Canadian Forest Service Publications

A 2 year study of virus chemical insecticide combination in the integrated control of the spurce budworm, Choristoneura fumiferana (Tortricidae: Lepidoptera). 1974. Morris, O.N.; Armstrong, J. A., Howse, G. M.; Cunningham, J.C. Canadian Entomologist 106:813-824.

Year: 1974

Issued by: Great Lakes Forestry Centre

Catalog ID: 33297

Language: English

Availability: PDF (request by e-mail)

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Abstract

During 1872, spruce budworm infested white spruce and balsam fir trees were sprayed aerially with a low dose of fenitrothion (0.25 oz AI/ac), entomopox virus (EPV) at 7.6 x 10" plyhedra/ac, nuclear polyhedrosis virus (NPV) at 2.7 x 10 plyhedra/ac, or each virus-fenitrothion combination. Fenitrothion (active ingredient), NPV< and EPV deposited at ground level at 5%, 31%, and 42%, respectively, of the amounts emitted. In the year of application, NPV + fenitrothion was highly effective in population reduction and foliage protection especially on balsma fir although a higher virus infection rate was found on white spruce3 than on balsam fir. EPV + fenitrothion also provided a high level of foliage protection apparently reduced surviving female: male sex ration to 1:2 compared with the normal 1:1 ratio. NPV+ insecticide cause highest larval mortality, highest incidence of virus, lowest rate of moth emergence, fewest progeny, and lowest rate of progeny survival. The natural incidence of microsporidia wa s low in all plots. In the year following application, the NPV + insecticide treated plot agian showed lowest population density, highest larval mortality and incidence of virus, and low defoliation and egg mass density. However, there was a higher proportion of viable eggs deposited than in the previous year. Egg parasitism by Tricholgramma minutum increased by 1.5 to 4.2% in plots treated with virus only and declined by 1.6 to 10.5% in insecticice treated pots and by 1.2% in untreated check plot. The transmission of the virus fromone year to the next is considered to be of paramount importance in the future use of this pathogen in spruce budworm control.