André Bélanger

Efficacy of essential oil of Ocimum basilicum L. and O. gratissimum L. applied as an insecticidal fumigant and powder to control Callosobruchus maculatus (Fab.) (Coleoptera: Bruchidae)

Essential oils from sweet basil, Ocimum basilicum, and African basil, O. gratissimum, (Labiatae) grown in Guinea were obtained by steam distillation. Following exposure of newly emerged adult beetles (Callosobruchus maculatus) to 12h of fumigation using pure essential oils at a dose of 25&mgr;l/vial, 80% mortality was recorded for O. basilicum, 70% for O. gratissimum and 0% in the control. A significant difference was observed between the responses of males and females with males exhibiting greater sensitivity. When 1g of aromatized powder was applied to adults, a 50% lethal concentration at 48h was found to be 65&mgr;l/g for O. basilicum and 116&mgr;l/g of O. gratissimum oils. The essential oils from the two plant species exhibited a significant effect both on the egg hatch rate and on the emergence of adults. The egg hatch rate was reduced to 3% with O. basilicum and 15% with O. gratissimum using an essential oil concentration of 30&mgr;l, whereas the egg hatch rate for the control was 95%. When compared with the control (97%), adult emergence dropped to 0% with O. basilicum and to 4% with O. gratissimum. Storage bioassays were run to assess the long-term effect of powders aromatized with essential oils of Ocimum. Complete protection was observed over 3 months starting at a dose of 400&mgr;l in the case of both oils. From a germination test, it was concluded that aromatized powders have no significant effect on the seed germination rate. After 5d, a rate of 88% germination was seen in seeds treated with aromatized powder and protected from insects, compared with 97% for untreated seeds that were not exposed to insects.

ACARICIDAL PROPERTIES OF ARTEMISIA ABSINTHIUM AND TANACETUM VULGARE (ASTERACEAE) ESSENTIAL OILS OBTAINED BY THREE METHODS OF EXTRACTION

Abstract Essential oils of Artemisia absinthium L. and Tanacetum vulgare L. were extracted by three methods, a microwave assisted process (MAP), distillation in water (DW) and direct steam distillation (DSD), and tested for their relative toxicity as contact acaricides to the twospotted spider mite, Tetranychus urticae Koch. All three extracts of A. absinthium and of T. vulgare were lethal to the spider mite but to variable degrees. The LC50 obtained from the DSD oil of A. absinthium was significantly lower (0.04 mg/cm2) than that of the MAP (0.13 mg/cm2) and DW (0.13 mg/cm2) oil of this plant species. DSD and DW extracts of T. vulgare were more toxic (75.6 and 60.4% mite mortality, respectively, at 4% concentration) to the spider mite than the MAP extract (16.7% mite mortality at 4% concentration). Chromatographic analysis indicated differences in composition between the more toxic DSD oil of A. absinthium and the other two extracts of this plant, indicating that a sesquiterpene (C15H24) compound present in the DSD oil and absent in the other two may enhance the toxicity of the DSD oil. Chemical analysis of the T. vulgare extracts indicated that β-thujone is by far the major compound of the oil (>87.6%) and probably contributes significantly to the acaricidal activity of the oil.

Effect of various essential oils on Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Essential oils were extracted from four West African plant species [Tagetes minuta (Family Compositae), Hyptis suaveolens (Family Labiatae), white basil Ocimum canum (Family Labiatae), and sweet basil O. basilicum (Family Labiatae)] by steam distillation. The oil of the pepper Piper guineense (Family Piperaceae), was extracted from the fruits by hydro distillation and ethanol extraction. Mixed essential oil and total ethanol extract was used. Kaolin powder (clay) was mixed (aromatized) with these different oils. Cowpea weevils were reared on chickpeas and newly emerged males and females were deposited on uninfested seeds. Bioassays, i.e. fumigation with pure essential oils and aromatized kaolin powders, were carried out on adults and eggs. Twenty four hours after fumigation, 99 and 0% adult mortality were observed, respectively, as the result of treatments with Ocimum basilicum and the control. The application of powders aromatized with the same oils to weevil pairs resulted in a complete lack of oviposition, whereas 31, 56 and 76 eggs were laid in the controls after 24, 48 and 72 h, respectively. Application of aromatized powders did not have a significant effect on egg hatching (50 out of 110 with O. canum, 100 out of 115 with O. basilicum and 100 out of 130 in the control sample) but did have a significant impact on adult emergence: 0% for the two treatments compared with 100% in the controls. Our results suggest that plants of the genus Ocimum can be used as an alternative to synthetic insecticides.

Essential oil composition of Ocimum basilicum L., O. gratissimum L. and O. suave L. in the Republic of Guinea

Specimens of Ocimum basilicum L., O. grattisimum and O. sauve L. were collected at Coyah, Kindia and Faranah in the Republic of Guinea (voucher specimens were deposited in the herbarium of the Environmental Studies and Research Center (ERSC), University of Conakry-Guinea). Steam distillation of the specimens was done at ESRC. The essential oil obtained was analysed by GC and GC – MS, and had the following major constituents: linalool (69%), eugenol (10%), t-α-bergamotene (3%) and thymol (2%) for O. basilicum; thymol (46%), p-cymeme (12%) and γ-terpene+t-sabiene hydrate (17%) for O. gratissimum; and p-cymeme (59%), α-thujene (10%), myrcene (7%) and thymol (7%) for O. sauve. A list of compounds is given for each plant species. Copyright

Understory light and root ginsenosides in forest-grown Panax quinquefolius

The objective of this study was to determine the relationship between light levels in the understory of a broadleaf forest and the content of six ginsenosides (Rg(1), Re, Rb(1), Rc, Rb(2,) and Rd) in 1- and 2-year-old American ginseng (Panax quinquefolius L.) roots. Our results revealed that ginsenoside contents in 1- and 2 year-old roots collected in September were significantly related to direct and total light levels, and duration of sunflecks. At this time, the effect of light levels accounted for up to 48 and 62% of the variation in ginsenoside contents of 1- and 2-year-old American ginseng roots. Also, red (R) and far red (FR) light, and the R:FR ratio significantly affected Rd, Rc, and Rg(1) contents in 2-year-old roots, accounting for up to 40% of the variation in ginsenoside contents.

Captan residue reduction in apples as a result of rinsing and peeling

Apples, treated with captan for disease control in a commercial orchard in Quebec, Canada, were collected and sorted into post-harvest preparation types (no preparation; rinse; rinse and peel). Captan residues were greatest (25.5-5100ng/g) in apples with no post-harvest preparation and lowest (0.146-136ng/g) in apples that had been rinsed and peeled prior to extraction and analysis. Residues were significantly lower (p=0.003) in apples that had been rinsed prior to extraction than in apples with no post-harvest preparation. Similarly, apples subjected to rinsing and peeling had significantly lower captan residues than had apples that had been rinsed alone (p<0.0001). Although captan residues in rinsed apples were approximately 50% lower than those in apples that received no post-harvest preparation, the reduction associated with peeling of apples was much greater (98%). Estimated mean captan intakes resulting from consumption of raw apples were established and single day intakes, based on apples with no preparation, ranged from 2.58μg/kg in females >70 years to 9.48μg/kg for individuals aged three years (at this age no distinction is made between males and females). Mean intakes estimated using rinsed and peeled apples were approximately two orders of magnitude lower than intakes estimated using apples with no post-harvest preparation, demonstrating the effect of post-harvest preparation on captan intakes. Mean captan intake estimates from all post-harvest preparation types were well below the World Health Organization acceptable daily intake of 100μg/kg/day, based on raw apple consumption.

Volatile monoterpenes in porophyllum gracile and p. ruderale (asteraceae): identification, localization and insecticidal synergism with α-terthienyl

Abstract Volatiles occurring in Porophyllum gracile and P. ruderale (Asteraceae) were identified in order to assess their role in integrated chemical defences against insects. Headspace and steam distillation techniques yielded a total of 12 mono- and sesquiterpenes and fatty acid derivatives. The glandular secretory cavities present on leaves of P. ruderale were large enough to permit direct sampling and were found to be particularly rich in volatile monoterpenes (73.6% of the integrated FID trace). Using reduction of relative growth rate of third instar Ostrinia nubilalis (Lepidoptera: Pyralidae) larvae as an index of insecticidal activity, the volatiles released from the secretory cavities located on the leaves of P. ruderale had no significant effect alone, but they synergized the effects of α-terthienyl, a toxic light-activated secondary compound also present in P. gracile and P. ruderale. This synergistic interaction was shown to be related to an enhanced accumulation of the α-terthienyl in O. nubilalis larvae when they were exposed to the volatiles emitted from the foliar secretory cavities of P. ruderale.

Some nutritional characteristics of beans, sweet corn and peas (raw, canned and frozen) produced in the province of Quebec

Abstract A three-year study was conducted to assess some nutrient contents of beans, sweet corn and peas (raw, canned and frozen) produced by four processing plants in the province of Quebec. Nutritional analysis were conducted on vitamin C, riboflavin, thiamin, minerals (Ca, Mg, K, Na, Fe) and fibers (solubles, insolubles and total). Results showed that the nutrient contents of raw and processed vegetables were quite different from those reported in the USDA Handbook no. 8–11. The differences were mainly due to vitamin C and mineral contents. Results also showed that raw vegetables when boiled under optimal conditions have nutrient contents similar to frozen vegetables and superior to canned vegetables. Among minerals Na was the most variable, probably due to variation in recipes from one processing plant to another. Na contents of canned vegetables were lower than the average values in the USDA tables. The study also provides new information on nutritive values of canned corn-on-the-cob which was not listed in USDA tables, and generates new nutrient data such as fibers (solubles, insolubles and total contents) to update the present food composition tables.

Variability in captan residues in apples from a Canadian orchard

Apple trees in an orchard in Quebec, Canada were treated, following label directions, with the fungicide captan (1,2,3,6-tetrahydro-N-(trichloromethylthio)phthalimide) during the 2003 agricultural season. A total of 142 apples from three rows of trees were selected for determination of captan by GC/MS. Individual apples were found to contain captan levels ranging from 16.9 to 6350 ng g−1. Only two individual apple samples exceeded the Canadian maximum residue limit (5000 ng g−1) for captan in apples. Six composite samples, comprising half portions of eight individual apples, were analysed from each of the three experimental rows. Composite samples ranged in concentration from 166 to 2620 ng g−1. The greatest uncertainty associated with the measured concentrations was due to variability among apples rather than the measurement of residue levels.

Toxicity and sublethal effects of an insecticidal soap on Aphidius colemani (Hymenoptera: Braconidae).

BACKGROUND The effects of an insecticidal soap on the survival, fitness and behaviour of an aphid parasitoid wasp, Aphidius colemani (Viereck), were studied in the laboratory. The LC(50) (soap concentration causing 50% mortality 24 h after treatment) was determined. The survival of parasitoid larvae (% adult emergence), fitness (tibia length of adults) and number of eggs produced per female parasitoid that survived in third- and fourth-instar aphids treated with insecticidal soap LC(50) were also assessed. The LC(50) for third- and fourth-instar aphids was determined to be 3.25 g L(-1). Acceptance by female parasitoids of aphids that survived their LC(50) was also tested. RESULTS The soap concentration causing 100% mortality in adult wasps 24 h after treatment was 17.5 g L(-1). The LC(50) was 2.75 g L(-1). Soap did not have any effect on the survival of parasitoid immatures or on the fitness or number of eggs produced per female parasitoid. Wasps that were in contact with treated aphids did not oviposit as much in them as in untreated aphids, indicating that female parasitoids detected aphids treated with insecticidal soap. CONCLUSION These data suggest that aphid parasitoids released following treatment with insecticidal soap are likely to accept a lower proportion of the surviving aphids. Biological control programmes could be ameliorated by soap applications if the latter were made 1 day before the release of wasps in the greenhouse.