Potential effects of oilseed rape expressing oryzacystatin-1 (OC-1) and of purified insecticidal proteins on larvae of the solitary bee Osmia bicornis

Despite their importance as pollinators in crops and wild plants, solitary bees have not previously been included in non-target testing of insect-resistant transgenic crop plants. Larvae of many solitary bees feed almost exclusively on pollen and thus could be highly exposed to transgene products expressed in the pollen. The potential effects of pollen from oilseed rape expressing the cysteine protease inhibitor oryzacystatin-1 (OC-1) were investigated on larvae of the solitary bee Osmia bicornis (= O. rufa). Furthermore, recombinant OC-1 (rOC-1), the Bt toxin Cry1Ab and the snowdrop lectin Galanthus nivalis agglutinin (GNA) were evaluated for effects on the life history parameters of this important pollinator. Pollen provisions from transgenic OC-1 oilseed rape did not affect overall development. Similarly, high doses of rOC-1 and Cry1Ab as well as a low dose of GNA failed to cause any significant effects. However, a high dose of GNA (0.1%) in the larval diet resulted in significantly increased development time and reduced efficiency in conversion of pollen food into larval body weight. Our results suggest that OC-1 and Cry1Ab expressing transgenic crops would pose a negligible risk for O. bicornis larvae, whereas GNA expressing plants could cause detrimental effects, but only if bees were exposed to high levels of the protein. The described bioassay with bee brood is not only suitable for early tier non-target tests of transgenic plants, but also has broader applicability to other crop protection products

Use of an innovative T-tube maze assay and the proboscis extension response assay to assess sublethal effects of GM products and pesticides on learning capacity of the honey bee Apis mellifera L.

Transgenic Cry1Ac+CpTI cotton (CCRI41) is a promising cotton cultivar throughout China but side effects and especially sublethal effects of this transgenic cultivar on beneficial insects remain poorly studied. More specifically potential sublethal effects on behavioural traits of the honey bee Apis mellifera L. have not been formally assessed despite the importance of honey bees for pollination. The goal of our study was to assess potential effects of CCRI41 cotton pollen on visual and olfactory learning by honey bees. After a 7-day oral chronic exposure to honey mixed with either CCRI41 pollen, imidacloprid-treated conventional pollen (used as positive sublethal control) or conventional pollen (control), learning performance was evaluated by the classical proboscis extension reflex (PER) procedure as well as a T-tube maze test. The latter assay was designed as a new device to assess potential side effects of pesticides on visual associative learning of honey bees. These two procedures were complementary because the former focused on olfactory learning while the latter was involved in visual learning based on visual orientation ability. Oral exposure to CCRI41 pollen did not affect learning capacities of honey bees in both the T-tube maze and PER tests. However, exposure to imidacloprid resulted in reduced visual learning capacities in T-tube maze evaluation and decreased olfactory learning performances measured with PER. The implications of these results are discussed in terms of risks of transgenic CCRI41 cotton crops for honey bees

Long-Term Vegetation Change in Central Africa: The Need for an Integrated Management Framework for Forests and Savannas

peer reviewedTropical forests and savannas are the main biomes in sub-Saharan Africa, covering most of the continent. Collectively they offer important habitat for biodiversity and provide multiple ecosystem services. Considering their global importance and the multiple sustainability challenges they face in the era of the Anthropocene, this chapter undertakes a comprehensive analysis of the past, present, and future vegetation patterns in central African forests and savannas. Past changes in climate, vegetation, land use, and human activity have affected the distribution of forests and savannas across central Africa. Currently, forests form a continuous block across the wet and moist areas of central Africa, and are characterized by high tree cover (>90% tree cover). Savannas and woodlands have lower tree cover (<40% tree cover), are found in drier sites in the north and south of the region, and are maintained by frequent fires. Recent tree cover loss (2000–2015) has been more important for forests than for savannas, which, however, reportedly experienced woody encroachment. Future cropland expansion is expected to have a strong impact on savannas, while the extent of climatic impacts depends on the actual scenario. We finally identify some of the policy implications for restoring ecosystems, expanding protected areas, and designing sustainable ecosystem management approaches in the region

Selective olfactory choices of the honeybee among sunflower aromas: a study by combined olfactory conditioning and chemical analysis

International audienceA bioassay based on an olfactory conditioning method simulating the foraging situation in laboratory conditions was coupled with chemical analysis of volatile sunflower blends. Behavioural data obtained from for-agers'responses to volatile fraction point out that honeybees need to use only a limited fraction acting as a "simplified aromatic pattern" of the plant, among hundreds of compounds constituting the whole aroma. This active fraction included 27 polar compounds among which 14 were identified. Extension of such data to crop pollination and plant improvement is discussed

A study of rapeseed (Brassica napus L. var. oleifera Metzger) flower nectar secretions

International audienc

Effect of queen pheromone on worker bees of different ages: behavioural and electrophysiological responses

The attraction responses of differently aged worker bees to queen pheromonal blends were studied in a 4-field airflow olfactometer. The effects of the nature of the queen signal — either the synthetic mixture shown to be behaviorally active by Slessor et al (1988), or a queen-head extract -, and the rearing conditions were investigated. The composition of the queen-head extract with respect to the constituents of the synthetic blend was chemically analyzed, and differences in amounts of components were discussed. Olfactory-based behavioral responses were elicited by both pheromonal signals; the queen-head extract induced higher responses than the synthetic mixture, the youngest bees of < 5 d old being the most responsive. Similar responses were found in queenless caged bees and in bees reared in a hive, suggesting that attraction to the queen was probably not influenced by prior experience, at least when deprivation to the queen signal occurred after emergence. Electroantennogram responses to the queen signals were recorded concurrently. Olfactory sensitivity was higher to the queen-head extract than to the synthetic pheromone, and was not age-dependent for the age groups tested. No correlation between the maturation of antennal responses and the maturation of behavioral responses was found

Nectar secretion in winter oilseed rape, Brassica napus quantitative and qualitative variability among 71 genotypes

International audienc

Age-related foraging behaviour in honey bees under artificial conditions

The distribution of foraging among 4 worker groups of different ages was observed in a flight room. Foraging was mostly performed by the oldest workers, who came to forage first and were the most numerous. Workers from the other groups visited the feeding station infrequently until the second half of the observation period, then increased their visits. Regardless of their age group, each individual coming to forage performed a constant average level of activity, despite some variability in the individual scores of visits. These experiments stressed a strong intra-age group interaction among a population of potential foragers, and allowed us to record data on both group and individual strategies. In conjunction with studies performed under natural conditions, our experiments conducted under artificial conditions may contribute to the analysis of some basic parameters of foraging behaviour

Age-related foraging behaviour in honey bees under artificial conditions

The distribution of foraging among 4 worker groups of different ages was observed in a flight room. Foraging was mostly performed by the oldest workers, who came to forage first and were the most numerous. Workers from the other groups visited the feeding station infrequently until the second half of the observation period, then increased their visits. Regardless of their age group, each individual coming to forage performed a constant average level of activity, despite some variability in the individual scores of visits. These experiments stressed a strong intra-age group interaction among a population of potential foragers, and allowed us to record data on both group and individual strategies. In conjunction with studies performed under natural conditions, our experiments conducted under artificial conditions may contribute to the analysis of some basic parameters of foraging behaviour