Historical and contemporary population genetics of the invasive western corn rootworm (Coleoptera: Chrysomelidae) in Croatia

Classical population genetic analyses were used to investigate populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, in Croatia in 1996 and 2009. The number of alleles was low in both 1996 and 2009; however, more alleles were found in the putative populations surveyed in 2009. Croatia had only 51% of the alleles recorded from the United States and 69% from Europe. However, 10 private (unique) alleles were found in Croatia, which were not found previously in Europe. Most populations were out of Hardy—Weinberg equilibrium, although no linkage disequilibrium was found. Low to no genetic differentiation was found between population pairwise comparisons in 1996, with a greater level of differentiation found between populations sampled in 2009. Using the program STRUCTURE, a single genetic cluster was found for populations sampled in 1996 and 2009. However, two genetic clusters were detected when the 1996 and 2009 data were combined, indicating significant temporal differentiation. Isolation by distance pattern of gene flow characterized populations sampled in 2009 only when the most distant population of Ogulin (the head of the expansion front) was included in the analysis. When Ogluin was excluded from the 2009 analysis no isolation by distance pattern was found. The possible impact that control practices have had on the population genetics of D. v. virgifera in Croatia from 1996 to 2009 are discussed in light of the temporal genetics differences found

Finite element analysis of vertically loaded cylindrical Ti implants

The following study was conducted in order to evaluate the effects of height, width and design variations on the stress distribution of vertically loaded, cylindrical titanium implants using finite element analysis (FEA). Three groups of cylindrical titanium TPS surface implants (Premium, Sweden & Martina, Italy) inserted into mandible segments were analysed. The three Premium implants in the first group were of different length (10.0, 11.5 and 13.0 mm) but possessed the same diameter of 3.80 mm. The second group consisted of three Premium implants with the same length of 11.5 mm but with different diameters (3.30, 3.80 and 4.25 mm). In the last group two different implant designs were compared, one featuring platform switching and a straight emergence profile and the other without platform switching. Overall, eight implant-bone samples were analyzed and the resulting stress distributions during vertical loading were obtained. For all eight samples, maximum stress values were found in the area of the implant neck and the stress values decreased in the apical direction. The higher stress values in the second group were detected in the implant with smaller diameter. It was noted that the implant with platform switching experienced lower stresses than the one without platform switching. Changes in length did not have any significant effect on the stress distribution. Under a vertical occlusal load, an implant with a larger diameter and with platform switching had the most favorable stress distribution throughout the implant structure and the adjacent bone tissue

Ecomorphological variation of the wireworm cephalic capsule: Studying the interaction of environment and geometric shape.

Studying the association between organismal morphology and environmental conditions has been very useful to test hypothesis regarding the influence of climate on shape. It has been long recognized that different environments produce dissimilar stress levels in insects, which can be reflected on the ability of an individual to overcome these pressures and spread further. Agriotes (Coleoptera: Elateridae) species infest agricultural fields in different parts of Croatia, inhabiting different climatic conditions. Previous biological studies have indicated that there is a relationship between some Agriotes biological parameters such as density and climatic conditions such as soil moisture and temperature. However, it is still unknown how these environmental properties influence the wireworm morphological structure. This is highly relevant because the head of this species is directly involved in the mobility in the soil, thus affecting the invasive capacity of this insect. Therefore the aim of this study was to assess the association between different climatic conditions and the morphological variation of Agriotes cephalic capsule. Advanced multivariate analysis and geometric morphometric tool were applied to study the covariation between shape and environmental variables. Partial Least Squares methods were used in order to analyse the association between the wireworm head shape and three different climatic conditions: soil type, temperature and rainfall. Our results showed that there is a high covariation between the wireworm head shape and the climatic conditions. It was suggested that the observed shape-environment association could be result of the high plasticity of this species in relation to its invasive capacity