Variations clonales de l'aptitude du pin sylvestre à assurer le développement de Diprion pini L (Hym, Diprionidae) en milieu naturel

Influence of some Scots pine clones on Diprion pini L (Hym, Diprionidae) development. Noxious effect in field. The study attempts to confirm in nature the noxious effect of some Scots pine clones from Polish origin on Diprion pini. Up to now, this noxiousness has only been proved in standard laboratory conditions by feeding the insects with cut pine shoots. Because significant natural populations were lacking during recent years, the first experiments were carried out in 1991, 1992 and 1993 with larvae issued from a permanent rearing strain of D pini. These larvae were transferred to tree collections of Orleans and Cadouin in Dordogne (France) and put on several vegetative copies of different Scots pine clones. These tests encountered many difficulties due to the weakness of the laboratory strain in natural climatic conditions, the lack of synchronization between reared insect and natural insect generations, the natural parasites and the distance between the lab and Cadouin. On the other hand, the real aptitudes of the clones in situ may only be proved during a real outbreak of the sawfly. However, an earlier mortality and a slower development are clearly shown when the insects develop on clones previously noted as unfavorable to D pini in laboratory bioassays.L'étude tend à confirmer sur le terrain la nocivité pour Diprion pini de clones de pin sylvestre de provenance polonaise jusqu'à présent testée seulement en conditions standard au laboratoire en nourrissant l'insecte avec des rameaux coupés. Du fait de l'absence de populations naturelles importantes au cours des années récentes, les premières expérimentations ont été réalisées en 1991, 1992 et 1993 avec des larves issues d'un élevage permanent de Diprion pini transportées sur les copies végétatives de différents clones dans les parcs à clones d'Orléans et de Cadouin en Dordogne, France. Bien que ces essais aient rencontré de réelles difficultés dues à la fragilité des insectes de laboratoire vis-à-vis des conditions climatiques, au problème de faire coïncider leur cycle biologique avec celui des insectes sur le terrain, au parasitisme naturel et à l'éloignement de Cadouin par rapport au site d'élevage des insectes, et bien que l'aptitude des clones in situ ne puisse vraiment être prouvée qu'au cours d'une véritable gradation de l'insecte, ils mettent clairement en évidence une mortalité plus précoce et un développement plus lent des insectes qui se sont développés sur les clones s'étant montrés défavorables à D pini en laboratoire

Sex pheromone of the pine sawfly, Gilpinia pallida: Chemical identification, synthesis, and biological activity

We present the identification of the sex pheromone in the pine sawfly, Gilpinia pallida, including analysis of the female pheromone content, male antennal response and attraction in the field, and synthesis of the most active pheromone component. Several 3,7-dimethyl-2-alkanols were identified from female whole-body extracts, including some compounds with a 2R configuration. This is the first observation of such compounds in a pine sawfly species. Antennae of male G. pallida responded strongly in electroantennograph (EAG) recordings to the (2S,3R,7R)-isomers of the propionates of 3,7-dimethyl-2-tridecanol, 3,7-dimethyl-2-tetradecanol, and 3,7-dimethyl-2-pentadecanol, as well as to the acetates of the tri- and pentadecanols (the acetate of the tetradecanol was not tested). The propionate of (2S,3R,7R)-3,7-dimethyl-2-tetradecanol caught more males in the field than the corresponding isomer of tri- or pentadecanol. We suggest that the (2S,3R,7R)-isomer of 3,7-dimethyl-2-tetradecanol is likely the main sex pheromone precursor in G. pallida, with a subsidiary role for the (2S,3R,7R)-isomer of the tridecanol. Preparation of highly pure (2R,3R,7R)- and (2S,3R,7R)-stereoisomers of 3,7-dimethyl-2-tetradecanol, including the biological active esters, was performed via chemoenzymatic methods and is described in detail

Complex patterns of global spread in invasive insects: eco-evolutionary and management consequences

The advent of simple and affordable tools for molecular identification of novel insect invaders and assessment of population diversity has changed the face of invasion biology in recent years. The widespread application of these tools has brought with it an emerging understanding that patterns in biogeography, introduction history and subsequent movement and spread of many invasive alien insects are far more complex than previously thought. We reviewed the literature and found that for a number of invasive insects, there is strong and growing evidence that multiple introductions, complex global movement, and population admixture in the invaded range are commonplace. Additionally, historical paradigms related to species and strain identities and origins of common invaders are in many cases being challenged. This has major consequences for our understanding of basic biology and ecology of invasive insects and impacts quarantine, management and biocontrol programs. In addition, we found that founder effects rarely limit fitness in invasive insects and may benefit populations (by purging harmful alleles or increasing additive genetic variance). Also, while phenotypic plasticity appears important post-establishment, genetic diversity in invasive insects is often higher than expected and increases over time via multiple introductions. Further, connectivity among disjunct regions of global invasive ranges is generally far higher than expected and is often asymmetric, with some populations contributing disproportionately to global spread. We argue that the role of connectivity in driving the ecology and evolution of introduced species with multiple invasive ranges has been historically underestimated and that such species are often best understood in a global context