Potential of the parasitic wasp Lariophagus distinguendus (FÖRSTER) (Hymenoptera: Pteromalidae) to control the tobacco beetle Lasioderma serricorne (F.) (Coleoptera: Anobiidae)

Die Lagererzwespe Lariophagus distinguendus ist eine generalistische Parasitoidenart, welche die Larven von mindestens 11 verschiedenen Käferarten parasitiert. Die Wirte leben alle entweder endophytisch in Samen oder in Kokons (STEIDLE & SCHÖLLER 1997). Bei der Parasitierung stechen die Weibchen die Samen oder Kokons an und legen jeweils ein Ei an die Außenseite der Wirtslarve (Abb. 1). Die Parasitioidenlarve frisst von außen an dem Wirt, der dabei abgetötet wird. Die Parasitoidenlarve verpuppt sich im Samen oder Kokon, aus dem schließlich eine erwachsene Wespe schlüpft. ...Lariophagus distinguendus (FÖRSTER) (Hymenoptera: Pteromalidae) is a parasitoid of larvae and pupae of a number of beetle species that are pests of stored products. For biological control of the granary weevil Sitophilus granarius (L.) (Coleoptera: Curculionidae) L. distinguendus is currently commercially available in Germany. To study the ability of this strain to parasitize the tobacco beetle and develop on this host, pairs of L. distinguendus were offered larvae of the tobacco beetle of three different age classes. The results reveal that L. distinguendus is able to develop on larvae of the tobacco beetle. Obviously, the oldest larval stage of the beetle is most suitable for development. This makes the strain of L. distinguendus utilised in this experiment generally suitable for the biological control of the tobacco beetle

Survival of near-critical branching Brownian motion

Consider a system of particles performing branching Brownian motion with negative drift $\mu = \sqrt{2 - \epsilon}$ and killed upon hitting zero. Initially there is one particle at $x>0$. Kesten showed that the process survives with positive probability if and only if $\epsilon>0$. Here we are interested in the asymptotics as \eps\to 0 of the survival probability $Q_\mu(x)$. It is proved that if $L= \pi/\sqrt{\epsilon}$ then for all $x \in \R$, $\lim_{\epsilon \to 0} Q_\mu(L+x) = \theta(x) \in (0,1)$ exists and is a travelling wave solution of the Fisher-KPP equation. Furthermore, we obtain sharp asymptotics of the survival probability when $x<L$ and $L-x \to \infty$. The proofs rely on probabilistic methods developed by the authors in a previous work. This completes earlier work by Harris, Harris and Kyprianou and confirms predictions made by Derrida and Simon, which were obtained using nonrigorous PDE methods

The maximum of the local time of a diffusion process in a drifted Brownian potential

We consider a one-dimensional diffusion process $X$ in a $(-\kappa/2)$-drifted Brownian potential for $\kappa\neq 0$. We are interested in the maximum of its local time, and study its almost sure asymptotic behaviour, which is proved to be different from the behaviour of the maximum local time of the transient random walk in random environment. We also obtain the convergence in law of the maximum local time of $X$ under the annealed law after suitable renormalization when $\kappa \geq 1$. Moreover, we characterize all the upper and lower classes for the hitting times of $X$, in the sense of Paul L\'evy, and provide laws of the iterated logarithm for the diffusion $X$ itself. To this aim, we use annealed technics.Comment: 38 pages, new version, merged with hal-00013040 (arXiv:math/0511053), with some additional result