The Canadian Entomologist 129: 871 -885 (1997) Ingestion of 0.1 yg of RH-5992, tebufenozide, by early 6th instar larvae of the spruce budworm, Choristoneura furniferana (Clem.), prior to the appearance of the ecdysone peak in the hemolymph, resulted in the induction of a precocious incomplete moult that was lethal. The larvae stopped feeding within 8 h post ingestion and remained quiescent just as they do in preparation for a normal moult. Head capsule slippage started at 12 h post ingestion, became pronounced by 24 h, and by 48 h an untanned new head capsule was visible behind the old one. The lack of tanning of the new cuticle was due to the failure of dopadecarboxylase gene expression. Although the old cuticle was loose around a the entire body, indicating that apolysis had occurred, there was no evidence of ecdysis of the old cuticle, suggesting that eclosion hormone was probably not released. Earlier instars required a lower dose than the later ones to elicit an "all or none" type of moulting response. The most effective routes of entry were by intrahemocoe8c injection, followed by ingestion. Topical application was effective only when nonaqueous carriers such as acetone or dimethyl sulfoxide were used. The larvae were unable to discriminate between treated and untreated diet over a 48-h period. The transcription factor, Choristoneura hormone receptor 3, which is normally expressed at the onset of the hemolymph ecdysone peak, was expressed in the epidermis 1 h post ingestion of RH-5992, reached a peak level by 3 h, and became undetectable by 24 h, confirming that this analogue acts through the ecdysone receptor system. Greenhouse tests using potted white spruce trees sprayed with RH-5992 and colonized with 4th-instar spruce budworm indicated that field dosages of 35,70,140, and 280 glha would all be effective. Ground spray trials conducted in a spruce budworm infested white spruce stand in Zec Casault, GaspC, Quebec, using a backpack sprayer showed that 270 glha of RH-5992 reduced the insect population by 100% with very little defoliation and was better than ~hlorfluazuron@ (an analogue of the chitin synthesis inhibitor, diflubenzuron or ~i m i l i n @ ) treatment, which was used as a positive control. The unique mode of action of this ecdysone agonist and its effectiveness as an environmentally benign control agent for the spruce budworm are discussed.

Outbreaks of the hemlock looper, Lambdina fiscellaria (Gueneé), are characterized by rapid increase and patchy distribution over widespread areas, which make it difficult to detect impending outbreaks. This is a major problem with this insect. Population forecasting is based on tedious and expensive egg surveys in which eggs are extracted from 1-m branches; careful observation is needed to avoid counting old unhatched eggs of previous year populations. The efficacy of artificial substrates as oviposition traps to sample hemlock looper eggs was tested as a means of improving outbreak detection and population forecasting. A white polyurethane foam substrate (1,095 lb/ft3) used with the Luminoc insect trap, a portable light trap, was highly efficient in sampling eggs of the hemlock looper. Foam strips placed on tree trunks at breast height were less efficient but easier and less expensive to use for the establishment of extensive survey networks. Estimates based on oviposition traps were highly correlated with those obtained from the 1-m branch extraction method. The oviposition trap is a standard, inexpensive, easy, and robust method that can be used by nonspecialists. This technique makes it possible to sample higher numbers of plots in widespread monitoring networks, which is crucial for improving the management of hemlock looper populations.

Larval populations of gypsy moth were monitored from June through July 1980 in southwestern Quebec, the northern edge of the insect's North American range. Larval activity on a total of 1870 trees representing 29 tree species was studied at 13 different sites. At least some gypsy moth larvae were found on all tree species, but different larval preferences for the available host trees were evident. Gypsy moth larvae preferentially attacked Quercusrubra L., Amelanchier spp., Populusgrandidentata Michx., Salix sp., and Ostryavirginiana (Mill) K. Koch. The larvae generally avoided members of the genus Fraxinus, Acernegundo L., A. pensylvanicum L., A. rubrum L., A. saccharinum L., Betulalutea Michx. f., Caryacordiformis (Wang) K. Koch, C. ovata (Mill) K. Koch., Juglanscinerea L., Pinusstrobus L., Populusdeltoides Marsh., Prunuspensylvanica L.f., Pyrusmalus L., and Ulmusrubra Muhl. The following species are best categorized as intermediate hosts whose utilization varies with forest composition: Acersaccharum Marsh., Betulapapyrifera Marsh., B. populifolia Marsh., Fagusgrandifolia Ehrh., Populustremuloides Michx., Prunusserotina Ehrh., Tiliaamericana L., and Ulmusamericana L. Some differences were found from host preferences reported for New England. For example, Ostryavirginiana is strongly preferred in Quebec in contrast to New England where it is only an intermediate host; Betulapopulifolia and Populustremuloides are both preferred in New England but classed as intermediate hosts in our study. Overall, the forest composition appears to play only a limited role in altering gypsy moth host selection, but does especially affect the utilization of intermediate hosts.

The quantification of the graft success is a key element to evaluate the efficiency of cellular therapies for several pathologies such as Duchenne muscular dystrophy. This study describes an approach to evaluate the success of myoblast transplantation (i.e., survival of the transplanted cells and the muscle fibers formed) by real-time imaging. C2C12 myoblasts were first transfected with a plasmid containing the human sodium iodide symporter (hNIS) gene. Specific uptake of the radioactive sodium pertechnetate (Na99mTcO4) by the hNIS-positive myoblasts was demonstrated in vitro, while only background level of Na99mTcO4 was observed within the control cells. The cells were then transplanted into the tibialis anterior (TA) muscle of mdx (X-linked dystrophic) mice. Following intraperitoneal administration of Na99mTcO4, scintigraphies were performed to detect hNIS-dependent Na99mTcO4 uptake within the TA. This approach permitted to evaluate the progression of the transplantation and the graft success without having to biopsy the animals during the follow-up period.

No abstract