No abstract

We describe a new and highly aggressive species of pine shoot beetle, Tomicus yunnanensis Kirkendall & Faccoli, which has been decimating Pinus yunnanensis forests in southwest China for almost three decades. This species was confused with T. piniperda until recent molecular studies showed the SW China populations to be quite divergent from T. piniperda of northeast China and Europe. The clearest morphological differences between these two species lie in the surface sculpture of the elytra: the new species has more widely spaced interstrial granules on the elytral disc, the punctures of interstria 2 on the declivity arranged irregularly and those of striae 1 and 3 smaller. The new species also has dense small hairs on the tip of the antennal club, while T. piniperda has only scattered small hairs on that segment. Mature T. piniperda specimens are uniformly black, while those of T. yunnanensis have the bulk of the elytra lighter than the base of the elytra and the pronotum. The new species is actually more similar to the Mediterranean species T. destruens, which differs in geographical distribution and in having the punctures of interstria 2 dense on the declivity and light-colored antennae. Species of Tomicus are of general concern to foresters because of their impact on conifer growth, but good illustrations for many species are lacking. We here provide a detailed key to all seven species of the genus (T. minor, T. piniperda, T. destruens, T. brevipilosus, T. yunnanensis and the virtually unknown T. puellus and T. pilifer) as well as diagnostic photographs and drawings. We summarize the biological differences between the new species and T. piniperda and recommend improved communication between taxonomists and forest entomologists, as avoidable taxonomic confusion such as that of T. yunnanensis and T. destruens with T. piniperda hinders the combatting of outbreaks of forest insects.

A. density- and frequency-dependent model for the evolution and maintenance of pseudogamous females is developed and analyzed. Ecological as well as evolutionary aspects of pseudogamy are discussed. Criteria are described for the stable coexistence of sexual females and pseudogamous females under natural conditions. The conditions for invasion of a normal bisexual population by pseudogamous females are less stringent than the conditions for stable coexistence. Hence, we expect that some populations will be characterized by unstable sex ratios over time (with the resulting local extinction due to lack of males) while other populations will be characterized by stable sex ratios over time. If high population sex ratios (i.e., many females to few males) are to be stable, the net population growth rate must be large, and there can be no successful male preference for sexual females.

We record 201 alien curculionoids established in Europe, of which 72 originate from outside Europe. Aliens to Europe belong to fi ve families, but four-fi fths of them are from the Curculionidae. Many families and subfamilies, including some species-rich ones, have few representatives among alien curculionoids, whereas some others are over-represented; these latter, Dryophthoridae, Cossoninae and specially Scolytinae, all contain many xylophagous species. Th e number of new records of alien species increases continuously, with an acceleration during the last decades. Aliens to Europe originate from all parts of the world, but mainly Asia; few alien curculionoids originate from Africa. Italy and France host the largest number of alien to Europe. Th e number of aliens per country decreases eastwards, but is mainly correlated with importations frequency and, secondarily, with climate. All alien curculionoids have been introduced accidentally via international shipping. Wood and seed borers are specially liable to human-mediated dispersal due to their protected habitat. Alien curculionoids mainly attack stems, and half of them are xylophagous. Th e majority of alien curculionoids live in human-modifi ed habitats, but many species live in forests and other natural or semi-natural habitats. Several species are pests, among which grain feeders as Sitophilus spp. are the most damaging.

A. density- and frequency-dependent model for the evolution and maintenance of pseudogamous females is developed and analyzed. Ecological as well as evolutionary aspects of pseudogamy are discussed. Criteria are described for the stable coexistence of sexual females and pseudogamous females under natural conditions. The conditions for invasion of a normal bisexual population by pseudogamous females are less stringent than the conditions for stable coexistence. Hence, we expect that some populations will be characterized by unstable sex ratios over time (with the resulting local extinction due to lack of males) while other populations will be characterized by stable sex ratios over time. If high population sex ratios (i.e., many females to few males) are to be stable, the net population growth rate must be large, and there can be no successful male preference for sexual females.