Timing of diapause initiation, metabolic changes and overwintering survival of the spruce budworm, Choristoneura fumiferana

1. Four groups of spruce budworm larvae, Choristoneura fumiferana , of the same physiological stage (at the beginning of diapause) were exposed to natural temperatures, starting in July, August, September and October. Post-diapause emergence and certain metabolites were monitored throughout the overwintering period.
2. Larval exposure to high temperatures for long periods before winter had a significant effect on temperature requirements for subsequent diapause development and apparently caused a certain amount of mortality, especially for those larvae that entered diapause earlier in the season.
3. Substantial loss of lipid and glycogen reserves was related to intensity of high temperature exposure during the pre-winter period, which in turn was associated with the timing of diapause initiation.
4. Patterns of glycerol accumulation during the winter were also influenced by temperature conditions in the early phase of diapause development.
5. Among several possible mortality factors, an extended cool period in spring was suggested as a potential cause of overwintering mortality, which was closely associated with a deficiency in energy reserves caused by high temperature exposure before winter.
6. These results stress the significant impact of pre-winter conditions on the overwintering process and highlight the importance of an ecophysiological approach to insect overwintering biology.     

Use of transferred nuclear overhauser effects to determine the conformation of 1-(3,4-dichlorophenyl)-2-aminopropane when bound to the active site of phenylethanolamine N-methyltransferace (PNMT)

Transferred two dimensional nuclear Overhauser effect spectroscopy (transferred NOESY) was used to show that the side chain of 1-(3,4-dichlorophenyl)-2-aminopropane (1) exists when bound at the active site of PNMT in an extended conformation (τ₂=167 – 180°) with the aromatic ring rotated out of the plane of the ethylamine side chain (τ₁ = 29 – 45°).     

An experimental study of the breakdown of submerged leaves by hyphomycetes and invertebrates in Morocco

SUMMARY. 1. Mechanisms of the breakdown of submerged leaves under the warm and dry Moroccan climate, including the interaction between hyphomycetes and invertebrates, were investigated.
2. Laboratory experiments were performed on dried leaves of Salix sp. and Nerium oleander .
3. During the first month under the experimental conditions, Melanopsis praemorsa, Physa acula (Gastropoda) and Hydropsyche maroccana (Trichoptera), respectively, were responsible for a loss of weight of 38, 21 and 13% in willow leaves, and 40, 15 and 8% in oleander leaves.
4. The weight lost by willow leaves inoculated with the fungi Alatospora acuminata, Anguillospora longissima, Lemonniera aquatica and Tetracladium marchalianum increased with time, but varied according to the fungal species. Loss of weight and increase in nitrate and phosphate content of the leaves were greatest with Lemonniera and smallest with Tetracladium .
5. When the leaves thus colonized by each of the four fungal species were exposed to each of the three invertebrates, the amount of material consumed increased with the time of fungal conditioning and varied according to the fungus and to the invertebrate. Greatest consumption was by Melanopsis feeding on leaves conditioned by Lemonniera , in which case assimilation percentage by the gastropod was as high as 75%.
6. Owing to their numbers in the field, and to the quantity of leaf material they ingest, gastropods appear as the main shredders in the streams considered, thus replacing the Crustacea that often play this part under temperate climates. Breakdown seems faster in Morocco than in France, mainly because of a shorter initial time lag in weight loss.