INFLUENCE OF DIET ON REPELLENT AND FEEDING-DETERRENT ACTIVITY OF LARVAL ORAL EXUDATE IN SPRUCE BUDWORMS (LEPIDOPTERA: TORTRICIDAE)

2000 ◽  
Vol 132 (1) ◽  
pp. 81-89 ◽  
Author(s):  
L.M. Poirier ◽  
J.H. Borden

AbstractA two-choice feeding bioassay was used to investigate the effects of larval source (colony versus wild larvae) and rearing medium (artificial versus foliar diet) on the feeding-deterrent activity of the oral exudate of the spruce budworm and the western spruce budworm, Choristoneura fumiferana (Clem.) and Choristoneura occidentalis Free., respectively. Feeding by both wild and colony larvae was deterred by conspecific oral exudate. Larvae reared on artificial diet responded to exudate from both diet- and foliage-reared larvae, whereas the foliage-reared larvae responded only to exudate from other foliage-reared larvae. These results suggest that differences exist between artificial diet- and foliage-reared larvae in the composition of oral exudate, in the concentrations of its biologically active constituents, or in differential sensitivity of diet- and foliage-reared larvae to exudate from foliage-reared larvae.

2011 ◽  
Vol 143 (4) ◽  
pp. 384-387 ◽  
Author(s):  
L.M. Poirier ◽  
J.H. Borden

AbstractA choice feeding bioassay was used to investigate the effects of artificial diet components on the repellency of larval oral secretions from western spruce budworm, Choristoneura occidentalis Freeman, to conspecific larvae. Oral secretions from insects fed on agar supplemented with linseed oil were as repellent as secretions from insects fed on complete artificial diet. Secretions from insects fed on agar alone, agar and casein, or agar and wheat germ were not significantly more repellent than distilled water; neither was linseed oil alone. Linseed oil consists of glycerides of several fatty acids, which are likely metabolized quickly in the insect gut; repellency of oral secretions could be due to any of the related fatty acids or metabolites.


1972 ◽  
Vol 104 (3) ◽  
pp. 417-426 ◽  
Author(s):  
R. L. Lyon ◽  
C. E. Richmond ◽  
J. L. Robertson ◽  
B. A. Lucas

AbstractThe western spruce budworm, Choiistoneura occidentalis Freeman, which normally passes through an obligate diapause in nature, was reared in the laboratory without diapause. The critical factor for preventing diapause appeared to be the physical environment presented to the first stage larvae. The response of C. occidentalis was flexible. The 2nd stage larvae could be made to diapause or forego diapause, depending on their rearing experience in the first stage. By eliminating diapause it was possible to rear about 7½ generations per year as against about 2¼ under normal diapause conditions. The diapause of the jack-pine budworm, C. pinus pinus Freeman, and C. lambertiana californica Powell, could be prevented by the same technique. The diapause of the spruce budworm, C. fumiferana (Clemens), could not be eliminated except after several generations of selection.


1982 ◽  
Vol 8 (2) ◽  
pp. 339-350 ◽  
Author(s):  
H. T. Cory ◽  
G. E. Daterman ◽  
G. D. Daves ◽  
L. L. Sower ◽  
R. F. Shepherd ◽  
...  

1992 ◽  
Vol 124 (2) ◽  
pp. 347-358 ◽  
Author(s):  
Roy F. Shepherd

AbstractIndividual larvae of western spruce budworm (Choristoneura occidentalis Freeman) were observed from overwintering emergence to pupation at six locations spread over a wide range of altitudes and thus climate. A weekly census of 100 lower-crown buds per plot indicated large differences in rates of bud development and larval survival among locations.Emerging second-instar larvae attempted to mine swelling buds of Douglas-fir. If the buds were hard and tight, larvae mined 1-year-old needles until penetrable buds were available. Larvae dispersed over the crowns with only one larva becoming established in each bud; thus, many early-emerging and surplus larvae could not find suitable feeding sites and disappeared. Within the protective bud, survival was high. After buds flushed and larvae became exposed, densities dropped, probably due to increased predation and decreased food quality. Correlations indicated a close association between larval survival for the exposed period between bud flush and pupation, and overall larval survival.Douglas-fir trees responded to initial bud removal, but not to needle removal, by inducing latent buds in the axils of needles to grow into active vegetative buds ready to develop and flush the next spring. The number of these new vegetative buds formed was greatest when the initial buds were removed early in the season before flush, and decreased thereafter. Trees with vigorous crowns had the greatest response to defoliation by inducing the largest number of latent buds into becoming active vegetative buds; these were found mainly on the 2- and 3-year-old internodes.


1977 ◽  
Vol 109 (9) ◽  
pp. 1153-1158 ◽  
Author(s):  
J. Wayne Brewer ◽  
J. O’Neal

AbstractThe insecticide acephate (0.5-dimethyl acetyl phosphoramidothioate) was applied at 0.5, 1.0, and 1.5 lb A.I./gal (.058, 0.118, 0.179 kg/l.) in aqueous solution to individual Douglas-fir trees infested with western spruce budworm, Choristoneura occidentalis Freeman, larvae in central Washington using hand held ground application equipment. Application was made when larvae were in the needle mining – bud mining stage at rates ranging from 2.58 to 5.10 gal/acre (3.97 to 7.84 l./ha). For all three concentrations, mortality of larvae inside needles was 94–98% after 1 day compared with a check mortality of 18% and larval mortality inside buds was 99% after 1 day compared with 23% for the check. Regression analyses indicated that defoliation was positively correlated with the number of needles mined the current year and per cent punctured buds, and negatively correlated with larval mortality inside both needles and buds. The data suggest that when applied at the rates used, acephate has some type of systemic action and can provide foliage protection during the year of application.


1982 ◽  
Vol 114 (1) ◽  
pp. 89-91 ◽  
Author(s):  
A. Moore ◽  
O. N. Morris

Bioassays of Bacillus thuringiensis (Bt.) are commonly performed by applying a serial dilution of the test sample to either foliage or artificial diet (Burges and Thompson 1971). In these assays the ingested dose is not measured directly, but is assumed to be proportional to the concentration of the sample applied to the diet. This assumption is valid only if the total amount of food ingested during the experiment is the same at all dosage levels. However, this assumption may not be true because Bt. inhibits feeding of some lepidoptera larvae (Burges and Thompson 1971). Furthermore, artificial diets usually contain nutrients and possibly antimicrobial agents which may interact with Bt.


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