ECONOMICS OF INSECTICIDAL CONTROL OF FLEA BEETLES (COLEOPTERA: CHRYSOMELIDAE) ATTACKING RAPE IN CANADA

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Abstract
The costs and benefits of insecticidal control and the losses attributable to flea beetle damage are estimated for oilseed rapes in Canada. Analyses of two farm surveys and reports on the efficacies of the various control practices conducted in test plots led us to calculate three sets of estimates based on different assumptions. Four-fold differences are observed between the lowest and highest estimates. The lowest estimates are adopted as the most realistic. The estimated losses were $72 million in 1979, 8% of the annual production. In 1979 growers spent about $12 million on insecticidal control which saved about $44 million worth of production. We conclude that flea beetle damage to rape causes an average annual yield loss of about 10% and is higher in Manitoba than Saskatchewan. The damage levels estimated from small test plots are higher, on average, than those in commercial fields, which accounts for most of the differences among estimates.