Articles
Onion maggot and onion thrips over forty years of integrated pest management
Article number
1398_15
Pages
109 – 116
Language
English
Abstract
An integrated pest management (IPM) program for onions began as a pilot project in the Holland Marsh, Ontario, Canada, in 1980. The IPM program has continued, with a few breaks, since then.
The main onion insect pest in 1980 was onion maggot (Delia antigua). Cutworms (Nocutidae) and onion thrips (Thrips tabaci) were considered occasional pests.
Cutworms continue to be an occasional and minor pest.
Onion maggot flies were monitored with yellow sticky traps and damage was assessed in grower fields.
Onion fly populations have decreased over time.
Population highs were over 100 flies per trap per day in 1981, with most fields having over 20 trap-1 day-1. In 2021, the highest onion fly counts on yellow sticky traps were 12 trap-1 day-1 and most fields had less than 5 trap-1 day-1. Insecticide foliar sprays were applied to control onion flies in the 1980s.
Currently, seed treatments, cyromazine or clothianidin and imidacloprid are used for onion maggot.
The reduction in onion fly populations is interesting, but the current levels can still cause over 50% damage in untreated onions.
With few tools currently available for control, the registration of additional seed treatment or in-furrow insecticides in Ontario, Canada is important for resistance management.
Onion thrips are scouted twice a week and are usually active from mid-June to the end of August.
The spray threshold for thrips was increased from one to three thrips per leaf, as the newer insecticides spirotetramat and spinetoram are very effective.
In 2021, thrips counts were below the spray threshold for most onion fields throughout the season.
The IPM program, in combination with effective insecticides, has reduced the populations of insect pests and the amount of insecticides applied to onions over the growing season.
Scouting for onion maggot flies and thrips continues to provide valuable information for onion growers in the Holland Marsh.
The main onion insect pest in 1980 was onion maggot (Delia antigua). Cutworms (Nocutidae) and onion thrips (Thrips tabaci) were considered occasional pests.
Cutworms continue to be an occasional and minor pest.
Onion maggot flies were monitored with yellow sticky traps and damage was assessed in grower fields.
Onion fly populations have decreased over time.
Population highs were over 100 flies per trap per day in 1981, with most fields having over 20 trap-1 day-1. In 2021, the highest onion fly counts on yellow sticky traps were 12 trap-1 day-1 and most fields had less than 5 trap-1 day-1. Insecticide foliar sprays were applied to control onion flies in the 1980s.
Currently, seed treatments, cyromazine or clothianidin and imidacloprid are used for onion maggot.
The reduction in onion fly populations is interesting, but the current levels can still cause over 50% damage in untreated onions.
With few tools currently available for control, the registration of additional seed treatment or in-furrow insecticides in Ontario, Canada is important for resistance management.
Onion thrips are scouted twice a week and are usually active from mid-June to the end of August.
The spray threshold for thrips was increased from one to three thrips per leaf, as the newer insecticides spirotetramat and spinetoram are very effective.
In 2021, thrips counts were below the spray threshold for most onion fields throughout the season.
The IPM program, in combination with effective insecticides, has reduced the populations of insect pests and the amount of insecticides applied to onions over the growing season.
Scouting for onion maggot flies and thrips continues to provide valuable information for onion growers in the Holland Marsh.
Publication
Authors
M.R. McDonald, K. Vander Kooi, T. Blauel
Keywords
Delia antiqua, Thrips tabaci, action thresholds, crop scouting, IPM, climate change
Groups involved
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