The sperm of Matsucoccus feytaudi (Insecta, Coccoidea): Can the microtubular bundle be considered as a true flagellum?

In the present work the spermiogenesis and sperm structure of Matsucoccus feytaudi, a primary pest of the maritime pine in southern eastern Europe, is studied. In addition to the already known characteristics of coccid sperm, such as the absence of the acrosome and mitochondria, and the presence of a bundle of microtubules responsible for sperm motility, a peculiar structure from which the microtubule bundle takes origin is described. Such a structure--a short cylinder provided with a central hub surrounded by several microtubules with a dense wall--is regarded as a Microtubule Organizing Centre (MTOC). During spermiogenesis, quartets of fused spermatids are formed; from each spermatid, a bundle of microtubules, generated by the MTOC, projects from the cell surface. Each cell has two centrioles, suggesting the lack of a meiotic process and the occurrence of parthenogenesis. At the end of the spermiogenesis, when the cysts containing bundles of sperm are formed, part of the nuclear material together with the MTOC structure is eliminated. Based on the origin of the microtubular bundle from the MTOC, the nature of the bundle as a flagellum is discussed.

Host egg age of Leptoglossus occidentalis (Heteroptera, Coreidae) and parasitism by Gryon pennsylvanicum (Hymenoptera, Platygastridae).

Leptoglossus occidentalis Heidemann (Heteroptera, Coreidae) is native to Western North America and is a serious pest for seed production of conifers. The pest was accidentally introduced into Europe in the 1990s. Since then, seed loss has been recorded in Pinus pinea (L.) forests, with a negative impact on the commercial production of pine nuts. Classical biological control of this pest in P. pinea stands is an attractive proposition. Previous work showed that the egg-parasitoid Gryon pennsylvanicum (Ashmead) (Hymenoptera, Platygastridae) had promising life history traits in laboratory studies using L. occidentalis eggs as host. In the present work, the effect of host egg age on parasitization rate was evaluated in the laboratory, using choice and no-choice tests. Host eggs ranged in age from < 24 h to within a day of hatching. Results showed that parasitization rate, juvenile survival rate, sex ratio, and longevity of female G. pennsylvanicum were not significantly affected by the age of the host eggs. However, egg-parasitoid development time was longer in older host eggs, and females were smaller than those that developed in younger host eggs. Parasitization behaviors (drumming, oviposition, and marking) were not affected by the age of the host. G. pennsylvanicum females tended to parasitize all available host eggs within a cluster before moving to a new cluster, without displaying a preferences for host egg age. The ability to exploit host eggs of any age class improves the prospect of successful classical biological control using this egg-parasitoid.

Major changes in the sex differences in cuticular chemical profiles of the western conifer seed bug (Leptoglossus occidentalis) after laboratory rearing.

Chemical compounds covering the insect cuticle have several functions ranging from protection against water loss to inter- and intra-specific communication. Their composition is determined by several intrinsic and extrinsic factors. Among these factors, laboratory rearing has been poorly investigated even though it has a strong potential for biasing behavioral experiments. We selected an invasive species with unknown cuticular mixtures as a model. Our aim was to describe its mixtures and to determine if highly simplified laboratory rearing conditions interact with sexual signatures. We analyzed the cuticle by means of two different techniques - gas chromatography/mass spectrometry (GC/MS) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) - to obtain data on a wide range of compounds with different molecular weight. We found that both sets of chemicals showed correlations with gender but also that cuticular waxes detected by GC/MS were highly dependent on rearing conditions, with a strong bias in sexual dimorphism. Conversely, the heavier signatures detected by MALDI-TOF showed a less clear diversification between sexes, although the discrimination power was unaffected by rearing conditions. The biological and practical implications of our findings are discussed.