Incidence of immigration in spruce budworm Choristoneura fumiferana (Lepidoptera: Tortricidae) was inferred with rules of thumb and numerical thresholds contrasting closed populations (residents >> migrants) versus populations subjected to major immigration event, based on attributes of daily time series of abundance at light traps (abundance, statistical mode, sex ratio and protandry level). The data set included time series with known migration event (Bas St‐Laurent, QC, 2013), which were used to calibrate numerical thresholds associated with immigration. The study site on west coast of Newfoundland provided a natural laboratory to infer long‐range immigration due to geographic isolation from the mainland, proximity to the coast and low population density at onset of the study. Time series between 2014 and 2016 exhibited trends consistent with scenario of closed population, including low numbers of budworms, limited variation in day‐to‐day abundance and strong level of protandry (males fly seasonally earlier than females). Time series with candidate major immigration event (Bas St‐Laurent 2013, Sally's Cove 2017, 2018) displayed specific combinations of parameters, including: (a) sharp increment (>one order of magnitude) in abundance of both males and females from one day to the next (statistical mode, approximately corresponding to timing of migration); (b) pure (100%) convergence of pulse detection interval (post‐immigration period when migrants with nonzero survival rate are collected at light traps) across traps for males and females and (c) overall absence of protandrous flight. Parameters related to immigration thresholds highlighted that females are more likely to migrate than males, as indicated by increased ratio of females per male during pulse detection interval. Aerial collection of adult spruce budworms with helikite in 2019 confirmed the preponderance of females among true migrants.

A 3-year study (2014)(2015)(2016) was conducted at Rocky Harbour near the west coast of Newfoundland, Canada, to record the abundance and phenology of adult spruce budworms captured at traps, using a factorial design (light traps and pheromone traps deployed contiguously or segregated spatially). Budworms were most abundant and occurred seasonally earlier in 2014 than in 2015 and 2016; these findings held generally true for males and females. The geographic setting of Newfoundland (large island isolated from the mainland by an oceanic barrier of >100 km across) provides an ideal location to discriminate local flight from long-range immigrations; in our study, however, immigrations cannot be ruled out for any single day of trapping due to broad overlap in emergence patterns at Rocky Harbour relative to forest stands with known populations of budworms on the mainland. Based on moderate daily variation in adult abundance, however, major immigration events (defined as external deposition of budworms with large numerical amplitude) likely did not take place at Rocky Harbor between 2014 and 2016. Males were more abundant at light traps coupled with pheromone traps, whereas abundance of males at pheromone traps was similar with or without contiguous light traps. This outcome may be mediated by lower range of attraction for light traps (usually <100 m) and (generally assumed to be several hundreds of meters). Females were equally abundant at light traps with or without pheromone traps. As expected, males were captured earlier in the season at pheromone traps than at light traps, and females occurred later in the season due to protandry. The onset of flight observed at light traps or pheromone traps in 2015 and 2016 occurred 10-15 days later than simulated predictions; caution is thus warranted as to conclusions derived on computer modeling of adult emergence.

Lethal and sublethal effects of Neemix 4.5 EC, a commercial neem preparation, on balsam fir sawfly, Neodiprion abietis (Harris), were determined in the laboratory. Larval mortality of N. abietis increased in a concentration-dependent manner, and lethal time decreased with increasing Neemix 4.5 EC concentration. Fifty percent of the larvae died after 4.6 d at a concentration of 90 ppm azadirachtin (AZA) and 12.3 d at a concentration of 0.08 ppm. Neemix 4.5 EC showed some deterrent effects to feeding site selection on N. abietis larvae at high concentrations, but not at low concentrations. Strong reduction of food intake by N. abietis larvae after exposure to Neemix 4.5 EC was demonstrated by significant reduction of frass production. Larvae fed on Neemix 4.5 EC-treated foliage at 90 ppm AZA produced only 16% as much frass as that produced by larvae fed on control foliage (0 ppm). Neemix 4.5 EC at a concentration of 0.08 ppm AZA retarded larval and pupal development. Sublethal doses significantly reduced pupal weight and adult emergence, although the sex ratio of N. abietis adults was not affected. Results indicate that sublethal effects of Neemix 4.5 EC on N. abietis may contribute greatly to the overall field efficacy.