Monitoring Nontarget Lepidoptera onRibes cereumto Investigate Side Effects of an Operational Application ofBacillus thuringiensissubsp.kurstaki

Wood production, wood technology, and biotechnological impacts

“…Monitoring in forests in British Columbia treated with Btk to control the western spruce budworm, for example, revealed negative effects also on nontarget Lepidoptera (Boulton et al 2002, Boulton 2004, Boulton & Otvos 2004. To exclude unwanted effects by freely spraying on uninvolved insects, newer developments make use of the bacterial endotoxin genes.…”

Monitoring native non-target Lepidoptera for three years following a high dose and volume application ofBacillus thuringiensissubsp.kurstaki

“…Immature Lepidoptera were collected by beating R. cereum foliage above a 2 m 6 3 m white sheet according to the protocol described by Boulton et al (2002). Sampling was restricted to R. cereum 1 ( 5 1 m tall) because this shrub is easy to sample, it generally grows in the open where Btk spray penetration is likely to be highest, and it hosts large numbers of immature Lepidoptera in the early spring when Btk is applied against western spruce budworm (Boulton et al, 2002).…”

“…Sampling was restricted to R. cereum 1 ( 5 1 m tall) because this shrub is easy to sample, it generally grows in the open where Btk spray penetration is likely to be highest, and it hosts large numbers of immature Lepidoptera in the early spring when Btk is applied against western spruce budworm (Boulton et al, 2002). The 25 min sampling effort included clipping the branches with pruning shears and striking the branches hard against a 1 m long steel pole over a 3 6 2 m white nylon sheet.…”

“…Several studies have reported that Btk treatments applied during early spring can cause immediate reductions in the population density of susceptible immature nontarget Lepidoptera (Miller, 1990(Miller, , 1992Sample et al, 1996;Wagner et al, 1996). Boulton et al (2002) found a similar decline of immature Lepidoptera on the shrub Ribes cereum Douglas (Grossulariaceae) following an operational spray program (30 BIU/ha in 2.4 L ha 7 1 ) targeting the western spruce budworm. Although the entire Lepidoptera guild on R. cereum, and two species within the guild-Gelechia ribesella Chambers (Gelechiidae) and Euhyponomeutoides gracilariella Busck (Yponomeutidae)-appeared to recover within 2 years of treatment, there are concerns that recovery may take longer if Btk is applied at a higher dose and volume.…”

“…Therefore, we compared our results with those of Boulton et al (2002), in which the non-target effects of an operational Btk application at the registered dose was assessed from 1998 -2000 in the same general area. Both studies used the same protocol for insect collection and were conducted in similar interior Douglasfir habitats near the town of Merritt, B.C.…”