Artificial diets for the production of natural enemies (predators and parasitoids) of greenhouse pest insects

The aim of this contract was to finalise in vitro rearing on artificial diets of entomophagous insects useful to control insect pests mainly in greenhouses through an analytical and rational approach. The work focuses on the development and optimisation of artificial diets for one coccinellid (Harmonia axyridis), two heteropteran predators (Orius laevigatus, Dicyphus tamaninii), and a braconid parasitoid of aphids (Aphidius ervi). The definition of the artificial diets was based on biochemical analyses of their natural food (aphids) or substitution food for the predators (Ephestia kuehniella eggs). Reliable quality control parameters of the entomophages produced were used in order to adjust dietary composition and formulation of the different diets tested.

Adult sampling and larva rearing of the cork oak pest Coraebus undatus (Coleoptera: Buprestidae)

Coraebus undatus is the main insect pest of cork oak worldwide. The larvae tunnel in the cortical cambium filling the bark with galleries and causing the cork to break at harvest. The first objective of this study was to test the effect of purple traps in the attraction of C. undatus because this colour is attractive to other buprestid beetles. The second objective was to develop a diet in which field-collected larvae could be reared to adulthood. Pairs of purple and clear (control) sticky traps were placed in a cork oak forest in Girona, Spain in the summer of 2008

Characterization of an antennal carboxylesterase from the pest moth Spodoptera littoralis degrading a host plant odorant.

Background: Carboxyl/cholinesterases (CCEs) are highly diversified in insects. These enzymes have a broad range of proposed functions, in neuro/developmental processes, dietary detoxification, insecticide resistance or hormone/pheromone degradation. As few functional data are available on purified or recombinant CCEs, the physiological role of most of these enzymes is unknown. Concerning their role in olfaction, only two CCEs able to metabolize sex pheromones have been functionally characterized in insects. These enzymes are only expressed in the male antennae, and secreted into the lumen of the pheromone-sensitive sensilla. CCEs able to hydrolyze other odorants than sex pheromones, such as plant volatiles, have not been identified. Methodology: In Spodoptera littoralis, a major crop pest, a diversity of antennal CCEs has been previously identified. We have employed here a combination of molecular biology, biochemistry and electrophysiology approaches to functionally characterize an intracellular CCE, SlCXE10, whose predominant expression in the olfactory sensilla suggested a role in olfaction. A recombinant protein was produced using the baculovirus system and we tested its catabolic properties towards a plant volatile and the sex pheromone components. Conclusion: We showed that SlCXE10 could efficiently hydrolyze a green leaf volatile and to a lesser extent the sex pheromone components. The transcript level in male antennae was also strongly induced by exposure to this plant odorant. In antennae, SlCXE10 expression was associated with sensilla responding to the sex pheromones and to plant odours. These results suggest that a CCE-based intracellular metabolism of odorants could occur in insect antennae, in addition to the extracellular metabolism occurring within the sensillar lumen. This is the first functional characterization of an Odorant- Degrading Enzyme active towards a host plant volatile.