Increasing spruce budworm defoliation increases catchment discharge in conifer forests.

Forest insect outbreaks cause significant reductions in the forest canopy through defoliation and tree mortality that modify the storage and flow of water, potentially altering catchment runoff and stream discharge patterns. Despite a growing understanding of the impacts of insect outbreaks on the hydrology of broadleaf forests, little is known about these impacts to catchment hydrology in northern conifer-dominated forests. We measured the effects of cumulative defoliation by spruce budworm (Choristoneura fumiferana) on stream discharge and runoff in 12 experimental catchments (6.33-9.85 km2) across the central Gaspé Peninsula in eastern Québec, Canada over a three-year period (2019-2021). Six catchments were aerially treated with BtK (Bacillus thuringiensis kurstaki) insecticide to suppress the outbreak and six catchments were left untreated, leading to a defoliation gradient across the study sites. Stage-discharge relationships were established between June and October from 2019 to 2021. Stream volumetric discharge (r = 0.71, p < 0.01, t(34) = 5.85), runoff (r = 0.55, p < 0.01, t(34) = 3.81) and runoff ratios (r = 0.67, p < 0.01, t(33) = 5.19) were all strongly positively correlated with cumulative defoliation intensity, likely by reducing available water storage in the catchment and therefore enhancing runoff generation. Seasonally, volumetric discharge, runoff, and runoff ratios were more strongly correlated with defoliation in the summer than autumn months, likely because available catchment storage was more limited following the freshet. Overall, we found that insect defoliation impacts forested catchment hydrology similar to other landscape disturbances, and such consequences should be considered in forest management and the control of forest insect outbreaks.

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Measurement of serum antibody in swine vaccinated with Bordetella bronchiseptica: comparison of agglutination and enzyme-linked immunosorbent assay methods.

The immune responses of 514 pigs from 5 swine breeds (Chester White, Duroc, Hampshire, Landrace, Yorkshire) to vaccination with Bordetella bronchiseptica were measured by agglutination and enzyme-linked immunosorbent assay (ELISA) methods. Both assays showed higher antibody levels in sera of pigs after vaccination than in sera of the pigs before vaccination. The variability of the responses among breeds was greater for the agglutination method than for the ELISA method. The ELISA proved to be more sensitive than the agglutination method and could detect antibody in serum samples diluted at least 100-fold more than those used in the agglutination procedure. The correlation of antibody titers obtained by the 2 methods was small, but statistically (P less than 0.01) significant. The ELISA should be useful for determinations of antibody responses of swine to B bronchiseptica.

Breed and swine lymphocyte antigen haplotype differences in agglutination titers following vaccination with B. bronchiseptica.

Genetic differences in immune response to B. bronchiseptica after vaccination with a commercial B. bronchiseptica bacterin were investigated in 1,069 8-wk-old pigs. These pigs were from 65 litters born in the spring and 66 litters born in the fall of 1982 and were purebreds from the Chester White (n = 128), Duroc (n = 281), Hampshire (n = 143), Landrace (n = 309) and Yorkshire (n = 208) breeds. Each litter was raised separately. Individual pigs were vaccinated im at 4 and 6 wk of age with 2 ml of B. bronchiseptica bacterin. At 8 wk of age, 8 ml of blood were collected from each animal and serum prepared to determine agglutinating antibody titers against B. bronchiseptica bacterin by a bacterial agglutination method. In addition, lymphocytes were separated from 1 ml of heparinized blood and used to determine Swine Lymphocyte Antigen (SLA) haplotypes by using cytotoxic antibodies against the SLA complex. Antisera for 3 SLA haplotypes were made available by the National Institutes of Health. Results indicated that breed of pig (P less than .01) and dam of pig (P less than .01) affected the immune response of the pig after B. bronchiseptica vaccination. Higher immune response was also associated (P less than .05) with one of the SLA haplotypes tested. Heritability estimates for immune response following vaccination were .10 +/- .12 (half-sib) and .42 +/- .19 (full-sib). Results suggest that the relationship of the SLA complex to immune response in the pig and nonadditive genetic and maternal effects on immune response should be further investigated.