Le potentiel de l’écologie chimique dans la lutte contre les insectes nuisibles

En nature, plusieurs organismes vivants émettent des substances chimiques médiatrices (infochimiques) lorsqu'ils créent des liens complexes et variés entre les individus de la même espèce ou d'espèces différentes. Dans cet article, nous décrivons comment certains insectes utilisent les substances infochimiques pour la recherche d'un partenaire sexuel, de sources de nourriture ou d'un lieu favorable pour la ponte. De plus, nous discutons de l'intérêt de bien comprendre les fondements de l'écologie chimique afin de promouvoir le développement et l'utilisation de méthodes de lutte plus efficaces contre les insectes nuisibles et plus acceptables pour l'environnement.Infochemicals are important in modulating a large number of both intra- and interspecific interactions in nature and in this paper we examine examples of their use by insects in the location of mates, food and suitable oviposition sites. Furthermore, we consider how an understanding of chemical ecology can be used to develop more efficient and ecologically acceptable pest management programs

Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the $\gamma p$ centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2

The chemical ecology of the Pacific beetle cockroach, Diploptera punctata

The cockroach, Diploptera punctata, has a wide geographic distribution throughout much of Asia and Hawaii, and as is one of the few vivaparous insect species know, it has been extensively studied by to gain insight into the underlying physiology of this unusual form of reproduction. However, there is not a great deal known about the mating behaviour of this species. We will present results, using populations from Hawaii and Thailand, showing that (i) there is very little interbreeding between the two populations, (ii) short distance pheromones are involved in mating, (iii) there are marked intersexual and inter-race differences in the cuticular profiles (iv) cuticular profiles change with age, and that in a Y tube olfactometer males respond preferentially to 5-day-old virgins over air but do not discriminate between air and newly - emerged virgins. The last observation was interesting, given that in the literature it has been reported that ma ting occurs just after the female has moulted, before her cuticle has even hardened. Furthermore, while newly - mated females show no overt courtship behaviour, older individuals do, including strong rejection behaviours when courted. We postulated that the idea that females normally mate immediately after emergence is an artefact of the rather simple cages used in laboratory rearings. We found that mating success declined as the complexity of the environment was increased, suggesting that in nature a female may hide during moulting and only mate once her cuticle has hardened