Minh-Hà Pham-Delègue

Foraging behaviour of honey bees (Apis mellifera L.) on transgenic oilseed rape (Brassica napus L. var. oleifera)

The impact of genetically modified oilseed rape (Brassica napus L.) on the foraging behaviour of honey bees (Apis mellifera L.) was evaluated on two different lines transformed to express constitutively heterologous chitinase in somatic tissue for enhanced disease resistance. Experiments were conducted in confinement in an indoor flight room with controlled conditions and in an outdoor flight cage with conditions more representative of the open environment. Foraging behaviour was analysed by observations of general bee behaviour (total number of visits) and of individual bee behaviour (using a video camera coupled with a special software program to process the data). The plants were analysed in terms of nectar quantity and quality (nectar volume and sugar content). The results showed no effects on bee foraging behaviour due to the modification of the genome of these plants by the introduction of a chitinase gene even though some differences between lines were found in the nectar. The methods applied in this original approach for the evaluation of the impact of genetically modified oilseed rape were shown to be sufficiently sensitive to detect changes in bee behaviour resulting from differences between plants.

Discrimination of oilseed rape volatiles by honey bee: Novel combined gas chromatographic-electrophysiological behavioral assay.

A novel technique for the simultaneous monitoring of electroan-tennogram (EAG) and conditioned proboscis extension (CPE) responses of honey bees to the effluent from a gas chromatograph (GC) was developed to locate biologically active components in blends of plant volatiles and to investigate odor recognition at the peripheral and behavioral levels. A six-component mixture, comprising compounds previously identified as oilseed rape floral volatiles, was used as the stimulus. Standard CPE and EAG recordings were done as a reference. EAG responses were elicited from unconditioned bees by all the components presented either in the coupled or the standard mode. Conditioned bees gave larger EAG responses than unconditioned bees, suggesting that antennal sensitivity is enhanced by conditioning. At the behavioral level, in both the standard and the coupled modes, only conditioned bees showed the proboscis extension response, with the majority of individuals responding to linalool, 2-phenylethanol, and benzyl alcohol.

Odour conditioning of ovipositor probing in a parasitic wasp

We investigated the occurrence of odour learning in the ovipositor probing activity of Leptopilina boulardi, a parasitoid of Drosophila larvae. A device was set up to observe the probing behaviour in response to an odour. Systematic and persistent probing in response to the odour (banana) was observed after associative conditioning, i.e., after the odour had been experienced while ovipositing. The percentage of females responding to the odour was also increased after oviposition experience alone or preceded by odour exposure. The induced responses were then less persistent than after associative conditioning, and also less selective because probing was triggered as a consequence of oviposition experience and not only upon odour delivery. This is the first demonstration of the role and nature of odour learning in ovipositor probing behaviour, the final step of host location by Leptopilina sp., and this activity appears to be much modulated by the wasps experience.

Real-time detection and analysis of the exploratory behavior of small animals

1. Reisser, W.: Bot. Acta 102, 117 (1989) 2. Mt~ller, D. G.: J. Plant Physiol. 137, 739 (1991) 3. Mtiller, D. G., Kawai, H., Stache, B., Lanka, S.: Bot. Acta 103, 72 (1990) 4. Reanney, D. C.: Int. Rev. Cytol. 37, 21 (1974) 5. Mtiller, D. G.: Mar. Ecol. Progr. Ser. 76, 101 (1991) 6. Wynne, M. J., in: Synopsis and classification of living organisms, Vol. 1, p. 115 (S. P. Baker, ed.). New York: McGraw-Hill 1982 7. Pedersen, P. M.: Nord. J. Bot. 9, 443 (1989)