Interspecific competition between three species of the genus Trichogramma (Hym., Trichogrammatidae)

3rd International Symposium "Trichogramma and other egg parasitoids". 3ème Symposium International "Les trichogrammes et autres parasites oophages", San Antonio (USA), 23-27 Sep 1990.For this study, three species of Trichogramma were submitted to competition in such a way that each competed with only one of the two other species simultaneously. The species were T. embryophagum Hartig, T. maidis Pintureau & Voegelé and T. buesi Voegelé. The host eggs Ephestia kuehniella (Lep., Pyralidae) were first parasitized by one of the species and when the first occupant was in a prenymphal instar (free living embryo, L1, L2 and L3), adults of the second species were allowed to parasitize the eggs containing the living instar of the first species. Unider these conditions, T. embryophagum eliminated the two other species, T. maidis just eliminated T. buesi but only in two situations (L2, and L3) and T. buesi was inactive in all situations. When host eggs are available in sufficient number, all three Trichogramma species show a high intra and interspecific discrimination for host eggs recently parasitized

Influence of the phototropism over the egg laying rhythm and emergence of three Trichogramma species (Hym., Trichogrammatidae)

4th European Workshop 'Insect parasitoids', held in Perugia, Italy, 3-5 April 1991.Published in Redia 74(3, Appendix): 309-314.The egg parasites of the genus Trichogramma (Hym., Trichogrammatidae), are important Biological auxiliaries used in over 20 million acres, in more the 20 countries around the word, for the control of agricultural pest namely lepidopterans (Trichogramma News, 1988), having Portugal a contribution of over 400 acres in 1990. The obtainment of the necessary amounts of Trichogramma with the desired quality, passes fundamentally by the knowledge of its biology and etology as well as by the usage of efficient production techniques. In this time, the influence of the photoperiod’s over the egg laying rhythm and emergence of three Trichogramma species. Trichogramma biesi VOEGELÉ, T. maidis PINTUREAU & VOEGELÉ and T. embryophagum HARTIG, accepted as representatives for three vegetables extracts, respectively of low medium and high altitudes, where studied

The strain-dependent spatial evolution of garnet in a high-pressure ductile shear zone from the Western Gneiss Region (Norway): a synchrotron X-ray microtomography study

Reaction and deformation microfabrics provide key information to understand the thermodynamic and kinetic controls of tectono‐metamorphic processes, however, they are usually analysed in two dimensions, omitting important information regarding the third spatial dimension. We applied synchrotron‐based X‐ray microtomography to document the evolution of a pristine olivine gabbro into a deformed omphacite–garnet eclogite in four dimensions, where the 4th dimension is represented by the degree of strain. In the investigated samples, which cover a strain gradient into a shear zone from the Western Gneiss Region (Norway), we focused on the spatial transformation of garnet coronas into elongated garnet clusters with increasing strain. The microtomographic data allowed quantification of garnet volume, shape and spatial arrangement evolution with increasing strain. The microtomographic observations were combined with light microscope and backscatter electron images as well as electron microprobe (EMPA) and electron backscatter diffraction (EBSD) analysis to correlate mineral composition and orientation data with the X‐ray absorption signal of the same mineral grains. With increasing deformation, the garnet volume almost triples. In the low‐strain domain, garnet grains form a well interconnected large garnet aggregate that develops throughout the entire sample. We also observed that garnet coronas in the gabbros never completely encapsulate olivine grains. In the most highly deformed eclogites, the oblate shapes of garnet clusters reflect a deformational origin of the microfabrics. We interpret the aligned garnet aggregates to direct synkinematic fluid flow, and consequently influence the transport of dissolved chemical components. EBSD analyses reveal that garnet shows a near‐random crystal preferred orientation that testifies no evidence for crystal plasticity. There is, however evidence for minor fracturing, neo‐nucleation and overgrowth. Microprobe chemical analysis revealed that garnet compositions progressively equilibrate to eclogite facies, becoming more almandine‐rich. We interpret these observations as pointing to a mechanical disintegration of the garnet coronas during strain localization, and their rearrangement into individual garnet clusters through a combination of garnet coalescence and overgrowth while the rock was deforming