at the Harrow Research
Station.
Releases of Encarsia formosa Gahan in Canada against Trialeurodes vaporariorum
(Westwood).
Source Numbers released- (thousands)
1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980
Harrow Research Station 10 150 943 3133 2148 1485 1157 6 IS 12 19
Greenhouse BiD-Controls 14 886 1028 47 41 81
OGVPMB" 500 750 2065 2160 lOSS 1265 550
Beller Yield Insects 2S 40
Applied Bio-Nomics 450 1750 588
* Parasitized whitefly pupae from which there is 90-98% emergence of adult parasitoids.
** Ontario Greenhouse Vegetable Producers' Marketing Board.
In 1979 a similar arrangement was set up in British Columbia so growers there and in
Alberta are supplied with E. formosa from Applied Bio-Nomics Ltd. The rearing
facilities were supplied by Agriculture Canada and technical support was given by the
British Columbia Department of Agriculture.
Better Yield Insects was recently established in Ontario to produce and sell E.
fonnosa and other biological control agents_ This source serves mainly hobby greenhouse
owners in the United States, but plans were made to supply greenhouse vegetable
growers in Ontario through OGVPMB, in 1981.
Most releases have resulted in establishment, as judged by the very few failures
reported. There have been cases where parasitoids were eliminated by an insecticide
application, but with just one spray they have survived in the pupal stage and continued
to multiply on the surviving whiteflies.
The overall incidence of whitefly in Essex County has been reduced to the point where it
is no longer a limiting factor in greenhouse tomato and cucumber production, and it is
seldom a problem on field vegetables. E. formosa are easily found outdoors every
summer.