65 research outputs found
Below ground efficiency of a parasitic wasp for Drosophila suzukii biocontrol in different soil types
The parasitoid wasp Trichopria drosophilae is promising as a biocontrol agent for controlling the ubiquitous pest Drosophila suzukii (Matsumura). Crucial for the successful implementation of any biocontrol agent is a high parasitisation rate by the parasitoid. Most studies investigating the parasitisation rate of D. suzukii pupae have focused on parasitisation in the fruit or in a petri dish. However, the predominant pupation site of D. suzukii in the field is the soil. Unfortunately, little is known on how well parasitoid wasps can detect and parasitise pupae of D. suzukii buried in the soil. Therefore, we conducted soil parasitisation experiments of T. drosophilae on D. suzukii pupae using two pupation depths in three different soil types (loamy sand, loam, and clay). In all three soil types, we found generally low D. suzukii pupae parasitisation rate by T. drosophilae, independent of the pupation depth. The pupation behaviour of D. suzukii and the parasitisation behaviour of T. drosophilae are discussed in detail. For pest control in most soil types, our results mean that the number of D. suzukii larvae pupating in the soil should be reduced, e.g., by adding a layer of sandy soil or covering the soil with plastic mulch. This might increase the probability of success when using T. drosophilae as a biocontrol agent
The preference of Trichopria drosophilae for pupae of Drosophila suzukii is independent of host size
Beziehungen zwischen Chlorosegrad, Eisengehalten und Blattwachstum von Weinreben auf verschiedenen Standorten
Relationship between chlorosis, iron and leaf growth in grapevines growing at different locationsAt different locations, samples from chlorotic and green leaves were taken periodically during the growing season. Leaf area, contents of chlorophyll, total iron and acid-soluble iron were determined in leaf samples from various positions within the shoots. At locations where chlorosis became evident during the growth period, analysis showed that these leaves had lower levels of both total iron and acid-soluble iron compared with leaves of locations without chlorosis. At all locations, a close linear correlation was found between the contents of acid-soluble iron and chlorophyll. For total iron this positive correlation was confined to the lower concentration range (50-90 ÎĽg Feig dry weight). The highest and lowest contents of total iron and of acid-soluble iron were found in the youngest leaves and in the leaves with the largest growth rate, respectively. This demonstrates 'dilution' and 'concentration' effects of iron in the leaf dry matter. Therefore, particular care is necessary in leaf sampling as a basis for causal interpretations of iron chlorosis.The results of the present study indicate that the lower uptake and translocation rates of iron rather than the 'inactivation' of iron within the shoots are responsible for chloros is at the various locations
Triangular mass matrices of quarks and Cabibbo-Kobayashi-Maskawa mixing
Every nonsingular fermion mass matrix, by an appropriate unitary
transformation of right-chiral fields, is equivalent to a triangular matrix.
Using the freedom in choosing bases of right-chiral fields in the minimal
standard model, reduction to triangular form reduces the well-known ambiguities
in reconstructing a mass matrix to trivial phase redefinitions. Furthermore,
diagonalization of the quark mass sectors can be shifted to one charge sector
only, without loosing the concise and economic triangular form. The
corresponding effective triangular mass matrix is reconstructed, up to trivial
phases, from the moduli of the CKM matrix elements, and vice versa, in a unique
way. A new formula for the parametrization independent CP-measure in terms of
observables is derived and discussed.Comment: 13 pages, Late
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