Publications by S. Holmes

Temporal variations in abiotic conditions exert little influence on diurnal activity of late-instar spruce budworm larvae on balsam fir

Thu, 28 Jun 2012

Spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), larvae can cause extensive defoliation in balsam fir (Abies balsamea [Linnaeus] Miller) and exhibit high temporal and spatial variability in individual behaviour. We gathered field data to determine the influence of daily and hourly variation in abiotic conditions on daytime activity patterns of late-instar budworm lavae on balsam fir. In both years of our study, less than 10% of larvae were observed feeding during the daytime. Most larvae observed were either resting, spinning silk, or roaming, although the proportion of individuals engaged in each activity varied between years, with more larvae in the first year roaming (48%) and in the second year either resting (38%) or spinning silk (42%). Daily and hourly variation in abiotic conditions had a limited influence on activity patterns. Our results indicate that in nature, mid- to late-instar budworm larvae maintain fairly consistent activity patterns across a wide range of abiotic conditions. We suggest that site-specific conditions, such as variation in host-plant quality and/or budworm population density, may be more important than weather in determining the relative frequencies of different larval activities in space and time.

Aerial application of nucleopolyhedrovirus induces decline in increasing and peaking populations of Neodiprion abietis

Fri, 29 Apr 2005

The potential role of diseasesin generating population cycles has often been advocated but has received little experimental support from the field. We introduced a nucleopolyhedrovirus (NeabNPV) into field populations of Neodiprion abietis (Harris), the balsam fir sawfly, to determine its role in the collapse of outbreaks and examine its potential for biological control. This was accomplished through the use of aerial applications of NeabNPV on increasing, peaking, and declining populations of its host. Results indicate that N. abietis densities were distinctly lower in the generation following an aerial application of NeabNPV, but only when treatments were directed against increasing or peaking populations. When directed against declining populations, NeabNPV applicatins apparently did not influence the natural collapse of outbreaks. Although the artificial introduction of NeabNPV did not consistenly affect densities of the treated generation, it had an effect on host biology in the weeks following the treatment as the incidence of NeabNPV infection increased and frass production (concomitant with larval feeding) decreased in treated areas. This study supports the hypothesis that NeabNPV epizootics initiate the decline of N. abietis populations. Our results also indicate that NeabNPV may provide an effective tactic to suppress increasing or peaking population outbreaks of N. abietis through the use of aerial applications of NeabNPV at rates as low as 1 X 10,000,000,000 polyhedral occlusion bodies per hectare.

Residual toxicity and droplet characteristics of Dipel formulations in spruce budworm microhabitat and on artificial surfaces after aerial application

Fri, 21 Jul 2000

Heterogeneity of spray deposit and efficacy within a single swath applied by aircraft over forest infested with spruce budworm, Choristoneura fumiferana (Clem.)

Fri, 21 Jul 2000

A preliminary report on the impact of aerially applied Zectran (Mexacarbate) insecticide on brain cholinesterase (CHE) activity of forest songbirds in New Brunswick, Canada. FPMI File Report 61.

Thu, 12 Jul 2012